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Sample records for suzuki coupling reactions

  1. Nanocatalysts for Suzuki cross-coupling reactions

    KAUST Repository

    Fihri, Aziz; Bouhrara, Mohamed; Nekoueishahraki, Bijan; Basset, Jean-Marie; Polshettiwar, Vivek

    2011-01-01

    This critical review deals with the applications of nanocatalysts in Suzuki coupling reactions, a field that has attracted immense interest in the chemical, materials and industrial communities. We intend to present a broad overview of nanocatalysts

  2. Nanocatalysts for Suzuki cross-coupling reactions

    KAUST Repository

    Fihri, Aziz

    2011-01-01

    This critical review deals with the applications of nanocatalysts in Suzuki coupling reactions, a field that has attracted immense interest in the chemical, materials and industrial communities. We intend to present a broad overview of nanocatalysts for Suzuki coupling reactions with an emphasis on their performance, stability and reusability. We begin the review with a discussion on the importance of Suzuki cross-coupling reactions, and we then discuss fundamental aspects of nanocatalysis, such as the effects of catalyst size and shape. Next, we turn to the core focus of this review: the synthesis, advantages and disadvantages of nanocatalysts for Suzuki coupling reactions. We begin with various nanocatalysts that are based on conventional supports, such as high surface silica, carbon nanotubes, polymers, metal oxides and double hydroxides. Thereafter, we reviewed nanocatalysts based on non-conventional supports, such as dendrimers, cyclodextrin and magnetic nanomaterials. Finally, we discuss nanocatalyst systems that are based on non-conventional media, i.e., fluorous media and ionic liquids, for use in Suzuki reactions. At the end of this review, we summarise the significance of nanocatalysts, their impacts on conventional catalysis and perspectives for further developments of Suzuki cross-coupling reactions (131 references). © 2011 The Royal Society of Chemistry.

  3. Suzuki-Miyaura cross-coupling reactions in aqueous media: Green and sustainable syntheses of biaryls

    KAUST Repository

    Polshettiwar, Vivek; Decottignies, Audrey; Len, Christophe; Fihri, Aziz

    2010-01-01

    Carbon-carbon cross-coupling reactions are among the most important processes in organic chemistry, and Suzuki-Miyaura reactions are among the most widely used protocols for the formation of carbon-carbon bonds. These reactions are generally

  4. Palladium supported on natural phosphate: Catalyst for Suzuki coupling reactions in water

    KAUST Repository

    Hassine, Ayoub

    2013-01-01

    The Suzuki-Miyaura coupling reaction is one of the most important synthetic catalytic reactions developed in the 20th century. However, the use of toxic organic solvents for this reaction still poses a scientific challenge and is an aspect of economical and ecological relevance. The use of water as a reaction medium overcomes this issue. In the present work, we described efficient Suzuki coupling reactions in water, without any phase transfer reagents and it is possible to couple challenging substrates like aryl chlorides. Notably, this protocol also works with ultra-low loading of catalyst with high turnover numbers. © 2012 Elsevier B.V.

  5. Suzuki-Miyaura cross-coupling reactions in aqueous media: Green and sustainable syntheses of biaryls

    KAUST Repository

    Polshettiwar, Vivek

    2010-02-28

    Carbon-carbon cross-coupling reactions are among the most important processes in organic chemistry, and Suzuki-Miyaura reactions are among the most widely used protocols for the formation of carbon-carbon bonds. These reactions are generally catalyzed by soluble palladium complexes with various ligands. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance. This Review will summarize various recently developed significant methods by which the Suzuki-Miyaura coupling was conducted in aqueous media, and analyzes if they are "real green" protocols. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Suzuki-Miyaura cross-coupling reactions in aqueous media: green and sustainable syntheses of biaryls.

    Science.gov (United States)

    Polshettiwar, Vivek; Decottignies, Audrey; Len, Christophe; Fihri, Aziz

    2010-05-25

    Carbon-carbon cross-coupling reactions are among the most important processes in organic chemistry, and Suzuki-Miyaura reactions are among the most widely used protocols for the formation of carbon-carbon bonds. These reactions are generally catalyzed by soluble palladium complexes with various ligands. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance. This Review will summarize various recently developed significant methods by which the Suzuki-Miyaura coupling was conducted in aqueous media, and analyzes if they are "real green" protocols.

  7. Microwave-Assisted Synthesis of 5-Phenyl-2-Hydroxyacetophenone Derivatives by a Green Suzuki Coupling Reaction

    Science.gov (United States)

    Soares, Pedro; Fernandes, Carlos; Chavarria, Daniel; Borges, Fernanda

    2015-01-01

    In recent years, the use of boron-containing reagents in palladium-assisted C-C coupling reactions (the Suzuki reaction) has gained prominence due to the vast array of reagents commercially available. Consequently, the generation of carbon-carbon bonds, namely of functionalized biphenyl systems, is at present considered the backbone of organic…

  8. Discovering Green, Aqueous Suzuki Coupling Reactions: Synthesis of Ethyl (4-Phenylphenyl)Acetate, a Biaryl with Anti-Arthritic Potential

    Science.gov (United States)

    Costa, Nancy E.; Pelotte, Andrea L.; Simard, Joseph M.; Syvinski, Christopher A.; Deveau, Amy M.

    2012-01-01

    Suzuki couplings are powerful chemical reactions commonly employed in academic and industrial research settings to generate functionalized biaryls. We have developed and implemented a discovery-based, microscale experiment for the undergraduate organic chemistry laboratory that explores green Suzuki coupling using water as the primary solvent.…

  9. Suzuki-Miyaura cross-coupling coupling reactions with low catalyst loading: a green and sustainable protocol in pure water.

    Science.gov (United States)

    Fihri, Aziz; Luart, Denis; Len, Christophe; Solhy, Abderrahim; Chevrin, Carole; Polshettiwar, Vivek

    2011-04-07

    The Suzuki-Miyaura coupling reaction represents one of the most important synthetic transformations developed in the 20th century. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance, and benign water as a reaction medium was found to be highly effective to overcome some of these issues. In the present manuscript, we described Suzuki-Miyaura coupling reactions in neat water, without using any phase transfer reagent. Notably, this protocol also works with ultra-low loading of catalyst with high turnover numbers and also able to couple challenging substrates like aryl chlorides. © The Royal Society of Chemistry 2011

  10. Suzuki-Miyaura cross-coupling coupling reactions with low catalyst loading: A green and sustainable protocol in pure water

    KAUST Repository

    Fihri, Aziz; Luart, Denis; Len, Christophe; Solhy, Abderrahim; Chevrin, Carole; Polshettiwar, Vivek

    2011-01-01

    The Suzuki-Miyaura coupling reaction represents one of the most important synthetic transformations developed in the 20th century. However, the use of toxic organic solvents remains a scientific challenge and an aspect of economical and ecological relevance, and benign water as a reaction medium was found to be highly effective to overcome some of these issues. In the present manuscript, we described Suzuki-Miyaura coupling reactions in neat water, without using any phase transfer reagent. Notably, this protocol also works with ultra-low loading of catalyst with high turnover numbers and also able to couple challenging substrates like aryl chlorides. © 2011 The Royal Society of Chemistry.

  11. Highly Efficient Synthesis of 2-Aryl-3-methoxyacrylates via Suzuki-Miyaura Coupling Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyung Ho; Lee, Chun Ho; Song, Young Seob; Park, No Kyun; Kim, Bum Tae; Heo, Jung Nyoung [Korea Research Institute of Chemical Technology, Daejeon (Korea, Republic of)

    2006-02-15

    We have developed a highly efficient and convergent synthesis of 2-aryl-3-methoxyacrylates via the Suzuki-Miyaura coupling reaction of α-iodo-β-methoxy-acrylate with arylboronic acids. The biological activities of 2-aryl-3-methoxyacrylate derivatives will be reported in due course. The Suzuki-Miyaura coupling reaction provides a convenient access to the carbon-carbon bond formation with high efficiency. Recently, a number of 2-aryl-3-methoxy-acrylates served as a key scaffold for the development of biologically active pharmaceuticals and agrochemicals. Especially, the discovery of the naturally-occurring fungicides, such as strobilurin A and oudemansin A, possessing a β-methoxyacrylate moiety was immediately seized great attention by industrial research groups to open a new era of the strobilurin family including azoxy-strobin and picoxystrobin.

  12. The Suzuki-Miyaura Cross-Coupling Reaction of Halogenated Aminopyrazoles: Method Development, Scope, and Mechanism of Dehalogenation Side Reaction.

    Science.gov (United States)

    Jedinák, Lukáš; Zátopková, Renáta; Zemánková, Hana; Šustková, Alena; Cankař, Petr

    2017-01-06

    The efficient Suzuki-Miyaura cross-coupling reaction of halogenated aminopyrazoles and their amides or ureas with a range of aryl, heteroaryl, and styryl boronic acids or esters has been developed. The method allowed incorporation of problematic substrates: aminopyrazoles bearing protected or unprotected pyrazole NH, as well as the free amino or N-amide group. Direct comparison of the chloro, bromo, and iodopyrazoles in the Suzuki-Miyaura reaction revealed that Br and Cl derivatives were superior to iodopyrazoles, as a result of reduced propensity to dehalogenation. Moreover, the mechanism and factors affecting the undesired dehalogenation side reaction were revealed.

  13. Efficient Sonogashira and Suzuki-Miyaura coupling reaction ...

    Indian Academy of Sciences (India)

    with short reaction time and good-to-excellent product yield. Keywords. Electrochemistry .... We started optimization study with variety of solvents (table 1, entry 1–6) ... did not show any significant increase in product yield. (table 1, entries 8 and ...

  14. Fibrous nano-silica (KCC-1)-supported palladium catalyst: Suzuki coupling reactions under sustainable conditions

    KAUST Repository

    Fihri, Aziz; Cha, Dong Kyu; Bouhrara, Mohamed; Al Mana, Noor; Polshettiwar, Vivek

    2011-01-01

    Noble amines recycled: Fibrous high-surface-area nano-silica functionalized with aminopropyl groups and loaded with well-dispersed Pd nanoparticles is evaluated for the Suzuki coupling of aromatic halides. It is active for the reaction of a range of aryl bromides and iodides as well as chlorides with aryl boronic acids in good to excellent yields. The catalyst can be recovered and reused for a number of cycles with negligible loss in activity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Fibrous nano-silica (KCC-1)-supported palladium catalyst: Suzuki coupling reactions under sustainable conditions

    KAUST Repository

    Fihri, Aziz

    2011-11-15

    Noble amines recycled: Fibrous high-surface-area nano-silica functionalized with aminopropyl groups and loaded with well-dispersed Pd nanoparticles is evaluated for the Suzuki coupling of aromatic halides. It is active for the reaction of a range of aryl bromides and iodides as well as chlorides with aryl boronic acids in good to excellent yields. The catalyst can be recovered and reused for a number of cycles with negligible loss in activity. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Hexacationic Dendriphos ligands in the Pd-catalyzed Suzuki-Miyaura cross-coupling reaction: scope and mechanistic studies

    NARCIS (Netherlands)

    Snelders, D.J.M.; van Koten, G.; Klein Gebbink, R.J.M.

    2009-01-01

    The combination of Pd2dba3·CHCl3and hexacationic triarylphosphine-based Dendriphos ligands (1-3) leads to a highly active catalytic system in the Suzuki-Miyaura cross-coupling reaction. Under relatively mild reaction conditions, nonactivated aryl bromides and activated aryl chlorides can be coupled

  17. Palladium nanoparticles as catalysts for reduction of Cr(VI) and Suzuki coupling reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lilan; Guo, Yali; Iqbal, Anam; Li, Bo; Deng, Min; Gong, Deyan; Liu, Weisheng; Qin, Wenwu, E-mail: qinww@lzu.edu.cn [Lanzhou University, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province and State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering (China)

    2017-04-15

    Herein, six kinds of PdNPs (including icosahedron, sphere, spindle, cube, rod, and wire) were synthesized via simple methods. The catalytic activities were investigated by the reduction reaction of Cr(VI) and Suzuki coupling reaction. Chemically synthesized morphologies of the six catalysis were characterized by transmission electron microscopy, field emission scanning electron microscopy, and X-ray diffraction, etc. Pd icosahedron shows a better catalytic property than other PdNPs with a rate constants 0.42 min{sup −1} for the reduction of Cr(VI). Moreover, the electrocatalyst shows that Pd icosahedron possesses a bigger surface area of 8.56 m{sup 2}/g than other nanoparticles, which is attributed to the better catalyst. The Pd icosahedron possesses a better catalytic property, attributing to the abundant exposed {111} facets with high activity on Pd icosahedron. The catalytic activities are closely related to the surface area with the following order: icosahedrons ≥ sphere > rod > spindle > cube > wire. The Pd icosahedron catalyst represents a strong activity for Suzuki coupling reaction as well, outweighting is 80%. The results reveal that Pd icosahedron acts as an efficient catalyst compared to other PdNPs (wire, rod, sphere, spindle, and cube).

  18. Preparation of Pd-Diimine@SBA-15 and Its Catalytic Performance for the Suzuki Coupling Reaction

    Directory of Open Access Journals (Sweden)

    Jiahuan Yu

    2016-11-01

    Full Text Available A highly efficient and stable Pd-diimine@SBA-15 catalyst was successfully prepared by immobilizing Pd onto diimine-functionalized mesoporous silica SBA-15. With the help of diimine functional groups grafted onto the SBA-15, Pd could be anchored on a support with high dispersion. Pd-diimine@SBA-15 catalyst exhibited excellent catalytic performance for the Suzuki coupling reaction of electronically diverse aryl halides and phenylboronic acid under mild conditions with an ultralow amount of Pd (0.05 mol % Pd. When the catalyst amount was increased, it could catalyze the coupling reaction of chlorinated aromatics with phenylboronic acid. Compared with the catalytic performances of Pd/SBA-15 and Pd-diimine@SiO2 catalysts, the Pd-diimine@SBA-15 catalyst exhibited higher hydrothermal stability and could be repeatedly used four times without a significant decrease of its catalytic activity.

  19. The Introduction of High-Throughput Experimentation Methods for Suzuki-Miyaura Coupling Reactions in University Education

    Science.gov (United States)

    Hoogenboom, Richard; Meier, Michael A. R.; Schubert, Ulrich S.

    2005-01-01

    A laboratory project permits for the discussion of the reaction mechanism of the Suzuki-Miyaura coupling reaction. The practical part of the project makes the students familiar with working under inert atmosphere but if the appropriate equipment for working under inert atmosphere is not available in a laboratory, novel catalysts that do not…

  20. Dinuclear Tetrapyrazolyl Palladium Complexes Exhibiting Facile Tandem Transfer Hydrogenation/Suzuki Coupling Reaction of Fluoroarylketone

    KAUST Repository

    Dehury, Niranjan

    2016-07-18

    Herein, we report an unprecedented example of dinuclear pyrazolyl-based Pd complexes exhibiting facile tandem catalysis for fluoroarylketone: Tetrapyrazolyl di-palladium complexes with varying Pd-Pd distances efficiently catalyze the tandem reaction involving transfer hydrogenation of fluoroarylketone to the corresponding alcohol and Suzuki-Miyaura cross coupling reaction of the resulting fluoroarylalcohol under moderate reaction conditions, to biaryl alcohol. The complex with the shortest Pd-Pd distance exhibits the highest tandem activity among its di-metallic analogues, and exceeds in terms of activity and selectivity the analogous mononuclear compound. The kinetics of the reaction indicates clearly that reductive transformation of haloarylketone into haloaryalcohol is the rate determining step in the tandem reaction. Interestingly while fluoroarylketone undergoes the multistep tandem catalysis, the chloro- and bromo-arylketones undergo only a single step C-C coupling reaction resulting in biarylketone as the final product. Unlike the pyrazole based Pd compounds, the precursor PdCl2 and the phosphine based relevant complexes (PPh3)2PdCl2 and (PPh3)4Pd are found to be unable to exhibit the tandem catalysis.

  1. Practical, economical, and eco-friendly starch-supported palladium catalyst for Suzuki coupling reactions.

    Science.gov (United States)

    Baran, Talat

    2017-06-15

    In catalytic systems, the support materials need to be both eco friendly and low cost as well as having high thermal and chemical stability. In this paper, a novel starch supported palladium catalyst, which had these outstanding properties, was designed and its catalytic activity was evaluated in a Suzuki coupling reaction under microwave heating with solvent-free and mild reaction conditions. The starch supported catalyst gave remarkable reaction yields after only 5min as a result of the coupling reaction of the phenyl boronic acid with 23 different substrates, which are bearing aril bromide, iodide, and chloride. The longevity of the catalyst was also investigated, and the catalyst could be reused for 10 runs. The starch supported Pd(II) catalyst yielded remarkable TON (up to 25,000) and TOF (up to 312,500) values by using a simple, fast and eco-friendly method. In addition, the catalytic performance of the catalyst was tested against different commercial palladium catalysts, and the green starch supported catalyst had excellent selectivity. The catalytic tests showed that the novel starch based palladium catalyst proved to be an economical and practical catalyst for the synthesis of biaryl compounds. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. A convergent approach to the total synthesis of telmisartan via a Suzuki cross-coupling reaction between two functionalized benzimidazoles.

    Science.gov (United States)

    Martin, Alex D; Siamaki, Ali R; Belecki, Katherine; Gupton, B Frank

    2015-02-06

    A direct and efficient total synthesis has been developed for telmisartan, a widely prescribed treatment for hypertension. This approach brings together two functionalized benzimidazoles using a high-yielding Suzuki reaction that can be catalyzed by either a homogeneous palladium source or graphene-supported palladium nanoparticles. The ability to perform the cross-coupling reaction was facilitated by the regio-controlled preparation of the 2-bromo-1-methylbenzimidazole precursor. This convergent approach provides telmisartan in an overall yield of 72% while circumventing many issues associated with previously reported processes.

  3. Ligand-Free Suzuki-Miyaura Coupling Reactions Using an Inexpensive Aqueous Palladium Source: A Synthetic and Computational Exercise for the Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Hill, Nicholas J.; Bowman, Matthew D.; Esselman, Brian J.; Byron, Stephen D.; Kreitinger, Jordan; Leadbeater, Nicholas E.

    2014-01-01

    An inexpensive procedure for introducing the Suzuki-Miyaura coupling reaction into a high-enrollment undergraduate organic chemistry laboratory course is described. The procedure employs an aqueous palladium solution as the catalyst and a range of para-substituted aryl bromides and arylboronic acids as substrates. The coupling reactions proceed…

  4. Miswak mediated green synthesized palladium nanoparticles as effective catalysts for the Suzuki coupling reactions in aqueous media

    Directory of Open Access Journals (Sweden)

    Mujeeb Khan

    2017-05-01

    Full Text Available Green and eco-friendly synthesis of palladium nanoparticles NPs is carried out under facile and eco-friendly conditions using an aqueous solution of Salvadora persica L. (SP root extract (RE as a bioreductant, which is commonly known as Miswak. The as-synthesized Pd NPs were characterized using various spectroscopic and microscopic techniques, including, UV–Vis spectroscopy, FT-IR spectroscopy, XRD, ICP-MS and TEM. Detailed investigations of the Pd NPs have confirmed that the polyphenolic phytomolecules present in the RE of Miswak not only act as a bioreductant by facilitating the reduction and growth of Pd NPs, but they also functionalize the surface of Pd NPs and stabilized them in various solvents. Furthermore, the catalytic activity of the green synthesized Pd NPs was also tested toward the Suzuki coupling reactions of various aryl halides in aqueous media. The as-prepared Pd NPs exhibited superior catalytic activity and reusability for the Suzuki coupling reaction in aqueous and aerobic conditions. The kinetics of the reaction studied by GC revealed that the conversion of various aryl halides to biphenyl takes place in a short time.

  5. Synthesis and Suzuki Cross-Coupling Reactions of 2,6-Bis(trifluoromethyl)pyridine-4-boronic Acid Pinacol Ester

    KAUST Repository

    Batool, Farhat

    2016-11-18

    Iridium-catalyzed aromatic borylation provides quick one-step access to 2,6-bis(trifluoromethyl)pyridine-4-boronic acid pinacol ester. Suzuki couplings of this highly electron-deficient pyridine-4-boronic ester with various (hetero)aryl bromides was successfully carried out and the coupled products were obtained in 46–95% isolated yields. Double and triple Suzuki couplings, with dibromo- and tribromoarenes, respectively, were also achieved. Thus demonstrating that this pyridine-4-boronic ester can be a useful source for the installation of one of the strongest electron-withdrawing aromatic group in organic compounds. Copyright © 2016, Georg Thieme Verlag. All rights reserved.

  6. Synthesis and Suzuki Cross-Coupling Reactions of 2,6-Bis(trifluoromethyl)pyridine-4-boronic Acid Pinacol Ester

    KAUST Repository

    Batool, Farhat; Emwas, Abdul-Hamid M.; Gao, Xin; Munawar, Munawar A.; Chotana, Ghayoor A.

    2016-01-01

    Iridium-catalyzed aromatic borylation provides quick one-step access to 2,6-bis(trifluoromethyl)pyridine-4-boronic acid pinacol ester. Suzuki couplings of this highly electron-deficient pyridine-4-boronic ester with various (hetero)aryl bromides was successfully carried out and the coupled products were obtained in 46–95% isolated yields. Double and triple Suzuki couplings, with dibromo- and tribromoarenes, respectively, were also achieved. Thus demonstrating that this pyridine-4-boronic ester can be a useful source for the installation of one of the strongest electron-withdrawing aromatic group in organic compounds. Copyright © 2016, Georg Thieme Verlag. All rights reserved.

  7. QuadraPure-Supported Palladium Nanocatalysts for Microwave-Promoted Suzuki Cross-Coupling Reaction under Aerobic Condition

    Directory of Open Access Journals (Sweden)

    Kin Hong Liew

    2014-01-01

    Full Text Available Cross-linked resin-captured palladium (XL-QPPd was readily prepared by simple physical adsorption onto the high loading QuadraPure macroporous resin and a subsequent reduction process. To enhance the mechanical stability, entrapped palladium nanocatalysts were cross-linked with succinyl chloride. Both transmission electron microscopy images and X-ray diffraction analysis revealed that the palladium nanoparticles were well dispersed with diameters ranging in 4–10 nm. The catalyst performed good catalytic activity in microwave-promoted Suzuki cross-coupling reactions in water under aerobic condition with mild condition by using various aryl halides and phenylboronic acid. In addition, the catalyst showed an excellent recyclability without significant loss of catalytic activity.

  8. Palladium on Carbon-Catalyzed Suzuki-Miyaura Coupling Reaction Using an Efficient and Continuous Flow System

    Directory of Open Access Journals (Sweden)

    Tomohiro Hattori

    2015-01-01

    Full Text Available The continuous flow Suzuki-Miyaura reaction between various haloarenes and arylboronic acids was successfully achieved within only ca. 20 s during the single-pass through a cartridge filled with palladium on carbon (Pd/C. No palladium leaching was observed in the collected reaction solution by atomic absorption spectrometry (detection limit: 1 ppm.

  9. Aqueous-phase Suzuki-Miyaura cross-coupling reactions of free halopurine bases

    Czech Academy of Sciences Publication Activity Database

    Čapek, Petr; Vrábel, Milan; Hasník, Zbyněk; Pohl, Radek; Hocek, Michal

    -, č. 20 (2006), s. 3515-3526 ISSN 0039-7881 R&D Projects: GA ČR(CZ) GA203/05/0043 Institutional research plan: CEZ:AV0Z40550506 Keywords : purines * cross-coupling * reactions Subject RIV: CC - Organic Chemistry Impact factor: 2.333, year: 2006

  10. Suzuki coupling reactions catalyzed by poly(N-ethyl-4-vinylpyridinium bromide stabilized palladium nanoparticles in aqueous solution

    Directory of Open Access Journals (Sweden)

    2008-04-01

    Full Text Available InIn this work, it was investigated to use of poly(N-ethyl-4-vinylpyridinium bromide stabilized palladium nanoparticles in the Suzuki reaction between phenylboronic acid and aryl halides in aqueous solution. The nanoparticles were isolated and re-used several times with low loss of activity.

  11. Palladium-catalyzed domino C,N-coupling/carbonylation/Suzuki coupling reaction: an efficient synthesis of 2-aroyl-/heteroaroylindoles.

    Science.gov (United States)

    Arthuis, Martin; Pontikis, Renée; Florent, Jean-Claude

    2009-10-15

    A convenient one-pot synthesis of 2-aroylindoles using a domino palladium-catalyzed C,N-coupling/carbonylation/C,C-coupling sequence is described. The reaction involved easily prepared 2-gem-dibromovinylanilines and boronic acids under carbon monoxide. Optimized reaction conditions allowed the construction of a wide variety of highly functionalized 2-aroyl-/heteroaroylindoles in satisfactory yields.

  12. Dinuclear Tetrapyrazolyl Palladium Complexes Exhibiting Facile Tandem Transfer Hydrogenation/Suzuki Coupling Reaction of Fluoroarylketone

    KAUST Repository

    Dehury, Niranjan; Maity, Niladri; Tripathy, Suman Kumar; Basset, Jean-Marie; Patra, Srikanta

    2016-01-01

    Herein, we report an unprecedented example of dinuclear pyrazolyl-based Pd complexes exhibiting facile tandem catalysis for fluoroarylketone: Tetrapyrazolyl di-palladium complexes with varying Pd-Pd distances efficiently catalyze the tandem reaction

  13. Pd-isatin Schiff base complex immobilized onγ-Fe2O3 as a magnetically recyclable catalyst for the Heck and Suzuki cross-coupling reactions

    Institute of Scientific and Technical Information of China (English)

    Sara Sobhani; Farzaneh Zarifi

    2015-01-01

    A Pd‐isatin Schiff base complex immobilized onγ‐Fe2O3 (Pd‐isatin Schiff base‐γ‐Fe2O3) was synthe‐sized and characterized by Fourier transform infrared, scanning electron microscopy, high resolu‐tion transmission electron microscopy, X‐ray diffraction, thermogravimetric gravimetric analysis, inductively‐coupled plasma, X‐ray photoelectron spectroscopy, and elemental analysis. It was used as a magnetically reusable Pd catalyst for the Heck and Suzuki cross‐coupling reactions.

  14. and Suzuki coupling reactions

    Indian Academy of Sciences (India)

    e-mail: aksingh@chemistry.iitd.ac.in. Abstract. ... chalcogen. These results are presented in this paper. 2. Experimental ... All the sol- vents were dried and distilled before use by well-known ... The precipitate was filtered, washed with cold ...

  15. Concise synthesis of the hasubanan alkaloid (±)-cepharatine A using a Suzuki coupling reaction to effect o,p-phenolic coupling.

    Science.gov (United States)

    Magnus, Philip; Seipp, Charles

    2013-09-20

    Suzuki coupling of 10 and 11 resulted in 9, which was O-alkylated to provide 12. Treatment of 12 with CsF in DMF resulted in the formation of the completed core structure 13 in a single step. Reductive amination of 13 completed the synthesis of (±)-cepharatine A, 4.

  16. Pd-bound functionalized mesoporous silica as active catalyst for Suzuki coupling reaction: Effect of OAcˉ, PPh3 and Clˉ ligands on catalytic activity

    Science.gov (United States)

    Das, Trisha; Uyama, Hiroshi; Nandi, Mahasweta

    2018-04-01

    Three new palladium catalysts, PdCat-I, PdCat-II and PdCat-III, immobilized over heterogeneous silica support have been synthesized using different ligands attached to the palladium precursor. The ligands that have been used in this study are acetate, triphenylphosphine and chloride in PdCat-I, PdCat-II and PdCat-III, respectively. The ligands have different effect on stability of the compounds and impart different oxidation states to the metal center. The materials have been characterized by powder X-ray diffraction, nitrogen adsorption-desorption studies, transmission electron microscopy, thermal analysis, and different spectroscopic techniques. The Pd-content of the samples have been determined by ICP-AES analysis. The materials have been used as catalysts for Suzuki coupling reaction of aryl halides with phenylboronic acid under mild conditions. A comparative study has been carried out to ascertain the effect of the nature of different ligands on the outcome of the catalytic reactions. Products have been identified and estimated by 1H NMR and gas chromatography. The results show that the best yields are obtained with the catalyst containing triphenylphosphine as the ligand in methanol. Such type of work to study the effect of ligand on Suzuki coupling reaction over functionalized mesoporous silica heterogeneous catalysts have not been carried out so far.

  17. Palladium Nanoparticles Immobilized on Poly(vinyl chloride-Supported Pyridinium as an Efficient and Recyclable Catalyst for Suzuki-Miyaura Cross-Coupling Reaction

    Directory of Open Access Journals (Sweden)

    Bo Zhou

    2011-01-01

    Full Text Available The palladium nanoparticles immobilized on the polymeric surface of poly(vinyl chloride-supported pyridinium (PVC-Py-Pd0 were achieved by a simple procedure by applying the corresponding functionalized polymer and palladium chloride in ethanol solution. The as-prepared catalyst (PVC-Py-Pd0 was found to be air and moisture stable and exhibits significant catalytic activity for Suzuki-Miyaura cross-coupling reaction of various aryl halides and phenylboronic acid under milder operating conditions. The procedure presented here showed several merits such as short reaction time, simple experimental and isolated procedure and excellent yields of products. Furthermore, the catalyst can be easily recovered and reused for at least six times with consistent activities.

  18. Synthesis and conformational analysis of new arylated-diphenylurea derivatives related to sorafenib drug via Suzuki-Miyaura cross-coupling reaction

    Science.gov (United States)

    Al-Masoudi, Najim A.; Essa, Ali Hashem; Alwaaly, Ahmed A. S.; Saeed, Bahjat A.; Langer, Peter

    2017-10-01

    Sorafenib, is a relatively new cytostatic drug approved for the treatment of renal cell and hepatocellular carcinoma. The development of new sorafenib analogues offers the possibility of generating structures of increased potency. To this end, a series of arylated-diphenylurea analogues 17-31 were synthesized via Suzuki-Miyaura coupling reaction, related to sorafenib by treatment of three diarylureas 2-4 having 3-bromo, 4-chloro and 2-iodo groups with various arylboronic acids. Conformational analysis of the new arylated urea analogues has been investigated using MOPAC 2016 of semi empirical PM7 Hamiltonian computational method. Our results showed that all compounds preferred the trans-trans conformations. Compound 17 has been selected to calculate the torsional energy profiles for rotation around the urea bonds and found to be existed predominantly in the trans-trans conformation with only very minimal fluctuation in conformation.

  19. Pd-catalyzed Suzuki-Miyaura coupling reaction in the synthesis of 5-aryl-1-[2-(phosphonomethoxy)ethyl]uracils as potential multisubstrate inhibitors of thymidine phosphorylase

    Czech Academy of Sciences Publication Activity Database

    Pomeisl, Karel; Holý, Antonín; Pohl, Radek

    2007-01-01

    Roč. 48, č. 17 (2007), s. 3065-3067 ISSN 0040-4039 R&D Projects: GA MŠk 1M0508 Grant - others:Descartes Prize(XE) HPAW-CT-2002-9001 Institutional research plan: CEZ:AV0Z40550506 Keywords : acyclic nucleoside phosphonates * thymidine phosphorylase * Suzuki coupling * pyrimidine Subject RIV: CC - Organic Chemistry Impact factor: 2.615, year: 2007

  20. Introducing Undergraduates to Research Using a Suzuki-Miyaura Cross-Coupling Organic Chemistry Miniproject

    Science.gov (United States)

    Oliveira, Deyvid G. M.; Rosa, Clarissa H.; Vargas, Bruna P.; Rosa, Diego S.; Silveira, Ma´rcia V.; de Moura, Neusa F.; Rosa, Gilber R.

    2015-01-01

    A five-week miniproject is described for an upper-division experimental organic chemistry course. The activities include synthesis of a phenylboronic acid via a Grignard reaction and its use in a Suzuki-Miyaura cross-coupling reaction. Technical skills and concepts normally presented in practical organic chemistry courses are covered, including…

  1. Elucidation of the structure-property relationship of p-type organic semiconductors through rapid library construction via a one-pot, Suzuki-Miyaura coupling reaction.

    Science.gov (United States)

    Fuse, Shinichiro; Matsumura, Keisuke; Wakamiya, Atsushi; Masui, Hisashi; Tanaka, Hiroshi; Yoshikawa, Susumu; Takahashi, Takashi

    2014-09-08

    The elucidation of the structure-property relationship is an important issue in the development of organic electronics. Combinatorial synthesis and the evaluation of systematically modified compounds is a powerful tool in the work of elucidating structure-property relationships. In this manuscript, D-π-A structure, 32 p-type organic semiconductors were rapidly synthesized via a one-pot, Suzuki-Miyaura coupling with subsequent Knoevenagel condensation. Evaluation of the solubility and photovoltaic properties of the prepared compounds revealed that the measured solubility was strongly correlated with the solubility parameter (SP), as reported by Fedors. In addition, the SPs were correlated with the Jsc of thin-film organic solar cells prepared using synthesized compounds. Among the evaluated photovoltaic properties of the solar cells, Jsc and Voc had strong correlations with the photoconversion efficiency (PCE).

  2. Ruphus-mediated Suzuki cross-coupling of secondary alkyl trifluoroborates

    NARCIS (Netherlands)

    Hoogenband, van den A.; Lange, J.H.M.; Terpstra, J.W.; Koch, M.; Visser, G.M.; Visser, de M.; Korstanje, T.J.; Jastrzebski, J.T.B.H.

    2008-01-01

    A Ruphos-mediated Suzuki cross-coupling between (hetero)aryl bromides and secondary alkyltrifluoroborates is described using palladium catalysis. The Ruphos ligand showed superior properties as compared to S-Phos in this type of reaction. This method constitutes a valuable extension to current

  3. Microwave-Assisted Synthesis of a MK2 Inhibitor by Suzuki-Miyaura Coupling for Study in Werner Syndrome Cells

    Directory of Open Access Journals (Sweden)

    Mark C. Bagley

    2015-06-01

    Full Text Available Microwave-assisted Suzuki-Miyaura cross-coupling reactions have been employed towards the synthesis of three different MAPKAPK2 (MK2 inhibitors to study accelerated aging in Werner syndrome (WS cells, including the cross-coupling of a 2-chloroquinoline with a 3-pyridinylboronic acid, the coupling of an aryl bromide with an indolylboronic acid and the reaction of a 3-amino-4-bromopyrazole with 4-carbamoylphenylboronic acid. In all of these processes, the Suzuki-Miyaura reaction was fast and relatively efficient using a palladium catalyst under microwave irradiation. The process was incorporated into a rapid 3-step microwave-assisted method for the synthesis of a MK2 inhibitor involving 3-aminopyrazole formation, pyrazole C-4 bromination using N-bromosuccinimide (NBS, and Suzuki-Miyaura cross-coupling of the pyrazolyl bromide with 4-carbamoylphenylboronic acid to give the target 4-arylpyrazole in 35% overall yield, suitable for study in WS cells.

  4. Natural phosphate-supported palladium: A highly efficient and recyclable catalyst for the suzuki-miyaura coupling under microwave irradiation

    KAUST Repository

    Hassine, Ayoub; Bouhrara, Mohamed; Sebti, Said; Solhy, Abderrahim; Mahfouz, Remi; Luart, Denis; Lene, Christophe; Fihri, Aziz

    2015-01-01

    This report explores Suzuki-Miyaura coupling under microwave irradiation, using a new generation of catalyst that is based on natural phosphate (NP) impregnated by palladium. This catalyst was prepared by the treatment of natural phosphate with bis(benzonitrile)palladium(II) chloride in acetone at room temperature. The catalyst displayed high catalytic activity for the Suzuki-Miyaura coupling of aryl bromides and chlorides with aryl boronic acids in pure water and with the use of microwave irradiation. The low-cost and availability of the solid support, mild reaction conditions, high yields of desired products, recyclability of the catalyst and short reaction times are the notable features of these methods.

  5. Natural phosphate-supported palladium: A highly efficient and recyclable catalyst for the suzuki-miyaura coupling under microwave irradiation

    KAUST Repository

    Hassine, Ayoub

    2015-01-19

    This report explores Suzuki-Miyaura coupling under microwave irradiation, using a new generation of catalyst that is based on natural phosphate (NP) impregnated by palladium. This catalyst was prepared by the treatment of natural phosphate with bis(benzonitrile)palladium(II) chloride in acetone at room temperature. The catalyst displayed high catalytic activity for the Suzuki-Miyaura coupling of aryl bromides and chlorides with aryl boronic acids in pure water and with the use of microwave irradiation. The low-cost and availability of the solid support, mild reaction conditions, high yields of desired products, recyclability of the catalyst and short reaction times are the notable features of these methods.

  6. Synthesis of Fluorescent 2-Substituted 6-(Het)aryl-7-deazapurine Bases {4-(Het)aryl-pyrrolo[2,3-d]pyrimidines} by Aqueous Suzuki-Miyaura Cross-Coupling Reactions

    Czech Academy of Sciences Publication Activity Database

    Sabat, Nazarii; Nauš, Petr; Matyašovský, Ján; Dziuba, Dmytro; Poštová Slavětínská, Lenka; Hocek, Michal

    2016-01-01

    Roč. 48, č. 7 (2016), s. 1029-1045 ISSN 0039-7881 R&D Projects: GA ČR GAP207/11/0344 Institutional support: RVO:61388963 Keywords : nucleobases * deazapurines * pyrrolo[2,3-d]pyrimidines * Suzuki cross - coupling * arylation Subject RIV: CC - Organic Chemistry Impact factor: 2.650, year: 2016

  7. Supported palladium nanoparticles synthesized by living plants as a catalyst for Suzuki-Miyaura reactions.

    Directory of Open Access Journals (Sweden)

    Helen L Parker

    Full Text Available The metal accumulating ability of plants has previously been used to capture metal contaminants from the environment; however, the full potential of this process is yet to be realized. Herein, the first use of living plants to recover palladium and produce catalytically active palladium nanoparticles is reported. This process eliminates the necessity for nanoparticle extraction from the plant and reduces the number of production steps compared to traditional catalyst palladium on carbon. These heterogeneous plant catalysts have demonstrated high catalytic activity in Suzuki coupling reactions between phenylboronic acid and a range of aryl halides containing iodo-, bromo- and chloro- moieties.

  8. An efficient protocol for the palladium-catalysed Suzuki-Miyaura cross-coupling

    KAUST Repository

    Marziale, Alexander N.; Jantke, Dominik; Faul, Stefan Holger; Reiner, Thomas; Herdtweck, Eberhardt; Eppinger, Jö rg

    2011-01-01

    The palladacyclic catalyst precursor received by ortho-palladation of ([1,1′-biphenyl]-2-yloxy)diisopropyl-phosphine represents a highly active system for Suzuki-Miyaura cross-coupling reactions when used in neat water. An efficient, broadly applicable and sustainable aqueous protocol was developed using 2.5 eq. of Na2CO3 as base, allowing the reaction to be performed under air and at ambient temperature with Pd loadings of 0.04 mol%. Coupling products are obtained in high yields and excellent purity by simple filtration with no organic solvents needed throughout the whole reaction. A broad variety of functional groups are tolerated and a large number of substrates can be applied with this protocol. The crystal structure of the palladacyclic catalyst precursor is presented as well as investigations targeting the nature of catalyst activation and the active catalytic species. © 2011 The Royal Society of Chemistry.

  9. Catalysis in the Service of Green Chemistry: Nobel Prize-Winning Palladium-Catalysed Cross-Couplings, Run in Water at Room Temperature: Heck, Suzuki-Miyaura and Negishi reactions carried out in the absence of organic solvents, enabled by micellar catalysis.

    Science.gov (United States)

    Lipshutz, Bruce H; Taft, Benjamin R; Abela, Alexander R; Ghorai, Subir; Krasovskiy, Arkady; Duplais, Christophe

    2012-04-01

    Palladium-catalysed cross-couplings, in particular Heck, Suzuki-Miyaura and Negishi reactions developed over three decades ago, are routinely carried out in organic solvents. However, alternative media are currently of considerable interest given an increasing emphasis on making organic processes 'greener'; for example, by minimising organic waste in the form of organic solvents. Water is the obvious leading candidate in this regard. Hence, this review focuses on the application of micellar catalysis, in which a 'designer' surfactant enables these award-winning coupling reactions to be run in water at room temperature.

  10. Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling in a Green Alcohol Solvent for an Undergraduate Organic Chemistry Laboratory

    Science.gov (United States)

    Hie, Liana; Chang, Jonah J.; Garg, Neil K.

    2015-01-01

    A modern undergraduate organic chemistry laboratory experiment involving the Suzuki-Miyaura coupling is reported. Although Suzuki-Miyaura couplings typically employ palladium catalysts in environmentally harmful solvents, this experiment features the use of inexpensive nickel catalysis, in addition to a "green" alcohol solvent. The…

  11. N-BUTYL SUBSTITUTED N-HETEROCYCLIC CARBENE-PD(II-PYRIDINE (PEPPSI COMPLEXES: SYNTHESIS, CHARACTERIZATION AND CATALYTIC ACTIVITY IN THE SUZUKI-MIYAURA REACTION

    Directory of Open Access Journals (Sweden)

    Rukiye Fırıncı

    2016-08-01

    Full Text Available A series of N-butyl substituted imidazolium salts, (1a-c and their pyridine enhanced precatalyst preparation stabilization and initiation (PEPPSI themed palladium N-heterocyclic carbene complexes (2a-c were synthesized and characterized. Pd-NHC complexes were fully determined by elemental analysis and spectroscopic. The synthesized complexes were tested in Suzuki-Miyaura cross-coupling reaction. These complexes were found to be efficient catalysts for the Suzuki-Miyaura reaction of phenylboronic acid with aryl bromides.

  12. Aziridine- and Azetidine-Pd Catalytic Combinations. Synthesis and Evaluation of the Ligand Ring Size Impact on Suzuki-Miyaura Reaction Issues

    Directory of Open Access Journals (Sweden)

    Hamza Boufroura

    2017-01-01

    Full Text Available The synthesis of new vicinal diamines based on aziridine and azetidine cores as well as the comparison of their catalytic activities as ligand in the Suzuki-Miyaura coupling reaction are described in this communication. The synthesis of three- and four-membered ring heterocycles substituted by a methylamine pendant arm is detailed from the parent nitrile derivatives. Complexation to palladium under various conditions has been examined affording vicinal diamines or amine-imidate complexes. The efficiency of four new catalytic systems is compared in the preparation of variously substituted biaryls. Aziridine- and azetidine-based catalytic systems allowed Suzuki-Miyaura reactions from aryl halides including chlorides with catalytic loadings until 0.001% at temperatures ranging from 100 °C to r.t. The evolution of the Pd-metallacycle ring strain moving from azetidine to aziridine in combination with a methylamine or an imidate pendant arm impacted the Suzuki-Miyaura reaction issue.

  13. Palladium Loaded on Magnetic Nanoparticles as Efficient and Recyclable Catalyst for the Suzuki- Miyaura Reaction

    Directory of Open Access Journals (Sweden)

    H. Khojasteh

    2015-07-01

    Full Text Available Palladium is the best metal catalyst for Suzuki cross coupling reaction for synthesize of unsymmetrical biaryl compounds. But its high cost limits its application in wide scale. Using of nanoscale particles as active catalytic cites is a good approach for reducing needed noble metal. By loading precious nanoparticles on magnetic nanocores as a support, recycling and reusing of catalyst will be possible. Magnetic nanoparticles have super paramagnetic feature and applying an external magnetic field can collect the supported catalyst from reaction milieu simply. In this work new palladium catalyst immobilized on modified magnetic nanoparticles containing NNO donor atoms were synthesized. Then the catalyst characterized by FT-IR spectroscopy, thermogravimetric analysis, X-ray diffraction and ICP. Prepared catalyst showed high activity in the Suzuki– Miyaura cross-coupling reaction of phenylboronic acid with aryl halides. Activity, Pd loading, reusability and Pd leaching of catalyst were studied. Results showed that the supported catalyst has the advantage to be completely recoverable with the simple application of an external magnetic field.

  14. Facile palladium catalyzed Suzuki-Miyaura coupling in air and water at ambient temperature

    KAUST Repository

    Marziale, Alexander N.; Faul, Stefan Holger; Reiner, Thomas; Schneider, Sven; Eppinger, Jö rg

    2010-01-01

    A new palladacyclic catalyst yields high activities in aqueous Suzuki-Miyaura coupling at room temperature. Using an optimized protocol, a broad range of products can be isolated in good to excellent yields and high purity by simple filtration. © 2010 The Royal Society of Chemistry.

  15. 'Click' dendritic phosphines: design, synthesis, application in Suzuki coupling, and recycling by nanofiltration

    NARCIS (Netherlands)

    Janssen, M.C.C.; Vogt, D.; Müller, C.

    2009-01-01

    A new synthetic route towards stable molecular-weight enlarged monodentate phosphine ligands via click chemistry was developed. These ligands were applied in the Pd-catalyzed Suzuki-Miyaura coupling of aryl halides and phenyl boronic acid. The supported systems show very similar activities compared

  16. Synthesis of new pyrrole–pyridine-based ligands using an in situ Suzuki coupling method

    Directory of Open Access Journals (Sweden)

    Matthias Böttger

    2012-07-01

    Full Text Available The compounds 6-(pyrrol-2-yl-2,2‘-bipyridine, 2-(pyrrol-2-yl-1,10-phenanthroline and 2-(2-(N-methylbenz[d,e]imidazole-6-(pyrrol-2-yl-pyridine were synthesized by using an in situ generated boronic acid for the Suzuki coupling. Crystals of the products could be grown and exhibited interesting structures by X-ray analysis, one of them showing a chain-like network with the adjacent molecules linked to each other via intermolecular N–H…N hydrogen bonds.

  17. Insights into the catalytic activity of [Pd(NHC)(cin)Cl] (NHC = IPr, IPrCl, IPrBr) complexes in the Suzuki-Miyaura reaction

    KAUST Repository

    Nolan, Steven Patrick

    2017-09-06

    The influence of C4,5-halogenation on palladium N-heterocyclic carbene complexes and their activity in the Suzuki-Miyaura reaction have been investigated. Two [Pd(NHC)(cin)Cl] complexes bearing IPrCl and IPrBr ligands were synthesized. After determining electronic and steric properties of these ligands, their properties were compared to those of [Pd(IPr)(cin)Cl]. The three palladium complexes were studied using DFT calculations to delineate their behaviour in the activation step leading to the putative 12-electron active catalyst. Experimentally, their catalytic activity in the Suzuki-Miyaura reaction involving a wide range of coupling partners (30 entries) at low catalyst loading was studied.

  18. Studies on Pd/NiFe2O4 catalyzed ligand-free Suzuki reaction in aqueous phase: synthesis of biaryls, terphenyls and polyaryls

    Directory of Open Access Journals (Sweden)

    Suresh B. Waghmode

    2011-03-01

    Full Text Available Palladium supported on nickel ferrite (Pd/NiF2O4 was found to be a highly active catalyst for the Suzuki coupling reaction between various aryl halides and arylboronic acids. The reaction gave excellent yields (70–98% under ligand free conditions in a 1:1 DMF/H2O solvent mixture, in short reaction times (10–60 min. The catalyst could be recovered easily by applying an external magnetic field. The polyaryls were similarly synthesized.

  19. Ligandless Suzuki-Miyaura reaction in neat water with or without native β-cyclodextrin as additive

    KAUST Repository

    Decottignies, Audrey

    2013-02-01

    Efficient green ligand-free Suzuki cross coupling in neat water was developed by using low loading of catalyst (0.5 mol%) in neat water in the presence or not of β-cyclodextrin (0.5 mol%) as additive at 25 C and 100 C respectively. © 2012 Elsevier B.V.

  20. Directed ortho metalation-based methodology. Halo-, nitroso-, and boro-induced ipso-desilylation. Link to an in situ Suzuki reaction.

    Science.gov (United States)

    Zhao, Zhongdong; Snieckus, Victor

    2005-06-23

    [reaction: see text] Treatment of DoM-derived silylated aromatics 2-4 under standard electrophilic halogenation conditions cleanly affords ipso-desilyation products 5-7, while nitration of methoxy-substituted analogues 8, 9 leads to non-ipso isomers 10, 12 and 11, 13, controlled by a silicon steric effect. Sequential ipso-borodesilylation of 2a, 3a, and 20 followed by treatment with aryl halides under Pd-catalyzed conditions constitutes an in situ Suzuki-Miyaura cross-coupling protocol to biaryls and heterobiaryls 23.

  1. Plant Extract Mediated Eco-Friendly Synthesis of Pd@Graphene Nanocatalyst: An Efficient and Reusable Catalyst for the Suzuki-Miyaura Coupling

    Directory of Open Access Journals (Sweden)

    Mujeeb Khan

    2017-01-01

    Full Text Available Suzuki-Miyaura coupling reaction catalyzed by the palladium (Pd-based nanomaterials is one of the most versatile methods for the preparation of biaryls. However, use of organic solvents as reaction medium causes a big threat to environment due to the generation of toxic byproducts as waste during the work up of these reactions. Therefore, the use of water as reaction media has attracted tremendous attention due to its environmental, economic, and safety benefits. In this study, we report on the synthesis of green Pd@graphene nanocatalyst based on an in situ functionalization approach which exhibited excellent catalytic activity towards the Suzuki–Miyaura cross-coupling reactions of phenyl halides with phenyl boronic acids under facile conditions in water. The green and environmentally friendly synthesis of Pd@graphene nanocatalyst (PG-HRG-Pd is carried out by simultaneous reduction of graphene oxide (GRO and PdCl2 using Pulicaria glutinosa extract (PGE as reducing and stabilizing agent. The phytomolecules present in the plant extract (PE not only facilitated the reduction of PdCl2, but also helped to stabilize the surface of PG-HRG-Pd nanocatalyst, which significantly enhanced the dispersibility of nanocatalyst in water. The identification of PG-HRG-Pd was established by various spectroscopic and microscopic techniques, including, high-resolution transmission electron microscopy (HRTEM, X-ray diffraction (XRD, ultraviolet–visible spectroscopy (UV-Vis, Fourier transform infrared spectroscopy (FT-IR, and Raman spectroscopy. The as-prepared PG-HRG-Pd nanocatalyst demonstrated excellent catalytic activity towards the Suzuki-Miyaura cross coupling reactions under aqueous, ligand free, and aerobic conditions. Apart from this the reusability of the catalyst was also evaluated and the catalyst yielded excellent results upon reuse for several times with marginal loss of its catalytic performance. Therefore, the method developed for the green

  2. Observation of Binuclear Palladium Clusters Upon ESI-MS Monitoring of the Suzuki-Miyaura Cross-Coupling Catalyzed by a Dichloro-bis(aminophosphine) Complex of Palladium

    Czech Academy of Sciences Publication Activity Database

    Agrawal, Divya; Schröder, Detlef; Frech, C. M.

    2011-01-01

    Roč. 30, č. 13 (2011), s. 3579-3587 ISSN 0276-7333 Institutional research plan: CEZ:AV0Z40550506 Keywords : catalysis * C-C coupling * electrospray ionization * palladium * Suzuki-Miyaura coupling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.963, year: 2011

  3. Palladium-catalyzed Suzuki-Miyaura coupling of amides by carbon-nitrogen cleavage: general strategy for amide N-C bond activation.

    Science.gov (United States)

    Meng, Guangrong; Szostak, Michal

    2016-06-15

    The first palladium-catalyzed Suzuki-Miyaura cross-coupling of amides with boronic acids for the synthesis of ketones by sterically-controlled N-C bond activation is reported. The transformation is characterized by operational simplicity using bench-stable, commercial reagents and catalysts, and a broad substrate scope, including substrates with electron-donating and withdrawing groups on both coupling partners, steric-hindrance, heterocycles, halides, esters and ketones. The scope and limitations are presented in the synthesis of >60 functionalized ketones. Mechanistic studies provide insight into the catalytic cycle of the cross-coupling, including the first experimental evidence for Pd insertion into the amide N-C bond. The synthetic utility is showcased by a gram-scale cross-coupling and cross-coupling at room temperature. Most importantly, this process provides a blueprint for the development of a plethora of metal catalyzed reactions of typically inert amide bonds via acyl-metal intermediates. A unified strategy for amide bond activation to enable metal insertion into N-C amide bond is outlined ().

  4. Insights into the catalytic activity of [Pd(NHC)(cin)Cl] (NHC = IPr, IPrCl, IPrBr) complexes in the Suzuki-Miyaura reaction

    KAUST Repository

    Nolan, Steven Patrick; Izquierdo, Frederic; Zinser, Caroline; Minenkov, Yury; Cordes, David; Slawin, Alexandra; Cavallo, Luigi; Nahra, Fady; Cazin, Catherine

    2017-01-01

    The influence of C4,5-halogenation on palladium N-heterocyclic carbene complexes and their activity in the Suzuki-Miyaura reaction have been investigated. Two [Pd(NHC)(cin)Cl] complexes bearing IPrCl and IPrBr ligands were synthesized. After

  5. Highly functionalized biaryls via Suzuki-Miyaura cross-coupling catalyzed by Pd@MOF under batch and continuous flow regimes.

    Science.gov (United States)

    Pascanu, Vlad; Hansen, Peter R; Bermejo Gómez, Antonio; Ayats, Carles; Platero-Prats, Ana E; Johansson, Magnus J; Pericàs, Miquel À; Martín-Matute, Belén

    2015-01-01

    A diverse set of more than 40 highly functionalized biaryls was synthesized successfully through the Suzuki-Miyaura cross-coupling reaction catalyzed by Pd nanoparticles supported in a functionalized mesoporous MOF (8 wt % Pd@MIL-101(Cr)-NH2 ). This could be achieved under some of the mildest conditions reported to date and a strong control over the leaching of metallic species could be maintained, despite the presence of diverse functional groups and/or several heteroatoms. Some of the targeted molecules are important intermediates in the synthesis of pharmaceuticals and we clearly exemplify the versatility of this catalytic system, which affords better yields than currently existing commercial procedures. Most importantly, Pd@MIL-101-NH2 was packed in a micro-flow reactor, which represents the first report of metallic nanoparticles supported on MOFs employed in flow chemistry for catalytic applications. A small library of 11 isolated compounds was created in a continuous experiment without replacing the catalyst, demonstrating the potential of the catalyst for large-scale applications. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Reusable Polymer-Supported Terpyridine Palladium Complex for Suzuki-Miyaura, Mizoroki-Heck, Sonogashira, and Tsuji-Trost Reaction in Water

    Directory of Open Access Journals (Sweden)

    Takuya Nagamine

    2011-03-01

    Full Text Available A novel heterogeneous transition-metal catalyst comprising a polymer-supported terpyridine palladium(II complex was prepared and found to promote the Suzuki-Miyaura, Mizoroki-Heck, Sonogashira, and Tsuji-Trost, reactions in water under aerobic conditions with a high to excellent yield. The catalyst was recovered by simple filtration and directly reused several times without loss of catalytic activity.

  7. [PdA (IPr*) (cinnamyl)Cl]: An efficient pre-catalyst for the preparation of tetra-ortho-substituted biaryls by Suzuki-Miyaura cross-coupling

    KAUST Repository

    Chartoire, Anthony

    2012-03-13

    The bigger the better: The new well-defined [Pd(IPr*)(cin)Cl] pre-catalyst is described (see scheme). This complex proves to be highly active in the Suzuki-Miyaura cross-coupling for the synthesis of tetra-ortho- substituted biaryls under mild conditions. IPr* is reported as the largest N-heterocyclic carbene (NHC) to date for [Pd(NHC)(cin)Cl] complexes, explaining the high reactivity observed for this complex in this challenging transformation. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. [PdA (IPr*) (cinnamyl)Cl]: An efficient pre-catalyst for the preparation of tetra-ortho-substituted biaryls by Suzuki-Miyaura cross-coupling

    KAUST Repository

    Chartoire, Anthony; Lesieur, Mathieu; Falivene, Laura; Slawin, Alexandra M. Z.; Cavallo, Luigi; Cazin, Catherine S J; Nolan, Steven P.

    2012-01-01

    The bigger the better: The new well-defined [Pd(IPr*)(cin)Cl] pre-catalyst is described (see scheme). This complex proves to be highly active in the Suzuki-Miyaura cross-coupling for the synthesis of tetra-ortho- substituted biaryls under mild conditions. IPr* is reported as the largest N-heterocyclic carbene (NHC) to date for [Pd(NHC)(cin)Cl] complexes, explaining the high reactivity observed for this complex in this challenging transformation. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Modular Stereoselective Synthesis of (1 -> 2)-C-Glycosides based on the sp(2)-sp(3) Suzuki-Miyaura Reaction

    Czech Academy of Sciences Publication Activity Database

    Oroszová, B.; Choutka, J.; Pohl, Radek; Parkan, K.

    2015-01-01

    Roč. 21, č. 19 (2015), s. 7043-7047 ISSN 0947-6539 Grant - others:GA ČR(CZ) GPP207/12/P713; GA ČR(CZ) GA15-17572S Institutional support: RVO:61388963 Keywords : C-disaccharides * C-glycosides * diastereoselectivity * Mitsunobu reaction * sp(2)-sp(3) coupling Subject RIV: CC - Organic Chemistry Impact factor: 5.771, year: 2015

  10. Water-dispersable hybrid Au-Pd nanoparticles as catalysts in ethanol oxidation, aqueous phase Suzuki-Miyaura and Heck reactions

    KAUST Repository

    Song, Hyon Min

    2012-01-01

    The catalytic activities of water-dispersable Au@Pd core-shell nanoparticles (NPs) and Au-Pd alloy NPs were examined. There is growing interest in Au-Pd hybridized NPs in a supported matrix or non-supported forms as catalysts in various reactions that are not limited to conventional Pd-related reactions. Four different Au@Pd core-shell NPs in this study were prepared at room temperature with help from the emulsion phase surrounding the Au core NPs. Au-Pd alloy NPs were prepared over 90 °C, and underwent phase transfer to aqueous medium for their catalytic use. Au@Pd core-shell NPs show catalytic activity in ethanol oxidation reactions as electrocatalysts, and both core-shell and alloy NPs are good to excellent catalysts in various Suzuki-Miyaura and Heck reactions as heterogeneous catalysts. Specifically, Au@Pd core-shell NPs with sharp branched arms show the highest yield in the reactions tested in this study. A relatively small amount (0.25 mol%) was used throughout the catalytic reactions. © 2012 The Royal Society of Chemistry.

  11. Aqueous microwaves assisted cross-coupling reactions applied to unprotected nucleosides.

    Directory of Open Access Journals (Sweden)

    CHRISTOPHE eLEN

    2015-02-01

    Full Text Available Nucleoside analogues have attracted much attention due to their potential biological activities. Amongst all synthetic nucleosides, C5-modified pyrimidines and C7- or C8-modified purines have mostly been prepared using palladium cross-coupling reactions and then studied as antitumoral and antiviral agents. Our objective is to focus this review on the Suzuki-Miyaura and on the Heck cross-couplings of nucleosides using microwave irradiations which are an alternative technology compatible with green chemistry and sustainable development.

  12. Tutvustatakse Suzuki meetodit

    Index Scriptorium Estoniae

    2001-01-01

    Jaapanlase Scinichi Suzuki (1898-1991) meetod rajaneb põhimõttel, et kõigil on sünnihetkest alates teatud võimekus omandada mitmesuguseid oskusi, mida saab arendada selleks loodud soodsas keskkonnas. Tema meetod on kasutusel muusikainstrumentide õpetamisel, koolieelikute muusikatundides ning üldainete õpetamisel. 2001.a. märtsis külastab Eestit ja annab kontserte grupp USA Capitali Ülikooli suzukiõpilasi, Kontsertide ajakava

  13. Palladium-catalyzed coupling reactions

    CERN Document Server

    Molnár, Árpád

    2013-01-01

    This handbook and ready reference brings together all significant issues of practical importance for interested readers in one single volume. While covering homogeneous and heterogeneous catalysis, the text is unique in focusing on such important aspects as using different reaction media, microwave techniques or catalyst recycling. It also provides a comprehensive treatment of modern-day coupling reactions and emphasizes those topics that show potential for future development, such as continuous flow systems, water as a reaction medium, and catalyst immobilization, among others. With i

  14. Palladium-Catalysed Coupling Reactions

    NARCIS (Netherlands)

    de Vries, Johannes G.; Beller, M; Blaser, HU

    2012-01-01

    Palladium-catalysed coupling reactions have gained importance as a tool for the production of pharmaceutical intermediates and to a lesser extent also for the production of agrochemicals, flavours and fragrances, and monomers for polymers. In this review only these cases are discussed where it seems

  15. Application of “Boomerang” Linear Polystyrene-Stabilized Pd Nanoparticles to a Series of C-C Coupling Reactions in Water

    Directory of Open Access Journals (Sweden)

    Atsushi Ohtaka

    2015-02-01

    Full Text Available The application of a catch-and-release system for soluble Pd species between water (reaction medium and polystyrene (polymer support was examined in the Suzuki coupling reaction with 2-bromothiophene and the Heck reaction with styrene or bromobenzene. Although a slight increase in particle size was observed by TEM after re-stabilization of the Pd species on linear polystyrene, no agglomeration was observed.

  16. Catalytic activity of some oxime-based Pd(II-complexes in Suzuki coupling of aryl and heteroaryl bromides in water

    Directory of Open Access Journals (Sweden)

    Kamal M. Dawood

    2017-05-01

    Full Text Available The catalytic activity of four Pd(II-complexes of benzoazole-oximes was extensively studied in Suzuki–Miyaura C–C cross coupling reactions in water, as an eco-friendly green solvent, under both thermal heating as well as microwave irradiation conditions. The cross-coupling reactions included different activated and deactivated aryl- or heteroaryl-bromides with several arylboronic acids. The protected oxime-complexes were found to be more efficient than the free ones.

  17. Autobiography: Kinuko Suzuki, MD.

    Science.gov (United States)

    Healy, Eileen

    2014-02-01

    The following reminiscence by Kinuko Suzuki is the 9th autobiography in a series published in the Journal of Neuropathology and Experimental Neurology. These have been solicited from senior members of the neuropathology community who have been noted leaders and contributors to neuroscience and to the American Association of Neuropathologists (AANP) and have a historical perspective of the importance of neuropathology in diagnosis, education, and research. It is hoped that this series will entertain, enlighten, and present members of the AANP with a better sense of the legacy that we have inherited, as well as reintroduce our respected neuroscientists as humans having interesting lives filled with joys and sorrows and allowing them to present their lives in their own words.MNH, RAS.

  18. The introduction of high-throughput experimentation methods for Suzuki-Miyaura coupling reactions in University education

    NARCIS (Netherlands)

    Hoogenboom, R.; Meier, M.A.R.; Schubert, U.S.

    2005-01-01

    Use of high-throughput experimentation is becoming common in industry. To prepare students to work with those novel techniques in their future careers, the utilization of an automated synthesis robot was integrated into an undergraduate research project. The practical course included performing a

  19. Planar geometry of 4-substituted-2,2'-bipyridines synthesized by Sonogashira and Suzuki cross-coupling reactions

    Energy Technology Data Exchange (ETDEWEB)

    Luong Thi, T. T., E-mail: thuyltt@hnue.edu.vn; Nguyen Bich, N.; Nguyen, H. [Hanoi National University of Education, Chemistry Department (Viet Nam); Van Meervelt, L., E-mail: luc.vanmeervelt@chem.kuleuven.be [KU Leuven, Chemistry Department (Belgium)

    2015-12-15

    Two 4-substituted 2,2'-bipyridines, namely 4-(ferrocenylethynyl)-2,2'-bipyridine (I) and 4-ferrocenyl-2,2'-bipyridine (II) have been synthesized and fully characterized via single-crystal X-ray diffraction and {sup 1}H and {sup 13}C NMR analyses. The π-conjugated system designed from 2,2'-bipyridine modified with the ferrocenylethynyl and ferrocenyl groups shows the desired planarity. In the crystal packing of I and II, the molecules arrange themselves in head-to-tail and head-to-head motifs, respectively, resulting in consecutive layers of ferrocene and pyridine moieties.

  20. Nucleation phenomena at Suzuki phases

    International Nuclear Information System (INIS)

    Acosta-Najarro, D.; Jose Y, M.

    1982-01-01

    Crystal of NaCl doped with Mn present regions with an increase in nucleation densities when observed by surface gold decoration; this increase is related to the nucleation of the Suzuki phases which are induced by cooling of the crystal matrix. Calculations based on atomistic nucleation theory are developed to explain the increased nucleation density. Experiments were made to compare with the theoretical results. In particular the density of nuclei was measured as a function of the rate or arrival of atoms to the surface. Therefore, the changes in the nucleation densities are explained in terms of change in migration energies between the Suzuki phase and the NaCl matrix excluding the possibility of nucleation induced by point defects. (author)

  1. Water-dispersable hybrid Au-Pd nanoparticles as catalysts in ethanol oxidation, aqueous phase Suzuki-Miyaura and Heck reactions

    KAUST Repository

    Song, Hyon Min; Moosa, Basem; Khashab, Niveen M.

    2012-01-01

    The catalytic activities of water-dispersable Au@Pd core-shell nanoparticles (NPs) and Au-Pd alloy NPs were examined. There is growing interest in Au-Pd hybridized NPs in a supported matrix or non-supported forms as catalysts in various reactions

  2. Nickel Chloride Promoted Glaser Coupling Reaction in Hot Water

    Institute of Scientific and Technical Information of China (English)

    Pin Hua LI; Lei WANG; Min WANG; Jin Can YAN

    2004-01-01

    A Glaser coupling reaction of terminal alkynes in the presence of nickel chloride without any organics and bases in hot water has been developed, which produces the corresponding homo-coupling products in good yields.

  3. Chiral PEPPSI Complexes: Synthesis, Characterization, and Application in Asymmetric Suzuki–Miyaura Coupling Reactions

    KAUST Repository

    Benhamou, Laure

    2014-01-13

    PEPPSI complexes incorporating chiral N-heterocyclic carbene (NHC) ligands based on 2,2-dimethyl-1-(o-substituted aryl)propan-1-amines were synthesized. Two complexes, with one saturated and one unsaturated NHC ligand, were structurally characterized. The chiral PEPPSI complexes were used in asymmetric Suzuki-Miyaura reactions, giving atropisomeric biaryl products in modest to good enantiomeric ratios. © 2013 American Chemical Society.

  4. Chiral PEPPSI Complexes: Synthesis, Characterization, and Application in Asymmetric Suzuki–Miyaura Coupling Reactions

    KAUST Repository

    Benhamou, Laure; Besnard, Cé line; Kü ndig, E. Peter

    2014-01-01

    PEPPSI complexes incorporating chiral N-heterocyclic carbene (NHC) ligands based on 2,2-dimethyl-1-(o-substituted aryl)propan-1-amines were synthesized. Two complexes, with one saturated and one unsaturated NHC ligand, were structurally characterized. The chiral PEPPSI complexes were used in asymmetric Suzuki-Miyaura reactions, giving atropisomeric biaryl products in modest to good enantiomeric ratios. © 2013 American Chemical Society.

  5. The Eschenmoser coupling reaction under continuous-flow conditions

    Science.gov (United States)

    Singh, Sukhdeep; Köhler, J Michael; Schober, Andreas

    2011-01-01

    Summary The Eschenmoser coupling is a useful carbon–carbon bond forming reaction which has been used in various different synthesis strategies. The reaction proceeds smoothly if S-alkylated ternary thioamides or thiolactames are used. In the case of S-alkylated secondary thioamides or thiolactames, the Eschenmoser coupling needs prolonged reaction times and elevated temperatures to deliver valuable yields. We have used a flow chemistry system to promote the Eschenmoser coupling under enhanced reaction conditions in order to convert the demanding precursors such as S-alkylated secondary thioamides and thiolactames in an efficient way. Under pressurized reaction conditions at about 220 °C, the desired Eschenmoser coupling products were obtained within 70 s residence time. The reaction kinetics was investigated and 15 examples of different building block combinations are given. PMID:21915222

  6. The Eschenmoser coupling reaction under continuous-flow conditions

    Directory of Open Access Journals (Sweden)

    Sukhdeep Singh

    2011-08-01

    Full Text Available The Eschenmoser coupling is a useful carbon–carbon bond forming reaction which has been used in various different synthesis strategies. The reaction proceeds smoothly if S-alkylated ternary thioamides or thiolactames are used. In the case of S-alkylated secondary thioamides or thiolactames, the Eschenmoser coupling needs prolonged reaction times and elevated temperatures to deliver valuable yields. We have used a flow chemistry system to promote the Eschenmoser coupling under enhanced reaction conditions in order to convert the demanding precursors such as S-alkylated secondary thioamides and thiolactames in an efficient way. Under pressurized reaction conditions at about 220 °C, the desired Eschenmoser coupling products were obtained within 70 s residence time. The reaction kinetics was investigated and 15 examples of different building block combinations are given.

  7. Surface-Activated Coupling Reactions Confined on a Surface.

    Science.gov (United States)

    Dong, Lei; Liu, Pei Nian; Lin, Nian

    2015-10-20

    Chemical reactions may take place in a pure phase of gas or liquid or at the interface of two phases (gas-solid or liquid-solid). Recently, the emerging field of "surface-confined coupling reactions" has attracted intensive attention. In this process, reactants, intermediates, and products of a coupling reaction are adsorbed on a solid-vacuum or a solid-liquid interface. The solid surface restricts all reaction steps on the interface, in other words, the reaction takes place within a lower-dimensional, for example, two-dimensional, space. Surface atoms that are fixed in the surface and adatoms that move on the surface often activate the surface-confined coupling reactions. The synergy of surface morphology and activity allow some reactions that are inefficient or prohibited in the gas or liquid phase to proceed efficiently when the reactions are confined on a surface. Over the past decade, dozens of well-known "textbook" coupling reactions have been shown to proceed as surface-confined coupling reactions. In most cases, the surface-confined coupling reactions were discovered by trial and error, and the reaction pathways are largely unknown. It is thus highly desirable to unravel the mechanisms, mechanisms of surface activation in particular, of the surface-confined coupling reactions. Because the reactions take place on surfaces, advanced surface science techniques can be applied to study the surface-confined coupling reactions. Among them, scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) are the two most extensively used experimental tools. The former resolves submolecular structures of individual reactants, intermediates, and products in real space, while the latter monitors the chemical states during the reactions in real time. Combination of the two methods provides unprecedented spatial and temporal information on the reaction pathways. The experimental findings are complemented by theoretical modeling. In particular, density

  8. Exact solutions of some coupled nonlinear diffusion-reaction ...

    Indian Academy of Sciences (India)

    certain coupled diffusion-reaction (D-R) equations of very general nature. In recent years, various direct methods have been proposed to find the exact solu- tions not only of nonlinear partial differential equations but also of their coupled versions. These methods include unified ansatz approach [3], extended hyperbolic func ...

  9. Suzuki ja Szilvay : meetodist ja individuaalsusest / Lembi Mets

    Index Scriptorium Estoniae

    Mets, Lembi

    2000-01-01

    23. ja 24. apr. esines Tallinnas ans. Helsingin Juniorijousten F-avain-sello-bassoryhmä. 3. mail esines Tallinnas keelpilliõpilaste orkester Suzuki Nordic String. Suzuki ja Szilvayde muusikaõpetuse meetoditest, nende erinevustest, kasutamisvõimalustest Eestis

  10. Structuring Pd Nanoparticles on 2H-WS2 Nanosheets Induces Excellent Photocatalytic Activity for Cross-Coupling Reactions under Visible Light.

    Science.gov (United States)

    Raza, Faizan; Yim, DaBin; Park, Jung Hyun; Kim, Hye-In; Jeon, Su-Ji; Kim, Jong-Ho

    2017-10-18

    Effective photocatalysts and their surface engineering are essential for the efficient conversion of solar energy into chemical energy in photocatalyzed organic transformations. Herein, we report an effective approach for structuring Pd nanoparticles (NPs) on exfoliated 2H-WS 2 nanosheets (WS 2 /PdNPs), resulting in hybrids with extraordinary photocatalytic activity in Suzuki reactions under visible light. Pd NPs of different sizes and densities, which can modulate the photocatalytic activity of the as-prepared WS 2 /PdNPs, were effectively structured on the basal plane of 2H-WS 2 nanosheets via a sonic wave-assisted nucleation method without any reductants at room temperature. As the size of Pd NPs on WS 2 /PdNPs increased, their photocatalytic activity in Suzuki reactions at room temperature increased substantially. In addition, it was found that protic organic solvents play a crucial role in activating WS 2 /PdNPs catalysts in photocatalyzed Suzuki reactions, although these solvents are generally considered much less effective than polar aprotic ones in the conventional Suzuki reactions promoted by heterogeneous Pd catalysts. A mechanistic investigation suggested that photogenerated holes are transferred to protic organic solvents, whereas photogenerated electrons are transferred to Pd NPs. This transfer makes the Pd NPs electron-rich and accelerates the rate-determining step, i.e., the oxidative addition of aryl halides under visible light. WS 2 /PdNPs showed the highest turnover frequency (1244 h -1 ) for photocatalyzed Suzuki reactions among previously reported photocatalysts.

  11. Cu(I)/Diamine-catalyzed Aryl-alkyne Coupling Reactions

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    CuI/ethylene diamine/K2CO3/dioxane is shown to be a useful system for the cross coupling reactions of various aryl iodides and bromides with aryl and alkyl alkynes. Compared to the conventional Sonogashira reactions, the new procedure is free of palladium and phosphines.

  12. A Colorimetric Chemodosimeter for Pd(II): A Method for Detecting Residual Palladium in Cross-Coupling Reactions

    Science.gov (United States)

    Houk, Ronald J. T.; Wallace, Karl J.; Hewage, Himali S.; Anslyn, Eric V.

    2008-01-01

    A colorimetric chemodosimeter (SQ1) for the detection of trace palladium salts in cross-coupling reactions mediated by palladium is described. Decolorization of SQ1 is affected by nucleophilic attack of ethanethiol in basic DMSO solutions. Thiol addition is determined to have an equilibrium constant (Keq) of 2.9 × 106 M-1, with a large entropic and modest enthalpic driving force. This unusual result is attributed to solvent effects arising from a strong coordinative interaction between DMSO and the parent squaraine. Palladium detection is achieved through thiol scavenging from the SQ1-ethanethiol complex leading to a color “turn-on” of the parent squaraine. It was found that untreated samples obtained directly from Suzuki couplings showed no response to the assay. However, treatment of the samples with aqueous nitric acid generates a uniform Pd(NO3)2 species, which gives an appropriate response. “Naked-eye” detection of Pd(NO3)2 was estimated to be as low as 0.5 ppm in solution, and instrument-based detection was tested as low as 100 ppb. The average error over the working range of the assay was determined to be 7%. PMID:19122841

  13. Powerful Learning Experiences and Suzuki Music Teachers

    Science.gov (United States)

    Reuning-Hummel, Carrie; Meyer, Allison; Rowland, Gordon

    2016-01-01

    Powerful Learning Experiences (PLEs) of Suzuki music teachers were examined in this fifth study in a series. The definition of a PLE is: "Experiences that stand out in memory because of their high quality, their impact on one's thoughts and actions over time, and their transfer to a wide range of contexts and circumstances." Ten…

  14. Application of Enzyme Coupling Reactions to Shift Thermodynamically Limited Biocatalytic Reactions

    DEFF Research Database (Denmark)

    Abu, Rohana; Woodley, John M.

    2015-01-01

    , it can be challenging to combine several engineered enzymes in vitro for the conversion of non-natural substrates. In this mini-review we focus on enzyme coupling reactions as a tool to alleviate thermodynamic constraints in synthetically useful biocatalytic reactions. The implications of thermodynamic...... shift the equilibrium of otherwise thermodynamically unfavourable reactions to give a higher conversion of the target product. By coupling an energetically unfavourable reaction with a more favourable one, the multi-enzyme cascade mimics the approach taken in nature in metabolic pathways. Nevertheless...

  15. A general A3: coupling reaction based on functionalized alkynes

    International Nuclear Information System (INIS)

    Wendler, Edison P.; Santos, Alcindo A. dos

    2013-01-01

    A range of hydroxypropargylpiperidones were efficiently obtained by a one-pot three-component coupling reaction of aldehydes, alkynols, and a primary amine equivalent (4-piperidone hydrochloride hydrate) in ethyl acetate using copper(I) chloride as a catalyst. The developed protocol proved to be equally efficient using a range of aliphatic aldehydes, including paraformaldehyde, and using protected and unprotected alkynols. (author)

  16. Coupling Effect between Mechanical Loading and Chemical Reactions

    Czech Academy of Sciences Publication Activity Database

    Klika, Václav; Maršík, František

    2009-01-01

    Roč. 113, č. 44 (2009), s. 14689-14697 ISSN 1520-6106 R&D Projects: GA ČR(CZ) GA106/08/0557 Institutional research plan: CEZ:AV0Z20760514 Keywords : coupling * dynamic loading * reaction kinetics Subject RIV: FI - Traumatology, Orthopedics Impact factor: 3.471, year: 2009

  17. Synthesis and cytostatic activity of substituted 6-phenylpurine bases and nucleosides: application of the Suzuki-Miyaura cross-coupling reactions of 6-chloropurine derivatives with phenylboronic acids

    Czech Academy of Sciences Publication Activity Database

    Hocek, Michal; Holý, Antonín; Votruba, Ivan; Dvořáková, H.

    2000-01-01

    Roč. 43, č. 9 (2000), s. 1817-1825 ISSN 0022-2623 R&D Projects: GA ČR GA203/98/P027; GA ČR GV203/96/K001 Institutional research plan: CEZ:AV0Z4055905 Subject RIV: CC - Organic Chemistry Impact factor: 4.134, year: 2000

  18. Cellular automaton model of coupled mass transport and chemical reactions

    International Nuclear Information System (INIS)

    Karapiperis, T.

    1994-01-01

    Mass transport, coupled with chemical reactions, is modelled as a cellular automaton in which solute molecules perform a random walk on a lattice and react according to a local probabilistic rule. Assuming molecular chaos and a smooth density function, we obtain the standard reaction-transport equations in the continuum limit. The model is applied to the reactions a + b ↔c and a + b →c, where we observe interesting macroscopic effects resulting from microscopic fluctuations and spatial correlations between molecules. We also simulate autocatalytic reaction schemes displaying spontaneous formation of spatial concentration patterns. Finally, we propose and discuss the limitations of a simple model for mineral-solute interaction. (author) 5 figs., 20 refs

  19. Acoustic wave propagation in fluids with coupled chemical reactions

    International Nuclear Information System (INIS)

    Margulies, T.S.; Schwarz, W.H.

    1984-08-01

    This investigation presents a hydroacoustic theory which accounts for sound absorption and dispersion in a multicomponent mixture of reacting fluids (assuming a set of first-order acoustic equations without diffusion) such that several coupled reactions can occur simultaneously. General results are obtained in the form of a biquadratic characteristic equation (called the Kirchhoff-Langevin equation) for the complex propagation variable chi = - (α + iω/c) in which α is the attenuation coefficient, c is the phase speed of the progressive wave and ω is the angular frequency. Computer simulations of sound absorption spectra have been made for three different chemical systems, each comprised of two-step chemical reactions using physico-chemical data available in the literature. The chemical systems studied include: (1) water-dioxane, (2) aqueous solutions of glycine and (3) cobalt polyphosphate mixtures. Explicit comparisons are made between the exact biquadratic characteristic solution and the approximate equation (sometimes referred to as a Debye equation) previously applied to interpret the experimental data for the chemical reaction contribution to the absorption versus frequency. The relative chemical reaction and classical viscothermal contributions to the sound absorption are also presented. Several discrepancies that can arise when estimating thermodynamic data (chemical reaction heats or volume changes) for multistep chemical reaction systems when making dilute solution or constant density assumptions are discussed

  20. Thin layer chromatography coupled with surface-enhanced Raman scattering as a facile method for on-site quantitative monitoring of chemical reactions.

    Science.gov (United States)

    Zhang, Zong-Mian; Liu, Jing-Fu; Liu, Rui; Sun, Jie-Fang; Wei, Guo-Hua

    2014-08-05

    By coupling surface-enhanced Raman spectroscopy (SERS) with thin layer chromatography (TLC), a facile and powerful method was developed for on-site monitoring the process of chemical reactions. Samples were preseparated on a TLC plate following a common TLC procedure, and then determined by SERS after fabricating a large-area, uniform SERS substrate on the TLC plate by spraying gold nanoparticles (AuNPs). Reproducible and strong SERS signals were obtained with substrates prepared by spraying 42-nm AuNPs at a density of 5.54 × 10(10) N/cm(2) on the TLC plate. The capacity of this TLC-SERS method was evaluated by monitoring a typical Suzuki coupling reaction of phenylboronic acid and 2-bromopyridine as a model. Results showed that this proposed method is able to identify reaction product that is invisible to the naked eye, and distinguish the reactant 2-bromopyridine and product 2-phenylpyridine, which showed almost the same retention factors (R(f)). Under the optimized conditions, the peak area of the characteristic Raman band (755 cm(-1)) of the product 2-phenylpyridine showed a good linear correlation with concentration in the range of 2-200 mg/L (R(2) = 0.9741), the estimated detection limit (1 mg/L 2-phenylpyridine) is much lower than the concentration of the chemicals in the common organic synthesis reaction system, and the product yield determined by the proposed TLC-SERS method agreed very well with that by UPLC-MS/MS. In addition, a new byproduct in the reaction system was found and identified through continuous Raman detection from the point of sample to the solvent front. This facile TLC-SERS method is quick, easy to handle, low-cost, sensitive, and can be exploited in on-site monitoring the processes of chemical reactions, as well as environmental and biological processes.

  1. Syntheses of the hexahydroindene cores of indanomycin and stawamycin by combinations of iridium-catalyzed asymmetric allylic alkylations and intramolecular Diels-Alder reactions.

    Science.gov (United States)

    Gärtner, Martin; Satyanarayana, Gedu; Förster, Sebastian; Helmchen, Günter

    2013-01-02

    Short and concise syntheses of the hexahydroindene cores of the antibiotics indanomycin (X-14547 A) and stawamycin are presented. Key methods used are an asymmetric iridium-catalyzed allylic alkylation, a modified Julia olefination, a Suzuki-Miyaura coupling, and an intramolecular Diels-Alder reaction. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Carbazole-based copolymers via direct arylation polymerization (DArP) for Suzuki-convergent polymer solar cell performance

    DEFF Research Database (Denmark)

    Gobalasingham, Nemal S.; Ekiz, Seyma; Pankow, Robert M.

    2017-01-01

    Although direct arylation polymerization (DArP) has recently emerged as an alternative to traditional cross-coupling methods like Suzuki polymerization, the evaluation of DArP polymers in practical applications like polymer solar cells (PSCs) is limited. Because even the presence of minute...

  3. Chemoselective Synthesis of 4,5-Diarylpyrrolo[2,3-d]pyrimidines (6,7-Diaryl-7-deazapurines) by Consecutive Suzuki and Liebeskind-Srogl Cross-Couplings

    Czech Academy of Sciences Publication Activity Database

    Krömer, M.; Klečka, Martin; Slavětínská, Lenka; Klepetářová, Blanka; Hocek, Michal

    2014-01-01

    Roč. 2014, č. 32 (2014), s. 7203-7210 ISSN 1434-193X Grant - others:GA ČR(CZ) GAP207/12/0205 Institutional support: RVO:61388963 Keywords : synthetic methods * chemoselectivity * cross - coupling * palladium * nitrogen heterocycles Subject RIV: CC - Organic Chemistry Impact factor: 3.065, year: 2014

  4. Kazama-Suzuki models as shifted bosonic lattices

    International Nuclear Information System (INIS)

    Buturovic, E.

    1992-01-01

    Some Kazama-Suzuki models admit a realization in terms of free bosons defined on a lattice. A criterion for such a realization and its construction are presented. Some examples are worked out. (orig.)

  5. Impact of phonon coupling on the radiative nuclear reaction characteristics

    Directory of Open Access Journals (Sweden)

    Achakovskiy Oleg

    2016-01-01

    Full Text Available The pygmy dipole resonance and photon strength functions (PSF in stable and unstable Ni and Sn isotopes are calculated within the microscopic self-consistent version of the extended theory of finite Fermi systems in the quasiparticle time blocking approximation. The approach includes phonon coupling (PC effects in addition to the standard QRPA approach. The Skyrme force SLy4 is used. A pygmy dipole resonance in 72Ni is predicted at the mean energy of 12.4 MeV exhausting 25.7% of the total energy-weighted sum rule. With our microscopic E1 PSFs in the EMPIRE 3.1 code, the following radiative nuclear reaction characteristics have been calculated for several stable and unstable even-even Sn and Ni isotopes: 1 neutron capture cross sections, 2 corresponding neutron capture gamma-spectra, 3 average radiative widths of neutron resonances. Here, three variants of the microscopic nuclear level density models have been used and a comparison with the phenomenological generalized superfluid model has been performed. In all the considered properties, including the recent experimental data for PSF in Sn isotopes, the PC contributions turned out to be significant, as compared with the QRPA one, and necessary to explain the available experimental data.

  6. Coupling between solute transport and chemical reactions models

    International Nuclear Information System (INIS)

    Samper, J.; Ajora, C.

    1993-01-01

    During subsurface transport, reactive solutes are subject to a variety of hydrodynamic and chemical processes. The major hydrodynamic processes include advection and convection, dispersion and diffusion. The key chemical processes are complexation including hydrolysis and acid-base reactions, dissolution-precipitation, reduction-oxidation, adsorption and ion exchange. The combined effects of all these processes on solute transport must satisfy the principle of conservation of mass. The statement of conservation of mass for N mobile species leads to N partial differential equations. Traditional solute transport models often incorporate the effects of hydrodynamic processes rigorously but oversimplify chemical interactions among aqueous species. Sophisticated chemical equilibrium models, on the other hand, incorporate a variety of chemical processes but generally assume no-flow systems. In the past decade, coupled models accounting for complex hydrological and chemical processes, with varying degrees of sophistication, have been developed. The existing models of reactive transport employ two basic sets of equations. The transport of solutes is described by a set of partial differential equations, and the chemical processes, under the assumption of equilibrium, are described by a set of nonlinear algebraic equations. An important consideration in any approach is the choice of primary dependent variables. Most existing models cannot account for the complete set of chemical processes, cannot be easily extended to include mixed chemical equilibria and kinetics, and cannot handle practical two and three dimensional problems. The difficulties arise mainly from improper selection of the primary variables in the transport equations. (Author) 38 refs

  7. Multi-reaction-channel fitting calculations in a coupled-channel model : Photoinduced strangeness production

    NARCIS (Netherlands)

    Scholten, O.; Usov, A.

    To describe photo- and meson-induced reactions on the nucleon, one is faced with a rather extensive coupled-channel problem Ignoring the effects of channel coupling, as one would do in describing a certain reaction at the tree level; invariably creates a large inconsistency between the different

  8. Kinetics of the Coupled Gas-Iron Reactions Involving Silicon and ...

    African Journals Online (AJOL)

    The kinetic study of coupled gas-iron reactions at 15600 has been carried out for the system involving liquid iron containing carbon and silicon and a gas phase consisting carbon monoxide, silicon monoxide and carbon dioxide. The coupled reactions are: (1) 200(g) = CO2 + C. (2) SiO (g) + CO (g) = Si ¸ CO (g). (3) SiO (g) + ...

  9. Transition-Metal-Catalyzed Decarbonylative Coupling Reactions: Concepts, Classifications, and Applications

    KAUST Repository

    Guo, Lin; Rueping, Magnus

    2018-01-01

    Transition metal‐catalyzed decarbonylative coupling reactions have emerged as a powerful alternative to conventional cross‐coupling protocols due to the advantages associated with the use of carbonyl‐containing functionalities as coupling electrophiles instead of commonly used organohalides or sulfates. A wide variety of novel transformations based on this concept have been successfully achieved, including decarbonylative carbon–carbon and carbon–heteroatom bond forming reactions. In this Review, we summarize the recent progress in this field and present a comprehensive overview of metal‐catalyzed decarbonylative coupling reactions with carbonyl derivatives.

  10. Transition-Metal-Catalyzed Decarbonylative Coupling Reactions: Concepts, Classifications, and Applications

    KAUST Repository

    Guo, Lin

    2018-05-14

    Transition metal‐catalyzed decarbonylative coupling reactions have emerged as a powerful alternative to conventional cross‐coupling protocols due to the advantages associated with the use of carbonyl‐containing functionalities as coupling electrophiles instead of commonly used organohalides or sulfates. A wide variety of novel transformations based on this concept have been successfully achieved, including decarbonylative carbon–carbon and carbon–heteroatom bond forming reactions. In this Review, we summarize the recent progress in this field and present a comprehensive overview of metal‐catalyzed decarbonylative coupling reactions with carbonyl derivatives.

  11. Statistical analysis of activation and reaction energies with quasi-variational coupled-cluster theory

    Science.gov (United States)

    Black, Joshua A.; Knowles, Peter J.

    2018-06-01

    The performance of quasi-variational coupled-cluster (QV) theory applied to the calculation of activation and reaction energies has been investigated. A statistical analysis of results obtained for six different sets of reactions has been carried out, and the results have been compared to those from standard single-reference methods. In general, the QV methods lead to increased activation energies and larger absolute reaction energies compared to those obtained with traditional coupled-cluster theory.

  12. A General Strategy for Nanohybrids Synthesis via Coupled Competitive Reactions Controlled in a Hybrid Process

    OpenAIRE

    Wang, Rongming; Yang, Wantai; Song, Yuanjun; Shen, Xiaomiao; Wang, Junmei; Zhong, Xiaodi; Li, Shuai; Song, Yujun

    2015-01-01

    A new methodology based on core alloying and shell gradient-doping are developed for the synthesis of nanohybrids, realized by coupled competitive reactions, or sequenced reducing-nucleation and co-precipitation reaction of mixed metal salts in a microfluidic and batch-cooling process. The latent time of nucleation and the growth of nanohybrids can be well controlled due to the formation of controllable intermediates in the coupled competitive reactions. Thus, spatiotemporal-resolved synthesi...

  13. Fe(HSO4)3 as an Efficient Catalyst for Diazotization and Diazo Coupling Reactions

    International Nuclear Information System (INIS)

    Rahimizadeh, Mohammad; Eshghi, Hossein; Shiri, Ali; Ghadamyari, Zohreh; Matin, Maryam M.; Pordeli, Parvaneh; Oroojalian, Fatemeh

    2012-01-01

    Diazo coupling reactions of aromatic amines with 2-naphthol in a green, efficient and easy procedure is described. Ferric hydrogensulfate catalyses this reaction in water at room temperature and short reaction time with high yields. The antibacterial activities of the synthesized compounds against four pathogenic bacteria are also investigated

  14. Regioselectivity and Enantioselectivity in Nickel-Catalysed Reductive Coupling Reactions of Alkynes

    Science.gov (United States)

    Moslin, Ryan M.; Miller-Moslin, Karen; Jamison, Timothy F.

    2011-01-01

    Nickel-catalysed reductive coupling reactions of alkynes have emerged as powerful synthetic tools for the selective preparation of functionalized alkenes. One of the greatest challenges associated with these transformations is control of regioselectivity. Recent work from our laboratory has provided an improved understanding of several of the factors governing regioselectivity in these reactions, and related studies have revealed that the reaction mechanism can differ substantially depending on the ligand employed. A discussion of stereoselective transformations and novel applications of nickel catalysis in coupling reactions of alkynes is also included. PMID:17971951

  15. Strong coupling QCD and the (π+,π-) reaction

    International Nuclear Information System (INIS)

    Miller, G.A.; Washington Univ., Seattle, WA

    1989-01-01

    Previous six-quark bag model calculations are in disagreement with new (π + , π - ) data, but conventional nucleonic calculations are generally successful. Six-quark bag models are related to perturbative QCD. I argue that the strong coupling limit of QCD (SCQCD) is a more appropriate starting point for nuclear physics. 15 refs., 3 figs

  16. Simulation of square wave voltammetry of three electrode reactions coupled by two reversible chemical reactions

    OpenAIRE

    Lovrić, Milivoj

    2017-01-01

    Three fast and reversible electrode reactions that are connected by two reversible chemical reactions that are permanently in the equilibrium are analysed theoretically for square wave voltammetry. The dependence of peak potentials on the dimensionless equilibrium constants of chemical reactions is calculated. The influence of the basic thermodynamic parameters on the square wave voltammetric responses is analysed.

  17. Determination of neutral current couplings from neutrino-induced semi-inclusive pion and inclusive reactions

    International Nuclear Information System (INIS)

    Hung, P.Q.

    1977-01-01

    It is shown that by looking at data from neutrino-induced semi-inclusive pion and inclusive reactions on isoscalar targets along, one can determine completely the neutral current couplings. Predictions for various models are also presented. (Auth.)

  18. Direct activation of allylic alcohols in palladium catalyzed coupling reactions

    NARCIS (Netherlands)

    Gümrükçü, Y.

    2014-01-01

    The direct use of allylic alcohols in substitution reactions without pre-activation of the hydroxyl-group into a better leaving group or the use of additional stoichiometric in situ activators remains challenging due to the poor leaving group ability of the hydroxyl-group. Hence, it is important to

  19. Pd(II/HPMoV-Catalyzed Direct Oxidative Coupling Reaction of Benzenes with Olefins

    Directory of Open Access Journals (Sweden)

    Yasutaka Ishii

    2010-03-01

    Full Text Available The direct aerobic coupling reaction of arenes with olefins was successfully achieved by the use of Pd(OAc2/molybdovanadophosphoric acid (HPMoV as a key catalyst under 1 atm of dioxygen. This catalytic system could be extended to the coupling reaction of various substituted benzenes with olefins such as acrylates, aclrolein, and ethylene through the direct aromatic C-H bond activation.

  20. Minimal coupling schemes in N-body reaction theory

    International Nuclear Information System (INIS)

    Picklesimer, A.; Tandy, P.C.; Thaler, R.M.

    1982-01-01

    A new derivation of the N-body equations of Bencze, Redish, and Sloan is obtained through the use of Watson-type multiple scattering techniques. The derivation establishes an intimate connection between these partition-labeled N-body equations and the particle-labeled Rosenberg equations. This result yields new insight into the implicit role of channel coupling in, and the minimal dimensionality of, the partition-labeled equations

  1. Mechanistic Implications for the Ni(I-Catalyzed Kumada Cross-Coupling Reaction

    Directory of Open Access Journals (Sweden)

    Linda Iffland

    2017-11-01

    Full Text Available Herein we report on the cross-coupling reaction of phenylmagnesium bromide with aryl halides using the well-defined tetrahedral Ni(I complex, [(TriphosNiICl] (Triphos = 1,1,1-tris(diphenylphosphinomethylethane. In the presence of 0.5 mol % [(TriphosNiICl], good to excellent yields (75–97% of the respective coupling products within a reaction time of only 2.5 h at room temperature were achieved. Likewise, the tripodal Ni(IIcomplexes [(κ2-TriphosNiIICl2] and [(κ3-TriphosNiIICl](X (X = ClO4, BF4 were tested as potential pre-catalysts for the Kumada cross-coupling reaction. While the Ni(II complexes also afford the coupling products in comparable yields, mechanistic investigations by UV/Vis and electron paramagnetic resonance (EPR spectroscopy indicate a Ni(I intermediate as the catalytically active species in the Kumada cross-coupling reaction. Based on experimental findings and density functional theory (DFT calculations, a plausible Ni(I-catalyzed reaction mechanism for the Kumada cross-coupling reaction is presented.

  2. A computational glance at organometallic cyclizations and coupling reactions

    OpenAIRE

    Fiser, Béla

    2016-01-01

    210 p. Organometallic chemistry is one of the main research topics in chemical science.Nowadays, organometallic reactions are the subject of intensive theoretical investigations.However, in many cases, only joint experimental and theoretical effortscould reveal the answers what we are looking for.The fruits of such experimental and theoretical co-operations will be presentedhere. In this work, we are going to deal with homogeneous organometallic catalysisusing computational chemical tools....

  3. Palladium-Catalyzed Cross-Coupling Reactions of Perfluoro Organic Compounds

    Directory of Open Access Journals (Sweden)

    Masato Ohashi

    2014-09-01

    Full Text Available In this review, we summarize our recent development of palladium(0-catalyzed cross-coupling reactions of perfluoro organic compounds with organometallic reagents. The oxidative addition of a C–F bond of tetrafluoroethylene (TFE to palladium(0 was promoted by the addition of lithium iodide, affording a trifluorovinyl palladium(II iodide. Based on this finding, the first palladium-catalyzed cross-coupling reaction of TFE with diarylzinc was developed in the presence of lithium iodide, affording α,β,β-trifluorostyrene derivatives in excellent yield. This coupling reaction was expanded to the novel Pd(0/PR3-catalyzed cross-coupling reaction of TFE with arylboronates. In this reaction, the trifluorovinyl palladium(II fluoride was a key reaction intermediate that required neither an extraneous base to enhance the reactivity of organoboronates nor a Lewis acid additive to promote the oxidative addition of a C–F bond. In addition, our strategy utilizing the synergetic effect of Pd(0 and lithium iodide could be applied to the C–F bond cleavage of unreactive hexafluorobenzene (C6F6, leading to the first Pd(0-catalyzed cross-coupling reaction of C6F6 with diarylzinc compounds.

  4. Sonogashira Coupling Reaction with Palladium Powder and Potassium Fluoride in Methanol

    Institute of Scientific and Technical Information of China (English)

    王磊; 李品华

    2003-01-01

    A Sonogashira coupling reaction of aromatic halides with terminal alkynes in the presence of palladium powder,potassium fluoride,cuprous iodide and triphenylphosphine in methanol,giving the corresponding coupling products aryl alkynes in good to excellent yiekls,was investigated.

  5. Pd-catalyzed coupling reaction on the organic monolayer: Sonogashira reaction on the silicon (1 1 1) surfaces

    International Nuclear Information System (INIS)

    Qu Mengnan; Zhang Yuan; He Jinmei; Cao Xiaoping; Zhang Junyan

    2008-01-01

    Iodophenyl-terminated organic monolayers were prepared by thermally induced hydrosilylation on hydrogen-terminated silicon (1 1 1) surfaces. The films were characterized by ellipsometry, contact-angle goniometry, and X-ray photoelectron spectroscopy (XPS). To modify the surface chemistry and the structure of the monolayers, the Sonogashira coupling reaction was performed on the as-prepared monolayers. The iodophenyl groups on the film surfaces reacted with 1-ethynyl-4-fluorobenzene or the 1-chloro-4-ethynylbenzene under the standard Sonogashira reaction conditions for attaching conjugated molecules via the formation of C-C bonds. It is expected that this surface coupling reaction will present a new method to modify the surface chemistry and the structure of monolayers

  6. New Oxime Ligand with Potential for Proton-Coupled Electron-Transfer Reactions

    DEFF Research Database (Denmark)

    Deville, Claire; Sundberg, Jonas; McKenzie, Christine Joy

    Proton-coupled electron-transfer (PCET) is found in a range of oxidation-reduction reactions in biology.1 This mechanism is of interest for applications in energy conversion processes. The PCET reaction has been shown to be facilitated when the proton is transferred to an intramolecular basic sit...

  7. A facile synthesis of new 5-aryl-thiophenes bearing sulfonamide moiety via Pd(0-catalyzed Suzuki–Miyaura cross coupling reactions and 5-bromothiophene-2-acetamide: As potent urease inhibitor, antibacterial agent and hemolytically active compounds

    Directory of Open Access Journals (Sweden)

    Mnaza Noreen

    2017-01-01

    Full Text Available The present study reports a convenient approach for the synthesis of thiophene sulfonamide derivatives (3a–3k via Suzuki cross coupling reaction. This method of synthesis involved the reactions of various aryl boronic acids and esters with 5-bromthiophene-2-sulfonamide (2 under mild and suitable temperature conditions. The compounds synthesized in the present study were subjected to urease inhibition and hemolytic activities. The substitution pattern and the electronic effects of different functional groups (i.e., Cl, CH3, OCH3, F etc. available on the aromatic ring are found to have significant effect on the overall results. The compound 5-Phenylthiophene-2-sulfonamide 3a showed the highest urease inhibition activity with IC50 value ∼ 30.8 μg/mL compared with the thiourea (used as standard having IC50 value ∼ 43 μg/mL. Moreover, almost all of the compounds were examined for the hemolytic activity against triton X-100 with positive results obtained in most of the cases. In addition, the antibacterial activities of the derivatives of 5-arylthiophene-2-sulfonamide and 5-bromothiophene-2-acetamide were also investigated during the course of the study.

  8. Coupled-channels analyses for 9,11Li + 208Pb fusion reactions with multi-neutron transfer couplings

    Science.gov (United States)

    Choi, Ki-Seok; Cheoun, Myung-Ki; So, W. Y.; Hagino, K.; Kim, K. S.

    2018-05-01

    We discuss the role of two-neutron transfer processes in the fusion reaction of the 9,11Li + 208Pb systems. We first analyze the 9Li + 208Pb reaction by taking into account the coupling to the 7Li + 210Pb channel. To this end, we assume that two neutrons are directly transferred to a single effective channel in 210Pb and solve the coupled-channels equations with the two channels. By adjusting the coupling strength and the effective Q-value, we successfully reproduce the experimental fusion cross sections for this system. We then analyze the 11Li + 208Pb reaction in a similar manner, that is, by taking into account three effective channels with 11Li + 208Pb, 9Li + 210Pb, and 7Li + 212Pb partitions. In order to take into account the halo structure of the 11Li nucleus, we construct the potential between 11Li and 208Pb with a double folding procedure, while we employ a Woods-Saxon type potential with the global Akyüz-Winther parameters for the other channels. Our calculation indicates that the multiple two-neutron transfer process plays a crucial role in the 11Li + 208Pb fusion reaction at energies around the Coulomb barrier.

  9. Potential Applications of Zeolite Membranes in Reaction Coupling Separation Processes

    Directory of Open Access Journals (Sweden)

    Tunde V. Ojumu

    2012-10-01

    Full Text Available Future production of chemicals (e.g., fine and specialty chemicals in industry is faced with the challenge of limited material and energy resources. However, process intensification might play a significant role in alleviating this problem. A vision of process intensification through multifunctional reactors has stimulated research on membrane-based reactive separation processes, in which membrane separation and catalytic reaction occur simultaneously in one unit. These processes are rather attractive applications because they are potentially compact, less capital intensive, and have lower processing costs than traditional processes. Therefore this review discusses the progress and potential applications that have occurred in the field of zeolite membrane reactors during the last few years. The aim of this article is to update researchers in the field of process intensification and also provoke their thoughts on further research efforts to explore and exploit the potential applications of zeolite membrane reactors in industry. Further evaluation of this technology for industrial acceptability is essential in this regard. Therefore, studies such as techno-economical feasibility, optimization and scale-up are of the utmost importance.

  10. Coupled processes of fluid flow, solute transport, and geochemical reactions in reactive barriers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeongkon; Schwartz, Franklin W.; Xu, Tianfu; Choi, Heechul, and Kim, In S.

    2004-01-02

    A complex pattern of coupling between fluid flow and mass transport develops when heterogeneous reactions occur. For instance, dissolution and precipitation reactions can change a porous medium's physical properties, such as pore geometry and thus permeability. These changes influence fluid flow, which in turn impacts the composition of dissolved constituents and the solid phases, and the rate and direction of advective transport. Two-dimensional modeling studies using TOUGHREACT were conducted to investigate the coupling between flow and transport developed as a consequence of differences in density, dissolution precipitation, and medium heterogeneity. The model includes equilibrium reactions for aqueous species, kinetic reactions between the solid phases and aqueous constituents, and full coupling of porosity and permeability changes resulting from precipitation and dissolution reactions in porous media. In addition, a new permeability relationship is implemented in TOUGHREACT to examine the effects of geochemical reactions and density difference on plume migration in porous media. Generally, the evolutions in the concentrations of the aqueous phase are intimately related to the reaction-front dynamics. Plugging of the medium contributed to significant transients in patterns of flow and mass transport.

  11. Applications of Palladium-Catalyzed C-N Cross-Coupling Reactions.

    Science.gov (United States)

    Ruiz-Castillo, Paula; Buchwald, Stephen L

    2016-10-12

    Pd-catalyzed cross-coupling reactions that form C-N bonds have become useful methods to synthesize anilines and aniline derivatives, an important class of compounds throughout chemical research. A key factor in the widespread adoption of these methods has been the continued development of reliable and versatile catalysts that function under operationally simple, user-friendly conditions. This review provides an overview of Pd-catalyzed N-arylation reactions found in both basic and applied chemical research from 2008 to the present. Selected examples of C-N cross-coupling reactions between nine classes of nitrogen-based coupling partners and (pseudo)aryl halides are described for the synthesis of heterocycles, medicinally relevant compounds, natural products, organic materials, and catalysts.

  12. Test of distorted wave kinematic coupling approximation calculations for knockout reactions

    International Nuclear Information System (INIS)

    Jain, A.K.

    1990-01-01

    A test has been devised to check the validity of conventional distorted-wave impulse approximation (DWIA) treatment of knockout reactions. The conventional DWIA formalism separates the three-body final state Schroedinger equation for a knockout reaction into two two-body Schroedinger equations by assuming an asymptotic constant value for the three-body coupling term commonly known as the kinematic coupling approximation (KCA). In the test case, which consists of an extreme asymmetric situation where one of the distorting optical potentials is assumed to vanish, the three-body final state Schroedinger equation can be solved exactly as a product of two two-body solutions using one particular set of relative coordinates. Large influence of the three-body coupling term is seen in the comparison of the exact and KCA results for (α,2α) and (p,pα) knockout reactions when the distorting optical potentials are weakly absorbing

  13. Coupled reactions by coupled enzymes : alcohol to lactone cascade with alcohol dehydrogenase-cyclohexanone monooxygenase fusions

    NARCIS (Netherlands)

    Aalbers, Friso S; Fraaije, Marco W

    2017-01-01

    The combination of redox enzymes for redox-neutral cascade reactions has received increasing appreciation. An example is the combination of an alcohol dehydrogenase (ADH) with a cyclohexanone monooxygenase (CHMO). The ADH can use NADP(+) to oxidize cyclohexanol to form cyclohexanone and NADPH. Both

  14. Monitoring chemical reactions by low-field benchtop NMR at 45 MHz: pros and cons.

    Science.gov (United States)

    Silva Elipe, Maria Victoria; Milburn, Robert R

    2016-06-01

    Monitoring chemical reactions is the key to controlling chemical processes where NMR can provide support. High-field NMR gives detailed structural information on chemical compounds and reactions; however, it is expensive and complex to operate. Conversely, low-field NMR instruments are simple and relatively inexpensive alternatives. While low-field NMR does not provide the detailed information as the high-field instruments as a result of their smaller chemical shift dispersion and the complex secondary coupling, it remains of practical value as a process analytical technology (PAT) tool and is complimentary to other established methods, such as ReactIR and Raman spectroscopy. We have tested a picoSpin-45 (currently under ThermoFisher Scientific) benchtop NMR instrument to monitor three types of reactions by 1D (1) H NMR: a Fischer esterification, a Suzuki cross-coupling, and the formation of an oxime. The Fischer esterification is a relatively simple reaction run at high concentration and served as proof of concept. The Suzuki coupling is an example of a more complex, commonly used reaction involving overlapping signals. Finally, the oxime formation involved a reaction in two phases that cannot be monitored by other PAT tools. Here, we discuss the pros and cons of monitoring these reactions at a low-field of 45 MHz by 1D (1) H NMR. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  15. Remodelling of cellular excitation (reaction) and intercellular coupling (diffusion) by chronic atrial fibrillation represented by a reaction-diffusion system

    Science.gov (United States)

    Zhang, Henggui; Garratt, Clifford J.; Kharche, Sanjay; Holden, Arun V.

    2009-06-01

    Human atrial tissue is an excitable system, in which myocytes are excitable elements, and cell-to-cell electrotonic interactions are via diffusive interactions of cell membrane potentials. We developed a family of excitable system models for human atrium at cellular, tissue and anatomical levels for both normal and chronic atrial fibrillation (AF) conditions. The effects of AF-induced remodelling of cell membrane ionic channels (reaction kinetics) and intercellular gap junctional coupling (diffusion) on atrial excitability, conduction of excitation waves and dynamics of re-entrant excitation waves are quantified. Both ionic channel and gap junctional coupling remodelling have rate dependent effects on atrial propagation. Membrane channel conductance remodelling allows the propagation of activity at higher rates than those sustained in normal tissue or in tissue with gap junctional remodelling alone. Membrane channel conductance remodelling is essential for the propagation of activity at rates higher than 300/min as seen in AF. Spatially heterogeneous gap junction coupling remodelling increased the risk of conduction block, an essential factor for the genesis of re-entry. In 2D and 3D anatomical models, the dynamical behaviours of re-entrant excitation waves are also altered by membrane channel modelling. This study provides insights to understand the pro-arrhythmic effects of AF-induced reaction and diffusion remodelling in atrial tissue.

  16. Double N-arylation reaction of polyhalogenated 4,4’-bipyridines. Expedious synthesis of functionalized 2,7-diazacarbazoles

    Directory of Open Access Journals (Sweden)

    Mohamed Abboud

    2012-02-01

    Full Text Available Unusual 2,7-diazacarbazoles were prepared in one step from readily available tetra-halogenated 4,4’-bipyridines by using a double N-arylation reaction in the presence of the Pd–XPhos catalyst system. Moderate to good yields were obtained in this site-selective Buchwald–Hartwig double amination. The functionalization of these tricyclic derivatives was performed by using Pd-catalyzed cross-coupling reactions such as the Stille and Suzuki couplings. Two compounds were analyzed by X-ray diffraction and show π–π stacking involving the diazacarbazole moieties and the phenyl rings of functionalized groups.

  17. The Manganese-Catalyzed Cross-Coupling Reaction and the Influence of Trace Metals

    DEFF Research Database (Denmark)

    Santilli, Carola; Beigbaghlou, Somayyeh Sarvi; Ahlburg, Andreas

    2017-01-01

    The substrate scope of the MnCl2-catalyzed cross-coupling between aryl halides and Grignard reagents has been extended to several methyl-substituted aryl iodides by performing the reaction at elevated temperature in a microwave oven. A radical clock experiment revealed the presence of an aryl...

  18. Analysis of coupled mass transfer and sol-gel reaction in a two-phase system

    NARCIS (Netherlands)

    Castelijns, H.J.; Huinink, H.P.; Pel, L.; Zitha, P.L.J.

    2006-01-01

    The coupled mass transfer and chemical reactions of a gel-forming compound in a two-phase system were studied in detail. Tetra-methyl-ortho-silicate (TMOS) is often used as a precursor in sol-gel chemistry to produce silica gels in aqueous systems. TMOS can also be mixed with many hydrocarbons

  19. Microwave-Enhanced Cross-Coupling Reactions Involving Alkynyltrifluoroborates with Aryl Bromides

    Directory of Open Access Journals (Sweden)

    George W. Kabalka

    2013-01-01

    Full Text Available Palladium-catalyzed alkynylation has emerged as one of the most reliable methods for the synthesis of alkynes which are often used in natural product syntheses and material science. An efficient method for coupling alkynyltrifluoroborates with various aryl bromides in the presence of a palladium catalyst has been developed using microwave irradiation. The microwave reactions are rapid and efficient.

  20. A general A{sup 3}: coupling reaction based on functionalized alkynes

    Energy Technology Data Exchange (ETDEWEB)

    Wendler, Edison P.; Santos, Alcindo A. dos, E-mail: alcindo@iq.usp.br [Universidade de Sao Paulo (IQ/USP), SP (Brazil). Inst. de Quimica

    2013-10-01

    A range of hydroxypropargylpiperidones were efficiently obtained by a one-pot three-component coupling reaction of aldehydes, alkynols, and a primary amine equivalent (4-piperidone hydrochloride hydrate) in ethyl acetate using copper(I) chloride as a catalyst. The developed protocol proved to be equally efficient using a range of aliphatic aldehydes, including paraformaldehyde, and using protected and unprotected alkynols. (author)

  1. Pd-Catalyzed Cross-Coupling Reactions of Amides and Aryl Mesylates

    Science.gov (United States)

    Dooleweerdt, Karin; Fors, Brett P.; Buchwald, Stephen L.

    2010-01-01

    A catalyst, based on a biarylphosphine ligand, for the Pd-catalyzed cross-coupling reactions of amides and aryl mesylates is described. This system allows an array of aryl and heteroaryl mesylates to be transformed into the corresponding N-arylamides in moderate to excellent yields. PMID:20420379

  2. Scandium(III) catalysis of transimination reactions. Independent and constitutionally coupled reversible processes.

    Science.gov (United States)

    Giuseppone, Nicolas; Schmitt, Jean-Louis; Schwartz, Evan; Lehn, Jean-Marie

    2005-04-20

    Sc(OTf)(3) efficiently catalyzes the self-sufficient transimination reaction between various types of C=N bonds in organic solvents, with turnover frequencies up to 3600 h(-)(1) and rate accelerations up to 6 x 10(5). The mechanism of the crossover reaction in mixtures of amines and imines is studied, comparing parallel individual reactions with coupled equilibria. The intrinsic kinetic parameters for isolated reactions cannot simply be added up when several components are mixed, and the behavior of the system agrees with the presence of a unique mediator that constitutes the core of a network of competing reactions. In mixed systems, every single amine or imine competes for the same central hub, in accordance with their binding affinity for the catalyst metal ion center. More generally, the study extends the basic principles of constitutional dynamic chemistry to interconnected chemical transformations and provides a step toward dynamic systems of increasing complexity.

  3. Methane coupling reaction in an oxy-steam stream through an OH radical pathway by using supported alkali metal catalysts

    KAUST Repository

    Liang, Yin; Li, Zhikao; Nourdine, Mohamed; Shahid, Salman; Takanabe, Kazuhiro

    2014-01-01

    A universal reaction mechanism involved in the oxidative coupling of methane (OCM) is demonstrated under oxy-steam conditions using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH

  4. Grassmannian topological Kazama-Suzuki models and cohomology

    International Nuclear Information System (INIS)

    Blau, M.; Hussain, F.; Thompson, G.

    1995-10-01

    We investigate in detail the topological gauged Wess-Zumino-Witten models describing topological Kazama-Suzuki models based on complex Grassmannians. We show that there is a topological sector in which the ring of observables (constructed from the Grassmann odd scalars of the theory) coincides with the classical cohomology ring of the Grassmanian for all values of the level k. We also analyze the general ring structure of bosonic correlation functions, uncovering a whole hierarchy of level-rank relations (including the standard level-rank duality) among models based on different Grassmannians. Using the previously established localization of the topological Kazama-Suzuki model to an Abelian topological field theory, we reduce the correlators to finite-dimensional purely algebraic expressions. As an application, these are evaluated explicitly for the CP(2) model at level k and shown for all k to coincide with the cohomological intersection numbers of the two-plane Grassmannian G(2,K + 2), thus realizing the level-rank duality between this model and the G(2, k + 2) model at level one. (author). 28 refs

  5. A review of post-column photochemical reaction systems coupled to electrochemical detection in HPLC

    International Nuclear Information System (INIS)

    Fedorowski, Jennifer; LaCourse, William R.

    2010-01-01

    Post-column photochemical reaction systems have developed into a common approach for enhancing conventional methods of detection in HPLC. Photochemical reactions as a means of 'derivatization' have a significant number of advantages over chemical reaction-based methods, and a significant effort has been demonstrated to develop an efficient photochemical reactor. When coupled to electrochemical (EC) detection, the technique allows for the sensitive and selective determination of a variety of compounds (e.g., organic nitro explosives, beta-lactam antibiotics, sulfur-containing antibiotics, pesticides and insecticides). This review will focus on developments and methods using post-column photochemical reaction systems followed by EC detection in liquid chromatography. Papers are presented in chronological order to emphasize the evolution of the approach and continued importance of the application.

  6. Using Multiscale Modeling to Study Coupled Flow, Transport, Reaction and Biofilm Growth Processes in Porous Media

    Science.gov (United States)

    Valocchi, A. J.; Laleian, A.; Werth, C. J.

    2017-12-01

    Perturbation of natural subsurface systems by fluid inputs may induce geochemical or microbiological reactions that change porosity and permeability, leading to complex coupled feedbacks between reaction and transport processes. Some examples are precipitation/dissolution processes associated with carbon capture and storage and biofilm growth associated with contaminant transport and remediation. We study biofilm growth due to mixing controlled reaction of multiple substrates. As biofilms grow, pore clogging occurs which alters pore-scale flow paths thus changing the mixing and reaction. These interactions are challenging to quantify using conventional continuum-scale porosity-permeability relations. Pore-scale models can accurately resolve coupled reaction, biofilm growth and transport processes, but modeling at this scale is not feasible for practical applications. There are two approaches to address this challenge. Results from pore-scale models in generic pore structures can be used to develop empirical relations between porosity and continuum-scale parameters, such as permeability and dispersion coefficients. The other approach is to develop a multiscale model of biofilm growth in which non-overlapping regions at pore and continuum spatial scales are coupled by a suitable method that ensures continuity of flux across the interface. Thus, regions of high reactivity where flow alteration occurs are resolved at the pore scale for accuracy while regions of low reactivity are resolved at the continuum scale for efficiency. This approach thus avoids the need for empirical upscaling relations in regions with strong feedbacks between reaction and porosity change. We explore and compare these approaches for several two-dimensional cases.

  7. Micro-coulometric study of bioelectrochemical reaction coupled with TCA cycle.

    Science.gov (United States)

    Tsujimura, Seiya; Fukuda, Jun; Shirai, Osamu; Kano, Kenji; Sakai, Hideki; Tokita, Yuichi; Hatazawa, Tsuyonobu

    2012-04-15

    The mediated electro-enzymatic electrolysis systems based on the tricarboxylic acid (TCA) cycle reaction were examined on a micro-bulk electrolytic system. A series of the enzyme-catalyzed reactions in the TCA cycle was coupled with electrode reaction. Electrochemical oxidation of NADH was catalyzed by diaphorase with an aid of a redox mediator with a formal potential of -0.15 V vs. Ag|AgCl. The mediator was also able to shuttle electrons between succinate dehydrogenase and electrode. The charge during the electrolysis increased on each addition of dehydrogenase reaction in a cascade of the TCA cycle. However, the electrolysis efficiencies were close to or less than 90% because of the product inhibition. Lactate oxidation to acetyl-CoA catalyzed by two NAD-dependent dehydrogenases was coupled with the bioelectrochemical TCA cycle reaction to achieve the 12-electron oxidation of lactate to CO(2). The charge passed in the bioelectrocatalytic oxidation of 5 nmol of lactate was 4 mC, which corresponds to 70% of the electrolysis efficiency. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Isovector couplings for nucleon charge-exchange reactions at intermediate energies

    International Nuclear Information System (INIS)

    Love, W.G.; Nakayama, K.; Franey, M.A.

    1987-01-01

    The isovector parts of the effective nucleon-nucleon interaction are studied by examination of the reaction /sup 14/C(p,n) at intermediate energies near zero momentum transfer with use of recently developed G-matrix and free--t-matrix interactions. The spin-independent coupling (V/sub tau/) exhibits a strong energy and density dependence which, in the case of the G matrix based on the Bonn potential, significantly improves the agreement between calculated values of chemical bondV/sub σ//sub tau//V/sub tau/chemical bond 2 at q = 0 and those recently extracted from the reaction /sup 14/C

  9. Reaction layer in U-7WT%MO/Al diffusion couples

    International Nuclear Information System (INIS)

    Mirandou, M.I.; Balart, S.N.; Ortiz, M.; Granovsky, M.S.

    2003-01-01

    New results of the reaction layer characterization between γ (U-7wt%Mo) alloy and Al, in chemical diffusion couples, are presented. The analysis was performed using optical and scanning electron microscopy with EDAX and X-ray diffraction techniques. Besides the main components (U, Mo)Al 3 and (U, Mo)Al 4 , already reported, two ternary compounds of high Al content have been identified in the reaction layer when it grew in retained or decomposed γ (U, Mo) phase, respectively. The drastic consequence on the interdiffusion behavior due to the thermal instability of the retained γ (U, Mo) phase is discussed. (author)

  10. Synthesis of most polyene natural product motifs using just 12 building blocks and one coupling reaction.

    Science.gov (United States)

    Woerly, Eric M; Roy, Jahnabi; Burke, Martin D

    2014-06-01

    The inherent modularity of polypeptides, oligonucleotides and oligosaccharides has been harnessed to achieve generalized synthesis platforms. Importantly, like these other targets, most small-molecule natural products are biosynthesized via iterative coupling of bifunctional building blocks. This suggests that many small molecules also possess inherent modularity commensurate with systematic building block-based construction. Supporting this hypothesis, here we report that the polyene motifs found in >75% of all known polyene natural products can be synthesized using just 12 building blocks and one coupling reaction. Using the same general retrosynthetic algorithm and reaction conditions, this platform enabled both the synthesis of a wide range of polyene frameworks that covered all of this natural-product chemical space and the first total syntheses of the polyene natural products asnipyrone B, physarigin A and neurosporaxanthin b-D-glucopyranoside. Collectively, these results suggest the potential for a more generalized approach to making small molecules in the laboratory.

  11. Synthesis of most polyene natural product motifs using just twelve building blocks and one coupling reaction

    Science.gov (United States)

    Woerly, Eric M.; Roy, Jahnabi; Burke, Martin D.

    2014-01-01

    The inherent modularity of polypeptides, oligonucleotides, and oligosaccharides has been harnessed to achieve generalized building block-based synthesis platforms. Importantly, like these other targets, most small molecule natural products are biosynthesized via iterative coupling of bifunctional building blocks. This suggests that many small molecules also possess inherent modularity commensurate with systematic building block-based construction. Supporting this hypothesis, here we report that the polyene motifs found in >75% of all known polyene natural products can be synthesized using just 12 building blocks and one coupling reaction. Using the same general retrosynthetic algorithm and reaction conditions, this platform enabled the synthesis of a wide range of polyene frameworks covering all of this natural product chemical space, and first total syntheses of the polyene natural products asnipyrone B, physarigin A, and neurosporaxanthin β-D-glucopyranoside. Collectively, these results suggest the potential for a more generalized approach for making small molecules in the laboratory. PMID:24848233

  12. Reaction monitoring using hyperpolarized NMR with scaling of heteronuclear couplings by optimal tracking

    Science.gov (United States)

    Zhang, Guannan; Schilling, Franz; Glaser, Steffen J.; Hilty, Christian

    2016-11-01

    Off-resonance decoupling using the method of Scaling of Heteronuclear Couplings by Optimal Tracking (SHOT) enables determination of heteronuclear correlations of chemical shifts in single scan NMR spectra. Through modulation of J-coupling evolution by shaped radio frequency pulses, off resonance decoupling using SHOT pulses causes a user-defined dependence of the observed J-splitting, such as the splitting of 13C peaks, on the chemical shift offset of coupled nuclei, such as 1H. Because a decoupling experiment requires only a single scan, this method is suitable for characterizing on-going chemical reactions using hyperpolarization by dissolution dynamic nuclear polarization (D-DNP). We demonstrate the calculation of [13C, 1H] chemical shift correlations of the carbanionic active sites from hyperpolarized styrene polymerized using sodium naphthalene as an initiator. While off resonance decoupling by SHOT pulses does not enhance the resolution in the same way as a 2D NMR spectrum would, the ability to obtain the correlations in single scans makes this method ideal for determination of chemical shifts in on-going reactions on the second time scale. In addition, we present a novel SHOT pulse that allows to scale J-splittings 50% larger than the respective J-coupling constant. This feature can be used to enhance the resolution of the indirectly detected chemical shift and reduce peak overlap, as demonstrated in a model reaction between p-anisaldehyde and isobutylamine. For both pulses, the accuracy is evaluated under changing signal-to-noise ratios (SNR) of the peaks from reactants and reaction products, with an overall standard deviation of chemical shift differences compared to reference spectra of 0.02 ppm when measured on a 400 MHz NMR spectrometer. Notably, the appearance of decoupling side-bands, which scale with peak intensity, appears to be of secondary importance.

  13. [Production of sugar syrup containing rare sugar using dual-enzyme coupled reaction system].

    Science.gov (United States)

    Han, Wenjia; Zhu, Yueming; Bai, Wei; Izumori, Ken; Zhang, Tongcun; Sun, Yuanxia

    2014-01-01

    Enzymatic conversion is very important to produce functional rare sugars, but the conversion rate of single enzymes is generally low. To increase the conversion rate, a dual-enzyme coupled reaction system was developed. Dual-enzyme coupled reaction system was constructed using D-psicose-3-epimerase (DPE) and L-rhamnose isomerase (L-RhI), and used to convert D-fructose to D-psicose and D-allose. The ratio of DPE and L-RhI was 1:10 (W/W), and the concentration of DPE was 0.05 mg/mL. The optimum temperature was 60 degrees C and pH was 9.0. When the concentration of D-fructose was 2%, the reaction reached its equilibrium after 10 h, and the yield of D-psicose and D-allose was 5.12 and 2.04 g/L, respectively. Using the dual-enzymes coupled system developed in the current study, we could obtain sugar syrup containing functional rare sugar from fructose-rich raw material, such as high fructose corn syrup.

  14. Vibronic coupling in ionized organic molecules: structural distortions and chemical reactions

    International Nuclear Information System (INIS)

    Williams, Ffrancon

    2003-01-01

    Ionized organic molecules (radical cations) in radiation chemistry are liable to undergo vibronic coupling whenever there is a relatively small energy gap (∼0.5-1.5 eV) between their ground and excited states. As a result of this mixing, the force constant for the symmetry-allowed vibrational mode that couples these states is lowered in the ground state of the radical cation so that deformation can take place more easily along this specific mode. This pseudo-Jahn-Teller effect can then result in a permanent structural distortion of the radical cation relative to the symmetry of the parent neutral molecule. It can also bring about an energetically favored pathway for a facile chemical rearrangement along a reaction coordinate defined by the coupling mode. Examples taken from matrix-isolation studies are used to illustrate these dramatic consequences of vibronic coupling in radical cations. Thus, the bicyclo[2.2.2]oct-2-ene and tetramethylurea radical cations are found to have twisted structures departing from the C 2v symmetry of their parent molecules, while the oxirane and bicyclo[1.1.1]pentane radical cations undergo ring-opening rearrangements along reaction coordinates that correspond to the deformational modes predicted by the pseudo-Jahn-Teller effect

  15. Heterogeneous redox reactions in groundwater flow systems - Investigation and application of two different coupled codes

    Energy Technology Data Exchange (ETDEWEB)

    Pfingsten, W.; Carnahan, C.L. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1995-05-01

    Two simulators of reactive chemical transport are applied to a set of problems involving heterogeneous reactions of uranium species. The simulators use similar algorithms to compute the heterogeneous chemical equilibria, but they use different approaches to the computation of solute transport and to the coupling of transport with chemical reactions. One simulator (MCOTAC) sequentially couples calculations of static chemical equilibria to a random-walk simulation of solute advection and dispersion. The other simulator (THCC) directly couples mass action relations for chemical equilibria to finite-difference representations of the solute transport equations. The aim of the comparison was to demonstrate the applicability of the newly developed code MCOTAC to redox problems, and to identify and investigate general differences between the two types of codes within these applications. The chosen heterogeneous redox systems are hypothetically generate systems which provide numerical difficulties within the coupled code calculation. Uranium, an important component of heterogeneous redox systems consisting of uraniferous solids and natural groundwaters, was chosen as a main component in the example redox systems because of practical interest for performance assessment of geological repositories for nuclear wastes. The calculations show reasonable agreement, in general, between the two computational approaches. Specific areas of disagreement arise from numerical difficulties to each approach. Such `benchmarking` can enhance confidence in the overall performance of individual simulators while identifying aspects that may require further investigations and possible modifications. (author) figs., tabs., 7 refs.

  16. THE LATEST ADVANCEMENTS IN THE ACYLATION REACTIONS VIA CROSS-DEHYDROGENATIVE COUPLING AND/OR METAL CATALYSTS

    Directory of Open Access Journals (Sweden)

    Soykan Ağar

    2017-12-01

    Full Text Available There are quite many examples in the scientific literature regarding the acylation reactions, especially the metal-catalyzed acylation reactions, metal-free acylation reactions, metal-catalyzed acylation via cross-dehydrogenative coupling (CDC reactions and metal-free acylation via cross-dehydrogenative coupling (CDC reactions. In this review paper, the most important examples of these domains were brought together and their mechanisms were exhibited in a clear, chronological format. Following these, the best example study towards green chemistry with a metal-free and high-yielding route was mentioned and discussed to demonstrate what has achieved in this field regarding the new acylation reaction mechanisms using the advantages of cross-dehydrogenative coupling (CDC reactions. The most prominent studies regarding these domains have been examined thoroughly and the latest progress in this field was explained in detail.

  17. Fe(HSO{sub 4}){sub 3} as an Efficient Catalyst for Diazotization and Diazo Coupling Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Rahimizadeh, Mohammad; Eshghi, Hossein; Shiri, Ali; Ghadamyari, Zohreh; Matin, Maryam M.; Pordeli, Parvaneh [Ferdowsi Univ. of Mashhad, Mashhad (Iran, Islamic Republic of); Oroojalian, Fatemeh [Univ. of Tehran, Tehran (Iran, Islamic Republic of)

    2012-12-15

    Diazo coupling reactions of aromatic amines with 2-naphthol in a green, efficient and easy procedure is described. Ferric hydrogensulfate catalyses this reaction in water at room temperature and short reaction time with high yields. The antibacterial activities of the synthesized compounds against four pathogenic bacteria are also investigated.

  18. Glaser coupling of polymers : side-reaction in huisgens "Click" coupling reaction and opportunity for polymers with focal diacetylene units in combination with ATRP

    NARCIS (Netherlands)

    Duxbury, C.J.; Cummins, D.M.; Heise, A.

    2009-01-01

    Atom, transfer radical polymerization (ATRP) was used in combination with Glaser type coupling, allowing the clean and efficient formation of symmetrically coupled polymers with a central diacetylene unit. The feasibility of the clean acetylene coupling was investigated with alkyne terminated

  19. Comparison of dynamical aspects of nonadiabatic electron, proton, and proton-coupled electron transfer reactions

    International Nuclear Information System (INIS)

    Hatcher, Elizabeth; Soudackov, Alexander; Hammes-Schiffer, Sharon

    2005-01-01

    The dynamical aspects of a model proton-coupled electron transfer (PCET) reaction in solution are analyzed with molecular dynamics simulations. The rate for nonadiabatic PCET is expressed in terms of a time-dependent probability flux correlation function. The impact of the proton donor-acceptor and solvent dynamics on the probability flux is examined. The dynamical behavior of the probability flux correlation function is dominated by a solvent damping term that depends on the energy gap correlation function. The proton donor-acceptor motion does not impact the dynamical behavior of the probability flux correlation function but does influence the magnitude of the rate. The approximations previously invoked for the calculation of PCET rates are tested. The effects of solvent damping on the proton donor-acceptor vibrational motion are found to be negligible, and the short-time solvent approximation, in which only equilibrium fluctuations of the solvent are considered, is determined to be valid for these types of reactions. The analysis of PCET reactions is compared to previous analyses of single electron and proton transfer reactions. The dynamical behavior is qualitatively similar for all three types of reactions, but the time scale of the decay of the probability flux correlation function is significantly longer for single proton transfer than for PCET and single electron transfer due to a smaller solvent reorganization energy for proton transfer

  20. Synthesis and catalytic activity of N-heterocyclic silylene (NHSi) cobalt hydride for Kumada coupling reactions.

    Science.gov (United States)

    Qi, Xinghao; Sun, Hongjian; Li, Xiaoyan; Fuhr, Olaf; Fenske, Dieter

    2018-02-20

    The electron-rich silylene Co(i) chloride 5 was obtained through the reaction of CoCl(PMe 3 ) 3 with chlorosilylene. Complex 5 reacted with 1,3-siladiazole HSiMe(NCH 2 PPh 2 ) 2 C 6 H 4 to give the silylene Co(iii) hydride 6 through chelate-assisted Si-H activation. To the best of our knowledge, complex 6 is the first example of Co(iii) hydride supported by N-heterocyclic silylene. Complexes 5 and 6 were fully characterized by spectroscopic methods and X-ray diffraction analysis. Complex 6 was used as an efficient precatalyst for Kumada cross-coupling reactions. Compared with the related complex 3 supported by only trimethylphosphine, complex 6 as a catalyst supported by both chlorosilylene and trimethylphosphine exhibits a more efficient performance for the Kumada cross-coupling reactions. A novel catalytic radical mechanism was suggested and experimentally verified. As an intermediate silylene cobalt(ii) chloride 6d was isolated and structurally characterized.

  1. Modeling networks of coupled enzymatic reactions using the total quasi-steady state approximation.

    Directory of Open Access Journals (Sweden)

    Andrea Ciliberto

    2007-03-01

    Full Text Available In metabolic networks, metabolites are usually present in great excess over the enzymes that catalyze their interconversion, and describing the rates of these reactions by using the Michaelis-Menten rate law is perfectly valid. This rate law assumes that the concentration of enzyme-substrate complex (C is much less than the free substrate concentration (S0. However, in protein interaction networks, the enzymes and substrates are all proteins in comparable concentrations, and neglecting C with respect to S0 is not valid. Borghans, DeBoer, and Segel developed an alternative description of enzyme kinetics that is valid when C is comparable to S0. We extend this description, which Borghans et al. call the total quasi-steady state approximation, to networks of coupled enzymatic reactions. First, we analyze an isolated Goldbeter-Koshland switch when enzymes and substrates are present in comparable concentrations. Then, on the basis of a real example of the molecular network governing cell cycle progression, we couple two and three Goldbeter-Koshland switches together to study the effects of feedback in networks of protein kinases and phosphatases. Our analysis shows that the total quasi-steady state approximation provides an excellent kinetic formalism for protein interaction networks, because (1 it unveils the modular structure of the enzymatic reactions, (2 it suggests a simple algorithm to formulate correct kinetic equations, and (3 contrary to classical Michaelis-Menten kinetics, it succeeds in faithfully reproducing the dynamics of the network both qualitatively and quantitatively.

  2. Oxidative coupling of methane. Still a challenge for catalyst development and reaction engineering

    Energy Technology Data Exchange (ETDEWEB)

    Schomaecker, R.; Arnd, S.; Beck, B. [Technical Univ. of Berlin (Germany). Dept. of Chemistry] [and others

    2013-11-01

    The oxidative coupling of methane to ethylene offers great industrial potential, because it would broaden the feedstock basis for chemical industry. Because methane is the most stable hydrocarbon, its activation requires high temperatures and it is a great scientific challenge to overcome the apparent yield limit of about 25%. This barrier has never been exceeded since the beginning of OCM research more than 20 years ago. Results and Discussion: This challenge is one of the key projects of the Cluster of Excellence UNICAT and requires joined efforts and contributions from many disciplines, because this reaction shows a combined surface/gas phase reaction mechanism which results in very unusual and complex dependencies on the reaction conditions. Although dozens of materials are known to catalyze the reaction, the selection of a catalyst suitable for an industrial process is difficult, due to severe stability problems of many materials. Li/MgO was chosen by the UNICAT-team as model catalyst, because of the extended literature about it. But it shows uncontrollable deactivation, no matter what precursor and method were used for its preparation. Nevertheless, it is a suitable catalyst for fundamental studies, due to its formal chemical simplicity. A key result of the joined research activities was the disproval of the Lunsford mechanism and the elucidation of the real function of lithium as a surface modifier creating a rough and defect-rich surface. For the development of an OCM process another catalyst, Na{sub 2}WO{sub 4}/Mn/SiO{sub 2}, was chosen from the rich literature on OCM. Although less is known about its structure and the reaction mechanism at this catalyst, its stability was the most important reason to select it for further engineering studies. Kinetic isotope measurements and studies in a TAP reactor demonstrate the similarity of the reaction mechanisms at both catalysts, despite the completely different materials. The selectivity is largely controlled by

  3. Optimality principle for the coupled chemical reactions of ATP synthesis and its molecular interpretation

    Science.gov (United States)

    Nath, Sunil

    2018-05-01

    Metabolic energy obtained from the coupled chemical reactions of oxidative phosphorylation (OX PHOS) is harnessed in the form of ATP by cells. We experimentally measured thermodynamic forces and fluxes during ATP synthesis, and calculated the thermodynamic efficiency, η and the rate of free energy dissipation, Φ. We show that the OX PHOS system is tuned such that the coupled nonequilibrium processes operate at optimal η. This state does not coincide with the state of minimum Φ but is compatible with maximum Φ under the imposed constraints. Conditions that must hold for species concentration in order to satisfy the principle of optimal efficiency are derived analytically and a molecular explanation based on Nath's torsional mechanism of energy transduction and ATP synthesis is suggested. Differences of the proposed principle with Prigogine's principle are discussed.

  4. A convenient catalyst system for microwave accelerated cross-coupling of a range of aryl boronic acids with aryl chlorides

    Directory of Open Access Journals (Sweden)

    Milton Edward J

    2007-05-01

    Full Text Available Abstract A convenient microwave accelerated cross-coupling procedure between aryl chlorides with a range of boronic acids has been developed. An explanation for the low reactivity of highly fluorinated boronic acids in Suzuki coupling is provided.

  5. Rapid syntheses of dehydrodiferulates via biomimetic radical coupling reactions of ethyl ferulate.

    Science.gov (United States)

    Lu, Fachuang; Wei, Liping; Azarpira, Ali; Ralph, John

    2012-08-29

    Dehydrodimerization of ferulates in grass cell walls provides a pathway toward cross-linking polysaccharide chains limiting the digestibility of carbohydrates by ruminant bacteria and in general affecting the utilization of grass as a renewable bioresource. Analysis of dehydrodiferulates (henceforth termed diferulates) in plant cell walls is useful in the evaluation of the quality of dairy forages as animal feeds. Therefore, there has been considerable demand for quantities of diferulates as standards for such analyses. Described here are syntheses of diferulates from ethyl ferulate via biomimetic radical coupling reactions using the copper(II)-tetramethylethylenediamine [CuCl(OH)-TMEDA] complex as oxidant or catalyst. Although CuCl(OH)-TMEDA oxidation of ethyl ferulate in acetonitrile produced mixtures composed of 8-O-4-, 8-5-, 8-8- (cyclic and noncyclic), and 5-5-coupled diferulates, a catalyzed oxidation using CuCl(OH)-TMEDA as catalyst and oxygen as an oxidant resulted in better overall yields of such diferulates. Flash chromatographic fractionation allowed isolation of 8-8- and 5-5-coupled diferulates. 8-5-Diferulate coeluted with 8-O-4-diferulate but was separated from it via crystallization; the 8-O-4 diferulate left in the mother solution was isolated by rechromatography following a simple tetrabutylammonium fluoride treatment that converted 8-5-diferulate to another useful diferulate, 8-5-(noncyclic) diferulate. Therefore, six of the nine (5-5, 8-O-4, 8-5-c, 8-5-nc, 8-5-dc, 8-8-c, 8-8-nc, 8-8-THF, 4-O-5) diferulic acids that have to date been found in the alkaline hydrolysates of plant cell walls can be readily synthesized by the CuCl(OH)-TMEDA catalyzed aerobic oxidative coupling reaction and subsequent saponification described here.

  6. Asymptotic stability of a coupled advection-diffusion-reaction system arising in bioreactor processes

    Directory of Open Access Journals (Sweden)

    Maria Crespo

    2017-08-01

    Full Text Available In this work, we present an asymptotic analysis of a coupled system of two advection-diffusion-reaction equations with Danckwerts boundary conditions, which models the interaction between a microbial population (e.g., bacteria, called biomass, and a diluted organic contaminant (e.g., nitrates, called substrate, in a continuous flow bioreactor. This system exhibits, under suitable conditions, two stable equilibrium states: one steady state in which the biomass becomes extinct and no reaction is produced, called washout, and another steady state, which corresponds to the partial elimination of the substrate. We use the linearization method to give sufficient conditions for the linear asymptotic stability of the two stable equilibrium configurations. Finally, we compare our asymptotic analysis with the usual asymptotic analysis associated to the continuous bioreactor when it is modeled with ordinary differential equations.

  7. New azo coupling reactions for visible spectrophotometric determination of salbutamol in bulk and pharmaceutical preparations

    International Nuclear Information System (INIS)

    Dhahir, S. A.

    2011-01-01

    The purpose of the present study was to develop a new, simple, cheap, fast, accurate, and sensitive colorimetric methods that can be used for the determination of salbutamol sulphate drug in pure from as well as in pharmaceutical formulations. The method is based on the reaction 2-chloro-4-nitroaniline with nitrite in acid medium to form diazonium ion, which is coupled with of salbutamol in basic medium to form azo dyes, showing yellow color and absorption maxima at 463 nm. Beer's law is obeyed in the concentration of 4-48μg/ml. The molar absorptivity and san dell's sensitivity are 5.27x103 L mole-1 cm-1, 0.015 μgcm-2, respectively. The optimum reaction conditions and other analytical parameters were evaluated. (author).

  8. Square Turing patterns in reaction-diffusion systems with coupled layers

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jing [State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871 (China); Wang, Hongli, E-mail: hlwang@pku.edu.cn, E-mail: qi@pku.edu.cn [State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871 (China); Center for Quantitative Biology, Peking University, Beijing 100871 (China); Ouyang, Qi, E-mail: hlwang@pku.edu.cn, E-mail: qi@pku.edu.cn [State Key Laboratory for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871 (China); Center for Quantitative Biology, Peking University, Beijing 100871 (China); The Peking-Tsinghua Center for Life Sciences, Beijing 100871 (China)

    2014-06-15

    Square Turing patterns are usually unstable in reaction-diffusion systems and are rarely observed in corresponding experiments and simulations. We report here an example of spontaneous formation of square Turing patterns with the Lengyel-Epstein model of two coupled layers. The squares are found to be a result of the resonance between two supercritical Turing modes with an appropriate ratio. Besides, the spatiotemporal resonance of Turing modes resembles to the mode-locking phenomenon. Analysis of the general amplitude equations for square patterns reveals that the fixed point corresponding to square Turing patterns is stationary when the parameters adopt appropriate values.

  9. A sensitive DNA biosensor based on a facile sulfamide coupling reaction for capture probe immobilization

    International Nuclear Information System (INIS)

    Wang, Qingxiang; Ding, Yingtao; Gao, Feng; Jiang, Shulian; Zhang, Bin; Ni, Jiancong; Gao, Fei

    2013-01-01

    Graphical abstract: A novel DNA biosensor was fabricated through a facile sulfamide coupling reaction between probe DNA and the sulfonic dye of 1-amino-2-naphthol-4-sulfonic acid that electrodeposited on a glassy carbon electrode. -- Highlights: •A versatile sulfonic dye of ANS was electrodeposited on a GCE. •A DNA biosensor was fabricated based on a facile sulfamide coupling reaction. •High probe DNA density of 3.18 × 10 13 strands cm −2 was determined. •A wide linear range and a low detection limit were obtained. -- Abstract: A novel DNA biosensor was fabricated through a facile sulfamide coupling reaction. First, the versatile sulfonic dye molecule of 1-amino-2-naphthol-4-sulfonate (AN-SO 3 − ) was electrodeposited on the surface of a glassy carbon electrode (GCE) to form a steady and ordered AN-SO 3 − layer. Then the amino-terminated capture probe was covalently grafted to the surface of SO 3 − -AN deposited GCE through the sulfamide coupling reaction between the amino groups in the probe DNA and the sulfonic groups in the AN-SO 3 − . The step-by-step modification process was characterized by electrochemistry and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Using Ru(NH 3 ) 6 3+ as probe, the probe density and the hybridization efficiency of the biosensor were determined to be 3.18 × 10 13 strands cm −2 and 86.5%, respectively. The hybridization performance of the biosensor was examined by differential pulse voltammetry using Co(phen) 3 3+/2+ (phen = 1,10-phenanthroline) as the indicator. The selectivity experiments showed that the biosensor presented distinguishable response after hybridization with the three-base mismatched, non-complementary and complementary sequences. Under the optimal conditions, the oxidation peak currents of Co(phen) 3 3+/2+ increased linearly with the logarithm values of the concentration of the complementary sequences in the range from 1.0 × 10 −13 M to 1.0 × 10 −8 M with

  10. Numerical simulations of heterogeneous chemical reactions coupled to fluid flow in varying thermal fields

    International Nuclear Information System (INIS)

    Carnahan, C.L.

    1991-11-01

    A numerical simulator of reactive chemical transport with coupling from precipitation-dissolution reactions to fluid flow, via changes of porosity and permeability, is applied to precipitation-dissolution of quartz and calcite in spatially and temporally variable fields of temperature. Significant effects on fluid flow are found in the quartz-silicic acid system in the presence of persistent, strong gradient of temperature. Transient heat flow in the quartz-silicic acid system and in a calcite-calcium ion-carbonato species system produces vanishingly small effects on fluid flow

  11. Interrogating the catalytic mechanism of nanoparticle mediated Stille coupling reactions employing bio-inspired Pd nanocatalysts

    Science.gov (United States)

    Pacardo, Dennis B.; Slocik, Joseph M.; Kirk, Kyle C.; Naik, Rajesh R.; Knecht, Marc R.

    2011-05-01

    To address issues concerning the global environmental and energy state, new catalytic technologies must be developed that translate ambient and efficient conditions to heavily used reactions. To achieve this, the structure/function relationship between model catalysts and individual reactions must be critically discerned to identify structural motifs responsible for the reactivity. This is especially true for nanoparticle-based systems where this level of information remains limited. Here we present evidence indicating that peptide-capped Pd nanoparticles drive Stille C-C coupling reactions via Pd atom leaching. Through a series of reaction studies, the materials are shown to be optimized for reactivity under ambient conditions where increases in temperature or catalyst concentration deactivate reactivity due to the leaching process. A quartz crystal microbalance analysis demonstrates that Pd leaching occurs during the initial oxidative addition step at the nanoparticle surface by aryl halides. Together, this suggests that peptide-based materials may be optimally suited for use as model systems to isolate structural motifs responsible for the generation of catalytically reactive materials under ambient synthetic conditions.

  12. Interrogating the catalytic mechanism of nanoparticle mediated Stille coupling reactions employing bio-inspired Pd nanocatalysts.

    Science.gov (United States)

    Pacardo, Dennis B; Slocik, Joseph M; Kirk, Kyle C; Naik, Rajesh R; Knecht, Marc R

    2011-05-01

    To address issues concerning the global environmental and energy state, new catalytic technologies must be developed that translate ambient and efficient conditions to heavily used reactions. To achieve this, the structure/function relationship between model catalysts and individual reactions must be critically discerned to identify structural motifs responsible for the reactivity. This is especially true for nanoparticle-based systems where this level of information remains limited. Here we present evidence indicating that peptide-capped Pd nanoparticles drive Stille C-C coupling reactions via Pd atom leaching. Through a series of reaction studies, the materials are shown to be optimized for reactivity under ambient conditions where increases in temperature or catalyst concentration deactivate reactivity due to the leaching process. A quartz crystal microbalance analysis demonstrates that Pd leaching occurs during the initial oxidative addition step at the nanoparticle surface by aryl halides. Together, this suggests that peptide-based materials may be optimally suited for use as model systems to isolate structural motifs responsible for the generation of catalytically reactive materials under ambient synthetic conditions. © The Royal Society of Chemistry 2011

  13. Determining Li+-Coupled Redox Targeting Reaction Kinetics of Battery Materials with Scanning Electrochemical Microscopy.

    Science.gov (United States)

    Yan, Ruiting; Ghilane, Jalal; Phuah, Kia Chai; Pham Truong, Thuan Nguyen; Adams, Stefan; Randriamahazaka, Hyacinthe; Wang, Qing

    2018-02-01

    The redox targeting reaction of Li + -storage materials with redox mediators is the key process in redox flow lithium batteries, a promising technology for next-generation large-scale energy storage. The kinetics of the Li + -coupled heterogeneous charge transfer between the energy storage material and redox mediator dictates the performance of the device, while as a new type of charge transfer process it has been rarely studied. Here, scanning electrochemical microscopy (SECM) was employed for the first time to determine the interfacial charge transfer kinetics of LiFePO 4 /FePO 4 upon delithiation and lithiation by a pair of redox shuttle molecules FcBr 2 + and Fc. The effective rate constant k eff was determined to be around 3.70-6.57 × 10 -3 cm/s for the two-way pseudo-first-order reactions, which feature a linear dependence on the composition of LiFePO 4 , validating the kinetic process of interfacial charge transfer rather than bulk solid diffusion. In addition, in conjunction with chronoamperometry measurement, the SECM study disproves the conventional "shrinking-core" model for the delithiation of LiFePO 4 and presents an intriguing way of probing the phase boundary propagations induced by interfacial redox reactions. This study demonstrates a reliable method for the kinetics of redox targeting reactions, and the results provide useful guidance for the optimization of redox targeting systems for large-scale energy storage.

  14. Diazo compounds and N-tosylhydrazones: novel cross-coupling partners in transition-metal-catalyzed reactions.

    Science.gov (United States)

    Xiao, Qing; Zhang, Yan; Wang, Jianbo

    2013-02-19

    Transition-metal-catalyzed carbene transformations and cross-couplings represent two major reaction types in organometallic chemistry and organic synthesis. However, for a long period of time, these two important areas have evolved separately, with essentially no overlap or integration. Thus, an intriguing question has emerged: can cross-coupling and metal carbene transformations be merged into a single reaction cycle? Such a combination could facilitate the development of novel carbon-carbon bond-forming methodologies. Although this concept was first explored about 10 years ago, rapid developments inthis area have been achieved recently. Palladium catalysts can be used to couple diazo compounds with a wide variety of organic halides. Under oxidative coupling conditions, diazo compounds can also react with arylboronic acids and terminal alkynes. Both of these coupling reactions form carbon-carbon double bonds. As the key step in these catalytic processes, Pd carbene migratory insertion plays a vital role in merging the elementary steps of Pd intermediates, leading to novel carbon-carbon bond formations. Because the diazo substrates can be generated in situ from N-tosylhydrazones in the presence of base, the N-tosylhydrazones can be used as reaction partners, making this type of cross-coupling reaction practical in organic synthesis. N-Tosylhydrazones are easily derived from the corresponding aldehydes or ketones. The Pd-catalyzed cross-coupling of N-tosylhydrazones is considered a complementary reaction to the classic Shapiro reaction for converting carbonyl functionalities into carbon-carbon double bonds. It can also serve as an alternative approach for the Pd-catalyzed cross-coupling of carbonyl compounds, which is usually achieved via triflates. The combination of carbene formation and cross-coupling in a single catalytic cycle is not limited to Pd-catalyzed reactions. Recent studies of Cu-, Rh-, Ni-, and Co-catalyzed cross-coupling reactions with diazo

  15. Palladium-Catalyzed Heck Coupling Reaction of Aryl Bromides in Aqueous Media Using Tetrahydropyrimidinium Salts as Carbene Ligands

    Directory of Open Access Journals (Sweden)

    İsmail Özdemir

    2010-01-01

    Full Text Available An efficient and stereoselective catalytic system for the Heck cross coupling reaction using novel 1,3-dialkyl-3,4,5,6-tetrahydropyrimidinium salts (1, LHX and Pd(OAc2 loading has been reported. The palladium complexes derived from the salts 1a-f prepared in situ exhibit good catalytic activity in the Heck coupling reaction of aryl bromides under mild conditions.

  16. Catalytic Upgrading of Biomass-Derived Compounds via C-C Coupling Reactions. Computational and Experimental Studies of Acetaldehyde and Furan Reactions in HZSM-5

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cong [Argonne National Lab. (ANL), Argonne, IL (United States); Evans, Tabitha J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Cheng, Lei [Argonne National Lab. (ANL), Argonne, IL (United States); Nimlos, Mark R. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Mukarakate, Calvin [National Renewable Energy Lab. (NREL), Golden, CO (United States); Robichaud, David J. [National Renewable Energy Lab. (NREL), Golden, CO (United States); Assary, Rajeev S. [Argonne National Lab. (ANL), Argonne, IL (United States); Curtiss, Larry A. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-10-02

    These catalytic C–C coupling and deoxygenation reactions are essential for upgrading of biomass-derived oxygenates to fuel-range hydrocarbons. Detailed understanding of mechanistic and energetic aspects of these reactions is crucial to enabling and improving the catalytic upgrading of small oxygenates to useful chemicals and fuels. Using periodic density functional theory (DFT) calculations, we have investigated the reactions of furan and acetaldehyde in an HZSM-5 zeolite catalyst, a representative system associated with the catalytic upgrading of pyrolysis vapors. Comprehensive energy profiles were computed for self-reactions (i.e., acetaldehyde coupling and furan coupling) and cross-reactions (i.e., acetaldehyde + furan) of this representative mixture. Major products proposed from the computations are further confirmed using temperature controlled mass spectra measurements. Moreover, the computational results show that furan interacts with acetaldehyde in HZSM-5 via an alkylation mechanism, which is more favorable than the self-reactions, indicating that mixing furans with aldehydes could be a promising approach to maximize effective C–C coupling and dehydration while reducing the catalyst deactivation (e.g., coke formation) from aldehyde condensation.

  17. Bite angle effects of diphosphines in C-C and C-X bond forming cross coupling reactions

    NARCIS (Netherlands)

    Birkholz, M.N.; Freixa, Z.; van Leeuwen, P.W.N.M.

    2009-01-01

    Catalytic reactions of C-C and C-X bond formation are discussed in this critical review with particular emphasis on cross coupling reactions catalyzed by palladium and wide bite angle bidentate diphosphine ligands. Especially those studies have been collected that allow comparison of the ligand bite

  18. RDH13L, an enzyme responsible for the aldehyde-alcohol redox coupling reaction (AL-OL coupling reaction) to supply 11-cis retinal in the carp cone retinoid cycle.

    Science.gov (United States)

    Sato, Shinya; Miyazono, Sadaharu; Tachibanaki, Shuji; Kawamura, Satoru

    2015-01-30

    Cone photoreceptors require effective pigment regeneration mechanisms to maintain their sensitivity in the light. Our previous studies in carp cones suggested the presence of an unconventional and very effective mechanism to produce 11-cis retinal, the necessary component in pigment regeneration. In this reaction (aldehyde-alcohol redox coupling reaction, AL-OL coupling reaction), formation of 11-cis retinal, i.e. oxidation of 11-cis retinol is coupled to reduction of an aldehyde at a 1:1 molar ratio without exogenous NADP(H) which is usually required in this kind of reaction. Here, we identified carp retinol dehydrogenase 13-like (RDH13L) as an enzyme catalyzing the AL-OL coupling reaction. RDH13L was partially purified from purified carp cones, identified as a candidate protein, and its AL-OL coupling activity was confirmed using recombinant RDH13L. We further examined the substrate specificity, subcellular localization, and expression level of RDH13L. Based on these results, we concluded that RDH13L contributes to a significant part, but not all, of the AL-OL coupling activity in carp cones. RDH13L contained tightly bound NADP(+) which presumably functions as a cofactor in the reaction. Mouse RDH14, a mouse homolog of carp RDH13L, also showed the AL-OL coupling activity. Interestingly, although carp cone membranes, carp RDH13L and mouse RDH14 all showed the coupling activity at 15-37 °C, they also showed a conventional NADP(+)-dependent 11-cis retinol oxidation activity above 25 °C without addition of aldehydes. This dual mechanism of 11-cis retinal synthesis attained by carp RDH13L and mouse RDH14 probably contribute to effective pigment regeneration in cones that function in the light. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Modeling of the Reaction Mechanism of Enzymatic Radical C–C Coupling by Benzylsuccinate Synthase

    Directory of Open Access Journals (Sweden)

    Maciej Szaleniec

    2016-04-01

    Full Text Available Molecular modeling techniques and density functional theory calculations were performed to study the mechanism of enzymatic radical C–C coupling catalyzed by benzylsuccinate synthase (BSS. BSS has been identified as a glycyl radical enzyme that catalyzes the enantiospecific fumarate addition to toluene initiating its anaerobic metabolism in the denitrifying bacterium Thauera aromatica, and this reaction represents the general mechanism of toluene degradation in all known anaerobic degraders. In this work docking calculations, classical molecular dynamics (MD simulations, and DFT+D2 cluster modeling was employed to address the following questions: (i What mechanistic details of the BSS reaction yield the most probable molecular model? (ii What is the molecular basis of enantiospecificity of BSS? (iii Is the proposed mechanism consistent with experimental observations, such as an inversion of the stereochemistry of the benzylic protons, syn addition of toluene to fumarate, exclusive production of (R-benzylsuccinate as a product and a kinetic isotope effect (KIE ranging between 2 and 4? The quantum mechanics (QM modeling confirms that the previously proposed hypothetical mechanism is the most probable among several variants considered, although C–H activation and not C–C coupling turns out to be the rate limiting step. The enantiospecificity of the enzyme seems to be enforced by a thermodynamic preference for binding of fumarate in the pro(R orientation and reverse preference of benzyl radical attack on fumarate in pro(S pathway which results with prohibitively high energy barrier of the radical quenching. Finally, the proposed mechanism agrees with most of the experimental observations, although the calculated intrinsic KIE from the model (6.5 is still higher than the experimentally observed values (4.0 which suggests that both C–H activation and radical quenching may jointly be involved in the kinetic control of the reaction.

  20. Vibronic coupling in ionized organic molecules. Structural distortions and chemical reactions

    International Nuclear Information System (INIS)

    Williams, F.

    2002-01-01

    Complete text of publication follows. Ionized organic molecules (radical cations, RC) are prone to undergo vibronic coupling whenever there is a relatively small energy gap ( 2v point group of the neutral parent molecule by twisting at the olefinic π bond to the lower C 2 symmetry in the RC (Chem. Eur. J. 2002, 8, 1074). These experiments clearly revealed a double minimum in the potential energy surface along the a 2 torsional mode. This is in accord with the coupling of the 2 B 1 and 2 B 2 Born-Oppenheimer states in C 2v symmetry, this mixing of the 2 B 1 π-ionized ground state and the 2 B 2 δ-ionized excited state being facilitated by the low (∼ 1.0 eV) gap between these states, as estimated from photoelectron spectroscopy. Turning to the second class of RC where unimolecular rearrangement reactions are promoted by vibronic interaction, several cases have emerged where the rearrangement would not be expected if it were based only on the ground-state properties of the RC. It was found (Chem. Phy. Lett. 1988, 143, 521) that the ethylene oxide RC undergoes C-C ring opening to the oxallyl species despite the fact that the ground state corresponds to ionization from the nonbonding oxygen π lone-pair orbital. The reaction develops excited-state character as a result of the vibronic mixing so that the activation barrier to ring opening is lowered. We will discuss the unusual rearrangements of the bicyclo[1.1.1.]pentane and [1.1.1]propellane RC from a similar perspective, emphasis being placed on the decisive role of symmetry in predicting the course of these rearrangements. We illustrate how this approach can reconcile conflicting considerations on some of the 'unexpected' reaction pathways followed by highly strained organic RC

  1. Coupled enzyme reactions performed in heterogeneous reaction media: experiments and modeling for glucose oxidase and horseradish peroxidase in a PEG/citrate aqueous two-phase system.

    Science.gov (United States)

    Aumiller, William M; Davis, Bradley W; Hashemian, Negar; Maranas, Costas; Armaou, Antonios; Keating, Christine D

    2014-03-06

    The intracellular environment in which biological reactions occur is crowded with macromolecules and subdivided into microenvironments that differ in both physical properties and chemical composition. The work described here combines experimental and computational model systems to help understand the consequences of this heterogeneous reaction media on the outcome of coupled enzyme reactions. Our experimental model system for solution heterogeneity is a biphasic polyethylene glycol (PEG)/sodium citrate aqueous mixture that provides coexisting PEG-rich and citrate-rich phases. Reaction kinetics for the coupled enzyme reaction between glucose oxidase (GOX) and horseradish peroxidase (HRP) were measured in the PEG/citrate aqueous two-phase system (ATPS). Enzyme kinetics differed between the two phases, particularly for the HRP. Both enzymes, as well as the substrates glucose and H2O2, partitioned to the citrate-rich phase; however, the Amplex Red substrate necessary to complete the sequential reaction partitioned strongly to the PEG-rich phase. Reactions in ATPS were quantitatively described by a mathematical model that incorporated measured partitioning and kinetic parameters. The model was then extended to new reaction conditions, i.e., higher enzyme concentration. Both experimental and computational results suggest mass transfer across the interface is vital to maintain the observed rate of product formation, which may be a means of metabolic regulation in vivo. Although outcomes for a specific system will depend on the particulars of the enzyme reactions and the microenvironments, this work demonstrates how coupled enzymatic reactions in complex, heterogeneous media can be understood in terms of a mathematical model.

  2. A coupled reaction and transport model for assessing the injection, migration and fate of waste fluids

    International Nuclear Information System (INIS)

    Liu, X.; Ortoleva, P.

    1996-01-01

    The use of reaction-transport modeling for reservoir assessment and management in the context of deep well waste injection is evaluated. The study is based on CIRF.A (Chemical Interaction of Rock and Fluid), a fully coupled multiphase flow, contaminant transport, and fluid and mineral reaction model. Although SWIFT (Sandia Waste-Isolation Flow and Transport Model) is often the numerical model of choice, it can not account for chemical reactions involving rock, wastes, and formation fluids and their effects on contaminant transport, rock permeability and porosity, and the integrity of the reservoir and confining units. CIRF.A can simulate all these processes. Two field cases of waste injection were simulated by CIRF.A. Both observation data and simulation results show mineral precipitation in one case and rock dissolution in another case. Precipitation and dissolution change rock porosity and permeability, and hence the pattern of fluid migration. The model is shown to be invaluable in analyzing near borehole and reservoir-scale effects during waste injection and predicting the 10,000 year fate of the waste plume. The benefits of using underpressured compartments as waste repositories were also demonstrated by CIRF.A simulations

  3. Advantageous Microwave-Assisted Suzuki Polycondensation for the Synthesis of Aniline-Fluorene Alternate Copolymers as Molecular Model with Solvent Sensing Properties

    Directory of Open Access Journals (Sweden)

    Rebeca Vázquez-Guilló

    2018-02-01

    Full Text Available Polymerization via Suzuki coupling under microwave (µW irradiation has been studied for the synthesis of poly{1,4-(2/3-aminobenzene-alt-2,7-(9,9-dihexylfluorene} (PAF, chosen as molecular model. Briefly, µW-assisted procedures accelerated by two orders of magnitude the time required when using classical polymerization processes, and the production yield was increased (>95%. In contrast, although the sizes of the polymers that were obtained by non-conventional heating reactions were reproducible and adequate for most applications, with this methodology the molecular weight of final polymers were not increased with respect to conventional heating. Asymmetric orientation of the amine group within the monomer and the assignments of each dyad or regioregularity, whose values ranged from 38% to 95% with this molecule, were analysed using common NMR spectroscopic data. Additionally, the synthesis of a new cationic polyelectrolyte, poly{1,4-(2/3-aminobenzene-co-alt-2,7-[9,9´-bis(6’’-N,N,N-trimethylammonium-hexylfluorene]} dibromide (PAFAm, from poly{1,4-(2/3-aminobenzene-co-alt-2,7-[9,9´-bis(6’’-bromohexylfluorene]} (PAFBr by using previously optimized conditions for µW-assisted heating procedures was reported. Finally, the characterization of the final products from these batches showed unkown interesting solvatochromic properties of the PAF molecule. The study of the solvatochromism phenomena, which was investigated as a function of the polarity of the solvents, showed a well-defined Lippert correlation, indicating that the emission shift observed in PAF might be due to its interaction with surrounding environment. Proven high sensitivity to changes of its environment makes PAF a promising candidate of sensing applications.

  4. Click and chemically triggered declick reactions through reversible amine and thiol coupling via a conjugate acceptor

    Science.gov (United States)

    Diehl, Katharine L.; Kolesnichenko, Igor V.; Robotham, Scott A.; Bachman, J. Logan; Zhong, Ye; Brodbelt, Jennifer S.; Anslyn, Eric V.

    2016-10-01

    The coupling and decoupling of molecular units is a fundamental undertaking of organic chemistry. Herein we report the use of a very simple conjugate acceptor, derived from Meldrum's acid, for the sequential ‘clicking’ together of an amine and a thiol in aqueous conditions at neutral pH. Subsequently, this linkage can be ‘declicked’ by a chemical trigger to release the original amine and thiol undisturbed. The reactivity differs from that of other crosslinking agents because the selectivity for sequential functionalization derives from an altering of the electrophilicity of the conjugate acceptor on the addition of the amine. We describe the use of the procedure to modify proteins, create multicomponent libraries and synthesize oligomers, all of which can be declicked to their starting components in a controlled fashion when desired. Owing to the mild reaction conditions and ease of use in a variety of applications, the method is predicted to have wide utility.

  5. A coupled model of transport-reaction-mechanics with trapping. Part I - Small strain analysis

    Science.gov (United States)

    Salvadori, A.; McMeeking, R.; Grazioli, D.; Magri, M.

    2018-05-01

    A fully coupled model for mass and heat transport, mechanics, and chemical reactions with trapping is proposed. It is rooted in non-equilibrium rational thermodynamics and assumes that displacements and strains are small. Balance laws for mass, linear and angular momentum, energy, and entropy are stated. Thermodynamic restrictions are identified, based on an additive strain decomposition and on the definition of the Helmholtz free energy. Constitutive theory and chemical kinetics are studied in order to finally write the governing equations for the multi-physics problem. The field equations are solved numerically with the finite element method, stemming from a three-fields variational formulation. Three case-studies on vacancies redistribution in metals, hydrogen embrittlement, and the charge-discharge of active particles in Li-ion batteries demonstrate the features and the potential of the proposed model.

  6. Numerical Model of Dephosphorization Reaction Kinetics in Top Blown Converter Coupled with Flow Field

    Science.gov (United States)

    Liu, Wei; Yang, Shufeng; Li, Jingshe; Wang, Minghui

    2017-07-01

    A 3D transient numerical model of dephosphorization kinetics coupled with flow field in a top blown converter was built. Through the model the dephosphorization reaction rate influenced by the oxygen jets and the steel flow were simulated. The results show that the dephosphorization rate at the droplet metal-slag interface is two orders of magnitude faster than that at bath metal-slag interface. When the lance oxygen pressure increases from 0.7 to 0.8 MPa, the dephosphorization rate increases notably and the end content of P has a decrease of 19 %. However, when the pressure continues rising to 0.9 MPa, the dephosphorization rate has no significant increase. In addition, the lance height shows a nearly linear relation to the end P content of steel, that the lower the height, the faster the dephosphorization rate.

  7. Implicit coupling of turbulent diffusion with chemical reaction mechanisms for prognostic atmospheric dispersion models

    Energy Technology Data Exchange (ETDEWEB)

    Berlowitz, D.R.

    1996-11-01

    In the last few decades the negative impact by humans on the thin atmospheric layer enveloping the earth, the basis for life on this planet, has increased steadily. In order to halt, or at least slow down this development, the knowledge and study of these anthropogenic influence has to be increased and possible remedies have to be suggested. An important tool for these studies are computer models. With their help the atmospheric system can be approximated and the various processes, which have led to the current situation can be quantified. They also serve as an instrument to assess short or medium term strategies to reduce this human impact. However, to assure efficiency as well as accuracy, a careful analysis of the numerous processes involved in the dispersion of pollutants in the atmosphere is called for. This should help to concentrate on the essentials and also prevent excessive usage of sometimes scarce computing resources. The basis of the presented work is the EUMAC Zooming Model (ETM), and particularly the component calculating the dispersion of pollutants in the atmosphere, the model MARS. The model has two main parts: an explicit solver, where the advection and the horizontal diffusion of pollutants are calculated, and an implicit solution mechanism, allowing the joint computation of the change of concentration due to chemical reactions, coupled with the respective influence of the vertical diffusion of the species. The aim of this thesis is to determine particularly the influence of the horizontal components of the turbulent diffusion on the existing implicit solver of the model. Suggestions for a more comprehensive inclusion of the full three dimensional diffusion operator in the implicit solver are made. This is achieved by an appropriate operator splitting. A selection of numerical approaches to tighten the coupling of the diffusion processes with the calculation of the applied chemical reaction mechanisms are examined. (author) figs., tabs., refs.

  8. A two-dimensional conjugated aromatic polymer via C-C coupling reaction

    Science.gov (United States)

    Liu, Wei; Luo, Xin; Bao, Yang; Liu, Yan Peng; Ning, Guo-Hong; Abdelwahab, Ibrahim; Li, Linjun; Nai, Chang Tai; Hu, Zhi Gang; Zhao, Dan; Liu, Bin; Quek, Su Ying; Loh, Kian Ping

    2017-06-01

    The fabrication of crystalline 2D conjugated polymers with well-defined repeating units and in-built porosity presents a significant challenge to synthetic chemists. Yet they present an appealing target because of their desirable physical and electronic properties. Here we report the preparation of a 2D conjugated aromatic polymer synthesized via C-C coupling reactions between tetrabromopolyaromatic monomers. Pre-arranged monomers in the bulk crystal undergo C-C coupling driven by endogenous solid-state polymerization to produce a crystalline polymer, which can be mechanically exfoliated into micrometre-sized lamellar sheets with a thickness of 1 nm. Isothermal gas-sorption measurements of the bulk material reveal a dominant pore size of ~0.6 nm, which indicates uniform open channels from the eclipsed stacking of the sheets. When employed as an organic anode in an ambient-temperature sodium cell, the material allows a fast charge/discharge of sodium ions, with impressive reversible capacity, rate capability and stability metrics.

  9. Polymer and Membrane Design for Low Temperature Catalytic Reactions

    KAUST Repository

    Villalobos, Luis Francisco; Xie, Yihui; Nunes, Suzana Pereira; Peinemann, Klaus-Viktor

    2016-01-01

    Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane's ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Polymer and Membrane Design for Low Temperature Catalytic Reactions

    KAUST Repository

    Villalobos, Luis Francisco

    2016-02-29

    Catalytically active asymmetric membranes have been developed with high loadings of palladium nanoparticles located solely in the membrane\\'s ultrathin skin layer. The manufacturing of these membranes requires polymers with functional groups, which can form insoluble complexes with palladium ions. Three polymers have been synthesized for this purpose and a complexation/nonsolvent induced phase separation followed by a palladium reduction step is carried out to prepare such membranes. Parameters to optimize the skin layer thickness and porosity, the palladium loading in this layer, and the palladium nanoparticles size are determined. The catalytic activity of the membranes is verified with the reduction of a nitro-compound and with a liquid phase Suzuki-Miyaura coupling reaction. Very low reaction times are observed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. New Diazo Coupling Reactions for Visible Spectrophotometric Determination of Alfuzosin in Pharmaceutical Preparations

    Directory of Open Access Journals (Sweden)

    M. Vamsi Krishna

    2007-01-01

    Full Text Available Simple, rapid and sensitive spectrophotometric procedures were developed for the analysis of Alfuzosin hydrochloride (AFZ in pure form as well as in pharmaceutical formulations. The methods are based on the reaction of AFZ with nitrite in acid medium to form diazonium ion, which is coupled with ethoxyethylenemaleic ester (Method A or ethylcyanoacetate (Method B or acetyl acetone (method C in basic medium to form azo dyes, showing absorption maxima at 440, 465 and 490 nm respectively. Beer’s law is obeyed in the concentration of 4-20 μg/mL of AFZ for methods A, B and 3-15 μg/mL of AFZ for method C. The molar absorptivity and sandell’s sensitivity of AFZ- ethoxyethylenemaleic ester, AFZ- ethylcyanoacetate and AFZ-acetyl acetone are1.90 × 104, 0.022; 1.93 × 104, 0.021 and 2.67 × 104 L mole-1 cm-1, 0.015 μg cm-2 respectively. The optimum reaction conditions and other analytical parameters were evaluated. The methods were successfully applied to the determination of AFZ in pharmaceutical formulations.

  12. Characterization of the reaction layer in U-7wt%Mo/Al diffusion couples

    Energy Technology Data Exchange (ETDEWEB)

    Mirandou, M.I.; Balart, S.N.; Ortiz, M.; Granovsky, M.S. E-mail: granovsk@cnea.gov.ar

    2003-11-15

    The reaction layer in chemical diffusion couples U-7wt%Mo/Al was investigated using optical and scanning electron microscopy, electron probe microanalysis and X-ray diffraction (XRD) techniques. When the U-7wt%Mo alloy was previously homogenized and the {gamma}(U, Mo) phase was retained, the formation of (U, Mo)Al{sub 3} and (U, Mo)Al{sub 4} was observed at 580 deg. C. Also a very thin band was detected close to the Al side, the structure of the ternary compound Al{sub 20}UMo{sub 2} might be assigned to it. When the decomposition of the {gamma}(U, Mo) took place, a drastic change in the diffusion behavior was observed. In this case, XRD indicated the presence of phases with the structures of (U, Mo)Al{sub 3}, Al{sub 43}U{sub 6}Mo{sub 4}, {gamma}(U, Mo) and {alpha}(U) in the reaction layer.

  13. Review on modeling development for multiscale chemical reactions coupled transport phenomena in solid oxide fuel cells

    International Nuclear Information System (INIS)

    Andersson, Martin; Yuan, Jinliang; Sunden, Bengt

    2010-01-01

    A literature study is performed to compile the state-of-the-art, as well as future potential, in SOFC modeling. Principles behind various transport processes such as mass, heat, momentum and charge as well as for electrochemical and internal reforming reactions are described. A deeper investigation is made to find out potentials and challenges using a multiscale approach to model solid oxide fuel cells (SOFCs) and combine the accuracy at microscale with the calculation speed at macroscale to design SOFCs, based on a clear understanding of transport phenomena, chemical reactions and functional requirements. Suitable methods are studied to model SOFCs covering various length scales. Coupling methods between different approaches and length scales by multiscale models are outlined. Multiscale modeling increases the understanding for detailed transport phenomena, and can be used to make a correct decision on the specific design and control of operating conditions. It is expected that the development and production costs will be decreased and the energy efficiency be increased (reducing running cost) as the understanding of complex physical phenomena increases. It is concluded that the connection between numerical modeling and experiments is too rare and also that material parameters in most cases are valid only for standard materials and not for the actual SOFC component microstructures.

  14. A coupled mechanical and chemical damage model for concrete affected by alkali–silica reaction

    Energy Technology Data Exchange (ETDEWEB)

    Pignatelli, Rossella, E-mail: rossellapignatelli@gmail.com [Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano (Italy); Lombardi Ingegneria S.r.l., Via Giotto 36, 20145 Milano (Italy); Comi, Claudia, E-mail: comi@stru.polimi.it [Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano (Italy); Monteiro, Paulo J.M., E-mail: monteiro@ce.berkeley.edu [Department of Civil and Environmental Engineering, University of California, Berkeley, CA 94720 (United States)

    2013-11-15

    To model the complex degradation phenomena occurring in concrete affected by alkali–silica reaction (ASR), we formulate a poro-mechanical model with two isotropic internal variables: the chemical and the mechanical damage. The chemical damage, related to the evolution of the reaction, is caused by the pressure generated by the expanding ASR gel on the solid concrete skeleton. The mechanical damage describes the strength and stiffness degradation induced by the external loads. As suggested by experimental results, degradation due to ASR is considered to be localized around reactive sites. The effect of the degree of saturation and of the temperature on the reaction development is also modeled. The chemical damage evolution is calibrated using the value of the gel pressure estimated by applying the electrical diffuse double-layer theory to experimental values of the surface charge density in ASR gel specimens reported in the literature. The chemo-damage model is first validated by simulating expansion tests on reactive specimens and beams; the coupled chemo-mechanical damage model is then employed to simulate compression and flexure tests results also taken from the literature. -- Highlights: •Concrete degradation due to ASR in variable environmental conditions is modeled. •Two isotropic internal variables – chemical and mechanical damage – are introduced. •The value of the swelling pressure is estimated by the diffuse double layer theory. •A simplified scheme is proposed to relate macro- and microscopic properties. •The chemo-mechanical damage model is validated by simulating tests in literature.

  15. Optimal control of a Cope rearrangement by coupling the reaction path to a dissipative bath or a second active mode

    International Nuclear Information System (INIS)

    Chenel, A.; Meier, C.; Dive, G.; Desouter-Lecomte, M.

    2015-01-01

    We compare the strategy found by the optimal control theory in a complex molecular system according to the active subspace coupled to the field. The model is the isomerization during a Cope rearrangement of Thiele’s ester that is the most stable dimer obtained by the dimerization of methyl-cyclopentadienenylcarboxylate. The crudest partitioning consists in retaining in the active space only the reaction coordinate, coupled to a dissipative bath of harmonic oscillators which are not coupled to the field. The control then fights against dissipation by accelerating the passage across the transition region which is very wide and flat in a Cope reaction. This mechanism has been observed in our previous simulations [Chenel et al., J. Phys. Chem. A 116, 11273 (2012)]. We compare here, the response of the control field when the reaction path is coupled to a second active mode. Constraints on the integrated intensity and on the maximum amplitude of the fields are imposed limiting the control landscape. Then, optimum field from one-dimensional simulation cannot provide a very high yield. Better guess fields based on the two-dimensional model allow the control to exploit different mechanisms providing a high control yield. By coupling the reaction surface to a bath, we confirm the link between the robustness of the field against dissipation and the time spent in the delocalized states above the transition barrier

  16. Uranium analysis in urine by inductively coupled plasma dynamic reaction cell mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Ejnik, John W. [Northern Michigan University, Chemistry Department, Marquette, MI (United States); Todorov, Todor I.; Mullick, Florabel G.; Centeno, Jose A. [Armed Forces Institute of Pathology (AFIP), Division of Biophysical Toxicology, Washington, DC (United States); Squibb, Katherine; McDiarmid, Melissa A. [University of Maryland, School of Medicine, Baltimore, MD (United States)

    2005-05-01

    Urine uranium concentrations are the best biological indicator for identifying exposure to depleted uranium (DU). Internal exposure to DU causes an increased amount of urine uranium and a decreased ratio of {sup 235}U/{sup 238}U in urine samples, resulting in measurements that vary between 0.00725 and 0.002 (i.e., natural and depleted uranium's {sup 235}U/{sup 238}U ratios, respectively). A method based on inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) was utilized to identify DU in urine by measuring the quantity of total U and the {sup 235}U/{sup 238}U ratio. The quantitative analysis was achieved using {sup 233}U as an internal standard. The analysis was performed both with and without the reaction gas oxygen. The reaction gas converted ionized {sup 235}U{sup +} and {sup 238}U{sup +} into {sup 235}UO{sub 2}{sup +} (m/z=267) and {sup 238}UO{sub 2}{sup +} (m/z=270). This conversion was determined to be over 90% efficient. A polyatomic interference at m/z 234.8 was successfully removed from the {sup 235}U signal under either DRC operating conditions (with or without oxygen as a reaction gas). The method was validated with 15 urine samples of known uranium compositions. The method detection limit for quantification was determined to be 0.1 pg U mL{sup -1} urine and an average coefficient of variation (CV) of 1-2% within the sample measurements. The method detection limit for determining {sup 235}U/{sup 238}U ratio was 3.0 pg U mL{sup -1} urine. An additional 21 patient samples were analyzed with no information about medical history. The measured {sup 235}U/{sup 238}U ratio within the urine samples correctly identified the presence or absence of internal DU exposure in all 21 patients. (orig.)

  17. Attention and Perseverance Behaviors of PreSchool Children Enrolled in Suzuki Violin Lessons and Other Activities.

    Science.gov (United States)

    Scott, Laurie

    1992-01-01

    Reports on a study of attention span and persevering behaviors of preschool children. Finds the Suzuki Method of violin instruction is associated with longer attention spans and more persevering behaviors than creative movement instruction or other preschool programs. Concludes that teachers prefer the Suzuki Method's approach to other forms of…

  18. Coupled-reaction-channel analysis of the (d,6Li) reaction on 24Mg and 26Mg to low-lying states

    International Nuclear Information System (INIS)

    Oelert, W.

    1986-01-01

    Experimental spectroscopic factors of the alpha-transfer reaction on nuclei of the sd-shell show rather strong inconsistencies and scatter much more strongly than explainable by the quoted errors. The poorer the quality of agreement between experimental and theoretical angular distribution shapes, the more inconsistent the comparison of spectroscopic factors either between different experiments or between theory and experiment. In view of the strong deformation of nuclei in the lower part of the sd-shell, higher-order reaction mechanisms are expected. A coupled-reaction-channel analysis for the transitions to the 0 + , 2 + , and 4 + states of the ground-state bands in 20 Ne and 22 Ne excited via the (d, 6 Li) reaction yields good agreement between experimental and theoretical angular distribution shapes as well as spectroscopic information. (orig.)

  19. Coupled Transport/Reaction Modelling of Copper Canister Corrosion Aided by Microbial Processes

    Energy Technology Data Exchange (ETDEWEB)

    Jinsong Liu [Royal Institute of Technology, Stockholm (Sweden). Dept. of Chemical Engineering and Technology

    2006-04-15

    Copper canister corrosion is an important issue in the concept of a nuclear fuel repository. Previous studies indicate that the oxygen-free copper canister could hold its integrity for more than 100,000 years in the repository environment. Microbial processes may reduce sulphate to sulphide and considerably increase the amount of sulphides available for corrosion. In this paper, a coupled transport/reaction model is developed to account for the transport of chemical species produced by microbial processes. The corroding agents like sulphide would come not only from the groundwater flowing in a fracture that intersects the canister, but also from the reduction of sulphate near the canister. The reaction of sulphate-reducing bacteria and the transport of sulphide in the bentonite buffer are included in the model. The depth of copper canister corrosion is calculated by the model. With representative 'central values' of the concentrations of sulphate and methane at repository depth at different sites in Fennoscandian Shield the corrosion depth predicted by the model is a few millimetres during 10{sup 5} years. As the concentrations of sulphate and methane are extremely site-specific and future climate changes may significantly influence the groundwater compositions at potential repository sites, sensitivity analyses have been conducted. With a broad perspective of the measured concentrations at different sites in Sweden and in Finland, and some possible mechanisms (like the glacial meltwater intrusion and interglacial seawater intrusion) that may introduce more sulphate into the groundwater at intermediate depths during future climate changes, higher concentrations of either/both sulphate and methane than what is used as the representative 'central' values would be possible. In worst cases. locally, half of the canister thickness could possibly be corroded within 10{sup 5} years.

  20. Coupled Transport/Reaction Modelling of Copper Canister Corrosion Aided by Microbial Processes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinsong [Royal Institute of Technology, Stockholm (Sweden). Dept. of Chemical Engineering and Technology

    2006-04-15

    Copper canister corrosion is an important issue in the concept of a nuclear fuel repository. Previous studies indicate that the oxygen-free copper canister could hold its integrity for more than 100,000 years in the repository environment. Microbial processes may reduce sulphate to sulphide and considerably increase the amount of sulphides available for corrosion. In this paper, a coupled transport/reaction model is developed to account for the transport of chemical species produced by microbial processes. The corroding agents like sulphide would come not only from the groundwater flowing in a fracture that intersects the canister, but also from the reduction of sulphate near the canister. The reaction of sulphate-reducing bacteria and the transport of sulphide in the bentonite buffer are included in the model. The depth of copper canister corrosion is calculated by the model. With representative 'central values' of the concentrations of sulphate and methane at repository depth at different sites in Fennoscandian Shield the corrosion depth predicted by the model is a few millimetres during 10{sup 5} years. As the concentrations of sulphate and methane are extremely site-specific and future climate changes may significantly influence the groundwater compositions at potential repository sites, sensitivity analyses have been conducted. With a broad perspective of the measured concentrations at different sites in Sweden and in Finland, and some possible mechanisms (like the glacial meltwater intrusion and interglacial seawater intrusion) that may introduce more sulphate into the groundwater at intermediate depths during future climate changes, higher concentrations of either/both sulphate and methane than what is used as the representative 'central' values would be possible. In worst cases. locally, half of the canister thickness could possibly be corroded within 10{sup 5} years.

  1. Coupled Transport/Reaction Modelling of Copper Canister Corrosion Aided by Microbial Processes

    International Nuclear Information System (INIS)

    Jinsong Liu

    2006-04-01

    Copper canister corrosion is an important issue in the concept of a nuclear fuel repository. Previous studies indicate that the oxygen-free copper canister could hold its integrity for more than 100,000 years in the repository environment. Microbial processes may reduce sulphate to sulphide and considerably increase the amount of sulphides available for corrosion. In this paper, a coupled transport/reaction model is developed to account for the transport of chemical species produced by microbial processes. The corroding agents like sulphide would come not only from the groundwater flowing in a fracture that intersects the canister, but also from the reduction of sulphate near the canister. The reaction of sulphate-reducing bacteria and the transport of sulphide in the bentonite buffer are included in the model. The depth of copper canister corrosion is calculated by the model. With representative 'central values' of the concentrations of sulphate and methane at repository depth at different sites in Fennoscandian Shield the corrosion depth predicted by the model is a few millimetres during 10 5 years. As the concentrations of sulphate and methane are extremely site-specific and future climate changes may significantly influence the groundwater compositions at potential repository sites, sensitivity analyses have been conducted. With a broad perspective of the measured concentrations at different sites in Sweden and in Finland, and some possible mechanisms (like the glacial meltwater intrusion and interglacial seawater intrusion) that may introduce more sulphate into the groundwater at intermediate depths during future climate changes, higher concentrations of either/both sulphate and methane than what is used as the representative 'central' values would be possible. In worst cases. locally, half of the canister thickness could possibly be corroded within 10 5 years

  2. Theory of potentiostatic current transients for coupled catalytic reaction at random corrugated fractal electrode

    International Nuclear Information System (INIS)

    Jha, Shailendra K.; Kant, Rama

    2010-01-01

    We developed a mathematical model for the first order homogeneous catalytic chemical reaction coupled with an electron transfer (EC') on a rough working electrode. Results are obtained for the various roughness models of electrode corrugations, viz., (i) roughness as an exact periodic function, (ii) roughness as a random function with known statistical properties, and (iii) roughness as a random function with statistical self-affine fractality over a finite range of length scales. Method of Green's function is used in the formulation to obtain second-order perturbation (in roughness profile) expressions for the concentration, the local current density and the current transients. A general operator structure between these quantities and arbitrary roughness profile is emphasized. The statistically averaged (randomly rough) electrode response is obtained by an ensemble averaging over all possible surface configurations. An elegant mathematical formula between the average electrochemical current transient and surface structure factor or power-spectrum of roughness is obtained. This formula is used to obtain an explicit equation for the current on an approximately self-affine (or realistic) fractal electrode with a limited range of length scales of irregularities. This description of realistic fractal is obtained by cutoff power law power-spectrum of roughness. The realistic fractal power-spectrum consists of four physical characteristics, viz., the fractal dimension (D H ), lower (l) and upper (L) cutoff length scales of fractality and a proportionality factor (μ), which is related to the topothesy or strength of fractality. Numerical calculations are performed on final results to understand the effect of catalytic reaction and fractal morphological characteristics on potentiostatic current transients.

  3. Substrate specificity and subcellular localization of the aldehyde-alcohol redox-coupling reaction in carp cones.

    Science.gov (United States)

    Sato, Shinya; Fukagawa, Takashi; Tachibanaki, Shuji; Yamano, Yumiko; Wada, Akimori; Kawamura, Satoru

    2013-12-20

    Our previous study suggested the presence of a novel cone-specific redox reaction that generates 11-cis-retinal from 11-cis-retinol in the carp retina. This reaction is unique in that 1) both 11-cis-retinol and all-trans-retinal were required to produce 11-cis-retinal; 2) together with 11-cis-retinal, all-trans-retinol was produced at a 1:1 ratio; and 3) the addition of enzyme cofactors such as NADP(H) was not necessary. This reaction is probably part of the reactions in a cone-specific retinoid cycle required for cone visual pigment regeneration with the use of 11-cis-retinol supplied from Müller cells. In this study, using purified carp cone membrane preparations, we first confirmed that the reaction is a redox-coupling reaction between retinals and retinols. We further examined the substrate specificity, reaction mechanism, and subcellular localization of this reaction. Oxidation was specific for 11-cis-retinol and 9-cis-retinol. In contrast, reduction showed low specificity: many aldehydes, including all-trans-, 9-cis-, 11-cis-, and 13-cis-retinals and even benzaldehyde, supported the reaction. On the basis of kinetic studies of this reaction (aldehyde-alcohol redox-coupling reaction), we found that formation of a ternary complex of a retinol, an aldehyde, and a postulated enzyme seemed to be necessary, which suggested the presence of both the retinol- and aldehyde-binding sites in this enzyme. A subcellular fractionation study showed that the activity is present almost exclusively in the cone inner segment. These results suggest the presence of an effective production mechanism of 11-cis-retinal in the cone inner segment to regenerate visual pigment.

  4. Kinetic Studies of Oxidative Coupling of Methane Reaction on Model Catalysts

    KAUST Repository

    Khan, Abdulaziz M.

    2016-04-26

    With the increasing production of natural gas as a result of the advancement in the technology, methane conversion to more valuable products has become a must. One of the most attractive processes which allow the utilization of the world’s most abundant hydrocarbon is the oxidative coupling. The main advantage of this process is the ability of converting methane into higher paraffins and olefins (primarily C2) in a direct way using a single reactor. Nevertheless, low C2+ yields have prevented the process to be commercialized despite the fact that great number of attempts to prepare catalysts were conducted so that it can be economically viable. Due to these limitations, understanding the mechanism and kinetics of the reaction can be utilized in improving the catalysts’ performance. The reaction involves the formation of methyl radicals that undergo gas-phase radical reactions. CH4 activation is believed to be done the surface oxygen species. However, recent studies showed that, in addition to the surface oxygen mediated pathway, an OH radical mediated pathway have a large contribution on the CH4 activation. The experiments of Li/MgO, Sr/La2O3 and NaWO4/SiO2 catalysts revealed variation of behavior in activity and selectivity. In addition, water effect analysis showed that Li/MgO deactivate at the presence of water due to sintering phenomena and the loss of active sites. On the other hand, negative effect on the C2 yield and CH4 conversion rate was observed with Sr/La2O3 with increasing the water partial pressure. Na2WO4/SiO2 showed a positive behavior with water in terms of CH4 conversion and C2 yield. In addition, the increment in CH4 conversion rate was found to be proportional with PO2 ¼ PH2O ½ which is consistent with the formation of OH radicals and the OH-mediated pathway. Experiments of using ring-dye laser, which is used to detect OH in combustion experiments, were tried in order to detect OH radicals in the gas-phase of the catalyst. Nevertheless

  5. Nuclear structure and nuclear reaction aspects of Faessler and Greiner's rotation-vibration coupling theory

    International Nuclear Information System (INIS)

    Aspelund, O.

    In the nuclear structure part, the foundations of Faessler and Greiner's rotation-vibration coupling theory are reviewed, whereafter an alternative derivation of Faessler and Greiner's Hamiltonian is presented. A non-spherical quadrupole phonon number N is defined and used in the matrix elements reported for odd-even/even-odd nuclei. These matrix elements are shown to evince oblate-prolate effects that can be exploited for assessing the signs of quadrupole deformations. In the nuclear reaction part, the wave functions emerging from the structure part are applied in a complete and consistent description of elastic and inelastic particle scattering, one-nucleon transfer, and particle/γ-ray angular correlations. The intentions are to demonstrate that anomolous angular distributions and 1=2 j-effects observed in one-nucleon transfer are interrelated phenomena, that can be satisfactorily explained in terms of the elementary vibrational excitation modes inherent in Faessler and Greiner's theory. The latter is regarded as a non-spherical approach to the theory of the quadrupole component of the nuclear potential energy surface. (Auth.)

  6. Coupled transport/reaction model of the properties of bentonite buffer in a repository

    International Nuclear Information System (INIS)

    Liu, Jinsong; Neretnieks, I.

    1996-11-01

    Two mechanisms that can affect the long-term properties of the bentonite buffer surrounding the canister in a final repository of spent nuclear fuel are studied. The two mechanisms are the oxidation of reducing minerals in the buffer by radiolytically generated oxidant, and the low-temperature alteration of Na-montmorillonite in the bentonite buffer to illite. A coupled mass transport with geochemical reaction model is used. Four cases have been considered, which differ in the assumptions of whether the radiolytically generated oxidant first oxidizes uraninite in the spent fuel, or it is directly transported to the bentonite to oxidize the pyrite. The cases also differ in the assumptions of varying initial concentrations of pyrite in the bentonite buffer. The modelling results show that, at low temperatures, the sodium montmorillonite in the bentonite buffer is chemically stable with respect to the chemical conditions of the near field. Alteration to illite and thus an increase in hydraulic conductivity and loss of swelling ability is not likely to occur. The radiolytically generated oxidant can possibly oxidize the reducing minerals in the bentonite buffer. A redox front can be generated. In all the cases considered in this study, the modelling results indicate that slightly less than 1% by weight of pyrite in the bentonite buffer will be able to ensure that the redox front does not penetrate through the bentonite buffer within 1 million years. 31 refs

  7. Mechanism of the Suzuki–Miyaura Cross-Coupling Reaction Mediated by [Pd(NHC)(allyl)Cl] Precatalysts

    KAUST Repository

    Meconi, Giulia Magi; Vummaleti, Sai V. C.; Luque-Urrutia, Jesú s Antonio; Belanzoni, Paola; Nolan, Steven P.; Jacobsen, Heiko; Cavallo, Luigi; Solà , Miquel; Poater, Albert

    2017-01-01

    (IPr); R = H (1), Me (2), gem-Me2 (3), Ph (4), X = Cl, Br). Next, we have investigated the Suzuki–Miyaura cross-coupling reaction for the active catalyst species IPr-Pd(0) using 4-chlorotoluene and phenylboronic acid as substrates and isopropyl alcohol as a

  8. The coupling effect of gas-phase chemistry and surface reactions on oxygen permeation and fuel conversion in ITM reactors

    KAUST Repository

    Hong, Jongsup

    2015-08-01

    © 2015 Elsevier B.V. The effect of the coupling between heterogeneous catalytic reactions supported by an ion transport membrane (ITM) and gas-phase chemistry on fuel conversion and oxygen permeation in ITM reactors is examined. In ITM reactors, thermochemical reactions take place in the gas-phase and on the membrane surface, both of which interact with oxygen permeation. However, this coupling between gas-phase and surface chemistry has not been examined in detail. In this study, a parametric analysis using numerical simulations is conducted to investigate this coupling and its impact on fuel conversion and oxygen permeation rates. A thermochemical model that incorporates heterogeneous chemistry on the membrane surface and detailed chemical kinetics in the gas-phase is used. Results show that fuel conversion and oxygen permeation are strongly influenced by the simultaneous action of both chemistries. It is shown that the coupling somewhat suppresses the gas-phase kinetics and reduces fuel conversion, both attributed to extensive thermal energy transfer towards the membrane which conducts it to the air side and radiates to the reactor walls. The reaction pathway and products, in the form of syngas and C2 hydrocarbons, are also affected. In addition, the operating regimes of ITM reactors in which heterogeneous- or/and homogeneous-phase reactions predominantly contribute to fuel conversion and oxygen permeation are elucidated.

  9. The coupling effect of gas-phase chemistry and surface reactions on oxygen permeation and fuel conversion in ITM reactors

    KAUST Repository

    Hong, Jongsup; Kirchen, Patrick; Ghoniem, Ahmed F.

    2015-01-01

    © 2015 Elsevier B.V. The effect of the coupling between heterogeneous catalytic reactions supported by an ion transport membrane (ITM) and gas-phase chemistry on fuel conversion and oxygen permeation in ITM reactors is examined. In ITM reactors

  10. Temporal viscosity modulations driven by a pH sensitive polymer coupled to a pH-changing chemical reaction.

    Science.gov (United States)

    Escala, D M; Muñuzuri, A P; De Wit, A; Carballido-Landeira, J

    2017-05-17

    The Formaldehyde-Sulfite (FS) and the Formaldehyde-Sulfite-Gluconolactone (FSG) systems are examples of complex chemical reactions accompanied by well-controlled variations in pH. While the FS system exhibits a clock behavior, in the FSG reaction, this mechanism is coupled with the hydrolysis of the gluconolactone which gives the possibility to show large temporal oscillations of pH in an open reactor. In this work, we show how these reactive systems, due to their organic nature, can be coupled with pH sensitive polymers, particularly with polyacrylic acid (PAA) to trigger temporal changes of viscosity. We characterize this coupled reactive system showing the effects of changes in the initial concentrations of the polymer and in the chemical reagents on the induction time, the magnitude of the pH variations and the temporal modifications of the viscosity.

  11. The Suzuki–Miyaura Cross-Coupling as a Versatile Tool for Peptide Diversification and Cyclization

    Directory of Open Access Journals (Sweden)

    Tom Willemse

    2017-02-01

    Full Text Available The (site-selective derivatization of amino acids and peptides represents an attractive field with potential applications in the establishment of structure–activity relationships and labeling of bioactive compounds. In this respect, bioorthogonal cross-coupling reactions provide valuable means for ready access to peptide analogues with diversified structure and function. Due to the complex and chiral nature of peptides, mild reaction conditions are preferred; hence, a suitable cross-coupling reaction is required for the chemical modification of these challenging substrates. The Suzuki reaction, involving organoboron species, is appropriate given the stability and environmentally benign nature of these reactants and their amenability to be applied in (partial aqueous reaction conditions, an expected requirement upon the derivatization of peptides. Concerning the halogenated reaction partner, residues bearing halogen moieties can either be introduced directly as halogenated amino acids during solid-phase peptide synthesis (SPPS or genetically encoded into larger proteins. A reversed approach building in boron in the peptidic backbone is also possible. Furthermore, based on this complementarity, cyclic peptides can be prepared by halogenation, and borylation of two amino acid side chains present within the same peptidic substrate. Here, the Suzuki–Miyaura reaction is a tool to induce the desired cyclization. In this review, we discuss diverse amino acid and peptide-based applications explored by means of this extremely versatile cross-coupling reaction. With the advent of peptide-based drugs, versatile bioorthogonal conversions on these substrates have become highly valuable.

  12. Nonadiabatic rate constants for proton transfer and proton-coupled electron transfer reactions in solution: Effects of quadratic term in the vibronic coupling expansion.

    Science.gov (United States)

    Soudackov, Alexander V; Hammes-Schiffer, Sharon

    2015-11-21

    Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency proton donor-acceptor vibrational modes. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term in the framework of the cumulant expansion framework may significantly impact the rate constants at high temperatures for proton transfer interfaces with soft proton donor-acceptor modes that are associated with small force constants and weak hydrogen bonds. The effects of the quadratic term may also become significant in these regimes when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant. In this case, however, the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances sampled. The effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances. Additionally, the rigorous relation between the cumulant expansion and thermal averaging approaches is clarified. In particular, the cumulant expansion rate constant includes effects from dynamical interference between the proton donor-acceptor and solvent motions and becomes equivalent to the thermally averaged rate constant when these dynamical effects are neglected. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton

  13. Nonadiabatic rate constants for proton transfer and proton-coupled electron transfer reactions in solution: Effects of quadratic term in the vibronic coupling expansion

    International Nuclear Information System (INIS)

    Soudackov, Alexander V.; Hammes-Schiffer, Sharon

    2015-01-01

    Rate constant expressions for vibronically nonadiabatic proton transfer and proton-coupled electron transfer reactions are presented and analyzed. The regimes covered include electronically adiabatic and nonadiabatic reactions, as well as high-frequency and low-frequency proton donor-acceptor vibrational modes. These rate constants differ from previous rate constants derived with the cumulant expansion approach in that the logarithmic expansion of the vibronic coupling in terms of the proton donor-acceptor distance includes a quadratic as well as a linear term. The analysis illustrates that inclusion of this quadratic term in the framework of the cumulant expansion framework may significantly impact the rate constants at high temperatures for proton transfer interfaces with soft proton donor-acceptor modes that are associated with small force constants and weak hydrogen bonds. The effects of the quadratic term may also become significant in these regimes when using the vibronic coupling expansion in conjunction with a thermal averaging procedure for calculating the rate constant. In this case, however, the expansion of the coupling can be avoided entirely by calculating the couplings explicitly for the range of proton donor-acceptor distances sampled. The effects of the quadratic term for weak hydrogen-bonding systems are less significant for more physically realistic models that prevent the sampling of unphysical short proton donor-acceptor distances. Additionally, the rigorous relation between the cumulant expansion and thermal averaging approaches is clarified. In particular, the cumulant expansion rate constant includes effects from dynamical interference between the proton donor-acceptor and solvent motions and becomes equivalent to the thermally averaged rate constant when these dynamical effects are neglected. This analysis identifies the regimes in which each rate constant expression is valid and thus will be important for future applications to proton

  14. The Conservation of Rhythm in Suzuki Violin Students: A Task Validation Study.

    Science.gov (United States)

    Nelson, David J.

    1984-01-01

    Twenty Suzuki violin students between four and eight years old were individually administered an author-designed rhythmic task and a series of standardized tasks that measured area and length conservation. The students' prior training was found to be less of a factor in rhythmic conservation than were age and area-length conservation. (Author/RM)

  15. Parental Involvement in the Musical Education of Violin Students: Suzuki and "Traditional" Approaches Compared

    Science.gov (United States)

    Bugeja, Clare

    2009-01-01

    This article investigates parental involvement in the musical education of violin students and the changing role of the parents' across the learning process. Two contexts were compared, one emphasising the Suzuki methodology and the other a "traditional" approach. Students learning "traditionally" are typically taught note reading from the…

  16. Learning with Sound Recordings: A History of Suzuki's Mediated Pedagogy

    Science.gov (United States)

    Thibeault, Matthew D.

    2018-01-01

    This article presents a history of mediated pedagogy in the Suzuki Method, the first widespread approach to learning an instrument in which sound recordings were central. Media are conceptualized as socially constituted: philosophical ideas, pedagogic practices, and cultural values that together form a contingent and changing technological…

  17. 76 FR 4991 - Petition for Exemption From the Vehicle Theft Prevention Standard; Suzuki

    Science.gov (United States)

    2011-01-27

    ... From the Vehicle Theft Prevention Standard; Suzuki AGENCY: National Highway Traffic Safety... of the Kizashi vehicle line in accordance with 49 CFR part 543, Exemption from the Theft Prevention... vehicle theft as compliance with the parts-marking requirements of the 49 CFR part 541, Federal Motor...

  18. Strategies for method development for an inductively coupled plasma mass spectrometer with bandpass reaction cell. Approaches with different reaction gases for the determination of selenium

    International Nuclear Information System (INIS)

    Hattendorf, Bodo; Guenther, Detlef

    2003-01-01

    An inductively coupled plasma mass spectrometer with dynamic reaction cell (DRC) was used to investigate different approaches for chemical resolution of Ar 2 + ions and to improve the determination of Se. Hydrogen, methane, oxygen and nitrous oxide were used as reaction gases. The method development for each approach consists of the acquisition of spectra for blank and spiked samples at different operating parameters, including reaction gas flow and transmission settings, of the DRC. Isotope ratio studies and the analytes signal to background ratio (SBR), were used as criteria to determine the operating conditions of the DRC where spectral interferences from the ion source or from polyatomic ions formed inside the DRC are minimized. Methane was found to provide the highest reaction efficiency for determination of Se. Nitrous oxide and oxygen also very efficiently suppress the Ar 2 + interference but reaction or scattering losses of Se + and SeO + are significant. Hydrogen is the least efficient gas for Ar 2 + reduction but little scattering or reactive loss lead to a good SBR. The determination of Se as SeO + was investigated with oxygen and nitrous oxide as reaction gases. The efficiency when using the oxygenation reaction was found to be similar to the efficiency for the charge transfer reactions but the slow oxygenation of the potentially interfering Mo + renders this approach less useful for analytical purposes. Using a natural water sample it could be shown that very good agreement is obtained using methane or hydrogen for analysis of 80 Se + at the μg/l level. Limits of detection are lowest (2 ng/l) when methane is used to suppress the Ar 2 + ion and when 80 Se + is used for analysis

  19. Isotopic labeling as a tool to establish intramolecular vibrational coupling: The reaction of 2-propanol on Mo(110)

    International Nuclear Information System (INIS)

    Uvdal, P.; Wiegand, B.C.; Serafin, J.G.; Friend, C.M.

    1992-01-01

    The reactions of 2-propanol on Mo(110) were investigated using temperature programmed reaction, high resolution electron energy loss, and x-ray photoelectron spectroscopies. 2-Propanol forms 2-propoxide upon adsorption at 120 K on Mo(110). The 2-propoxide intermediate deoxygenates via selective γ C--H bond scission to eliminate propene as well as C--O bond hydrogenolysis to form trace amounts of propane. The C--O bond of 2-propoxide is estimated to be nearly perpendicular to the surface. Selective isotopic labeling was used to establish the coupling between the C--O stretch and modes associated with the hydrocarbon framework. The degree of coupling was strongly affected by bonding to the surface, primarily due to weakening of the C--O bond when 2-propoxide is bound to Mo(110). Selective isotopic labeling was, therefore, essential in making vibrational assignments and in identifying key reaction steps. Only a small kinetic isotope effect was observed during reaction of (CD 3 )(CH 3 )CHOH, consistent with a substantial component of C--O bond breaking in the transition state for propene elimination. Coupling of the C--O stretch to motion of the methyl group is also suggested to be important in the transition state for propene elimination

  20. HYDROBIOGEOCHEM: A coupled model of HYDROlogic transport and mixed BIOGEOCHEMical kinetic/equilibrium reactions in saturated-unsaturated media

    Energy Technology Data Exchange (ETDEWEB)

    Yeh, G.T.; Salvage, K.M. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Civil and Environmental Engineering; Gwo, J.P. [Oak Ridge National Lab., TN (United States); Zachara, J.M.; Szecsody, J.E. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-07-01

    The computer program HYDROBIOGEOCHEM is a coupled model of HYDROlogic transport and BIOGEOCHEMical kinetic and/or equilibrium reactions in saturated/unsaturated media. HYDROBIOGEOCHEM iteratively solves the two-dimensional transport equations and the ordinary differential and algebraic equations of mixed biogeochemical reactions. The transport equations are solved for all aqueous chemical components and kinetically controlled aqueous species. HYDROBIOGEOCHEM is designed for generic application to reactive transport problems affected by both microbiological and geochemical reactions in subsurface media. Input to the program includes the geometry of the system, the spatial distribution of finite elements and nodes, the properties of the media, the potential chemical and microbial reactions, and the initial and boundary conditions. Output includes the spatial distribution of chemical and microbial concentrations as a function of time and space, and the chemical speciation at user-specified nodes.

  1. A dispersive optical model potential for nucleon induced reactions on 238U and 232Th nuclei with full coupling

    Directory of Open Access Journals (Sweden)

    Chiba Satoshi

    2013-03-01

    Full Text Available A dispersive coupled-channel optical model potential (DCCOMP that couples the ground-state rotational and low-lying vibrational bands of 238U and 232Th nuclei is studied. The derived DCCOMP couples almost all excited levels below 1 MeV of excitation energy of the corresponding even-even actinides. The ground state, octupole, beta, gamma, and non-axial bands are coupled. The first two isobar analogue states (IAS populated in the quasi-elastic (p,n reaction are also coupled in the proton induced calculation, making the potential approximately Lane consistent. The coupled-channel potential is based on a soft-rotor description of the target nucleus structure, where dynamic vibrations are considered as perturbations of the rigid rotor underlying structure. Matrix elements required to use the proposed structure model in Tamura coupled-channel scheme are derived. Calculated ratio R(U238/Th232 of the total cross-section difference to the averaged σT for 238U and 232Th nuclei is shown to be in excellent agreement with measured data.

  2. Stereospecific nickel-catalyzed cross-coupling reactions of alkyl ethers: enantioselective synthesis of diarylethanes.

    Science.gov (United States)

    Taylor, Buck L H; Swift, Elizabeth C; Waetzig, Joshua D; Jarvo, Elizabeth R

    2011-01-26

    Secondary benzylic ethers undergo stereospecific substitution reactions with Grignard reagents in the presence of nickel catalysts. Reactions proceed with inversion of configuration and high stereochemical fidelity. This reaction allows for facile enantioselective synthesis of biologically active diarylethanes from readily available optically enriched carbinols.

  3. A coupled mechanical-chemical model for reflecting the influence of stress on oxidation reactions in thermal barrier coating

    Science.gov (United States)

    Chen, Lin; Yueming, Li

    2018-06-01

    In this paper, a coupled mechanical-chemical model is established based on the thermodynamic framework, in which the contribution of chemical expansion to free energy is introduced. The stress-dependent chemical potential equilibrium at the gas-solid interface and the stress gradient-dependent diffusion equation as well as a so-called generalized force which is conjugate to the oxidation rate are derived from the proposed model, which could reflect the influence of stresses on the oxidation reaction. Based on the proposed coupled mechanical-chemical model, a user element subroutine is developed in ABAQUS. The numerical simulation of the high temperature oxidation in the thermal barrier coating is carried out to verify the accuracy of the proposed model, and then the influence of stresses on the oxidation reaction is investigated. In thermally grown oxide, the considerable stresses would be induced by permanent volumetric swelling during the oxidation. The stresses play an important role in the chemical potential equilibrium at the gas-solid interface and strongly affect the oxidation reaction. The gradient of the stresses, however, only occurs in the extremely thin oxidation front layer, which plays a very limited role in the oxidation reaction. The generalized force could be divided into the stress-dependent and the stress-independent parts. Comparing with the stress-independent part, the stress-dependent part is smaller, which has little influence on oxidation reaction.

  4. Cationic Pd(II-catalyzed C–H activation/cross-coupling reactions at room temperature: synthetic and mechanistic studies

    Directory of Open Access Journals (Sweden)

    Takashi Nishikata

    2016-05-01

    Full Text Available Cationic palladium(II complexes have been found to be highly reactive towards aromatic C–H activation of arylureas at room temperature. A commercially available catalyst [Pd(MeCN4](BF42 or a nitrile-free cationic palladium(II complex generated in situ from the reaction of Pd(OAc2 and HBF4, effectively catalyzes C–H activation/cross-coupling reactions between aryl iodides, arylboronic acids and acrylates under milder conditions than those previously reported. The nature of the directing group was found to be critical for achieving room temperature conditions, with the urea moiety the most effective in promoting facile coupling reactions at an ortho C–H position. This methodology has been utilized in a streamlined and efficient synthesis of boscalid, an agent produced on the kiloton scale annually and used to control a range of plant pathogens in broadacre and horticultural crops. Mechanistic investigations led to a proposed catalytic cycle involving three steps: (1 C–H activation to generate a cationic palladacycle; (2 reaction of the cationic palladacycle with an aryl iodide, arylboronic acid or acrylate, and (3 regeneration of the active cationic palladium catalyst. The reaction between a cationic palladium(II complex and arylurea allowed the formation and isolation of the corresponding palladacycle intermediate, characterized by X-ray analysis. Roles of various additives in the stepwise process have also been studied.

  5. Lewis Acid Catalyzed Asymmetric Three-Component Coupling Reaction: Facile Synthesis of α-Fluoromethylated Tertiary Alcohols.

    Science.gov (United States)

    Aikawa, Kohsuke; Kondo, Daisuke; Honda, Kazuya; Mikami, Koichi

    2015-12-01

    A chiral dicationic palladium complex is found to be an efficient Lewis acid catalyst for the synthesis of α-fluoromethyl-substituted tertiary alcohols using a three-component coupling reaction. The reaction transforms three simple and readily available components (terminal alkyne, arene, and fluoromethylpyruvate) to valuable chiral organofluorine compounds. This strategy is completely atom-economical and results in perfect regioselectivities and high enantioselectivities of the corresponding tertiary allylic alcohols in good to excellent yields. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Treatment of ammonia in waste air using packed column coupling with chemical reaction

    Directory of Open Access Journals (Sweden)

    Thepchai, R.

    2007-05-01

    Full Text Available Ammonia is a common chemical used in various industries. Emission of air contaminated with ammonia to the atmosphere without any treatment causes several effects on human health and environment.A high efficiency method for ammonia removal from waste air is then necessary. In this research, an absorption coupling with chemical reaction was investigated for ammonia removal from waste air using a packedcolumn. The packed column of 10 cm diameter and 200 cm height was packed with 1.4x1.4 cm Raschig rings. Three liquids including water, NaOCl and H2SO4 solution were used as an absorbent for the investigation.The objectives of this research were to determine a suitable absorbent and the optimum condition for ammonia removal from waste air. The packed column was operated at room temperature and atmosphericpressure. The tested conditions were as follows: the gas to liquid ratio (G:L ratio was 35-90 m3 gas/m3 liquid, the inlet concentration of ammonia was 150-500 ppm and the air flow rate was 18 m3/h. The results showedthat the ammonia removal efficiency depends on type of the absorbent and the operating condition. The efficiencies increased with decreasing of G:L ratio and with increasing absorbent concentration. They were70%, 80-92%, and 95-100% for pure water, sodium hypochlorite solution and sulphuric acid solution, respectively. The efficiency decreased with time when water was used as an absorbent while it was almostconstant when NaOCl and H2SO4 solution were applied. The ammonia removal efficiency when using H2SO4 as the absorbent was not dependent on G:L ratio and inlet ammonia concentration, in the range used in thisinvestigation. Since H2SO4 solution gave the highest removal efficiency and can reduce ammonia concentration in waste air to levels which meet the TLV-TWA standard, it is recommended as an absorbent solution forammonia removal from waste air.

  7. Reactions to framing of cessation messages: insights from dual-smoker couples.

    Science.gov (United States)

    Lipkus, Isaac M; Ranby, Krista W; Lewis, Megan A; Toll, Benjamin

    2013-12-01

    Couples in which both members smoke (dual-smoker couples) have not been the explicit target of cessation interventions. Quit rates are lower and relapse rates are higher among individuals in dual-smoker couples. A potentially effective strategy to motivate dual-smoker couples to quit is to convey messages that highlight how the positive outcomes of quitting (gain frame) or the negative outcomes of continued smoking (loss frame) affect the couple rather than the individual smoker. We explored whether dual-smoker couples' smoking behaviors (e.g., amount smoked) and desire to quit would differ as a function of message frame (gain vs. loss) or outcome focus (individual vs. couple). Dual-smoker couples (N = 40) completed a baseline survey and were then randomized to review gain- or loss-framed messages that varied whether the outcomes influenced the individual or the couple. Main outcomes were desire to quit after reading messages and smoking behaviors at a 1-month follow-up. Couple-focused messages produced the strongest desire to quit and decreased amount of cigarettes smoked at follow-up. The latter effect was mediated by desire to quit. Loss-framed messages produced inconsistent effects on desire to quit. There were no significant interactions between outcome focus and message framing. Findings suggest that messages emphasizing how smoking affects both partners can motivate cessation among dual-smoker couples. Contrary to findings showing that gain-framed messages motivate cessation targeting individual smokers, results suggest that loss-framed messages may be more persuasive than gain-framed messages when the target of the outcome involves significant others.

  8. Coupled reaction-diffusion equations to model the fission gas release in the irradiation of the uranium dioxide

    International Nuclear Information System (INIS)

    Moyano, Edgardo A.; Scarpettini, Alberto F.

    2003-01-01

    A semi linear model of weakly coupled parabolic p.d.e. with reaction-diffusion is investigated. The system describes fission gas transfer from grain interior of UO 2 to grain boundaries. The problem is studied in a bounded domain. Using the upper-lower solutions method, two monotone sequences for the finite differences equations are constructed. Reasons are mentioned that allow to affirm that in the proposed functional sector the algorithm converges to the unique solution of the differential system. (author)

  9. Fermionic reaction coordinates and their application to an autonomous Maxwell demon in the strong-coupling regime

    Science.gov (United States)

    Strasberg, Philipp; Schaller, Gernot; Schmidt, Thomas L.; Esposito, Massimiliano

    2018-05-01

    We establish a theoretical method which goes beyond the weak-coupling and Markovian approximations while remaining intuitive, using a quantum master equation in a larger Hilbert space. The method is applicable to all impurity Hamiltonians tunnel coupled to one (or multiple) baths of free fermions. The accuracy of the method is in principle not limited by the system-bath coupling strength, but rather by the shape of the spectral density and it is especially suited to study situations far away from the wide-band limit. In analogy to the bosonic case, we call it the fermionic reaction coordinate mapping. As an application, we consider a thermoelectric device made of two Coulomb-coupled quantum dots. We pay particular attention to the regime where this device operates as an autonomous Maxwell demon shoveling electrons against the voltage bias thanks to information. Contrary to previous studies, we do not rely on a Markovian weak-coupling description. Our numerical findings reveal that in the regime of strong coupling and non-Markovianity, the Maxwell demon is often doomed to disappear except in a narrow parameter regime of small power output.

  10. Cu(OAc)2 catalyzed Sonogashira cross-coupling reaction in amines

    Institute of Scientific and Technical Information of China (English)

    Sheng Mei Guo; Chen Liang Deng; Jin Heng Li

    2007-01-01

    A simple Cu(OAc)2 catalyzed Sonogashira coupling protocol is presented. It was found that the couplings of a variety of aryl halides with terminal alkynes were conducted smoothly to afford the corresponding desired products in moderate to excellent yields, using Cu(OAc)2 as the catalyst and Et3N as the solvent.

  11. Uudised : TÜ Kammerkoor laulis Rootsis. Suzuki Nordic String Eestis. Vello Loogna sünnipäevakontsert / Valdur Liiv

    Index Scriptorium Estoniae

    Liiv, Valdur

    2000-01-01

    TÜ Kammerkoor esines ülestõusmispühadel Rootsi kirikutes. Põhjamaade laste keelpilliorkester esineb Eestis 1., 2. ja 3. mail. Lühidalt Suzuki pedagoogikast. V. Loogna 60. juubeli kontserdist 30. apr. Estonia kontserdisaalis

  12. Phase Equilibria of the Sn-Ni-Si Ternary System and Interfacial Reactions in Sn-(Cu)/Ni-Si Couples

    Science.gov (United States)

    Fang, Gu; Chen, Chih-chi

    2015-07-01

    Interfacial reactions in Sn/Ni-4.5 wt.%Si and Sn-Cu/Ni-4.5 wt.%Si couples at 250°C, and Sn-Ni-Si ternary phase equilibria at 250°C were investigated in this study. Ni-Si alloys, which are nonmagnetic, can be regarded as a diffusion barrier layer material in flip chip packaging. Solder/Ni-4.5 wt.%Si interfacial reactions are crucial to the reliability of soldered joints. Phase equilibria information is essential for development of solder/Ni-Si materials. No ternary compound is present in the Sn-Ni-Si ternary system at 250°C. Extended solubility of Si in the phases Ni3Sn2 and Ni3Sn is 3.8 and 6.1 at.%, respectively. As more Si dissolves in these phases their lattice constants decrease. No noticeable ternary solubility is observed for the other intermetallics. Interfacial reactions in solder/Ni-4.5 wt.%Si are similar to those for solder/Ni. Si does not alter the reaction phases. No Si solubility in the reaction phases was detected, although rates of growth of the reaction phases were reduced. Because the alloy Ni-4.5 wt.%Si reacts more slowly with solders than pure Ni, the Ni-4.5 wt.%Si alloy could be a potential new diffusion barrier layer material for flip chip packaging.

  13. Novel synthesis of methoxymethyl benzene by electrochemical coupling reaction of toluene with methanol in ionic liquid media.

    Science.gov (United States)

    Chen, Fengtao; Wang, Bo; Ma, Hongzhu

    2009-06-15

    An ionic liquid (1-butyl-3-methylimidazolium dibutyl phosphate) was prepared and characterized by cyclic voltammogram (CV) and Fourier transform infrared spectrometer (FT-IR). The ionic liquid exhibited good catalytic activity for the electrochemical reaction of toluene with methanol assisted with a pair of porous graphite plane electrodes and product yield higher than 56% was observed. In addition, the electrochemical process was detected by UV-vis spectrum and the products were analyzed by gas chromatography/mass spectrometry (GC/MS). According to the experimental results, a possible free radical reaction mechanism was proposed. It may be concluded that a simply and feasible electrochemical coupling reaction at room temperature and atmospheric pressure may be possible. Compared with methyl tert-butyl ether (MTBE), the main product (methoxymethyl benzene) used as booster to improve fuel combustion was also studied.

  14. Synthesis of 2-vinylic indoles and derivatives via a Pd-catalyzed tandem coupling reaction.

    Science.gov (United States)

    Fayol, Aude; Fang, Yuan-Qing; Lautens, Mark

    2006-09-14

    A novel one-step synthesis of valuable 2-vinylic indoles and their tricycle derivatives is described. This reaction, which utilizes a gem-dibromovinyl unit as a readily available starting material, occurs via an efficient Pd-catalyzed tandem Buchwald-Hartwig/Heck reaction.

  15. Pengaruh Pelaksanaan Pelatihan terhadap Kinerja Karyawan PT. Sejahtera Buana Trada Cabang Pekanbaru (Kasus Karyawan Bagian Marketing Dealer Suzuki Mobil)

    OpenAIRE

    Juwita, Ratna; ", Suryalena

    2016-01-01

    The purpose of this study was to determine the effect of exercise training on the performance of employees of PT. Sejahtera Buana Trada Branch Pekanbaru (Case Employee Suzuki Car Dealer Marketing Division). This research was conducted at PT. Sejahtera Buana Trada Branch Pekanbaru (Suzuki Car Dealer) located in the SM. Amin Number.89 Simpang Baru Tampan. In this research method used is a method of statistical tests with SPSS, where samples were used that employee marketing division of PT. Seja...

  16. Effect of the Pauli principle and channel coupling on the nuclear reactions, 2

    International Nuclear Information System (INIS)

    Kanada, Hiroyuki; Kaneko, Tsuneo; Nomoto, Morikazu

    1976-01-01

    The effect of the Pauli principle on nuclear reactions of a six-nucleon system is investigated in the presence of a breakup channel, by using the resonating group method (RGM). The microscopic treatment with full exchange effects for the t( 3 He, d) 4 He reaction is examined together with the 3 He-t and d- 4 He elastic scattering. It is shown that the exchange effects (especially owing to the Pauli principle) play an important role in the differential cross section in the backward region. The t( 3 He, d) 4 He reaction is examined by decomposing the reaction processes into three terms, that is, proton stripping, neutron pick-up and residual processes. The asymmetry of the angular distribution for the t( 3 He, d) 4 He reaction is also discussed. (auth.)

  17. Investigation of Thermochemistry Associated with the Carbon–Carbon Coupling Reactions of Furan and Furfural Using ab Initio Methods

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Cong; Assary, Rajeev S.; Curtiss, Larry A.

    2014-06-26

    Upgrading of furan and small oxygenates obtained from the decomposition of cellulosic materials via formation of carbon-carbon bonds is critical to effective conversion of biomass to liquid transportation fuels. Simulation-driven molecular level understanding of carbon-carbon bond formation is required to design efficient catalysts and processes. Accurate quantum chemical methods are utilized here to predict the reaction energetics for conversion of furan (C4H4O) to C5-C8 ethers and the transformation of furfural (C5H6O2) to C13-C26 alkanes. Furan, can be coupled with various C1 to C4 lower molecular weight carbohydrates obtained from the pyrolysis via Diels-Alder type reactions in the gas phase to produce C5-C8 cyclic ethers. The computed reaction barriers for these reactions (~25 kcal/mol) are lower than the cellulose activation or decomposition reactions (~50 kcal/mol). Cycloaddition of C5-C8 cyclo-ethers with furans can also occur in the gas phase, and the computed activation energy is similar to that of the first Diels-Alder reaction. Furfural, obtained from biomass, can be coupled with aldehydes or ketones with α-hydrogen atoms to form longer chain aldol products and these aldol products can undergo vapor phase hydrocycloaddition (activation barrier of ~20 kcal/mol) to form the precursors of C26 cyclic hydrocarbons. These thermochemical studies provide the basis for further vapor phase catalytic studies required for upgrading of furans/furfurals to longer chain hydrocarbons.

  18. Methane coupling reaction in an oxy-steam stream through an OH radical pathway by using supported alkali metal catalysts

    KAUST Repository

    Liang, Yin

    2014-03-24

    A universal reaction mechanism involved in the oxidative coupling of methane (OCM) is demonstrated under oxy-steam conditions using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from a H 2O-O2 reaction followed by C-H activation in CH 4 with an OH radical. Thus, the presence of water enhances both the CH4 conversion rate and the C2 selectivity. This OH radical pathway that is selective for the OCM was observed for the catalyst without Mn, which suggests clearly that Mn is not the essential component in a selective OCM catalyst. The experiments with different catalyst compositions revealed that the OH.-mediated pathway proceeded in the presence of catalysts with different alkali metals (Na, K) and different oxo anions (W, Mo). This difference in catalytic activity for OH radical generation accounts for the different OCM selectivities. As a result, a high C2 yield is achievable by using Na2WO4/SiO2, which catalyzes the OH.-mediated pathway selectively. Make it methane: A universal reaction mechanism involved in the oxidative coupling of methane is demonstrated under oxy-stream conditions by using alkali-metal-based catalysts. Rigorous kinetic measurements indicated a reaction mechanism that is consistent with OH radical formation from an H2O-O2 reaction, followed by C-H activation in CH4 with an OH radical. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A HIGHLY STEREOSELECTIVE, NOVEL COUPLING REACTION BETWEEN ALKYNES WITH ALDEHYDES. (R828129)

    Science.gov (United States)

    In the presence of indium triflate or gallium chloride, a novel coupling between internal alkynes and aldehydes occurred to give unsaturated ketones and [4+1] annulation products. Graphical Abstrac...

  20. Optical trapping via guided resonance modes in a Slot-Suzuki-phase photonic crystal lattice.

    Science.gov (United States)

    Ma, Jing; Martínez, Luis Javier; Povinelli, Michelle L

    2012-03-12

    A novel photonic crystal lattice is proposed for trapping a two-dimensional array of particles. The lattice is created by introducing a rectangular slot in each unit cell of the Suzuki-Phase lattice to enhance the light confinement of guided resonance modes. Large quality factors on the order of 10⁵ are predicted in the lattice. A significant decrease of the optical power required for optical trapping can be achieved compared to our previous design.

  1. kinetics of the coupled gas-iron reactions involving silicon and carbon

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... out for the system involving liquid iron containing carbon and silicon and a gas ... in content with liquid iron at. 15600C, the ... of carbon monoxide bubbles at the. Slag - metal ..... equilibrium strongly make chemical reactions.

  2. Kinetic Studies of Oxidative Coupling of Methane Reaction on Model Catalysts

    KAUST Repository

    Khan, Abdulaziz M.

    2016-01-01

    the process to be commercialized despite the fact that great number of attempts to prepare catalysts were conducted so that it can be economically viable. Due to these limitations, understanding the mechanism and kinetics of the reaction can be utilized

  3. Carbon-coated magnetic palladium: applications in partial oxidation of alcohols and coupling reactions.

    Science.gov (United States)

    Magnetic carbon supported Pd catalyst has been synthesized via in situ generation of nanoferrites and incorporation of carbon from renewable cellulose via calcination; catalyst can be used for oxidation of alcohols, amination reaction and arylation of aryl halides (cross coupli...

  4. Coupling of kinetic Monte Carlo simulations of surface reactions to transport in a fluid for heterogeneous catalytic reactor modeling

    International Nuclear Information System (INIS)

    Schaefer, C.; Jansen, A. P. J.

    2013-01-01

    We have developed a method to couple kinetic Monte Carlo simulations of surface reactions at a molecular scale to transport equations at a macroscopic scale. This method is applicable to steady state reactors. We use a finite difference upwinding scheme and a gap-tooth scheme to efficiently use a limited amount of kinetic Monte Carlo simulations. In general the stochastic kinetic Monte Carlo results do not obey mass conservation so that unphysical accumulation of mass could occur in the reactor. We have developed a method to perform mass balance corrections that is based on a stoichiometry matrix and a least-squares problem that is reduced to a non-singular set of linear equations that is applicable to any surface catalyzed reaction. The implementation of these methods is validated by comparing numerical results of a reactor simulation with a unimolecular reaction to an analytical solution. Furthermore, the method is applied to two reaction mechanisms. The first is the ZGB model for CO oxidation in which inevitable poisoning of the catalyst limits the performance of the reactor. The second is a model for the oxidation of NO on a Pt(111) surface, which becomes active due to lateral interaction at high coverages of oxygen. This reaction model is based on ab initio density functional theory calculations from literature.

  5. Couplings

    Science.gov (United States)

    Stošić, Dušan; Auroux, Aline

    Basic principles of calorimetry coupled with other techniques are introduced. These methods are used in heterogeneous catalysis for characterization of acidic, basic and red-ox properties of solid catalysts. Estimation of these features is achieved by monitoring the interaction of various probe molecules with the surface of such materials. Overview of gas phase, as well as liquid phase techniques is given. Special attention is devoted to coupled calorimetry-volumetry method. Furthermore, the influence of different experimental parameters on the results of these techniques is discussed, since it is known that they can significantly influence the evaluation of catalytic properties of investigated materials.

  6. From Cycling Between Coupled Reactions to the Cross-Bridge Cycle: Mechanical Power Output as an Integral Part of Energy Metabolism

    Directory of Open Access Journals (Sweden)

    Frank Diederichs

    2012-10-01

    Full Text Available ATP delivery and its usage are achieved by cycling of respective intermediates through interconnected coupled reactions. At steady state, cycling between coupled reactions always occurs at zero resistance of the whole cycle without dissipation of free energy. The cross-bridge cycle can also be described by a system of coupled reactions: one energising reaction, which energises myosin heads by coupled ATP splitting, and one de-energising reaction, which transduces free energy from myosin heads to coupled actin movement. The whole cycle of myosin heads via cross-bridge formation and dissociation proceeds at zero resistance. Dissipation of free energy from coupled reactions occurs whenever the input potential overcomes the counteracting output potential. In addition, dissipation is produced by uncoupling. This is brought about by a load dependent shortening of the cross-bridge stroke to zero, which allows isometric force generation without mechanical power output. The occurrence of maximal efficiency is caused by uncoupling. Under coupled conditions, Hill’s equation (velocity as a function of load is fulfilled. In addition, force and shortening velocity both depend on [Ca2+]. Muscular fatigue is triggered when ATP consumption overcomes ATP delivery. As a result, the substrate of the cycle, [MgATP2−], is reduced. This leads to a switch off of cycling and ATP consumption, so that a recovery of [ATP] is possible. In this way a potentially harmful, persistent low energy state of the cell can be avoided.

  7. Modeling multicomponent ionic transport in groundwater with IPhreeqc coupling: Electrostatic interactions and geochemical reactions in homogeneous and heterogeneous domains

    DEFF Research Database (Denmark)

    Muniruzzaman, Muhammad; Rolle, Massimo

    2016-01-01

    is coupled with the geochemical code PHREEQC-3 by utilizing the IPhreeqc module, thus enabling to perform the geochemical calculations included in the PHREEQC's reaction package. The multicomponent reactive transport code is benchmarked with different 1-D and 2-D transport problems. Successively...... the electrostatic interactions during transport of charged ions in physically and chemically heterogeneous porous media. The modeling approach is based on the local charge balance and on the description of compound-specific and spatially variable diffusive/dispersive fluxes. The multicomponent ionic transport code......, conservative and reactive transport examples are presented to demonstrate the capability of the proposed model to simulate transport of charged species in heterogeneous porous media with spatially variable physical and chemical properties. The results reveal that the Coulombic cross-coupling between dispersive...

  8. Redox and Lewis acid relay catalysis: a titanocene/zinc catalytic platform in the development of multicomponent coupling reactions.

    Science.gov (United States)

    Gianino, Joseph B; Campos, Catherine A; Lepore, Antonio J; Pinkerton, David M; Ashfeld, Brandon L

    2014-12-19

    A titanocene-catalyzed multicomponent coupling is described herein. Using catalytic titanocene, phosphine, and zinc dust, zinc acetylides can be generated from the corresponding iodoalkynes to affect sequential nucleophilic additions to aromatic aldehydes. The intermediate propargylic alkoxides are trapped in situ with acetic anhydride, which are susceptible to a second nucleophilic displacement upon treatment with a variety of electron-rich species, including acetylides, allyl silanes, electron-rich aromatics, silyl enol ethers, and silyl ketene acetals. Additionally, employing cyclopropane carboxaldehydes led to ring-opened products resulting from iodine incorporation. Taken together, these results form the basis for a new mode of three-component coupling reactions, which allows for rapid access to value added products in a single synthetic operation.

  9. On the nature of organic and inorganic centers that bifurcate electrons, coupling exergonic and endergonic oxidation-reduction reactions.

    Science.gov (United States)

    Peters, John W; Beratan, David N; Schut, Gerrit J; Adams, Michael W W

    2018-04-19

    Bifurcating electrons to couple endergonic and exergonic electron-transfer reactions has been shown to have a key role in energy conserving redox enzymes. Bifurcating enzymes require a redox center that is capable of directing electron transport along two spatially separate pathways. Research into the nature of electron bifurcating sites indicates that one of the keys is the formation of a low potential oxidation state to satisfy the energetics required of the endergonic half reaction, indicating that any redox center (organic or inorganic) that can exist in multiple oxidation states with sufficiently separated redox potentials should be capable of electron bifurcation. In this Feature Article, we explore a paradigm for bifurcating electrons down independent high and low potential pathways, and describe redox cofactors that have been demonstrated or implicated in driving this unique biochemistry.

  10. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation

    KAUST Repository

    Minenkov, Yury; Bistoni, Giovanni; Riplinger, Christoph; Auer, Alexander A.; Neese, Frank; Cavallo, Luigi

    2017-01-01

    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes

  11. Reaction

    African Journals Online (AJOL)

    abp

    19 oct. 2017 ... Reaction to Mohamed Said Nakhli et al. concerning the article: "When the axillary block remains the only alternative in a 5 year old child". .... Bertini L1, Savoia G, De Nicola A, Ivani G, Gravino E, Albani A et al ... 2010;7(2):101-.

  12. Mesoporous tungsten oxynitride as electrocatalyst for promoting redox reactions of vanadium redox couple and performance of vanadium redox flow battery

    Science.gov (United States)

    Lee, Wonmi; Jo, Changshin; Youk, Sol; Shin, Hun Yong; Lee, Jinwoo; Chung, Yongjin; Kwon, Yongchai

    2018-01-01

    For enhancing the performance of vanadium redox flow battery (VRFB), a sluggish reaction rate issue of V2+/V3+ redox couple evaluated as the rate determining reaction should be addressed. For doing that, mesoporous tungsten oxide (m-WO3) and oxyniride (m-WON) structures are proposed as the novel catalysts, while m-WON is gained by NH3 heat treatment of m-WO3. Their specific surface area, crystal structure, surface morphology and component analysis are measured using BET, XRD, TEM and XPS, while their catalytic activity for V2+/V3+ redox reaction is electrochemically examined. As a result, the m-WON shows higher peak current, smaller peak potential difference, higher electron transfer rate constant and lower charge transfer resistance than other catalysts, like the m-WO3, WO3 nanoparticle and mesoporous carbon, proving that it is superior catalyst. Regarding the charge-discharge curve tests, the VRFB single cell employing the m-WON demonstrates high voltage and energy efficiencies, high specific capacity and low capacity loss rate. The excellent results of m-WON are due to the reasons like (i) reduced energy band gap, (ii) reaction familiar surface functional groups and (ii) greater electronegativity.

  13. Controlling site selectivity in Pd-catalyzed oxidative cross-coupling reactions.

    Science.gov (United States)

    Lyons, Thomas W; Hull, Kami L; Sanford, Melanie S

    2011-03-30

    This paper presents a detailed investigation of the factors controlling site selectivity in the Pd-mediated oxidative coupling of 1,3-disubstituted and 1,2,3-trisubstituted arenes (aryl-H) with cyclometalating substrates (L~C-H). The influence of both the concentration and the steric/electronic properties of the quinone promoter are studied in detail. In addition, the effect of steric/electronic modulation of the carboxylate ligand is discussed. Finally, we demonstrate that substitution of the carboxylate for a carbonate X-type ligand leads to a complete reversal in site selectivity for many arene substrates. The origins of these trends in site selectivity are discussed in the context of the mechanism of Pd-catalyzed oxidative cross-coupling.

  14. High throughput reaction screening using desorption electrospray ionization mass spectrometry.

    Science.gov (United States)

    Wleklinski, Michael; Loren, Bradley P; Ferreira, Christina R; Jaman, Zinia; Avramova, Larisa; Sobreira, Tiago J P; Thompson, David H; Cooks, R Graham

    2018-02-14

    We report the high throughput analysis of reaction mixture arrays using methods and data handling routines that were originally developed for biological tissue imaging. Desorption electrospray ionization (DESI) mass spectrometry (MS) is applied in a continuous on-line process at rates that approach 10 4 reactions per h at area densities of up to 1 spot per mm 2 (6144 spots per standard microtiter plate) with the sprayer moving at ca. 10 4 microns per s. Data are analyzed automatically by MS using in-house software to create ion images of selected reagents and products as intensity plots in standard array format. Amine alkylation reactions were used to optimize the system performance on PTFE membrane substrates using methanol as the DESI spray/analysis solvent. Reaction times can be screening of processes like N -alkylation and Suzuki coupling reactions as reported herein. Products and by-products were confirmed by on-line MS/MS upon rescanning of the array.

  15. Analysis of phosphorus herbicides by ion-pairing reversed-phase liquid chromatography coupled to inductively coupled plasma mass spectrometry with octapole reaction cell.

    Science.gov (United States)

    Sadi, Baki B M; Vonderheide, Anne P; Caruso, Joseph A

    2004-09-24

    A reversed phase ion-pairing high performance liquid chromatographic (RPIP-HPLC) method is developed for the separation of two phosphorus herbicides, Glufosinate and Glyphosate as well as Aminomethylphosphonic acid (AMPA), the major metabolite of Glyphosate. Tetrabutylammonium hydroxide is used as the ion-pairing reagent in conjunction with an ammonium acetate/acetic acid buffering system at pH 4.7. An inductively coupled plasma mass spectrometer (ICP-MS) is coupled to the chromatographic system to detect the herbicides at m/z = 31P. Historically, phosphorus has been recognized as one of the elements difficult to analyze in argon plasma. This is due to its relatively high ionization potential (10.5 eV) as well as the inherent presence of the polyatomic interferences 14N16O1H+ and 15N16O+ overlapping its only isotope at m/z = 31. An octapole reaction cell is utilized to minimize the isobaric polyatomic interferences and to obtain the highest signal-to-background ratio. Detection limits were found to be in the low ppt range (25-32 ng/l). The developed method is successfully applied to the analysis of water samples collected from the Ohio River and spiked with a standard compounds at a level of 20 microg/l.

  16. Coupling IR Thermography and BIA to analyse body reaction after one acupuncture session

    International Nuclear Information System (INIS)

    Piquemal, M

    2013-01-01

    Coupling both thermography and bio-Impedance, some biophysical acupuncture mechanisms are statically studied on a small population of 18 subjects. Results show that a possible way of understanding acupuncture, in an electrical way, should be to consider ionic flux redistribution between vascular and extra cell compartments. This is a two steps mechanism. The first one is starting with needles insertion and the second one is lasting with more intensity after removing them from skin.

  17. Carbon-carbon coupling reactions of medium-sized N-containing dications

    Czech Academy of Sciences Publication Activity Database

    Zins, Emilie-Laure; Schröder, Detlef

    2010-01-01

    Roč. 114, č. 19 (2010), s. 5989-5996 ISSN 1089-5639 R&D Projects: GA ČR GA203/09/1223 Grant - others: ERC (XE) HORIZOMS AdG226373 Institutional research plan: CEZ:AV0Z40550506 Keywords : C-C coupling * dications * methane * pyridine * Titan Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.732, year: 2010

  18. Coupling IR Thermography and BIA to analyse body reaction after one acupuncture session

    Science.gov (United States)

    Piquemal, M.

    2013-04-01

    Coupling both thermography and bio-Impedance, some biophysical acupuncture mechanisms are statically studied on a small population of 18 subjects. Results show that a possible way of understanding acupuncture, in an electrical way, should be to consider ionic flux redistribution between vascular and extra cell compartments. This is a two steps mechanism. The first one is starting with needles insertion and the second one is lasting with more intensity after removing them from skin.

  19. Reaction

    African Journals Online (AJOL)

    raoul

    12 janv. 2012 ... Key words: Métastase, rate, colon, carcinome. Received: 28/12/2011 - Accepted: 09/01/2012 - Published: ... tomodensitométriques au moment du diagnostic du cancer primitif ou lors du suivi radiologique régulier des patients atteints de cancers. Le recours à la TEP-FDG couplée au scanner serait d'un ...

  20. Channel coupling in A(e,e N)B reactions

    CERN Document Server

    Kell, J

    1999-01-01

    The sensitivity of momentum distributions, recoil polarization observables, and response functions for nucleon knockout by polarized electron scattering to channel coupling in final-state interactions is investigated using a model in which both the distorting and the coupling potentials are constructed by folding density-dependent nucleon-nucleon effective interactions with nuclear transition densities. Elastic reorientation, inelastic scattering, and charge exchange are included for all possible couplings within the model space. Calculations for sup 1 sup 6 O are presented for 200 and 433 MeV ejectile energies, corresponding to proposed experiments at MAMI and TJNAF, and for sup 1 sup 2 C at 70 and 270 MeV, corresponding to experiments at NIKHEF and MIT-Bates. The relative importance of charge exchange decreases as the ejectile energy increases, but remains significant for 200 MeV. Both proton and neutron knockout cross sections for large recoil momenta, p sub m greater than 300 MeV/c, are substantially affe...

  1. How low does iron go? Chasing the active species in fe-catalyzed cross-coupling reactions.

    Science.gov (United States)

    Bedford, Robin B

    2015-05-19

    The catalytic cross-coupling reactions of organic halides or related substrates with organometallic nucleophiles form the cornerstone of many carbon-carbon bond-forming processes. While palladium-based catalysts typically mediate such reactions, there are increasing concerns about the long-term sustainability of palladium in synthesis. This is due to the high cost of palladium, coupled with its low natural abundance, environmentally deleterious extraction (∼6 g of metal are produced per ton of ore), toxicity, and competition for its use from the automotive and consumer electronics sectors. Therefore, there is a growing interest in replacing palladium-based catalysts with those incorporating more earth-abundant elements. With its low cost, high natural abundance, and low toxicity, iron makes a particularly appealing alternative, and accordingly, the development of iron-catalyzed cross-coupling is undergoing explosive growth. However, our understanding of the mechanisms that underpin the iron-based catalytic cycles is still very much in its infancy. Mechanistic insight into catalytic reactions is not only academically important but also allows us to maximize the efficiency of processes or even to develop entirely new transformations. Key to the development of robust mechanistic models for cross-coupling is knowing the lowest oxidation state in the cycle. Once this is established, we can explore subsequent redox processes and build the catalytic manifold. Until we know with confidence what the lowest oxidation state is, any cycles proposed are largely just guesswork. To date, Fe(-II), Fe(-I), Fe(0), Fe(I), and Fe(II) have been proposed as contenders for the lowest-oxidation-state species in the cycle in iron-catalyzed cross-coupling; the aim of this Account is to pull together the various pieces of evidence in support, or otherwise, of each of these suggestions in turn. There currently exists no direct evidence that oxidation states below Fe(0) are active in the

  2. Reaction channel coupling effects for nucleons on 16O: Induced undularity and proton-neutron potential differences

    Science.gov (United States)

    Keeley, N.; Mackintosh, R. S.

    2018-01-01

    Background: Precise fitting of scattering observables suggests that the nucleon-nucleus interaction is l dependent. Such l dependence has been shown to be S -matrix equivalent to an undulatory l -independent potential. The undulations include radial regions where the imaginary term is emissive. Purpose: To study the dynamical polarization potential (DPP) generated in proton-16O and neutron-16O interaction potentials by coupling to pickup channels. Undulatory features occurring in these DPPs can be compared with corresponding features of empirical optical model potentials (OMPs). Furthermore, the additional inclusion of coupling to vibrational states of the target will provide evidence for dynamically generated nonlocality. Methods: The fresco code provides the elastic channel S -matrix Sl j for chosen channel couplings. Inversion, Sl j→V (r ) +l .s VSO(r ) , followed by subtraction of the bare potential, yields an l -independent and local representation of the DPP due to the chosen couplings. Results: The DPPs have strongly undulatory features, including radial regions of emissivity. Certain features of empirical DPPs appear, e.g., the full inverted potential has emissive regions. The DPPs for different collective states are additive except near the nuclear center, whereas the collective and reaction channel DPPs are distinctly nonadditive over a considerable radial range, indicating dynamical nonlocality. Substantial differences between the DPPs due to pickup coupling for protons and neutrons occur; these imply a greater difference between proton and neutron OMPs than the standard phenomenological prescription. Conclusions: The onus is on those who object to undularity in the local and l -independent representation of nucleon elastic scattering to show why such undulations do not occur. This work suggests that it is not legitimate to halt model-independent fits to high-quality data at the appearance of undularity.

  3. Coupled Diffusion and Reaction Processes in Rock Matrices: Impact on Dilute Groundwater Plumes

    Science.gov (United States)

    2015-12-28

    35    3.6.3-Diffusion-Reaction Cell Construction using 40 mL Vials Gas tight extraction cells were designed and constructed to serve as a means to...ground surface GC gas chromatograph HPLC high-performance liquid chromatography ISCO in situ chemical oxidation MNA monitored natural attenuation...fracture-matrix interface. Mazurek et al. (1996) showed that fractures within shales were coated with birnessite and gypsum. Thus, the impacts of

  4. A chip-type thin-layer electrochemical cell coupled with capillary electrophoresis for online separation of electrode reaction products

    Energy Technology Data Exchange (ETDEWEB)

    He, Jian-Bo, E-mail: jbhe@hfut.edu.cn; Cui, Ting; Zhang, Wen-Wen; Deng, Ning

    2013-07-05

    Graphical abstract: -- Highlights: •A new coupling of thin-layer electrolysis with capillary electrophoresis (CE). •Rapid electrolysis, direct sampling followed by online CE separation. •At least 13 products of quercetin oxidation were separated. •Thermodynamic and kinetic parameters were determined from CE peak areas. -- Abstract: A coupling technique of thin-layer electrolysis with high-performance capillary electrophoresis/UV–vis technique(EC/HPCE/UV–vis) is developed for online separation and determination of electrode reaction products. A chip-type thin-layer electrolytic (CTE) cell was designed and fabricated, which contains a capillary channel and a background electrolyte reservoir, allowing rapid electrolysis, direct sampling and online electrophoretic separation. This chip-type setup was characterized based on an electrophoresis expression of Nernst equation that was applied to the redox equilibrium of o-tolidine at different potentials. The utility of the method was demonstrated by separating and determining the electro-oxidation products of quercetin in different pH media. Two main products were always found in the studied time, potential and pH ranges. The variety of products increased not only with increasing potential but also with increasing pH value, and in total, at least 13 products were observed in the electropherograms. This work illustrates a novel example of capillary electrophoresis used online with thin-layer electrolysis to separate and detect electrode reaction products.

  5. Solid state reaction studies in Fe3O4–TiO2 system by diffusion couple method

    International Nuclear Information System (INIS)

    Ren, Zhongshan; Hu, Xiaojun; Xue, Xiangxin; Chou, Kuochih

    2013-01-01

    Highlights: •The solid state reactions of Fe2O3-TiO2 system was studied by the diffusion couple method. •Different products were formed by diffusion, and the FeTiO3 was more stable phase. •The inter-diffusion coefficients and diffusion activation energy were estimated. -- Abstract: The solid state reactions in Fe 3 O 4 –TiO 2 system has been studied by diffusion couple experiments at 1323–1473 K, in which the oxygen partial pressure was controlled by the CO–CO 2 gas mixture. The XRD analysis was used to confirm the phases of the inter-compound, and the concentration profiles were determined by electron probe microanalysis (EPMA). Based on the concentration profile of Ti, the inter-diffusion coefficients in Fe 3 O 4 phase, which were both temperature and concentration of Ti ions dependent, were calculated by the modified Boltzmann–Matano method. According to the relation between the thickness of diffusion layer and temperature, the diffusion coefficient of the Fe 3 O 4 –TiO 2 system was obtained. According to the Arrhenius equation, the estimated diffusion activation energy was about 282.1 ± 18.8 kJ mol −1

  6. A chip-type thin-layer electrochemical cell coupled with capillary electrophoresis for online separation of electrode reaction products

    International Nuclear Information System (INIS)

    He, Jian-Bo; Cui, Ting; Zhang, Wen-Wen; Deng, Ning

    2013-01-01

    Graphical abstract: -- Highlights: •A new coupling of thin-layer electrolysis with capillary electrophoresis (CE). •Rapid electrolysis, direct sampling followed by online CE separation. •At least 13 products of quercetin oxidation were separated. •Thermodynamic and kinetic parameters were determined from CE peak areas. -- Abstract: A coupling technique of thin-layer electrolysis with high-performance capillary electrophoresis/UV–vis technique(EC/HPCE/UV–vis) is developed for online separation and determination of electrode reaction products. A chip-type thin-layer electrolytic (CTE) cell was designed and fabricated, which contains a capillary channel and a background electrolyte reservoir, allowing rapid electrolysis, direct sampling and online electrophoretic separation. This chip-type setup was characterized based on an electrophoresis expression of Nernst equation that was applied to the redox equilibrium of o-tolidine at different potentials. The utility of the method was demonstrated by separating and determining the electro-oxidation products of quercetin in different pH media. Two main products were always found in the studied time, potential and pH ranges. The variety of products increased not only with increasing potential but also with increasing pH value, and in total, at least 13 products were observed in the electropherograms. This work illustrates a novel example of capillary electrophoresis used online with thin-layer electrolysis to separate and detect electrode reaction products

  7. Detection of Maillard reaction products by a coupled HPLC-Fraction collector technique and FTIR characterization of Cu(II)-complexation with the isolated species

    Science.gov (United States)

    Ioannou, Aristos; Daskalakis, Vangelis; Varotsis, Constantinos

    2017-08-01

    The isolation of reaction products of asparagine with reducing sugars at alkaline pH and high temperature has been probed by a combination of high performance liquid chromatography (HPLC) coupled with a Fraction Collector. The UV-vis and FTIR spectra of the isolated Maillard reaction products showed structure-sensitive changes as depicted by deamination events and formation of asparagine-saccharide conjugates. The initial reaction species of the Asn-Gluc reaction were also characterized by Density Functional Theory (DFT) methods. Evidence for Cu (II) metal ion complexation with the Maillard reaction products is supported by UV-vis and FTIR spectroscopy.

  8. Spectroscopic factors with coupled-cluster connecting ab initio nuclear structure to reactions

    International Nuclear Information System (INIS)

    Jensen, Oeyvind

    2011-02-01

    This thesis has two parts. Tools and theory are presented in the first part, and papers with specific applications to nuclear physics are collected in the second part. A synopsis of theoretical foundations and basic techniques for many body quantum physics is presented in the context of a computer implementation of Wick's theorem for the symbolic algebra system SymPy. A pedagogical introduction to the implemented Python module is presented, and non-trivial aspects of the implemented simplification algorithms are discussed. Computer aided manipulations of second quantization expressions relieves practitioners of laborious and error-prone hand calculations necessary for the derivation of programmable equations. Theoretical developments of the Coupled-Cluster method (CCM) at Singles- and-Doubles level (CCSD) for the calculation of spectroscopic factors (SF) and radial overlap functions are presented. Algebraic expressions are derived from novel diagram techniques. CCM is one of the most successful methods for accurate numerical quantum mechanical simulations of medium sized many-body systems studied within Chemistry and Nuclear Physics. The recently developed spherical formulation of CCM is presented and alternative coupling schemes of quantum mechanical angular momentum are discussed in the context of a computer implementation for Racah algebra with SymPy. A pedagogical introduction to this functionality is given and it is used to derive angular momentum coupled expressions for efficient calculation of the spectroscopic factor diagrams. The first research paper presents a calculation of spectroscopic factors with CCSD. Details of the calculation is presented and convergence properties, as well as the dependence on various model parameters are discussed. Interactions with different cut-offs are employed and the dependence of the SF on the interactions are studied. In the second paper we employ the angular momentum coupled SF expressions and the spherical formulation

  9. Coupled channel theory of pion--deuteron reaction applied to threshold scattering

    International Nuclear Information System (INIS)

    Mizutani, T.; Koltun, D.S.

    1977-01-01

    Scattering and absorption of pions by a nuclear target are treated together in a coupled channel theory. The theory is developed explicitly for the problem of pion scattering and absorption by a deuteron. The equations are presented in terms of the integral equations of three-body scattering theory. The method is then applied in an approximate from to calculate the contribution of pion absorption to the scattering length for pion--deuteron scattering. The sensitivity of the calculated results to the model assumptions and approximations is investigated

  10. The coupling of ω-transaminase and Oppenauer oxidation reactions via intra-membrane multicomponent diffusion – A process model for the synthesis of chiral amines

    DEFF Research Database (Denmark)

    Esparza-Isunza, T.; González-Brambila, M.; Gani, Rafiqul

    2015-01-01

    amine product. Using 2-propylamine as the amine donor of the ω-transaminase reaction, gives acetone as a by-product, which in turn allows the coupling of the ω-transaminase reaction with the Oppenauer oxidation. The Oppenauer reaction converts secondary alcohols into ketones, and these can subsequently......In this study we consider the theoretical coupling of an otherwise thermodynamically limited ω-transaminase reaction to an Oppenauer oxidation, in order to shift the equilibria of both reactions, with the aim of achieving a significant (and important) increase in the yield of the desired chiral...... of this paper is to report the development of a mathematical model as a tool for the simulation and potential design of such a process for the production of a range of chiral amines. The mathematical model developed considers that each reaction is performed in a single ideally mixed isothermal reactor operating...

  11. Effects of doping in 25-atom bimetallic nanocluster catalysts for carbon–carbon coupling reaction of iodoanisole and phenylacetylene

    Directory of Open Access Journals (Sweden)

    Zhimin Li

    2016-10-01

    Full Text Available We here report the catalytic effects of foreign atoms (Cu, Ag, and Pt doped into well-defined 25-gold-atom nanoclusters. Using the carbon-carbon coupling reaction of p-iodoanisole and phenylacetylene as a model reaction, the gold-based bimetallic MxAu25−x(SR18 (–SR=–SCH2CH2Ph nanoclusters (supported on titania were found to exhibit distinct effects on the conversion of p-iodoanisole as well as the selectivity for the Sonogashira cross-coupling product, 1-methoxy-4-(2-phenylethynylbenzene. Compared to Au25(SR18, the centrally doped Pt1Au24(SR18 causes a drop in catalytic activity but with the selectivity retained, while the AgxAu25−x(SR18 nanoclusters gave an overall performance comparable to Au25(SR18. Interestingly, CuxAu25−x(SR18 nanoclusters prefer the Ullmann homo-coupling pathway and give rise to product 4,4′-dimethoxy-1,1′-biphenyl, which is in opposite to the other three nanocluster catalysts. Our overall conclusion is that the conversion of p-iodoanisole is largely affected by the electronic effect in the bimetallic nanoclusters’ 13-atom core (i.e., Pt1Au12, CuxAu13−x, and Au13, with the exception of Ag doping, and that the selectivity is primarily determined by the type of atoms on the MxAu12−x shell (M=Ag, Cu, and Au in the nanocluster catalysts.

  12. Sensitive electrochemical monitoring of nucleic acids coupling DNA nanostructures with hybridization chain reaction

    International Nuclear Information System (INIS)

    Zhuang, Junyang; Fu, Libing; Xu, Mingdi; Yang, Huanghao; Chen, Guonan; Tang, Dianping

    2013-01-01

    Graphical abstract: -- Highlights: •A new signal-on metallobioassay was developed for detection of nucleic acids. •Target-triggered long-range self-assembled DNA nanostructures are used for amplification of electronic signal. •Hybridization chain reaction is utilized for construction of long-range DNA nanostructures. -- Abstract: Methods based on metal nanotags have been developed for metallobioassay of nucleic acids, but most involve complicated labeling or stripping procedures and are unsuitable for routine use. Herein, we report the proof-of-concept of a novel and label-free metallobioassay for ultrasensitive electronic determination of human immunodeficiency virus (HIV)-related gene fragments at an ultralow concentration based on target-triggered long-range self-assembled DNA nanostructures and DNA-based hybridization chain reaction (HCR). The signal is amplified by silver nanotags on the DNA duplex. The assay mainly consists of capture probe, detection probe, and two different DNA hairpins. In the presence of target DNA, the capture probe immobilized on the sensor sandwiches target DNA with the 3′ end of detection probe. Another exposed part of detection probe at the 5′ end opens two alternating DNA hairpins in turn, and propagates a chain reaction of hybridization events to form a nicked double-helix. Finally, numerous silver nanotags are immobilized onto the long-range DNA nanostructures, each of which produces a strong electronic signal within the applied potentials. Under optimal conditions, the target-triggered long-range DNA nanostructures present good electrochemical behaviors for the detection of HIV DNA at a concentration as low as 0.5 fM. Importantly, the outstanding sensitivity can make this approach a promising scheme for development of next-generation DNA sensors without the need of enzyme labeling or fluorophore labeling

  13. Gas cooled fast reactor materials: compatibility and reaction kinetics of fuel/matrices couples

    International Nuclear Information System (INIS)

    Lechelle, J.; Aufore, L.; Basini, V.; Belin, R.; Vaudez, S.

    2004-01-01

    Fourth Generation Gas cooled Fast Reactor concept implies a fast neutron spectrum and aims to lead to an iso-generation of minor actinides. Criteria have been defined for these fuels such as: high core filling factor, efficient fuel cooling, low operation temperature, i.e. 400-850 deg C, good fission product retention, burn-ups in the range of 5-8 atom%, Pu content in the range of 15-25%. Materials matching this demand are considered: mixed uranium - plutonium nitrides and carbides as fuels, whereas TiN, TiC, ZrN, ZrC, SiC are investigated as inert matrices. Thermo-chemical compatibility studies have been carried out, mostly for (U,Pu)N/SiC and (U,Pu)N/TiN couples. They have been associated to matching diffusional studies. For the first studies, accidental reactor conditions have been chosen (1600 deg C) so as to select a couple. Results are presented in terms of nature and quantity of resulting phases identified by XRD and SEM for thermodynamical equilibrium experiments. (authors)

  14. A coupling alternative to reactive transport simulations for long-term prediction of chemical reactions in heterogeneous CO2 storage systems

    Directory of Open Access Journals (Sweden)

    M. De Lucia

    2015-02-01

    Full Text Available Fully coupled, multi-phase reactive transport simulations of CO2 storage systems can be approximated by a simplified one-way coupling of hydrodynamics and reactive chemistry. The main characteristics of such systems, and hypotheses underlying the proposed alternative coupling, are (i that the presence of CO2 is the only driving force for chemical reactions and (ii that its migration in the reservoir is only marginally affected by immobilisation due to chemical reactions. In the simplified coupling, the exposure time to CO2 of each element of the hydrodynamic grid is estimated by non-reactive simulations and the reaction path of one single batch geochemical model is applied to each grid element during its exposure time. In heterogeneous settings, analytical scaling relationships provide the dependency of velocity and amount of reactions to porosity and gas saturation. The analysis of TOUGHREACT fully coupled reactive transport simulations of CO2 injection in saline aquifer, inspired to the Ketzin pilot site (Germany, both in homogeneous and heterogeneous settings, confirms that the reaction paths predicted by fully coupled simulations in every element of the grid show a high degree of self-similarity. A threshold value for the minimum concentration of dissolved CO2 considered chemically active is shown to mitigate the effects of the discrepancy between dissolved CO2 migration in non-reactive and fully coupled simulations. In real life, the optimal threshold value is unknown and has to be estimated, e.g. by means of 1-D or 2-D simulations, resulting in an uncertainty ultimately due to the process de-coupling. However, such uncertainty is more than acceptable given that the alternative coupling enables using grids of the order of millions of elements, profiting from much better description of heterogeneous reservoirs at a fraction of the calculation time of fully coupled models.

  15. Optimization of induced crystallization reaction in a novel process of nutrients removal coupled with phosphorus recovery from domestic wastewater

    Directory of Open Access Journals (Sweden)

    Zou Haiming

    2017-12-01

    Full Text Available Phosphorus removal and recovery from domestic wastewater is urgent nowadays. A novel process of nutrients removal coupled with phosphorus recovery from domestic sewage was proposed and optimization of induced crystallization reaction was performed in this study. The results showed that 92.3% of phosphorus recovery via induced Hydroxyapatite crystallization was achieved at the optimum process parameters: reaction time of 80 min, seed crystal loads of 60 g/L, pH of 8.5, Ca/P mole ratio of 2.0 and 4.0 L/min aeration rate when the PO43--P concentration was 10 mg/L in the influent, displaying an excellent phosphorus recovery performance. Importantly, it was found that the effect of reaction temperature on induced Hydroxyapatite crystallization was slight, thus favoring practical application of phosphorus recovery method described in this study. From these results, the proposed method of induced HAP crystallization to recover phosphorus combined with nutrients removal can be an economical and effective technology, probably favoring the water pollution control and phosphate rock recycle.

  16. An accurate potential energy surface for the F + H2 → HF + H reaction by the coupled-cluster method

    International Nuclear Information System (INIS)

    Chen, Jun; Sun, Zhigang; Zhang, Dong H.

    2015-01-01

    A three dimensional potential energy surface for the F + H 2 → HF + H reaction has been computed by the spin unrestricted coupled cluster method with singles, doubles, triples, and perturbative quadruples [UCCSDT(2) Q ] using the augmented correlation-consistent polarised valence quadruple zeta basis set for the fluorine atom and the correlation-consistent polarised valence quadruple zeta basis set for the hydrogen atom. All the calculations are based on the restricted open-shell Hartree-Fock orbitals, together with the frozen core approximations, and the UCCSD(T)/complete basis set (CBS) correction term was included. The global potential energy surface was calculated by fitting the sampled ab initio points without any scaling factor for the correlation energy part using a neutral network function method. Extensive dynamics calculations have been carried out on the potential energy surface. The reaction rate constants, integral cross sections, product rotational states distribution, and forward and backward scattering as a function of collision energy of the F + HD → HF + D, F + HD → DF + H, and F + H 2 reaction, were calculated by the time-independent quantum dynamics scattering theory using the new surface. The satisfactory agreement with the reported experimental observations previously demonstrates the accuracy of the new potential energy surface

  17. Influence of Proton Acceptors on the Proton-Coupled Electron Transfer Reaction Kinetics of a Ruthenium-Tyrosine Complex.

    Science.gov (United States)

    Lennox, J Christian; Dempsey, Jillian L

    2017-11-22

    A polypyridyl ruthenium complex with fluorinated bipyridine ligands and a covalently bound tyrosine moiety was synthesized, and its photo-induced proton-coupled electron transfer (PCET) reactivity in acetonitrile was investigated with transient absorption spectroscopy. Using flash-quench methodology with methyl viologen as an oxidative quencher, a Ru 3+ species is generated that is capable of initiating the intramolecular PCET oxidation of the tyrosine moiety. Using a series of substituted pyridine bases, the reaction kinetics were found to vary as a function of proton acceptor concentration and identity, with no significant H/D kinetic isotope effect. Through analysis of the kinetics traces and comparison to a control complex without the tyrosine moiety, PCET reactivity was found to proceed through an equilibrium electron transfer followed by proton transfer (ET-PT) pathway in which irreversible deprotonation of the tyrosine radical cation shifts the ET equilibrium, conferring a base dependence on the reaction. Comprehensive kinetics modeling allowed for deconvolution of complex kinetics and determination of rate constants for each elementary step. Across the five pyridine bases explored, spanning a range of 4.2 pK a units, a linear free-energy relationship was found for the proton transfer rate constant with a slope of 0.32. These findings highlight the influence that proton transfer driving force exerts on PCET reaction kinetics.

  18. Spectrophotometric Determination of Reboxetine through Condensation and Diazo-Coupling Reactions

    Directory of Open Access Journals (Sweden)

    K. Srikanth

    2011-01-01

    Full Text Available In the present study, two simple, sensitive and reproducible visible spectrophotometric methods were developed for the determination of reboxetine in pure form and in pharmaceutical formulations. The methods involve acid hydrolysis of reboxetine methane sulphonate (Reboxetine as methane sulphonate and the product obtained was used for the estimation. Out of the two methods developed in the laboratory, the first method involves the condensation reaction of hydrolysed reboxetine methane sulphonate with ethyl acetoacetate in sulphuric acid medium and the second method involves the diazocoupling reaction of hydrolysed reboxetine methane sulphonate with diazotized p-sulphanilic acid in alkaline medium. They have absorption maxima at 400 nm and 430 nm respectively and obey Beer’s law in the concentration ranges of 0.5 - 0.3 μgmL-1 and 1.0 - 7.5 μgmL-1 respectively. Results of analysis were validated statistically and by recovery studies. The apparent molar absorptivity values (∈max obtained are 7.549 x 104 L mol-1 cm-11 and 2.656x104 Lmol-1cm-1 respectively. Both these have correlation coefficient value of 0.9999. The proposed methods have good precision and accuracy.

  19. One-electron transfer reactions of the couple NAD./NADH

    International Nuclear Information System (INIS)

    Grodkowski, J.; Neta, P.; Carlson, B.W.; Miller, L.

    1983-01-01

    One-electron transfer reactions involving nicotinamide-adenine dinucleotide in its oxidized and reducd forms (NAD./NADH) were studied by pulse radiolysis in aqueous solutions. One-electron oxidation of NADH by various phenoxyl radicals and phenothiazine cation radicals was found to take place with rate constants in the range of 10 5 to 10 8 M -1 s -1 , depending on the redox potential of the oxidizing species. In all cases, NAD. is formed quantitatively with no indication for the existence of the protonated form (NADH + .). The spectrum of NAD., as well as the rates of oxidation of NADH by phenoxyl and by (chlorpromazine) + . were independent of pH between pH 4.5 and 13.5. Reaction of deuterated NADH indicated only a small kinetic isotope effect. All these findings point to an electron transfer mechanism. On the other hand, attempts to observe the reverse electron transfer, i.e., one-electron reduction of NAD. to NADH by radicals such as semiquinones, showed that k was less than 10 4 to 10 5 M -1 s -1 , so that it was unobservable. Consequently, it was not possible to achieve equilibrium conditions which would have permitted the direct measurement of the redox potential for NAD./NADH. One-electron reduction of NAD. appears to be an unlikely process. 1 table

  20. Flame Atmospheric Pressure Chemical Ionization Coupled with Negative Electrospray Ionization Mass Spectrometry for Ion Molecule Reactions.

    Science.gov (United States)

    Cheng, Sy-Chyi; Bhat, Suhail Muzaffar; Shiea, Jentaie

    2017-07-01

    Flame atmospheric pressure chemical ionization (FAPCI) combined with negative electrospray ionization (ESI) mass spectrometry was developed to detect the ion/molecule reactions (IMRs) products between nitric acid (HNO 3 ) and negatively charged amino acid, angiotensin I (AI) and angiotensin II (AII), and insulin ions. Nitrate and HNO 3 -nitrate ions were detected in the oxyacetylene flame, suggesting that a large quantity of nitric acid (HNO 3 ) was produced in the flame. The HNO 3 and negatively charged analyte ions produced by a negative ESI source were delivered into each arm of a Y-shaped stainless steel tube where they merged and reacted. The products were subsequently characterized with an ion trap mass analyzer attached to the exit of the Y-tube. HNO 3 showed the strongest affinity to histidine and formed (M histidine -H+HNO 3 ) - complex ions, whereas some amino acids did not react with HNO 3 at all. Reactions between HNO 3 and histidine residues in AI and AII resulted in the formation of dominant [M AI -H+(HNO 3 )] - and [M AII -H+(HNO 3 )] - ions. Results from analyses of AAs and insulin indicated that HNO 3 could not only react with basic amino acid residues, but also with disulfide bonds to form [M-3H+(HNO 3 ) n ] 3- complex ions. This approach is useful for obtaining information about the number of basic amino acid residues and disulfide bonds in peptides and proteins. Graphical Abstract ᅟ.

  1. A redescription of Zavrelia simantoneoa (Sasa, Suzuki and Sakai, 1998 comb. nov.

    Directory of Open Access Journals (Sweden)

    Tadashi Kobayashi

    2014-12-01

    Full Text Available Examination of the holotype of Micropsectra simantoneoa Sasa, Suzuki and Sakai, 1998 revealed that the species should be transferred to the genus Zavrelia. The male adult has hairy eyes, antennae with 10 flagellomeres, a costa ending proximal to the tip of M3+4, and a short and flattened superior volsella. This is the second Zavrelia species from Japan, and the 11th in the world.Article submitted 25. September 2014, accepted 16. October 2014, published 22. December 2014.

  2. Disentangling effects of breakup coupling and incomplete fusion in 6Li + 232Th reaction

    International Nuclear Information System (INIS)

    Jha, V.; Parkar, V.V.; Mohanty, A.K.; Kailas, S.

    2014-01-01

    A component of fusion that is very important but quite difficult to evaluate is the incomplete fusion (ICF), in which only a part of the nucleus fuses with the target. ICF occurs together with the usual complete fusion (CF), in which the whole projectile fuses or all the projectile fragments after breakup fuse with the target nucleus. The ICF leads to the flux removal from the fusion channel and its calculation is essential for a comprehensive description of the fusion process. In the present work, a recently developed method of calculating the ICF cross-section (σ ICF ) is used in a novel way to disentangle the ICF effect on the fusion process from those due to breakup couplings. The total fusion cross-section σ TF and σ ICF for the 6 Li + 232 Th system are calculated at energies above and below the Coulomb barrier, where the measured fusion-fission data is available

  3. Approaches to Modeling Coupled Flow and Reaction in a 2-D Cementation Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Steefel, Carl; Cochepin, B.; Trotignon, L.; Bildstein, O.; Steefel, C.; Lagneau, V.; van der Lee, J.

    2008-04-01

    Porosity evolution at reactive interfaces is a key process that governs the evolution and performances of many engineered systems that have important applications in earth and environmental sciences. This is the case, for example, at the interface between cement structures and clays in deep geological nuclear waste disposals. Although in a different transport regime, similar questions arise for permeable reactive barriers used for biogeochemical remediation in surface environments. The COMEDIE project aims at investigating the coupling between transport, hydrodynamics and chemistry when significant variations of porosity occur. The present work focuses on a numerical benchmark used as a design exercise for the future COMEDIE-2D experiment. The use of reactive transport simulation tools like Hytec and Crunch provides predictions of the physico-chemical evolutions that are expected during the future experiments in laboratory. Focus is given in this paper on the evolution during the simulated experiment of precipitate, permeability and porosity fields. A first case is considered in which the porosity is constant. Results obtained with Crunch and Hytec are in relatively good agreement. Differences are attributable to the models of reactive surface area taken into account for dissolution/precipitation processes. Crunch and Hytec simulations taking into account porosity variations are then presented and compared. Results given by the two codes are in qualitative agreement, with differences attributable in part to the models of reactive surface area for dissolution/precipitation processes. As a consequence, the localization of secondary precipitates predicted by Crunch leads to lower local porosities than for predictions obtained by Hytec and thus to a stronger coupling between flow and chemistry. This benchmark highlights the importance of the surface area model employed to describe systems in which strong porosity variations occur as a result of dissolution

  4. Kinetic Monte Carlo modeling of chemical reactions coupled with heat transfer.

    Science.gov (United States)

    Castonguay, Thomas C; Wang, Feng

    2008-03-28

    In this paper, we describe two types of effective events for describing heat transfer in a kinetic Monte Carlo (KMC) simulation that may involve stochastic chemical reactions. Simulations employing these events are referred to as KMC-TBT and KMC-PHE. In KMC-TBT, heat transfer is modeled as the stochastic transfer of "thermal bits" between adjacent grid points. In KMC-PHE, heat transfer is modeled by integrating the Poisson heat equation for a short time. Either approach is capable of capturing the time dependent system behavior exactly. Both KMC-PHE and KMC-TBT are validated by simulating pure heat transfer in a rod and a square and modeling a heated desorption problem where exact numerical results are available. KMC-PHE is much faster than KMC-TBT and is used to study the endothermic desorption of a lattice gas. Interesting findings from this study are reported.

  5. Investigation of the Pyridinium Ylide—Alkyne Cycloaddition as a Fluorogenic Coupling Reaction

    Directory of Open Access Journals (Sweden)

    Simon Bonte

    2016-03-01

    Full Text Available The cycloaddition of pyridinium ylides with alkynes was investigated under mild conditions. A series of 13 pyridinium salts was prepared by alkylation of 4-substituted pyridines. Their reactivity with propiolic ester or amide in various reaction conditions (different temperatures, solvents, added bases was studied, and 11 indolizines, with three points of structural variation, were, thus, isolated and characterized. The highest yields were obtained when electron-withdrawing groups were present on both the pyridinium ylide, generated in situ from the corresponding pyridinium salt, and the alkyne (X, Z = ester, amide, CN, carbonyl, etc.. Electron-withdrawing substituents, lowering the acid dissociation constant (pKa of the pyridinium salts, allow the cycloaddition to proceed at pH 7.5 in aqueous buffers at room temperature.

  6. Charged Porous Polymers using a Solid C-O Cross-Coupling Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengfei; Jiang, Xueguang; Wan, Shun; Dai, Sheng

    2015-07-15

    Here in this paper, we report a green, fast, efficient mechanochemical strategy for charged porous polymers (CPPs). A cationic CPP with basic anions and an anionic CPP with Li+ cations were fabricated by solid grinding under solvent-free conditions. Compared with solution-based synthesis, mechanochemical grinding can shorten the reaction time from dozens of hours to several minutes (60–90 min) to form polymers possessing a high molecular mass and low polydispersity. During the construction of CPPs, a Pd-catalyzed solid polycondensation based on unactivated organic linkers was introduced. In particular, CPPs with basic phenolic or proline anions showed good activity and stability in SO2 capture, and Li+-functionalized CPPs can be post-modified to CPPs with other metal ions by ion exchange, highlighting the tailorable feature of ionic-modified CPPs.

  7. Charged Porous Polymers using a Solid C-O Cross-Coupling Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengfei; Jiang, Xueguang; Wan, Shun; Dai, Sheng

    2015-07-15

    Herein, we report a green, fast, efficient mechanochemical strategy for charged porous polymers (CPPs). A cationic CPP with basic anions and an anionic CPP with Li+ cations were fabricated by solid grinding under solvent-free conditions. Compared with solution-based synthesis, mechanochemical grinding can shorten the reaction time from dozens of hours to several minutes (60–90 min) to form polymers possessing a high molecular mass and low polydispersity. During the construction of CPPs, a Pd-catalyzed solid polycondensation based on unactivated organic linkers was introduced. In particular, CPPs with basic phenolic or proline anions showed good activity and stability in SO2 capture, and Li+-functionalized CPPs can be post-modified to CPPs with other metal ions by ion exchange, highlighting the tailorable feature of ionic-modified CPPs.

  8. Coupled sensitizer-catalyst dyads: electron-transfer reactions in a perylene-polyoxometalate conjugate.

    Science.gov (United States)

    Odobel, Fabrice; Séverac, Marjorie; Pellegrin, Yann; Blart, Errol; Fosse, Céline; Cannizzo, Caroline; Mayer, Cédric R; Elliott, Kristopher J; Harriman, Anthony

    2009-01-01

    Ultrafast discharge of a single-electron capacitor: A variety of intramolecular electron-transfer reactions are apparent for polyoxometalates functionalized with covalently attached perylene monoimide chromophores, but these are restricted to single-electron events. (et=electron transfer, cr=charge recombination, csr=charge-shift reaction, PER=perylene, POM=polyoxometalate).A new strategy is introduced that permits covalent attachment of an organic chromophore to a polyoxometalate (POM) cluster. Two examples are reported that differ according to the nature of the anchoring group and the flexibility of the linker. Both POMs are functionalized with perylene monoimide units, which function as photon collectors and form a relatively long-lived charge-transfer state under illumination. They are reduced to a stable pi-radical anion by electrolysis or to a protonated dianion under photolysis in the presence of aqueous triethanolamine. The presence of the POM opens up an intramolecular electron-transfer route by which the charge-transfer state reduces the POM. The rate of this process depends on the molecular conformation and appears to involve through-space interactions. Prior reduction of the POM leads to efficient fluorescence quenching, again due to intramolecular electron transfer. In most cases, it is difficult to resolve the electron-transfer products because of relatively fast reverse charge shift that occurs within a closed conformer. Although the POM can store multiple electrons, it has not proved possible to use these systems as molecular-scale capacitors because of efficient electron transfer from the one-electron-reduced POM to the excited singlet state of the perylene monoimide.

  9. Preparation and Characterization of Pd Modified TiO2 Nanofiber Catalyst for Carbon–Carbon Coupling Heck Reaction

    Directory of Open Access Journals (Sweden)

    Leah O. Nyangasi

    2017-01-01

    Full Text Available TiO2 fibers were prepared through electrospinning of poly methyl methacrylate (PMMA and titanium isopropoxide (TIP solution followed by calcination of fibers in air at 500°C. Cetyltrimethylammonium bromide (CTAB protected palladium nanoparticles (Pd NPs prepared through reduction method were successfully adsorbed on the TiO2 nanofibers (NF. Combined studies of X-ray diffraction (XRD, scanning electron microscope (SEM, and transmission electron microscope (TEM indicated that the synthesized Pd/TiO2 had anatase. BET indicated that the synthesized TiO2 and Pd/TiO2 had a surface area of 53.4 and 43.4 m2/g, respectively. The activity and selectivity of 1 mol% Pd/TiO2 in the Heck reaction have been investigated towards the Mizoroki-Heck carbon–carbon cross-coupling of bromobenzene (ArBr and styrene. Temperature, time, solvent, and base were optimized and catalyst was recycled thrice. 1H NMR and 13C NMR indicated that stilbene, a known compound from literature, was obtained in various Heck reactions at temperatures between 100°C and 140°C but the recyclability was limited due to some palladium leaching and catalyst poisoning which probably arose from some residual carbon from the polymer. The catalyst was found to be highly active under air atmosphere with reaction temperatures up to 140°C. Optimized reaction condition resulted in 89.7% conversions with a TON of 1993.4 and TOF value of 332.2 hr−1.

  10. Electrochemistry coupled to (LC-)MS for the simulation of oxidative biotransformation reactions of PAHs.

    Science.gov (United States)

    Wigger, Tina; Seidel, Albrecht; Karst, Uwe

    2017-06-01

    Electrochemistry coupled to liquid chromatography and mass spectrometry was used for simulating the biological and environmental fate of polycyclic aromatic hydrocarbons (PAHs) as well as for studying the PAH degradation behavior during electrochemical remediation. Pyrene and benzo[a]pyrene were selected as model compounds and oxidized within an electrochemical thin-layer cell equipped with boron-doped diamond electrode. At potentials of 1.2 and 1.6 V vs. Pd/H 2 , quinones were found to be the major oxidation products for both investigated PAHs. These quinones belong to a large group of PAH derivatives referred to as oxygenated PAHs, which have gained increasing attention in recent years due to their high abundance in the environment and their significant toxicity. Separation of oxidation products allowed the identification of two pyrene quinone and three benzo[a]pyrene quinone isomers, all of which are known to be formed via photooxidation and during mammalian metabolism. The good correlation between electrochemically generated PAH quinones and those formed in natural processes was also confirmed by UV irradiation experiments and microsomal incubations. At potentials higher than 2.0 V, further degradation of the initial oxidation products was observed which highlights the capability of electrochemistry to be used as remediation technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Self-powered gustation electronic skin for mimicking taste buds based on piezoelectric-enzymatic reaction coupling process

    Science.gov (United States)

    Zhao, Tianming; Fu, Yongming; He, Haoxuan; Dong, Chuanyi; Zhang, Linlin; Zeng, Hui; Xing, Lili; Xue, Xinyu

    2018-02-01

    A new self-powered wearable gustation electronic skin for mimicking taste buds has been realized based on enzyme-modified/ZnO nanowire arrays on patterned-electrode flexible substrate. The e-skin can actively taste beverages or fruits without any external electric power. Through the piezoelectric-enzymatic reaction coupling effect, the nanowires can harvest the mechanical energy of body movement and output piezoelectric signal. The piezoelectric output is significantly dependent on the concentration of target analyte. The response for detecting 2 × 10-2 M ascorbic acid (ascorbate acid oxidase@ZnO) is up to 171.747, and the selectivity is high. The response for detecting 50% alcohol (alcohol oxidase@ZnO) is up to 45.867. Our results provide a new research direction for the development of multifunctional e-skin and expand the study scope for self-powered bionic systems.

  12. Bioinspired Syntheses of Dimeric Hydroxycinnamic Acids (Lignans and Hybrids, Using Phenol Oxidative Coupling as Key Reaction, and Medicinal Significance Thereof

    Directory of Open Access Journals (Sweden)

    George E. Magoulas

    2014-11-01

    Full Text Available Lignans are mainly dimers of 4-hydroxycinnamic acids (HCAs and reduced analogs thereof which are produced in Nature through phenol oxidative coupling (POC as the primary C-C or C-O bond-forming reaction under the action of the enzymes peroxidases and laccases. They present a large structural variety and particularly interesting biological activities, therefore, significant efforts has been devoted to the development of efficient methodologies for the synthesis of lignans isolated from natural sources, analogs and hybrids with other biologically interesting small molecules. We summarize in the present review those methods which mimic Nature for the assembly of the most common lignan skeleta by using either enzymes or one-electron inorganic oxidants to effect POC of HCAs and derivatives, such as esters and amides, or cross-POC of pairs of HCAs or HCAs with 4-hydrocycinnamyl alcohols. We, furthermore, provide outlines of mechanistic schemes accounting for the formation of the coupled products and, where applicable, indicate their potential application in medicine.

  13. Optimization of hydrogen production via coupling of the Fischer-Tropsch synthesis reaction and dehydrogenation of cyclohexane in GTL technology

    International Nuclear Information System (INIS)

    Rahimpour, M.R.; Bahmanpour, A.M.

    2011-01-01

    In this study, a thermally-coupled reactor containing the Fischer-Tropsch synthesis reaction in the exothermic side and dehydrogenation of cyclohexane in the endothermic side has been modified using a hydrogen perm-selective membrane as the shell of the reactor to separate the produced hydrogen from the dehydrogenation process. Permeated hydrogen enters another section called permeation side to be collected by Argon, known as the sweep gas. This three-sided reactor has been optimized using differential evolution (DE) method to predict the conditions at which the reactants' conversion and also the hydrogen recovery yield would be maximized. Minimizing the CO 2 and CH 4 yield in the reactor's outlet as undesired products is also considered in the optimization process. To reach this goal, optimal initial molar flow rate and inlet temperature of three sides as well as pressure of the exothermic side have been calculated. The obtained results have been compared with the conventional reactor data of the Research Institute of Petroleum Industry (RIPI), the membrane dual - type reactor suggested for Fischer-Tropsch synthesis, and the membrane coupled reactor presented for methanol synthesis. The comparison shows acceptable enhancement in the reactor's performance and that the production of hydrogen as a valuable byproduct should also be considered.

  14. Radical O-O coupling reaction in diferrate-mediated water oxidation studied using multireference wave function theory.

    Science.gov (United States)

    Kurashige, Yuki; Saitow, Masaaki; Chalupský, Jakub; Yanai, Takeshi

    2014-06-28

    The O-O (oxygen-oxygen) bond formation is widely recognized as a key step of the catalytic reaction of dioxygen evolution from water. Recently, the water oxidation catalyzed by potassium ferrate (K2FeO4) was investigated on the basis of experimental kinetic isotope effect analysis assisted by density functional calculations, revealing the intramolecular oxo-coupling mechanism within a di-iron(vi) intermediate, or diferrate [Sarma et al., J. Am. Chem. Soc., 2012, 134, 15371]. Here, we report a detailed examination of this diferrate-mediated O-O bond formation using scalable multireference electronic structure theory. High-dimensional correlated many-electron wave functions beyond the one-electron picture were computed using the ab initio density matrix renormalization group (DMRG) method along the O-O bond formation pathway. The necessity of using large active space arises from the description of complex electronic interactions and varying redox states both associated with two-center antiferromagnetic multivalent iron-oxo coupling. Dynamic correlation effects on top of the active space DMRG wave functions were additively accounted for by complete active space second-order perturbation (CASPT2) and multireference configuration interaction (MRCI) based methods, which were recently introduced by our group. These multireference methods were capable of handling the double shell effects in the extended active space treatment. The calculations with an active space of 36 electrons in 32 orbitals, which is far over conventional limitation, provide a quantitatively reliable prediction of potential energy profiles and confirmed the viability of the direct oxo coupling. The bonding nature of Fe-O and dual bonding character of O-O are discussed using natural orbitals.

  15. Mathematical modeling of the coupled transport and electrochemical reactions in solid oxide steam electrolyzer for hydrogen production

    International Nuclear Information System (INIS)

    Ni, Meng; Leung, Michael K.H.; Leung, Dennis Y.C.

    2007-01-01

    A mathematical model was developed to simulate the coupled transport/electrochemical reaction phenomena in a solid oxide steam electrolyzer (SOSE) at the micro-scale level. Ohm's law, dusty gas model (DGM), Darcy's law, and the generalized Butler Volmer equation were employed to determine the transport of electronic/ionic charges and gas species as well as the electrochemical reactions. Parametric analyses were performed to investigate the effects of operating parameters and micro-structural parameters on SOSE potential. The results substantiated the fact that SOSE potential could be effectively decreased by increasing the operating temperature. In addition, higher steam molar fraction would enhance the operation of SOSE with lower potential. The effect of particle sizes on SOSE potential was studied with due consideration on the SOSE activation and concentration overpotentials. Optimal particle sizes that could minimize the SOSE potential were obtained. It was also found that decreasing electrode porosity could monotonically decrease the SOSE potential. Besides, optimal values of volumetric fraction of electronic particles were found to minimize electrode total overpotentials. In order to optimize electrode microstructure to minimize SOSE electricity consumption, the concept of 'functionally graded materials (FGM)' was introduced to lower the SOSE potential. The advanced design of particle size graded SOSE was found effective for minimizing electrical energy consumption resulting in efficient SOSE hydrogen production. The micro-scale model was capable of predicting SOSE hydrogen production performance and would be a useful tool for design optimization

  16. Non-Covalent Fluorescent Labeling of Hairpin DNA Probe Coupled with Hybridization Chain Reaction for Sensitive DNA Detection.

    Science.gov (United States)

    Song, Luna; Zhang, Yonghua; Li, Junling; Gao, Qiang; Qi, Honglan; Zhang, Chengxiao

    2016-04-01

    An enzyme-free signal amplification-based assay for DNA detection was developed using fluorescent hairpin DNA probes coupled with hybridization chain reaction (HCR). The hairpin DNAs were designed to contain abasic sites in the stem moiety. Non-covalent labeling of the hairpin DNAs was achieved when a fluorescent ligand was bound to the abasic sites through hydrogen bonding with the orphan cytosine present on the complementary strand, accompanied by quench of ligand fluorescence. As a result, the resultant probes, the complex formed between the hairpin DNA and ligand, showed almost no fluorescence. Upon hybridization with target DNA, the probe underwent a dehybridization of the stem moiety containing an abasic site. The release of ligand from the abasic site to the solution resulted in an effective fluorescent enhancement, which can be used as a signal. Compared with a sensing system without HCR, a 20-fold increase in the sensitivity was achieved using the sensing system with HCR. The fluorescent intensity of the sensing system increased with the increase in target DNA concentration from 0.5 nM to 100 nM. A single mismatched target ss-DNA could be effectively discriminated from complementary target DNA. Genotyping of a G/C single-nucleotide polymorphism of polymerase chain reaction (PCR) products was successfully demonstrated with the sensing system. Therefore, integrating HCR strategy with non-covalent labeling of fluorescent hairpin DNA probes provides a sensitive and cost-effective DNA assay. © The Author(s) 2016.

  17. Highly active and non-corrosive catalytic systems for the coupling reactions of ethylene oxide and CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuyao; Jin, So Jeong; Kim, Young Jin; Lee, Je Seung; Kim, Hoon Sik [Dept. of Chemistry and Research Institute of Basic Sciences, Kyung Hee University, Seoul (Korea, Republic of); Hong, Jongki; Lee, Won Woong [College of Pharmacy, Kyung Hee University, Seoul (Korea, Republic of); Ryu, Jung Bok [R and D Center, Chuncheon (Korea, Republic of)

    2017-02-15

    Lithium halide-based molten salts (LiX-[BMIm]Br) synthesized from the reactions of lithium halides (LiX, X = Cl or Br) with 1-butyl-3-methylimidazolium bromide ([BMIm]Br), and their catalytic performances and corrosivities were tested for the coupling reactions of ethylene oxide with carbon dioxide to produce ethylene carbonate. The activity of a molten salt was influenced with the change of halide ion. At a fixed molar amount of LiX, the activity of LiX-[BMIm]Br increased with increasing molar ratio of LiX/[BMIm]Br up to 1–1.25, and then decreased thereafter. Fast atom bombardment mass spectral analysis of LiBr-[BMIm]Br, obtained by dissolving LiBr in [BMIm]Br in a 1:1 molar ratio, implies that [Li{sub a} X{sub a+1}]{sup −} are active species for the carboxylation of ethylene oxide with LiX-[BMIm]Br. The corrosion test toward carbon steel coupons demonstrates that all the Cl-containing molten salts are corrosive, whereas the salts without containing Cl{sup −} are non-corrosive under the carboxylation condition.

  18. Mechanism of the Suzuki–Miyaura Cross-Coupling Reaction Mediated by [Pd(NHC)(allyl)Cl] Precatalysts

    KAUST Repository

    Meconi, Giulia Magi

    2017-05-24

    Density functional theory calculations have been used to investigate the activation mechanism for the precatalyst series [Pd]-X-1–4 derived from [Pd(IPr)(R-allyl)X] species by substitutions at the terminal position of the allyl moiety ([Pd] = Pd(IPr); R = H (1), Me (2), gem-Me2 (3), Ph (4), X = Cl, Br). Next, we have investigated the Suzuki–Miyaura cross-coupling reaction for the active catalyst species IPr-Pd(0) using 4-chlorotoluene and phenylboronic acid as substrates and isopropyl alcohol as a solvent. Our theoretical findings predict an upper barrier trend, corresponding to the activation mechanism for the [Pd]-Cl-1–4 series, in good agreement with the experiments. They indeed provide a quantitative explanation of the low yield (12%) displayed by [Pd]-Cl-1 species (ΔG⧧ ≈ 30.0 kcal/mol) and of the high yields (≈90%) observed in the case of [Pd]-Cl-2–4 complexes (ΔG⧧ ≈ 20.0 kcal/mol). Additionally, the studied Suzuki–Miyaura reaction involving the IPr-Pd(0) species is calculated to be thermodynamically favorable and kinetically facile. Similar investigations for the [Pd]-Br-1–4 series, derived from [Pd(IPr)(R-allyl)Br], indicate that the oxidative addition step for IPr-Pd(0)-mediated catalysis with 4-bromotoluene is kinetically more favored than that with 4-chlorotoluene. Finally, we have explored the potential of Ni-based complexes [Ni((IPr)(R-allyl)X] (X = Cl, Br) as Suzuki–Miyaura reaction catalysts. Apart from a less endergonic reaction energy profile for both precatalyst activation and catalytic cycle, a steep increase in the predicted upper energy barriers (by 2.0–15.0 kcal/mol) is calculated in the activation mechanism for the [Ni]-X-1–4 series compared to the [Pd]-X-1–4 series. Overall, these results suggest that Ni-based precatalysts are expected to be less active than the Pd-based precatalysts for the studied Suzuki–Miyaura reaction.

  19. Coupling between mass transfer and chemical reactions during the absorption of CO2 in a NaHCO3-Na2CO3 brine :experimental and theoretical study

    OpenAIRE

    Wylock, Christophe; Colinet, Pierre; Cartage, Thierry; Haut, Benoît

    2008-01-01

    This work deals with the study of the gas-liquid mass transfer, coupled with chemical reactions. The case of carbonic gas absorption in a brine of sodium carbonate and bicarbonate is investigated. It is performed in collaboration with Solvay SA. The aim of this work is to get a better understanding of this phenomenon. It would permit an optimization of the refined sodium bicarbonate production process. The basis of developed mathematical models is presented. The CO2 absorption is coupled with...

  20. Selective coupling reaction between 2,6-diiodoanisoles and terminal alkynes catalyzed by Pd(PPh32Cl2 and CuI

    Directory of Open Access Journals (Sweden)

    Allan F. C. Rossini

    2012-06-01

    Full Text Available The cross-coupling reaction between aryl halides and terminal alkynes, catalyzed by palladium complexes and copper (I salts, consists in an efficient synthetic tool for the formation of C-C bonds, resulting in disubstituted acetylenic compounds. Accordingly, in this work we present our preliminary results involving the selective cross-coupling reaction between 2,6-diiodoanisoles and terminal alkynes, catalyzed by Pd(PPh32Cl2 and CuI, in the formation of 2-iodo-alkynylanisoles (scheme 1.

  1. Study of NaCl:Mn2+ nanostructures in the Suzuki phase by optical spectroscopy and atomic force microscopy

    International Nuclear Information System (INIS)

    Mejía-Uriarte, E.V.; Kolokoltsev, O.; Navarrete Montesinos, M.; Camarillo, E.; Hernández A, J.; Murrieta S, H.

    2015-01-01

    NaCl:Mn 2+ nanostructures in the Suzuki phase have been studied by fluorescence (emission and excitation) spectroscopy and atomic force microscopy (AFM) as a function of temperature. The “as-grown” samples give rise to two broad emission bands that peak at 508 (green emission) and 610 nm (red emission). The excitation spectrum shows peaks at 227 nm and 232 nm for emission wavelengths at 508 nm and 610 nm, respectively. When the samples are heated continuously from room temperature up to 220 °C, the green emission (associated to the excitation peak at 227 nm) disappears at a temperature close to 120 °C, whilst only the red emission remains, which is characteristic of manganese ions. AFM images on the (0 0 1) surface (freshly cleaved) show several conformations of nanostructures, such as disks of 20–50 nm in diameter. Particularly, the images also reveal nanostructures with rectangular shape of ~280×160 nm 2 and ~6 nm height; these are present only in samples with green emission associated to the Suzuki phase. Then, the evidence suggests that this topographic configuration might be related to the interaction with the first neighbors and the next neighbors, according to the configuration that has been suggested for the Suzuki phase. - Highlights: • NaCl:Mn 2+ single crystals in the Suzuki phase contain rectangular nanostructures. • Double emission of manganese ions: green (508 nm) and red (610 nm) bands. • The excitation peak at 227 nm is attributed to rectangular nanostructures. • The green emission band associated to Suzuki phase is extinguished at 120 °C

  2. Determination of Se at low concentration in coal by collision/reaction cell technology inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Henn, Alessandra S.; Rondan, Filipe S.; Mesko, Marcia F.; Mello, Paola A.; Perez, Magali; Armstrong, Joseph; Bullock, Liam A.; Parnell, John; Feldmann, Joerg; Flores, Erico M. M.

    2018-05-01

    A method is proposed for the determination of selenium at low concentration in coal by collision/reaction cell technology inductively coupled plasma mass spectrometry (CRC-ICP-MS). Samples were decomposed by high pressure microwave-assisted wet digestion (MAWD) using 250 mg of coal, a mixture of 5 mL of 14.4 mol L-1 HNO3 and 1 mL of 40% HF and 70 min of heating program (200 °C and 40 bar). Hydrogen gas used in the collision/reaction cell was investigated to minimize the argon-based interferences at m/z 77, 78 and 80. The rejection parameter (RPq) and the H2 gas flow rate were set to 0.45 and 4.8 mL min-1, respectively. The use of H2 in the cell resulted in other polyatomic interferences, such as 76Ge1H+, 79Br1H+ and 81Br1H+, which impaired Se determination using 77Se, 80Se and 82Se isotopes, thus Se determination was carried out by monitoring only 78Se isotope. Selenium was determined in certified reference materials of coal (NIST 1635 and SARM 20) and an agreement better than 95% was observed between the results obtained by CRC-ICP-MS and the certified values. Under optimized conditions, the instrumental limit of detection was 0.01 μg L-1 and the method limit of detection was 0.01 μg g-1, which was suitable for Se determination at very low concentration in coal.

  3. FeCl3- and GaCl3-Catalyzed Dehydrative Coupling Reaction of Chromone-Derived Morita-Baylis-Hillman Alcohols with Terminal Alkynes%FeCl3- and GaCl3-Catalyzed Dehydrative Coupling Reaction of Chromone-Derived Morita-Baylis-Hillman Alcohols with Terminal Alkynes

    Institute of Scientific and Technical Information of China (English)

    武陈; 曾皓; 刘哲; 刘利; 王东; 陈拥军

    2011-01-01

    FeCl3- and GaCl3-catalyzed dehydrative coupling reactions of chromone-derived Morita-Baylis-Hillman (MBH) alcohols with terminal alkynes were developed. The reactions provided exclusively a-regioselective and acetylene-substituted products in good yields.

  4. I + (H2O)2 → HI + (H2O)OH Forward and Reverse Reactions. CCSD(T) Studies Including Spin-Orbit Coupling.

    Science.gov (United States)

    Wang, Hui; Li, Guoliang; Li, Qian-Shu; Xie, Yaoming; Schaefer, Henry F

    2016-03-03

    The potential energy profile for the atomic iodine plus water dimer reaction I + (H2O)2 → HI + (H2O)OH has been explored using the "Gold Standard" CCSD(T) method with quadruple-ζ correlation-consistent basis sets. The corresponding information for the reverse reaction HI + (H2O)OH → I + (H2O)2 is also derived. Both zero-point vibrational energies (ZPVEs) and spin-orbit (SO) coupling are considered, and these notably alter the classical energetics. On the basis of the CCSD(T)/cc-pVQZ-PP results, including ZPVE and SO coupling, the forward reaction is found to be endothermic by 47.4 kcal/mol, implying a significant exothermicity for the reverse reaction. The entrance complex I···(H2O)2 is bound by 1.8 kcal/mol, and this dissociation energy is significantly affected by SO coupling. The reaction barrier lies 45.1 kcal/mol higher than the reactants. The exit complex HI···(H2O)OH is bound by 3.0 kcal/mol relative to the asymptotic limit. At every level of theory, the reverse reaction HI + (H2O)OH → I + (H2O)2 proceeds without a barrier. Compared with the analogous water monomer reaction I + H2O → HI + OH, the additional water molecule reduces the relative energies of the entrance stationary point, transition state, and exit complex by 3-5 kcal/mol. The I + (H2O)2 reaction is related to the valence isoelectronic bromine and chlorine reactions but is distinctly different from the F + (H2O)2 system.

  5. Sensitivity of fusion and quasi-elastic barrier distributions of {sub 16}O+{sub 144}Sm reaction on the coupling radius parameter

    Energy Technology Data Exchange (ETDEWEB)

    Zamrun, Muhammad; Usman, Ida; Variani, Viska Inda [Department of Physics, Haluoleo University, Kendari, Sulawesi Tengagra, 93232 (Indonesia); Kassim, Hasan Abu [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2014-03-05

    We study the heavy-ion collision at sub-barrier energies of {sub 16}O+{sub 144}Sm system using full order coupled-channels formalism. We especially investigate the sensitivity of fusion and quasi-elastic barrier distributions for this system on the coupling radius parameter. We found that the coupled-channels calculations of the fusion and the quasi-elastic barrier distributions are sensitive to the coupling radius for this reaction in contrast to the fusion and quasi-elastic cross section. Our study indicates that the larger coupling radius, i.e., r{sub coup}=1.20, is required by the experimental quasi-elastic barrier distribution. However, the experimental fusion barrier distribution compulsory the small value, i.e., r{sub coup}=1.06.

  6. ESTUDIO DEL MODELO DE PROPAGACIÓN SUZUKI PARA REDES MÓVILES

    Directory of Open Access Journals (Sweden)

    Gina Sierra

    2013-12-01

    Full Text Available Este artículo presenta brevemente la teoría fundamental del Modelo Suzuki comúnmente usado para modelar la propagación en canales inalámbricos. El modelo toma en cuenta los efectos del sombreado y del multi-trayecto de manera simultánea. Además, se valida el modelo mediante una comparación estadística entre mediciones realizadas en el entorno real y simulaciones realizadas en MATLAB® a través de la generación de series de tiempo Suzuki distribuidas. Las mediciones se realizaron durante diez horas sobre la banda de frecuencias entre 850 MHz y 900 MHz. Con los datos obtenidos en medición durante los primeros cinco minutos, se caracterizó el canal inalámbrico para cada una de las frecuencias muestreadas calculando la media y desviación estándar de la señal recibida. Estos dos parámetros fueron introducidos como variables de entrada para la generación de las respectivas series de tiempo. Para cada frecuencia se realizaron simulaciones prediciendo los niveles de la señal que se obtendrían durante diez horas. Finalmente, se calculó el error cuadrático medio entre los valores medidos y los valores generados en simulación. Los resultados obtenidos demuestran que el modelo es válido como una herramienta de predicción de las características de propagación en comunicaciones móviles.

  7. Monoterpene separation by coupling proton transfer reaction time-of-flight mass spectrometry with fastGC.

    Science.gov (United States)

    Materić, Dušan; Lanza, Matteo; Sulzer, Philipp; Herbig, Jens; Bruhn, Dan; Turner, Claire; Mason, Nigel; Gauci, Vincent

    2015-10-01

    Proton transfer reaction mass spectrometry (PTR-MS) is a well-established technique for real-time analysis of volatile organic compounds (VOCs). Although it is extremely sensitive (with sensitivities of up to 4500 cps/ppbv, limits of detection monoterpenes, which belong to the most important plant VOCs, still cannot be distinguished so more traditional technologies, such as gas chromatography mass spectrometry (GC-MS), have to be utilised. GC-MS is very time consuming (up to 1 h) and cannot be used for real-time analysis. Here, we introduce a sensitive, near-to-real-time method for plant monoterpene research-PTR-MS coupled with fastGC. We successfully separated and identified six of the most abundant monoterpenes in plant studies (α- and β-pinenes, limonene, 3-carene, camphene and myrcene) in less than 80 s, using both standards and conifer branch enclosures (Norway spruce, Scots pine and black pine). Five monoterpenes usually present in Norway spruce samples with a high abundance were separated even when the compound concentrations were diluted to 20 ppbv. Thus, fastGC-PTR-ToF-MS was shown to be an adequate one-instrument solution for plant monoterpene research.

  8. Electromigration-induced cracks in Cu/Sn3.5Ag/Cu solder reaction couple at room temperature

    International Nuclear Information System (INIS)

    He Hongwen; Xu Guangchen; Guo Fu

    2009-01-01

    Electromigration (EM) behavior of Cu/Sn 3.5 Ag/Cu solder reaction couple was investigated with a high current density of 5 x 10 3 A/cm 2 at room temperature. One dimensional structure, copper wire/solder ball/copper wire SRC was designed and fabricated to dissipate the Joule heating induced by the current flow. In addition, thermomigration effect was excluded due to the symmetrical structure of the SRC. The experimental results indicated that micro-cracks initially appeared near the cathode interface between solder matrix and copper substrate after 474 h current stressing. With current stressing time increased, the cracks propagated and extended along the cathode interface. It should be noted that the continuous Cu 6 Sn 5 intermetallic compounds (IMCs) layer both at the anode and at the cathode remained their sizes. Interestingly, tiny cracks appeared at the root of some long column-type Cu 6 Sn 5 at the cathode interface due to the thermal stress.

  9. Spectrophotometric Determination of the Trace Amount of Thallium in Water and Urine Samples by Novel Oxidative Coupling Reaction

    Directory of Open Access Journals (Sweden)

    P. Nagaraja

    2009-01-01

    Full Text Available A novel, simple, rapid, sensitive and selective method has been proposed for the trace determination of thallium by spectrophotometric detection. This method is based on the oxidation of MBTH (3-methyl-2-benzothiazolinone hydrazone hydrochloride by thallium(III to form diazonium cation, which couples with IPH (Imipramine hydrochloride in phosphoric acid medium at room temperature giving a blue colored species having a maximum absorption at 635 nm. The reagents and manifold variables influences on the sensitivity were investigated and the optimum reaction conditions have been established. The calibration curve was found to be linear over the range 0.1-5 μg mL-1 with the molar absorptivity and Sandell’s sensitivity of 2.9x104 L mol-1 cm-1, 0.0071 μg cm-2 respectively. The tolerance limit of the method towards various ions usually associated with thallium has been detected. The relative standard deviation for five replicate determination of 2μg mL-1 thallium was 0.47%. The method has been successfully applied for the determination of thallium(ІΙΙ and thallium(I in synthetic, standard reference materials, water and urine samples with satisfactory results. The performance of the proposed method was evaluated in terms of student’s t-test and variance ratio F-test, to find out the significance of proposed method over the reported methods.

  10. Role of pendant proton relays and proton-coupled electron transfer on the hydrogen evolution reaction by nickel hangman porphyrins

    Science.gov (United States)

    Bediako, D. Kwabena; Solis, Brian H.; Dogutan, Dilek K.; Roubelakis, Manolis M.; Maher, Andrew G.; Lee, Chang Hoon; Chambers, Matthew B.; Hammes-Schiffer, Sharon; Nocera, Daniel G.

    2014-01-01

    The hangman motif provides mechanistic insights into the role of pendant proton relays in governing proton-coupled electron transfer (PCET) involved in the hydrogen evolution reaction (HER). We now show improved HER activity of Ni compared with Co hangman porphyrins. Cyclic voltammogram data and simulations, together with computational studies using density functional theory, implicate a shift in electrokinetic zone between Co and Ni hangman porphyrins due to a change in the PCET mechanism. Unlike the Co hangman porphyrin, the Ni hangman porphyrin does not require reduction to the formally metal(0) species before protonation by weak acids in acetonitrile. We conclude that protonation likely occurs at the Ni(I) state followed by reduction, in a stepwise proton transfer–electron transfer pathway. Spectroelectrochemical and computational studies reveal that upon reduction of the Ni(II) compound, the first electron is transferred to a metal-based orbital, whereas the second electron is transferred to a molecular orbital on the porphyrin ring. PMID:25298534

  11. Detection of Food Spoilage and Pathogenic Bacteria Based on Ligation Detection Reaction Coupled to Flow-Through Hybridization on Membranes

    Directory of Open Access Journals (Sweden)

    K. Böhme

    2014-01-01

    Full Text Available Traditional culturing methods are still commonly applied for bacterial identification in the food control sector, despite being time and labor intensive. Microarray technologies represent an interesting alternative. However, they require higher costs and technical expertise, making them still inappropriate for microbial routine analysis. The present study describes the development of an efficient method for bacterial identification based on flow-through reverse dot-blot (FT-RDB hybridization on membranes, coupled to the high specific ligation detection reaction (LDR. First, the methodology was optimized by testing different types of ligase enzymes, labeling, and membranes. Furthermore, specific oligonucleotide probes were designed based on the 16S rRNA gene, using the bioinformatic tool Oligonucleotide Retrieving for Molecular Applications (ORMA. Four probes were selected and synthesized, being specific for Aeromonas spp., Pseudomonas spp., Shewanella spp., and Morganella morganii, respectively. For the validation of the probes, 16 reference strains from type culture collections were tested by LDR and FT-RDB hybridization using universal arrays spotted onto membranes. In conclusion, the described methodology could be applied for the rapid, accurate, and cost-effective identification of bacterial species, exhibiting special relevance in food safety and quality.

  12. Efficient Construction of Energetic Materials via Nonmetallic Catalytic Carbon-Carbon Cleavage/Oxime-Release-Coupling Reactions.

    Science.gov (United States)

    Zhao, Gang; He, Chunlin; Yin, Ping; Imler, Gregory H; Parrish, Damon A; Shreeve, Jean'ne M

    2018-03-14

    The exploitation of C-C activation to facilitate chemical reactions is well-known in organic chemistry. Traditional strategies in homogeneous media rely upon catalyst-activated or metal-mediated C-C bonds leading to the design of new processes for applications in organic chemistry. However, activation of a C-C bond, compared with C-H bond activation, is a more challenging process and an underdeveloped area because thermodynamics does not favor insertion into a C-C bond in solution. Carbon-carbon bond cleavage through loss of an oxime moiety has not been reported. In this paper, a new observation of self-coupling via C-C bond cleavage with concomitant loss of oxime in the absence of metals (either metal-complex mediation or catalysis) results in dihydroxylammonium 5,5-bistetrazole-1,10-diolate (TKX-50) as well as N, N'-([3,3'-bi(1,2,4-oxadiazole)]-5,5'-diyl)dinitramine, a potential candidate for a new generation of energetic materials.

  13. Build/Couple/Pair Strategy Combining the Petasis 3-Component Reaction with Ru-Catalyzed Ring-Closing Metathesis and Isomerization

    DEFF Research Database (Denmark)

    Ascic, Erhad; Le Quement, Sebastian Thordal; Ishøy, Mette

    2012-01-01

    A “build/couple/pair” pathway for the systematic synthesis of structurally diverse small molecules is presented. The Petasis 3-component reaction was used to synthesize anti-amino alcohols displaying pairwise reactive combinations of alkene moieties. Upon treatment with a ruthenium alkylidene...

  14. /sup 16/O(/sup 16/O, /sup 12/C)/sup 20/Ne reaction in the framework of the coupled channel formalism

    Energy Technology Data Exchange (ETDEWEB)

    Krause, O; Scheid, W; Greiner, W [Frankfurt Univ. (Germany, F.R.). Inst. fuer Theoretische Physik

    1974-01-01

    The transfer reaction /sup 16/O(/sup 16/O, /sup 12/C)/sup 20/Ne is treated in the coupled channel formalism. The influence of the transfer channels on the intermediate structure in the elastic excitation function is discussed. The /sup 16/O and /sup 20/Ne-nuclei are described in an ..cap alpha..-cluster model.

  15. Reaction path of the oxidative coupling of methane over a lithium-doped magnesium oxide catalyst : Factors affecting the Rate of Total Oxidation of Ethane and Ethylene

    NARCIS (Netherlands)

    Roos, J.A.; Korf, S.J.; Veehof, R.H.J.; van Ommen, J.G.; Ross, J.R.H.

    1989-01-01

    Experiments using gas mixtures of O2, C2H6 or C2H4 and CH4 or He have been carried out with a Li/MgO catalyst using a well-mixed reaction system which show that the total oxidation products, CO and CO2, are formed predominantly from ethylene, formed in the oxidative coupling of methane. It is

  16. Determination of citrus limonoid glucosides by high performance liquid chromatography coupled to post-column reaction with Ehrlich’s Reagent

    Science.gov (United States)

    A method for the identification and quantification of citrus limonoid glucosides in juices based upon high performance liquid chromatography (HPLC) separation coupled to post-column reaction with Ehrlichs’s reagent has been developed. This method utilizes a phenyl stationary phase and an isocratic ...

  17. Efficient one-pot enzymatic synthesis of alpha-(1 -> 4)-glucosidic disaccharides through a coupled reaction catalysed by Lactobacillus acidophilus NCFM maltose phosphorylase

    DEFF Research Database (Denmark)

    Nakai, Hiroyuki; Dilokpimol, Adiphol; Abou Hachem, Maher

    2010-01-01

    Lactobacillus acidophilus NCFM maltose phosphorylase (LaMalP) of glycoside hydrolase family 65 catalysed enzymatic synthesis of alpha-(1 -> 4)-glucostdic disacchandes from maltose and five monosacchandes in a coupled phosphorolysis/reverse phosphorolysis one-pot reaction Thus phosphorolysis...

  18. New Cu-based catalysts supported on TiO2 films for Ullmann SnAr-type C-O coupling reactions

    NARCIS (Netherlands)

    Benaskar, F.; Engels, V.; Rebrov, E.; Patil, N.G.; Meuldijk, J.; Thuene, P.C.; Magusin, P.C.M.M.; Mezari, B.; Hessel, V.; Hulshof, L.A.; Hensen, E.J.M.; Wheatley, A.E.H.; Schouten, J.C.

    2012-01-01

    New routes for the preparation of highly active TiO2-supported Cu and CuZn catalysts have been developed for CO coupling reactions. Slurries of a titania precursor were dip-coated onto glass beads to obtain either structured mesoporous or non-porous titania thin films. The Cu and CuZn nanoparticles,

  19. Effects of Erotic Films of Sexual Behavior of Married Couples. Sex-guilt and Reactions to Pornographic Films. Exposure to Pornography, Character, and Sexual Deviance: A Retrospective Survey.

    Science.gov (United States)

    Mann, Jay; And Others

    This paper reviews some of the findings from two studies of the reactions of single college students and married couples who viewed one of two pornographic films. Findings from the first study included: (1) women were aroused as much as men upon viewing the film showing intercourse; they were less aroused and the men were more aroused after the…

  20. Coupled-channel calculation for cross section of fusion and barrier distribution of {}^{16,17,18}O + {}^{16}O reactions

    Science.gov (United States)

    Fereidonnejad, R.; Sadeghi, H.; Ghambari, M.

    2018-03-01

    In this work, the effect of multi-phonon excitation on heavy-ion fusion reactions has been studied and fusion barrier distributions of energy intervals near and below the Coulomb barrier have been studied for 16,17,18O + 16O reactions. The structure and deformation of nuclear projectiles have been studied. Given the adaptation of computations to experimental data, our calculations predict the behavior of reactions in intervals of energy in which experimental measurements are not available. In addition the S-factor for these reactions has been calculated. The results showed that the structure and deformation of a nuclear projectile are important factors. The S-factor, obtained in the coupled-channel calculations for the {}^{16}O + {}^{16}O, {}^{17}O +{}^{16}O and {}^{18}O +{}^{16}O reactions, showed good agreement with the experimental data and had a maximum value at an energy near 5, 4.5 and 4 MeV, respectively.

  1. Cross-Dehydrogenative Coupling Reactions Between P(O)-H and X-H (X = S, N, O, P) Bonds.

    Science.gov (United States)

    Hosseinian, Akram; Farshbaf, Sepideh; Fekri, Leila Zare; Nikpassand, Mohammad; Vessally, Esmail

    2018-05-26

    P(O)-X (X = S, N, O, P) bond-containing compounds have extensive application in medicinal chemistry, agrochemistry, and material chemistry. These useful organophosphorus compounds also have many applications in organic synthesis. In light of the importance of titled compounds, there is continuing interest in the development of synthetic methods for P(O)-X bonds construction. In the last 4 years, the direct coupling reaction of P(O)-H compounds with thiols, alcohols, and amines/amides has received much attention because of the atom-economic character. This review aims to give an overview of new developments in cross-dehydrogenative coupling reactions between P(O)-H and X-H (X = S, N, O, P) bonds, with special emphasis on the mechanistic aspects of the reactions.

  2. Free-radical coupling, cleavage, and redox reactions in 60Co γ radiolysis of aqueous methyl acetate. Effects of additives

    International Nuclear Information System (INIS)

    Bernath, T.; Parsons, G.H. Jr.; Cohen, S.G.

    1975-01-01

    Reaction of methyl acetate with e - /sub aq/ may lead to CH 3 C(O )OCH 3 (I - ), CH 3 C(OH)OCH 3 (II), and CH 3 CO (IIA), and with .OH and H. to .CH 2 CO 2 CH 3 (III), and to CH 3 CO 2 CH 2 . (IV). Methyl acetate is consumed, G = --3.5, and the loss is decreased by formate which scavenges .H and .OH, and increased by N 2 O which converts e - /sub aq/ to .OH. Hydrogen is formed, G = 1.1, and this is decreased by scavengers for H., and increased by H + which converts e - /sub aq/ to H.. In radiolysis of 0.027 M methyl acetate, 1.5 x 10 22 ev/l., radical combination products are: ethylene diacetate (CH 3 CO 2 CH 2 CH 2 OCOCH 3 ) (EDA), G = 0.48, from IV + IV; methyl β-acetoxypropionate (CH 3 CO 2 CH 2 CH 2 CO 2 CH 3 ) (MAP), G = 0.28, from IV + III; dimethyl succinate (DMS), G = 0.05, from III + III; and a mixture of methyl acetoacetate and acetonyl acetate (MAA and AA), (MAS and AA), G = 0.07. Biacetyl is not observed. β-Mercaptopropionic acid, 0.0005 M, prevents formation of coupling products, as it reduces radicals III and IV, and thiyl radical oxidizes radical II back to methyl acetate. Other sources of .OH, Fenton's reagent and H 2 O 2 -uv, lead to EDA, MAP, and DMS with a high IV/III ratio. H. preferentially attacks acyl C--H; .OH preferentially attacks alkoxyl C--H. Yields of radicals involved in formation of coupling products and acetic acid are estimated: G(II and IIA) = 1.2; G(III) = 1.4; G(IV) = 1.7. Part of the radicals, G approximately 1.6, regenerate methyl acetate by self-repair reduction of IV and III by II. Deuterium is introduced into methyl acetate during radiolysis in D 2 O. (U.S.)

  3. Laser ablation inductively coupled plasma dynamic reaction cell mass spectrometry for the multi-element analysis of polymers

    Science.gov (United States)

    Resano, M.; García-Ruiz, E.; Vanhaecke, F.

    2005-11-01

    In this work, the potential of laser ablation-inductively coupled plasma-mass spectrometry for the fast analysis of polymers has been explored. Different real-life samples (polyethylene shopping bags, an acrylonitrile butadiene styrene material and various plastic bricks) as well as several reference materials (VDA 001 to 004, Cd in polyethylene) have been selected for the study. Two polyethylene reference materials (ERM-EC 680 and 681), for which a reference or indicative value for the most relevant metals is available, have proved their suitability as standards for calibration. Special attention has been paid to the difficulties expected for the determination of Cr at the μg g - 1 level in this kind of materials, due to the interference of ArC + ions on the most abundant isotopes of Cr. The use of ammonia as a reaction gas in a dynamic reaction cell is shown to alleviate this problem, resulting in a limit of detection of 0.15 μg g - 1 for this element, while limiting only modestly the possibilities of the technique for simultaneous multi-element analysis. In this regard, As is the analyte most seriously affected by the use of ammonia, and its determination has to be carried out in vented mode, at the expense of measuring time. In all cases studied, accurate results could be obtained for elements ranging in content from the sub-μg g - 1 level to tens of thousands of μg g - 1 . However, the use of an element of known concentration as internal standard may be needed for materials with a matrix significantly different from that of the standard (polyethylene in this work). Precision ranged between 5% and 10% RSD for elements found at the 10 μg g - 1 level or higher, while this value could deteriorate to 20% for analytes found at the sub-μg g - 1 level. Overall, the technique evaluated presents many advantages for the fast and accurate multi-element analysis of these materials, avoiding laborious digestion procedures and minimizing the risk of analyte losses due

  4. Ion-neutral gas reactions in a collision/reaction cell in inductively coupled plasma mass spectrometry: Correlation of ion signal decrease to kinetic rate constants

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Patrick J. [Trace Element Research Laboratory, School of Earth Sciences, The Ohio State University, 125 S. Oval Mall, Columbus, OH 43210 (United States); Department of Chemistry, The Ohio State University, 120 18th Avenue, Columbus, OH 43210 (United States); Olesik, John W., E-mail: olesik.2@osu.edu [Trace Element Research Laboratory, School of Earth Sciences, The Ohio State University, 125 S. Oval Mall, Columbus, OH 43210 (United States)

    2015-03-01

    Reaction gas flow rate dependent Ar{sub 2}{sup +} and Ar{sup +} signals are correlated to fundamental kinetic rate coefficients. A simple calculation, assuming that gas exits the reaction cell due only to effusion, is described to estimate the gas pressure in the reaction cell. The value of the product of the kinetic rate constant and the ion residence time in the reaction cell can be determined from experimental measurement of the decrease in an ion signal as a function of reaction gas flow rate. New kinetic rate constants are determined for the reaction of CH{sub 3}F with Ar{sup +} and Ar{sub 2}{sup +}. - Highlights: • How to determine pressure and the product of the kinetic rate constant times the ion residence time in reaction cell • Relate measured ICP-DRC-MS signals versus gas flow rate to kinetic rate constants measured previously using SIFT-MS • Describe how to determine previously unmeasured kinetic rate constants using ICP-DRC-MS.

  5. The Coupled Photothermal Reaction and Transport in a Laser Additive Metal Nanolayer Simultaneous Synthesis and Pattering for Flexible Electronics

    Directory of Open Access Journals (Sweden)

    Song-Ling Tsai

    2016-01-01

    Full Text Available The Laser Direct Synthesis and Patterning (LDSP technology has advantages in terms of processing time and cost compared to nanomaterials-based laser additive microfabrication processes. In LDSP, a scanning laser on the substrate surface induces chemical reactions in the reactive liquid solution and selectively deposits target material in a preselected pattern on the substrate. In this study, we experimentally investigated the effect of the processing parameters and type and concentration of the additive solvent on the properties and growth rate of the resulting metal film fabricated by this LDSP technology. It was shown that reactive metal ion solutions with substantial viscosity yield metal films with superior physical properties. A numerical analysis was also carried out the first time to investigate the coupled opto-thermo-fluidic transport phenomena and the effects on the metal film growth rate. To complete the simulation, the optical properties of the LDSP deposited metal film with a variety of thicknesses were measured. The characteristics of the temperature field and the thermally induced flow associated with the moving heat source are discussed. It was shown that the processing temperature range of the LDSP is from 330 to 390 K. A semi-empirical model for estimating the metal film growth rate using this process was developed based on these results. From the experimental and numerical results, it is seen that, owing to the increased reflectivity of the silver film as its thickness increases, the growth rate decreases gradually from about 40 nm at initial to 10 nm per laser scan after ten scans. This self-controlling effect of LDSP process controls the thickness and improves the uniformity of the fabricated metal film. The growth rate and resulting thickness of the metal film can also be regulated by adjustment of the processing parameters, and thus can be utilized for controllable additive nano/microfabrication.

  6. An oxidative cross-coupling reaction of 4-hydroxydithiocoumarin and amines/thiols using a combination of I2 and TBHP: access to lead molecules for biomedical applications.

    Science.gov (United States)

    Mahato, Karuna; Arora, Neha; Ray Bagdi, Prasanta; Gattu, Radhakrishna; Ghosh, Siddhartha Sankar; Khan, Abu T

    2018-02-06

    A metal-free I 2 /TBHP induced highly atom economic and operationally simple oxidative cross-coupling reaction has been developed for the direct synthesis of sulfenamides/sulfanes/disulfides from the reaction of 4-hydroxydithiocoumarin and amines/thiols. The novelties of the present protocol are unprecedented S-C bond formation in addition to S-N and S-S bonds, shorter reaction time, mild and environmentally benign reaction conditions, functional group tolerance and moderate to excellent yields. Moreover, the four newly synthesized compounds namely 4q, 6d, 6e and 7a exhibit anti-proliferative activity against the breast cancer cell line MCF7, and may be lead molecules for future drug development.

  7. Spectroscopy of particle-phonon coupled states in $^{133}$Sb by the cluster transfer reaction of $^{132}$Sn on $^{7}$Li

    CERN Multimedia

    We propose to investigate, with MINIBALL coupled to T-REX, the one-valence-proton $^{133}$Sb nucleus by the cluster transfer reaction of $^{132}$Sn on $^{7}$Li. The excited $^{133}$Sb will be populated by transfer of a triton into $^{132}$Sn, followed by the emission of an $\\alpha$-particle (detected in T-REX) and 2 neutrons. The aim of the experiment is to locate states arising from the coupling of the valence proton of $^{133}$Sb to the collective low-lying phonon excitations of $^{132}$Sn (in particular the 3$^−$). According to calculations in the weak-coupling approach, these states lie in the 4$\\, - \\,$5 MeV excitation energy region and in the spin interval 1/2$\\, - \\,$ 19/2, i.e., in the region populated by the cluster transfer reaction. The results will be used to perform advanced tests of different types of nuclear interactions, usually employed in the description of particle-phonon coupled excitations. States arising from couplings of the proton with simpler core excitations, involving few nucleons...

  8. A global model for SF6 plasmas coupling reaction kinetics in the gas phase and on the surface of the reactor walls

    International Nuclear Information System (INIS)

    Kokkoris, George; Panagiotopoulos, Apostolos; Gogolides, Evangelos; Goodyear, Andy; Cooke, Mike

    2009-01-01

    Gas phase and reactor wall-surface kinetics are coupled in a global model for SF 6 plasmas. A complete set of gas phase and surface reactions is formulated. The rate coefficients of the electron impact reactions are based on pertinent cross section data from the literature, which are integrated over a Druyvesteyn electron energy distribution function. The rate coefficients of the surface reactions are adjustable parameters and are calculated by fitting the model to experimental data from an inductively coupled plasma reactor, i.e. F atom density and pressure change after the ignition of the discharge. The model predicts that SF 6 , F, F 2 and SF 4 are the dominant neutral species while SF 5 + and F - are the dominant ions. The fit sheds light on the interaction between the gas phase and the reactor walls. A loss mechanism for SF x radicals by deposition of a fluoro-sulfur film on the reactor walls is needed to predict the experimental data. It is found that there is a net production of SF 5 , F 2 and SF 6 , and a net consumption of F, SF 3 and SF 4 on the reactor walls. Surface reactions as well as reactions between neutral species in the gas phase are found to be important sources and sinks of the neutral species.

  9. A Copper-Based Metal-Organic Framework as an Efficient and Reusable Heterogeneous Catalyst for Ullmann and Goldberg Type C–N Coupling Reactions

    Directory of Open Access Journals (Sweden)

    Wei Long

    2015-11-01

    Full Text Available A highly porous metal-organic framework (Cu-TDPAT, constructed from a paddle-wheel type dinuclear copper cluster and 2,4,6-tris(3,5-dicarboxylphenylamino-1,3,5-triazine (H6TDPAT, has been tested in Ullmann and Goldberg type C–N coupling reactions of a wide range of primary and secondary amines with halobenzenes, affording the corresponding N-arylation compounds in moderate to excellent yields. The Cu-TDPAT catalyst could be easily separated from the reaction mixtures by simple filtration, and could be reused at least five times without any significant degradation in catalytic activity.

  10. Modular Approach to Heterogenous Catalysis. Manipulation of Cross-Coupling Catalyst Activity

    Czech Academy of Sciences Publication Activity Database

    Štibingerová, Iva; Voltrová, Svatava; Kočová, Šárka; Lindale, M.; Šrogl, Jiří

    2016-01-01

    Roč. 18, č. 2 (2016), s. 312-315 ISSN 1523-7060 R&D Projects: GA MŠk LH12012 Institutional support: RVO:61388963 Keywords : polysiloxane gels * Suzuki coupling * palladium nanoparticles Subject RIV: CC - Organic Chemistry Impact factor: 6.579, year: 2016

  11. A four-component coupling reaction of carbon dioxide, amines, cyclic ethers and 3-triflyloxybenzynes for the synthesis of functionalized carbamates.

    Science.gov (United States)

    Xiong, Wenfang; Qi, Chaorong; Cheng, Ruixiang; Zhang, Hao; Wang, Lu; Yan, Donghao; Jiang, Huanfeng

    2018-04-27

    A novel four-component coupling reaction of carbon dioxide, amines, cyclic ethers and 3-triflyloxybenzynes has been developed for the first time, providing an efficient method for the synthesis of a series of functionalized carbamate derivatives in moderate to high yields. The process proceeds under mild, transition metal-free and fluoride-free conditions, leading to the formation of two new C-O bonds, one new C-N bond and one C-H bond in a single step.

  12. Iron-catalysed fluoroaromatic coupling reactions under catalytic modulation with 1,2-bis(diphenylphosphino)benzene.

    Science.gov (United States)

    Hatakeyama, Takuji; Kondo, Yoshiyuki; Fujiwara, Yu-Ichi; Takaya, Hikaru; Ito, Shingo; Nakamura, Eiichi; Nakamura, Masaharu

    2009-03-14

    A catalytic amount of 1,2-bis(diphenylphosphino)benzene (DPPBz) achieves selective cleavage of sp(3)-carbon-halogen bond in the iron-catalysed cross-coupling between polyfluorinated arylzinc reagents and alkyl halides, which was unachievable with a stoichiometric modifier such as TMEDA; the selective iron-catalysed fluoroaromatic coupling provides easy and practical access to polyfluorinated aromatic compounds.

  13. Selective C–C Coupling Reaction of Dimethylphenol to Tetramethyldiphenoquinone Using Molecular Oxygen Catalyzed by Cu Complexes Immobilized in Nanospaces of Structurally-Ordered Materials

    Directory of Open Access Journals (Sweden)

    Zen Maeno

    2015-02-01

    Full Text Available Two high-performance Cu catalysts were successfully developed by immobilization of Cu ions in the nanospaces of poly(propylene imine (PPI dendrimer and magadiite for the selective C–C coupling of 2,6-dimethylphenol (DMP to 3,3',5,5'-tetramethyldiphenoquinone (DPQ with O2 as a green oxidant. The PPI dendrimer encapsulated Cu ions in the internal nanovoids to form adjacent Cu species, which exhibited significantly high catalytic activity for the regioselective coupling reaction of DMP compared to previously reported enzyme and metal complex catalysts. The magadiite-immobilized Cu complex acted as a selective heterogeneous catalyst for the oxidative C–C coupling of DMP to DPQ. This heterogeneous catalyst was recoverable from the reaction mixture by simple filtration, reusable without loss of efficiency, and applicable to a continuous flow reactor system. Detailed characterization using ultraviolet-visible (UV-vis, Fourier transform infrared (FTIR, electronic spin resonance (ESR, and X-ray absorption fine structure (XAFS spectroscopies and the reaction mechanism investigation revealed that the high catalytic performances of these Cu catalysts were ascribed to the adjacent Cu species generated within the nanospaces of the PPI dendrimer and magadiite.

  14. Pd-PEPPSI-IPent-SiO2 : A Supported Catalyst for Challenging Negishi Coupling Reactions in Flow.

    Science.gov (United States)

    Price, Gregory A; Hassan, Abbas; Chandrasoma, Nalin; Bogdan, Andrew R; Djuric, Stevan W; Organ, Michael G

    2017-10-16

    A silica-supported precatalyst, Pd-PEPPSI-IPent-SiO 2 , has been prepared and evaluated for its proficiency in the Negishi cross-coupling of hindered and electronically deactivated coupling partners. The precatalyst Pd-PEPPSI-IPent loaded onto packed bed columns shows high catalytic activity for the room-temperature coupling of deactivated/hindered biaryl partners. Also for the first time, the flowed Csp 3 -Csp 2 coupling of secondary alkylzinc reagents to (hetero)aromatics has been achieved with high selectivity with Pd-PEPPSI-IPent-SiO 2 . These couplings required residence times as short as 3 minutes to effect completion of these challenging transformations with excellent selectivity for the nonrearranged product. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. NUMERICAL TECHNIQUES TO SOLVE CONDENSATIONAL AND DISSOLUTIONAL GROWTH EQUATIONS WHEN GROWTH IS COUPLED TO REVERSIBLE REACTIONS (R823186)

    Science.gov (United States)

    Noniterative, unconditionally stable numerical techniques for solving condensational anddissolutional growth equations are given. Growth solutions are compared to Gear-code solutions forthree cases when growth is coupled to reversible equilibrium chemistry. In all cases, ...

  16. Flow chemistry as a discovery tool to access sp2-sp3 cross-coupling reactions via diazo compounds.

    Science.gov (United States)

    Tran, Duc N; Battilocchio, Claudio; Lou, Shing-Bong; Hawkins, Joel M; Ley, Steven V

    2015-02-01

    The work takes advantage of an important feature of flow chemistry, whereby the generation of a transient species (or reactive intermediate) can be followed by a transfer step into another chemical environment, before the intermediate is reacted with a coupling partner. This concept is successfully applied to achieve a room temperature sp 2 -sp 3 cross coupling of boronic acids with diazo compounds, these latter species being generated from hydrazones under flow conditions using MnO 2 as the oxidant.

  17. Cathodic over-potential and hydrogen partial pressure coupling in hydrogen evolution reaction of marine steel under hydrostatic pressure

    International Nuclear Information System (INIS)

    Xiong, X.L.; Zhou, Q.J.; Li, J.X.; Volinsky, Alex A.; Su, Y.J.

    2017-01-01

    Highlights: •Hydrostatic pressure increases the Volmer and the Heyrovsky reactions rates. •Hydrostatic pressure decreases the Tafel reaction rate. •Hydrogen adsorption conditions change with pressure under −1.2 and −1.3 V SSE . •Under −1.2 and −1.3 V SSE , the Heyrovsky reaction dominates the hydrogen recombination. •Under −1.0 and −1.1 V SSE , the Tafel reaction dominates the hydrogen recombination. -- Abstract: A new electrochemical impedance spectroscopy (EIS) model, which considers both the Tafel recombination and the Heyrovsky reaction under permeable boundary conditions, was developed to characterize the kinetic parameters of the hydrogen evolution reaction (HER) under hydrostatic pressure. The effect of the hydrostatic pressure on the kinetic parameters of the HER and the permeation of A514 steel in alkaline solution were measured using potentiodynamic polarization, the Devanathan cell hydrogen permeation, and EIS. The hydrostatic pressure accelerates the Volmer reaction and inhibits the Tafel recombination, which increases the number of adsorbed hydrogen atoms. On the other hand, the pressure accelerates the Heyrovsky reaction, which decreases the amount of adsorbed hydrogen atoms. At 10 to 40 MPa hydrostatic pressure within the −1.0 to −1.1 V SSE cathodic potential region, the HER is controlled by hydrogen partial pressure, and hydrogen adsorption is the Langmuir type. Within the −1.2 to −1.3 V SSE cathodic potential region, the HER is controlled by the potential, and hydrogen adsorption gradually transfers from the Langmuir type to the Temkin type with increasing hydrostatic pressure.

  18. Morphological patterns of lip prints in Mangaloreans based on Suzuki and Tsuchihashi classification

    Science.gov (United States)

    Jeergal, Prabhakar A; Pandit, Siddharth; Desai, Dinkar; Surekha, R; Jeergal, Vasanti A

    2016-01-01

    Introduction: Cheiloscopy is the study of the furrows or grooves present on the red part or vermilion border of the human lips. The present study aims to classify the characteristics of lip prints and to know the most common morphological pattern specific to Mangalorean people of Southern India. For the first time, this study also assesses the association between gender and different lip segments within a population. Materials and Methods: A total of 200 residents of Mangalore (100 males and 100 females) were included of age ranging from 18 years to 60 years. Materials used to take the impression of lips included red lipstick, A4 size white bond paper and cellophane tape. The prints obtained were scanned using a Canon Image Scanner and stored in a folder on a personal computer. The images were cropped and inverted in gray scale using Adobe Photoshop software. Each lip print was divided into eight segments and was examined. Suzuki and Tsuchihashi's classification (1970) was used to classify the types of grooves, and the results were statistically analyzed. Six types of grooves were recorded in the Mangalorean's lips. Statistical Analysis: Association between gender and different lip segments was tested using Chi-square analysis in the given population. Results: In males, the groove Type I' was the highest recorded followed by Type III, Type II, Type I, Type IV and Type V in descending order. In females, Type I' was the highest recorded followed by Type II, Type III, Type IV, Type I and Type V in descending order. Conclusion: Males and females displayed statistically significant differences in lip print patterns for different lip sites: lower medial lip, as well as upper and lower lateral segments. Only the upper medial lip segment displayed no statistically significant difference in lip print pattern between males and females. This shows that the distribution of lip prints is generally dissimilar for males and females, with varying predominance according to lip

  19. Higher spin currents in the enhanced N=3 Kazama-Suzuki model

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Changhyun; Kim, Hyunsu [Department of Physics, Kyungpook National University,Taegu 41566 (Korea, Republic of)

    2016-12-01

    The N=3 Kazama-Suzuki model at the ‘critical’ level has been found by Creutzig, Hikida and Ronne. We construct the lowest higher spin currents of spins ((3/2),2,2,2,(5/2),(5/2),(5/2),3) in terms of various fermions. In order to obtain the operator product expansions (OPEs) between these higher spin currents, we describe three N=2 OPEs between the two N=2 higher spin currents denoted by ((3/2),2,2,(5/2)) and (2,(5/2),(5/2),3) (corresponding 36 OPEs in the component approach). Using the various Jacobi identities, the coefficient functions appearing on the right hand side of these N=2 OPEs are determined in terms of central charge completely. Then we describe them as one single N=3 OPE in the N=3 superspace. The right hand side of this N=3 OPE contains the SO(3)-singlet N=3 higher spin multiplet of spins (2,(5/2),(5/2),(5/2),3,3,3,(7/2)), the SO(3)-singlet N=3 higher spin multiplet of spins ((5/2),3,3,3,(7/2),(7/2),(7/2),4), and the SO(3)-triplet N=3 higher spin multiplets where each multiplet has the spins (3,(7/2),(7/2),(7/2),4,4,4,(9/2)), in addition to N=3 superconformal family of the identity operator. Finally, by factoring out the spin-(1/2) current of N=3 linear superconformal algebra generated by eight currents of spins ((1/2),1,1,1,(3/2),(3/2),(3/2),2), we obtain the extension of so-called SO(3) nonlinear Knizhnik Bershadsky algebra.

  20. Palladium nanoparticles immobilized on multifunctional ‎hyperbranched polyglycerol-grafted magnetic nanoparticles as a ‎sustainable and efficient catalyst for C-C coupling reactions

    Directory of Open Access Journals (Sweden)

    Mina Amini

    2016-07-01

    Full Text Available This study offers an exclusive class of magnetic nanoparticles supported hyperbranched polyglycerol (MNP/HPG that was functionalized with citric acid (MNP/HPG-CA as a host immobilization of palladium nanoparticles. The MNP/HPG-CA/Pd catalyst was fully characterized using some different techniques such as thermogravimetric analysis (TGA, x-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, energy-dispersive x-ray spectroscopy (EDX, inductively coupled plasma (ICP and x-ray photoelectron spectroscopy (XPS. The new catalytic system showed high activity for the Suzuki–Miyaura cross-coupling and Heck reaction under mild and green conditions. Besides, the MNP/HPG-CA/Pd was found to be a convenient catalyst for copper-free Sonogashira coupling reaction in water as a green solvent at room temperature. Moreover, the catalyst could be recovered easily and reused several times without significant loss of reactivity. Ease of preparation, oxygen insensitive, phosphine-free, air- and moisture-stable, and high reusability of this immobilized palladium catalyst are the noteworthy advantages of this catalytic system.

  1. A Versatile Route to Unstable Diazo Compounds via Oxadiazolines and their Use in Aryl–Alkyl Cross‐Coupling Reactions

    Science.gov (United States)

    Greb, Andreas; Poh, Jian‐Siang; Greed, Stephanie; Battilocchio, Claudio; Pasau, Patrick; Blakemore, David C.

    2017-01-01

    Abstract Coupling of readily available boronic acids and diazo compounds has emerged recently as a powerful metal‐free carbon–carbon bond forming method. However, the difficulty in forming the unstable diazo compound partner in a mild fashion has hitherto limited their general use and the scope of the transformation. Here, we report the application of oxadiazolines as precursors for the generation of an unstable family of diazo compounds using flow UV photolysis and their first use in divergent protodeboronative and oxidative C(sp2)−C(sp3) cross‐coupling processes, with excellent functional‐group tolerance. PMID:29088512

  2. A fully coupled diffusion-reaction scheme for moisture sorption-desorption in an anhydride-cured epoxy resin

    KAUST Repository

    El Yagoubi, Jalal; Lubineau, Gilles; Roger, Frederic; Verdu, Jacques

    2012-01-01

    Thermoset materials frequently display non-classical moisture sorption behaviors. In this paper, we investigated this issue from an experimental point of view as well as in terms of modeling the water transport. We used the gravimetric technique to monitor water uptake by epoxy samples, with several thicknesses exposed to different levels of humidity during absorption and desorption tests. Our results revealed that the polymer displays a two-stage behavior with a residual amount of water that is desorbed progressively. We proposed a phenomenological reaction-diffusion scheme to describe this behavior. The model describes water transport as a competition between diffusion and the reaction, during which the local diffusivity and solubility depend on the local advancement of the reaction. We then implemented our model using COMSOL Multiphysics and identified it using a MATLAB-COMSOL optimization tool and the experimental data. We discussed the relation between the hydrophilicity of the product of the reaction and the diffusion behavior. We examined the reaction-induced modification of the water concentration field. It is worth noting that part of the phenomenology can be explained by the presence of hydrolyzable groups. © 2012 Elsevier Ltd. All rights reserved.

  3. A fully coupled diffusion-reaction scheme for moisture sorption-desorption in an anhydride-cured epoxy resin

    KAUST Repository

    El Yagoubi, Jalal

    2012-11-01

    Thermoset materials frequently display non-classical moisture sorption behaviors. In this paper, we investigated this issue from an experimental point of view as well as in terms of modeling the water transport. We used the gravimetric technique to monitor water uptake by epoxy samples, with several thicknesses exposed to different levels of humidity during absorption and desorption tests. Our results revealed that the polymer displays a two-stage behavior with a residual amount of water that is desorbed progressively. We proposed a phenomenological reaction-diffusion scheme to describe this behavior. The model describes water transport as a competition between diffusion and the reaction, during which the local diffusivity and solubility depend on the local advancement of the reaction. We then implemented our model using COMSOL Multiphysics and identified it using a MATLAB-COMSOL optimization tool and the experimental data. We discussed the relation between the hydrophilicity of the product of the reaction and the diffusion behavior. We examined the reaction-induced modification of the water concentration field. It is worth noting that part of the phenomenology can be explained by the presence of hydrolyzable groups. © 2012 Elsevier Ltd. All rights reserved.

  4. Sonogashira cross-coupling under non-basic conditions. Flow chemistry as a new paradigm in reaction control

    Czech Academy of Sciences Publication Activity Database

    Voltrová, Svatava; Šrogl, Jiří

    2014-01-01

    Roč. 1, č. 9 (2014), s. 1067-1071 ISSN 2052-4129 R&D Projects: GA MŠk LH12013 Institutional support: RVO:61388963 Keywords : Sonogashira * cross-coupling * flow chemistry Subject RIV: CC - Organic Chemistry

  5. The efficient synthesis of 2-arylpyrimidine acyclic nucleoside phosphonates using Liebeskind-Srogl cross-coupling reaction

    Czech Academy of Sciences Publication Activity Database

    Břehová, Petra; Česnek, Michal; Dračínský, Martin; Holý, Antonín; Janeba, Zlatko

    2011-01-01

    Roč. 67, č. 38 (2011), s. 7379-7385 ISSN 0040-4020 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : Liebeskind-Srogl cross - coupling * acyclic nucleoside phosphonates * pyrimidines * arylboronic acids * microwave Subject RIV: CC - Organic Chemistry Impact factor: 3.025, year: 2011

  6. A General Regioselective Synthesis of 2,4-Diarylpyrimidines from 2-Thiouracil through Two Orthogonal Cross-Coupling Reactions

    Czech Academy of Sciences Publication Activity Database

    Čerňová, Miroslava; Pohl, Radek; Klepetářová, Blanka; Hocek, Michal

    2012-01-01

    Roč. 23, č. 9 (2012), s. 1305-1308 ISSN 0936-5214 Grant - others:GA ČR(CZ) GAP207/12/0205 Institutional support: RVO:61388963 Keywords : pyrimidines * uracil * cross - coupling * palladium Subject RIV: CC - Organic Chemistry Impact factor: 2.655, year: 2012

  7. A computational method for the coupled solution of reaction-diffusion equations on evolving domains and manifolds: Application to a model of cell migration and chemotaxis.

    Science.gov (United States)

    MacDonald, G; Mackenzie, J A; Nolan, M; Insall, R H

    2016-03-15

    In this paper, we devise a moving mesh finite element method for the approximate solution of coupled bulk-surface reaction-diffusion equations on an evolving two dimensional domain. Fundamental to the success of the method is the robust generation of bulk and surface meshes. For this purpose, we use a novel moving mesh partial differential equation (MMPDE) approach. The developed method is applied to model problems with known analytical solutions; these experiments indicate second-order spatial and temporal accuracy. Coupled bulk-surface problems occur frequently in many areas; in particular, in the modelling of eukaryotic cell migration and chemotaxis. We apply the method to a model of the two-way interaction of a migrating cell in a chemotactic field, where the bulk region corresponds to the extracellular region and the surface to the cell membrane.

  8. Mechanistic studies on the phosphoramidite coupling reaction in oligonucleotide synthesis. I. Evidence for nudeophilic catalysis by tetrazole and rate variations with the phosphorus substituents

    DEFF Research Database (Denmark)

    Dahl, Bjarne H.; Nielsen, John; Dahl, Otto

    1987-01-01

    , and that dialkylammonium tetrazolide salts are inhibitors. These and other facts are evidence that the reactions are subjected to nucleophilic catalysis by tetrazole, in addition to acid catalysis. The rate variations with phosphorus substituents of 1a-h are NEt 2 > NRr12 > N(CH 2CH 2)O > NMePh, and OMe > OCH 2CH 2CN......Tetrazole catalyzed reactions of a series of phosphoramidites, 5′ -O- DMTdT-3′-O-P(OR 1)NRNR22 (1a-h), with 3′ O-SiBu tPh 2-6-N-benzoyl-dA (2a) in acetonitrite solution have been studied. It is found that the coupling rate depends very much on whether tetrazole is added before or after 2a...

  9. Heterologous Expression of Phanerochaete chrysoporium Glyoxal Oxidase and its Application for the Coupled Reaction with Manganese Peroxidase to Decolorize Malachite Green

    Science.gov (United States)

    Son, Yu-Lim; Kim, Hyoun-Young; Thiyagarajan, Saravanakumar; Xu, Jing Jing

    2012-01-01

    cDNA of the glx1 gene encoding glyoxal oxidase (GLX) from Phanerochaete chrysosporium was isolated and expressed in Pichia pastoris. The recombinant GLX (rGLX) produces H2O2 over 7.0 nmol/min/mL using methyl glyoxal as a substrate. Use of rGLX as a generator of H2O2 improved the coupled reaction with recombinant manganese peroxidase resulting in decolorization of malachite green up to 150 µM within 90 min. PMID:23323052

  10. Magnetic Pd-Fe{sub 3}O{sub 4} heterodimer nanocrystals as recoverable catalysts for ligand-free hiyama cross-coupling reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woong Sup; Byun, Sang Moon; Kwon, Jung Min; Kim, B. Moon [Dept. of Chemistry, College of Natural Sciences, Seoul National University, Seoul (Korea, Republic of)

    2016-12-15

    Ligand-free Hiyama cross-coupling reaction was achieved through the use of Pd-Fe{sub 3}O{sub 4} heterodimeric nanocrystals (1 mol% in Pd) as recyclable catalysts. The nanocrystal catalysts exhibited good activities accommodating a variety of substrates including aryl bromides and iodides with substituents of varying electronic and steric properties. Furthermore, the nanocrystal catalyst could be conveniently recovered with the aid of an external magnet and recycled five times without the loss of catalytic activity to a considerable degree.

  11. Diamond functionalization with light-harvesting molecular wires: improved surface coverage by optimized Suzuki cross-coupling conditions

    Czech Academy of Sciences Publication Activity Database

    Yeap, W. S.; Bevk, D.; Liu, X.; Krýsová, Hana; Pasquarelli, A.; Vanderzande, D.; Lutsen, L.; Kavan, Ladislav; Fahlman, M.; Maes, W.; Haenen, K.

    2014-01-01

    Roč. 4, AUG 2014 (2014), s. 42044-42053 ISSN 2046-2069 R&D Projects: GA ČR GA13-31783S Institutional support: RVO:61388955 Keywords : Functionalizations * Light-harvesting * Molecular wires Subject RIV: CG - Electrochemistry Impact factor: 3.840, year: 2014

  12. New air-stable planar chiral ferrocenyl monophosphine ligands: Suzuki cross-coupling of aryl chlorides and bromides

    DEFF Research Database (Denmark)

    Jensen, Jakob Feldthusen; Johannsen, Mogens

    2003-01-01

    GraphicA novel class of planar chiral electron-rich monophosphine ligands has been developed. The modular design allows a short and efficient synthesis of an array of aryl-ferrocenyl derivatives carrying the donating bis(dicyclohexyl)phosphino moiety. These new ligands have successfully been...

  13. Transient core characteristics of small molten salt reactor coupling problem between heat transfer/flow and nuclear fission reaction

    International Nuclear Information System (INIS)

    Yamamoto, Takahisa; Mitachi, Koshi

    2004-01-01

    This paper performed the transient core analysis of a small Molten Salt Reactor (MSR). The emphasis is that the numerical model employed in this paper takes into account the interaction among fuel salt flow, nuclear reaction and heat transfer. The model consists of two group diffusion equations for fast and thermal neutron fluexs, balance equations for six-group delayed neutron precursors and energy conservation equations for fuel salt and graphite moderator. The results of transient analysis are that (1) fission reaction (heat generation) rate significantly increases soon after step reactivity insertion, e.g., the peak of fission reaction rate achieves about 2.7 times larger than the rated power 350 MW when the reactivity of 0.15% Δk/k 0 is inserted to the rated state, and (2) the self-control performance of the small MSR effectively works under the step reactivity insertion of 0.56% Δk/k 0 , putting the fission reaction rate back on the rated state. (author)

  14. A Versatile Route to Unstable Diazo Compounds via Oxadiazolines and their Use in Aryl-Alkyl Cross-Coupling Reactions.

    Science.gov (United States)

    Greb, Andreas; Poh, Jian-Siang; Greed, Stephanie; Battilocchio, Claudio; Pasau, Patrick; Blakemore, David C; Ley, Steven V

    2017-12-22

    Coupling of readily available boronic acids and diazo compounds has emerged recently as a powerful metal-free carbon-carbon bond forming method. However, the difficulty in forming the unstable diazo compound partner in a mild fashion has hitherto limited their general use and the scope of the transformation. Here, we report the application of oxadiazolines as precursors for the generation of an unstable family of diazo compounds using flow UV photolysis and their first use in divergent protodeboronative and oxidative C(sp 2 )-C(sp 3 ) cross-coupling processes, with excellent functional-group tolerance. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Synthesis of Novel Aliphatic N-sulfonylamidino Thymine Derivatives by Cu(I)-catalyzed Three-component Coupling Reaction

    OpenAIRE

    Krstulović, Luka; Ismaili, Hamit; Višnjevac, Aleksandar; Glavaš-Obrovac, Ljubica; Žinić, Biserka

    2012-01-01

    A series of new aliphatic N-sulfonylamidino thymine derivatives containing nucleobase, N-sulfonyl and amidine pharmacophores in the structure were synthesized by Cu(I)-catalyzed threecomponent coupling of 1-propargyl thymine, benzenesulfonyl azides and amines or ammonium salts. Preliminary in vitro antitumor screening (human cervix adenocarcinoma -HeLa and leukemia cells - Jurkat) revealed promising activities of N,N-diethyl- (2) and N-4-cyanobenzyl- (6) derivatives of 4-acetamido...

  16. Cross-Coupling Reaction of Saccharide-Based Alkenyl Boronic Acids with Aryl Halides: The Synthesis of Bergenin

    Czech Academy of Sciences Publication Activity Database

    Parkan, K.; Pohl, Radek; Kotora, M.

    2014-01-01

    Roč. 20, č. 15 (2014), s. 4414-4419 ISSN 0947-6539 Grant - others:GA ČR(CZ) GPP207/12/P713; GA ČR(CZ) GA13-15915S Institutional support: RVO:61388963 Keywords : CC coupling * glycosides * natural products * protecting groups * synthetic methods Subject RIV: CC - Organic Chemistry Impact factor: 5.731, year: 2014

  17. Perchlorate-Coupled Carbon Monoxide (CO Oxidation: Evidence for a Plausible Microbe-Mediated Reaction in Martian Brines

    Directory of Open Access Journals (Sweden)

    Marisa R. Myers

    2017-12-01

    Full Text Available The presence of hydrated salts on Mars indicates that some regions of its surface might be habitable if suitable metabolizable substrates are available. However, several lines of evidence have shown that Mars’ regolith contains only trace levels of the organic matter needed to support heterotrophic microbes. Due to the scarcity of organic carbon, carbon monoxide (CO at a concentration of about 700 parts per million (about 0.4 Pa might be the single most abundant readily available substrate that could support near-surface bacterial activity. Although a variety of electron acceptors can be coupled to CO oxidation, perchlorate is likely the most abundant potential oxidant in Mars’ brines. Whether perchlorate, a potent chaotrope, can support microbial CO oxidation has not been previously documented. We report here the first evidence for perchlorate-coupled CO oxidation based on assays with two distinct euryarchaeal extreme halophiles. CO oxidation occurred readily in 3.8 M NaCl brines with perchlorate concentrations from 0.01 to 1 M. Both isolates were able to couple CO with perchlorate or chlorate under anaerobic conditions with or without nitrate as an inducer for nitrate reductase, which serves as a perchlorate reductase in extreme halophiles. In the presence of perchlorate, CO concentrations were reduced to levels well below those found in Mars’ atmosphere. This indicates that CO could contribute to the survival of microbial populations in hydrated salt formations or brines if water activities are suitably permissive.

  18. Multi-element Analysis of variable sample matrices using collision/reaction cell inductively coupled plasma mass spectrometry

    International Nuclear Information System (INIS)

    Zahran, N.F.; Helal, A.I.; Amr, M.A.; Amr, M.A.; Al-saad, K.A.

    2008-01-01

    An ICP-MS with an octopole reaction/collision cell is used for the multielement determination of trace elements in water, plants, and soil samples. The use of a reaction or collision gas reduces serious spectral interferences from matrix elements such as Ar Cl or Ar Na. The background equivalent concentration (BEC) is reduced one order of magnitude at helium flow rate of 1 mL/min. Certified reference material namely , NIST Water-1643d, Tomato leaves 1573a, and Montana soil 2711 are used. The trace elements Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Cd and Pb are determined in the different matrices with a accuracy better than 8% to the certified values

  19. Quadrupole-octupole coupled states in 112Cd populated in the 111Cd(d ⃗,p ) reaction

    Science.gov (United States)

    Jamieson, D. S.; Garrett, P. E.; Bildstein, V.; Demand, G. A.; Finlay, P.; Green, K. L.; Leach, K. G.; Phillips, A. A.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Ball, G. C.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.

    2014-11-01

    States in 112Cd have been studied with the 111Cd(d ⃗,p ) 12Cd reaction using 22 MeV polarized deuterons. The protons from the reaction were momentum analyzed with a Q3D magnetic spectrograph, and spectra have been recorded with a position-sensitive detector located on the focal plane. Angular distributions of cross sections and analyzing powers have been constructed for the low-lying negative-parity states observed, including the 3-,4-, and 5- members of the previously assigned quadrupole-octupole quintuplet. The 5- member at 2373-keV possess the second largest spectroscopic strength observed, and is reassigned as having the s1/2⊗h11/2 two-quasineutron configuration as the dominate component of its wave function.

  20. Coarse grain model for coupled thermo-mechano-chemical processes and its application to pressure-induced endothermic chemical reactions

    International Nuclear Information System (INIS)

    Antillon, Edwin; Banlusan, Kiettipong; Strachan, Alejandro

    2014-01-01

    We extend a thermally accurate model for coarse grain dynamics (Strachan and Holian 2005 Phys. Rev. Lett. 94 014301) to enable the description of stress-induced chemical reactions in the degrees of freedom internal to the mesoparticles. Similar to the breathing sphere model, we introduce an additional variable that describes the internal state of the particles and whose dynamics is governed both by an internal potential energy function and by interparticle forces. The equations of motion of these new variables are derived from a Hamiltonian and the model exhibits two desired features: total energy conservation and Galilean invariance. We use a simple model material with pairwise interactions between particles and study pressure-induced chemical reactions induced by hydrostatic and uniaxial compression. These examples demonstrate the ability of the model to capture non-trivial processes including the interplay between mechanical, thermal and chemical processes of interest in many applications. (paper)

  1. Solid state reaction studies in Fe{sub 3}O{sub 4}–TiO{sub 2} system by diffusion couple method

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Zhongshan [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Hu, Xiaojun, E-mail: huxiaojun@ustb.edu.cn [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Xue, Xiangxin [School of Materials and Metallurgy, Northeastern University, Shenyang 110006 (China); Chou, Kuochih [State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083 (China); School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2013-12-15

    Highlights: •The solid state reactions of Fe2O3-TiO2 system was studied by the diffusion couple method. •Different products were formed by diffusion, and the FeTiO3 was more stable phase. •The inter-diffusion coefficients and diffusion activation energy were estimated. -- Abstract: The solid state reactions in Fe{sub 3}O{sub 4}–TiO{sub 2} system has been studied by diffusion couple experiments at 1323–1473 K, in which the oxygen partial pressure was controlled by the CO–CO{sub 2} gas mixture. The XRD analysis was used to confirm the phases of the inter-compound, and the concentration profiles were determined by electron probe microanalysis (EPMA). Based on the concentration profile of Ti, the inter-diffusion coefficients in Fe{sub 3}O{sub 4} phase, which were both temperature and concentration of Ti ions dependent, were calculated by the modified Boltzmann–Matano method. According to the relation between the thickness of diffusion layer and temperature, the diffusion coefficient of the Fe{sub 3}O{sub 4}–TiO{sub 2} system was obtained. According to the Arrhenius equation, the estimated diffusion activation energy was about 282.1 ± 18.8 kJ mol{sup −1}.

  2. Practical synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides via conventional and decarboxylative copper-free Sonogashira coupling reactions

    Directory of Open Access Journals (Sweden)

    Andrea Caporale

    2014-02-01

    Full Text Available Two efficient protocols for the palladium-catalyzed synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides in the absence of copper were developed. A simple catalytic system consisting of Pd(OAc2 and P(p-tol3 using DBU as the base and THF as the solvent was found to be highly effective for the coupling reaction of 2-methyl-3-butyn-2-ol (4 with a wide range of aryl bromides in good to excellent yields. Analogously, the synthesis of aryl-2-methyl-3-butyn-2-ols was performed also through the decarboxylative coupling reaction of 4-hydroxy-4-methyl-2-pentynoic acid with aryl bromides, using a catalyst containing Pd(OAc2 in combination with SPhos or XPhos in the presence of tetra-n-butylammonium fluoride (TBAF as the base and THF as the solvent. Therefore, new efficient approaches to the synthesis of terminal acetylenes from widely available aryl bromides rather than expensive iodides and using 4 or propiolic acid rather than TMS-acetylene as inexpensive alkyne sources are described.

  3. Difference in chemical reactions in bulk plasma and sheath regions during surface modification of graphene oxide film using capacitively coupled NH{sub 3} plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sung-Youp; Kim, Chan; Kim, Hong Tak, E-mail: zam89blue@gmail.com [Department of Physics, Kyungpook National University, Daegu 702-701 (Korea, Republic of)

    2015-09-14

    Reduced graphene oxide (r-GO) films were obtained from capacitively coupled NH{sub 3} plasma treatment of spin-coated graphene oxide (GO) films at room temperature. Variations were evaluated according to the two plasma treatment regions: the bulk plasma region (R{sub bulk}) and the sheath region (R{sub sheath}). Reduction and nitridation of the GO films began as soon as the NH{sub 3} plasma was exposed to both regions. However, with the increase in treatment time, the reduction and nitridation reactions differed in each region. In the R{sub bulk}, NH{sub 3} plasma ions reacted chemically with oxygen functional groups on the GO films, which was highly effective for reduction and nitridation. While in the R{sub sheath}, physical reactions by ion bombardment were dominant because plasma ions were accelerated by the strong electrical field. The accelerated plasma ions reacted not only with the oxygen functional groups but also with the broken carbon chains, which caused the removal of the GO films by the formation of hydrocarbon gas species. These results showed that reduction and nitridation in the R{sub bulk} using capacitively coupled NH{sub 3} plasma were very effective for modifying the properties of r-GO films for application as transparent conductive films.

  4. Synthesis and Characterization of Graphene and Graphene Oxide Based Palladium Nanocomposites and Their Catalytic Applications in Carbon-Carbon Cross-Coupling Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Minjae [Kunsan National Univ., Gunsan (Korea, Republic of); Kim, Bohyun; Lee, Yuna; Kim, Beomtae; Park, Joon B. [Chonbuk National Univ., Jeonju (Korea, Republic of)

    2014-07-15

    We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in H{sub 2} and O{sub 2} gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance.

  5. Synthesis and Characterization of Graphene and Graphene Oxide Based Palladium Nanocomposites and Their Catalytic Applications in Carbon-Carbon Cross-Coupling Reactions

    International Nuclear Information System (INIS)

    Lee, Minjae; Kim, Bohyun; Lee, Yuna; Kim, Beomtae; Park, Joon B.

    2014-01-01

    We have developed an efficient method to generate highly active Pd and PdO nanoparticles (NPs) dispersed on graphene and graphene oxide (GO) by an impregnation method combined with thermal treatments in H 2 and O 2 gas flows, respectively. The Pd NPs supported on graphene (Pd/G) and the PdO NPs supported on GO (PdO/GO) demonstrated excellent carbon-carbon cross-coupling reactions under a solvent-free, environmentally-friendly condition. The morphological and chemical structures of PdO/GO and Pd/G were fully characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). We found that the remarkable reactivity of the Pd/G and PdO/GO catalysts toward the cross-coupling reaction is attributed to the high degree of dispersion of the Pd and PdO NPs while the oxidative states of Pd and the oxygen functionalities of graphene oxide are not critical for their catalytic performance

  6. Simulation of coupled geochemical reactions and hydrodynamical processes in porous media - application to CO2 storage and uranium exploitation

    International Nuclear Information System (INIS)

    Lagneau, Vincent

    2013-01-01

    This report is a snapshot after sixteen years of research in the field of reactive transport, since the beginning of my Ph.D. in 1997. The research revolves around two poles: on the one hand the development of the reactive transport code Hytec, on the other hand application of the code in different fields of the Earth Sciences. The first two parts of the report detail several key points from this research work, most of them published or being published, following the dual development/application logic. The last part opens towards interesting future work. Development of a reactive transport code: The first part, mostly numeric analysis, details the main features of the code Hytec, in which I have been heavily involved since I joined the laboratory. The underlying equations of the model are given. The resolution methods rely on a finite volume discretization over a Voronoi mesh for the whole hydrodynamic part (flow, transport, heat). Coupling between chemistry and transport is performed through a sequential iterative scheme. Specific developments are then presented. The feedback of chemistry on transport requires specific coupling treatment to ensure convergence to the correct solution: the effects need to be taken care of within the coupling iterations. Dual porosity simulation can be elegantly simulated by duplicating the chemical nodes. Integrating the simulation of gases have implications on the flow (simultaneous resolution of the pressure and saturation equations), and transport-solver (species in the gas phase independently of the water phase), and finally coupling with chemistry and gas-water equilibrium. Applications The Hytec code is used in various domains of the Earth Sciences, in and out our laboratory notably by the members of the consortium Pole Geochimie Transport (Reactive transport group). The document details two families of applications I have been particularly interested in over these years. The geologic storage of CO 2 is a potential technology

  7. Exploring possible reaction pathways for the o-atom transfer reactions to unsaturated substrates catalyzed by a [Ni-NO2 ] ↔ [Ni-NO] redox couple using DFT methods.

    Science.gov (United States)

    Tsipis, Athanassios C

    2017-07-15

    The (nitro)(N-methyldithiocarbamato)(trimethylphospane)nickel(II), [Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] complex catalyses efficiently the O-atom transfer reactions to CO and acetylene. Energetically feasible sequence of elementary steps involved in the catalytic cycle of the air oxidation of CO and acetylene are proposed promoted by the Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] ↔ Ni(NO 2 )(S 2 CNHMe)(PMe 3 ) redox couple using DFT methods both in vacuum and dichloromethane solutions. The catalytic air oxidation of HC≡CH involves formation of a five-member metallacycle intermediate, via a [3 + 2] cyclo-addition reaction of HC≡CH to the Ni-N = O moiety of the Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] complex, followed by a β H-atom migration toward the C α carbon atom of the coordinated acetylene and release of the oxidation product (ketene). The geometric and energetic reaction profile for the reversible [Ni( κN1-NO 2 )(S 2 CNHMe)(PMe 3 )] ⇌ [Ni( κO,O2-ONO)(S 2 CNHMe)(PMe 3 )] linkage isomerization has also been modeled by DFT calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  8. Convergent Synthesis of the Potent P2Y Receptor Antagonist MG 50-3-1 Based on a Regioselective Ullmann Coupling Reaction

    Directory of Open Access Journals (Sweden)

    Christa E. Müller

    2012-03-01

    Full Text Available MG 50-3-1 (3, trisodium 1-amino-4-{4-[4-chloro-6-(2-sulfophenylamino-1,3,5-triazin-2-ylamino]-2-sulfophenylamino}-9,10-dioxo-9,10-dihydroanthracene 2-sulfonate is the most potent and selective antagonist (IC50 4.6 nM for “P2Y1-like” nucleotide-activated membrane receptors in guinea-pig taenia coli responsible for smooth muscle relaxation. Full characterization of the compound, however, e.g., at the human P2Y1 receptor, which is a novel potential target for antithrombotic drugs, as well as other P2 receptor subtypes, has been hampered due to difficulties in synthesizing the compound in sufficient quantity. MG 50-3-1 would be highly useful as a biological tool for detailed investigation of signal transduction in the gut. We have now developed a convenient, fast, mild, and efficient convergent synthesis of 3 based on retrosynthetic analysis. A new, regioselective Ullmann coupling reaction under microwave irradiation was successfully developed to obtain 1-amino-4-(4-amino-2-sulfophenylamino-9,10-dioxo-9,10-dihydro­anthracene 2-sulfonate (8. Four different copper catalysts (Cu, CuCl, CuCl2, and CuSO4 were investigated at different pH values of sodium phosphate buffer, and in water in the absence or presence of base. Results showed that CuSO4 in water in the presence of triethylamine provided the best conditions for the regioselective Ullmann coupling reaction yielding the key intermediate compound 8. A new synthon (sodium 2-(4,6-dichloro-1,3,5-triazin-2-ylaminobenzenesulfonate, 13 which can easily be obtained on a gram scale was prepared, and 13 was successfully coupled with 8 yielding the target compound 3.

  9. Mn3O4 anchored on carbon nanotubes as an electrode reaction catalyst of V(IV)/V(V) couple for vanadium redox flow batteries

    International Nuclear Information System (INIS)

    He, Zhangxing; Dai, Lei; Liu, Suqin; Wang, Ling; Li, Chuanchang

    2015-01-01

    Highlights: • Mn 3 O 4 /MWCNTs (multi-walled carbon nanotubes) composite fabricated by a simple solvothermal method was developed as electrochemical catalyst of V(IV)/V(V) redox couple for vanadium redox flow batteries for the first time. • The electrocatalytic kinetics of the redox reactions of three electrocatalysts (pure Mn 3 O 4 , pure MWCNTs, Mn 3 O 4 /MWCNTs) were compared, and were in the order of Mn 3 O 4 /MWCNTs > MWCNTs > Mn 3 O 4 . • The cell using Mn 3 O 4 /MWCNTs has lower electrochemical polarization, with larger discharge capacity and energy efficiency. The average energy efficiency of the cell using Mn 3 O 4 /MWCNTs is 84.65%, 3.73% higher than that of the pristine cell. - Abstract: Mn 3 O 4 /MWCNTs (multi-walled carbon nanotubes) composite fabricated by a simple solvothermal method was developed as electrochemical catalyst of V(IV)/V(V) redox couple for vanadium redox flow batteries. The electrochemical activity of V(IV)/V(V) redox couple can be enhanced by the electrochemical catalysts (Mn 3 O 4 , MWCNTs, Mn 3 O 4 /MWCNTs), and the electrocatalytic kinetics of the redox reactions were in the order of Mn 3 O 4 /MWCNTs > MWCNTs > Mn 3 O 4 . The cell using Mn 3 O 4 /MWCNTs composite as electrochemical catalyst was assembled and the charge-discharge performance was evaluated. Compared with the pristine cell, the cell using positive graphite felt modified by Mn 3 O 4 /MWCNTs had lower electrochemical polarization, larger discharge capacity and energy efficiency. The average energy efficiency of the cell using modified positive electrode for 50 cycles was 84.65%, 3.73% higher than that of the pristine cell. The superior electrocatalytic performance of Mn 3 O 4 /MWCNTs composite was mainly due to the effective mixed conducting network, facilitating the electron transport and ion diffusion in the electrode/electrolyte interface

  10. Treatment for the recoil effects of the multi-step heavy-ion nucleon transfers with the orthogonalized coupled-reaction-channel theory

    International Nuclear Information System (INIS)

    Misono, S.; Imanishi, B.

    1997-02-01

    We have investigated recoil effects in heavy-ion reactions for the nucleon transfers, and the validity of the spatially local approximation for the non-local transfer interaction defined by the orthogonalized coupled-reaction-channel (OCRC) theory. This approximation makes it easier to treat multi-step transfer processes with the coupled channel method and makes it possible to define the nucleon molecular orbitals with the inclusion of the recoil effects. The transfer interaction is expanded in a power series of the momentum operator, and is approximated by the first order term, i.e., the spatially local term. The numerical calculation for the core-symmetric systems 12 C+ 13 C and 16 O+ 17 O with this approximation shows that the recoil effects are well included in the results at energies lower than a few MeV/nucleon. Furthermore, the OCRC formalism allows us even to employ the complete no-recoil approximation for the calculation of cross sections, even though it is not adequate to use this approximation in the distorted wave Born approximation (DWBA) method. As to polarization, however, the no-recoil approximation is not good even in the OCRC formalism. We discuss the recoil effects on nucleon molecular-orbital states. It is shown that states of the covalent molecular orbitals of the valence (transferred) nucleon are little affected by the recoil effects, as already suggested by Korotky et al. in the full finite-range DWBA analysis of the transfer reaction, 13 C( 13 C, 12 C) 14 C. (author). 59 refs

  11. Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

    Science.gov (United States)

    Ahmed, Nesreen S.; Menzel, Robert; Wang, Yifan; Garcia-Gallastegui, Ainara; Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N.; Mokhtar, Mohamed

    2017-02-01

    Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

  12. An accurate potential energy surface for the F + H{sub 2} → HF + H reaction by the coupled-cluster method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jun; Sun, Zhigang, E-mail: zsun@dicp.ac.cn, E-mail: zhangdh@dicp.ac.cn; Zhang, Dong H., E-mail: zsun@dicp.ac.cn, E-mail: zhangdh@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics and Center for Theoretical Computational Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2015-01-14

    A three dimensional potential energy surface for the F + H{sub 2} → HF + H reaction has been computed by the spin unrestricted coupled cluster method with singles, doubles, triples, and perturbative quadruples [UCCSDT(2){sub Q}] using the augmented correlation-consistent polarised valence quadruple zeta basis set for the fluorine atom and the correlation-consistent polarised valence quadruple zeta basis set for the hydrogen atom. All the calculations are based on the restricted open-shell Hartree-Fock orbitals, together with the frozen core approximations, and the UCCSD(T)/complete basis set (CBS) correction term was included. The global potential energy surface was calculated by fitting the sampled ab initio points without any scaling factor for the correlation energy part using a neutral network function method. Extensive dynamics calculations have been carried out on the potential energy surface. The reaction rate constants, integral cross sections, product rotational states distribution, and forward and backward scattering as a function of collision energy of the F + HD → HF + D, F + HD → DF + H, and F + H{sub 2} reaction, were calculated by the time-independent quantum dynamics scattering theory using the new surface. The satisfactory agreement with the reported experimental observations previously demonstrates the accuracy of the new potential energy surface.

  13. Investigation of 112Cd via the (d,p) Reaction and a Reassessment of the Quadrupole-Octupole Coupled Excitation

    Science.gov (United States)

    Jamieson, D. S.; Garrett, P. E.; Ball, G. C.; Demand, G. A.; Faestermann, T.; Finlay, P.; Green, K. L.; Hertenberger, R.; Leach, K. G.; Phillips, A. A.; Sumithrarachchi, C. S.; Svensson, C. E.; Triambak, S.; Wirth, H.-F.; Wong, J.

    The single-particle neutron states in 112Cd have been probed with the 111Cd(d,p) reaction. Beams of up to 1.2 µA of polarized 22 MeV deuterons bombarded 111Cd targets. The reaction protons were momentum analyzed with a Q3D magnetic spectrograph, with spectra were recorded at 10 angles between 10 and 60° with a resolution of 6-7 keV FWHM. In addition to the (d,p) transfer data, (d,d) elastic-scattering data were also obtained and used to ascertain the proper optical model parameters. Cross sections and analyzing powers for all levels observed to be populated were fit to results of DWBA and ADWA calculations, and spectroscopic factors were determined. The 5- level at 2373 keV, previously assigned as a member on the quadrupole-octupole quintuplet set of states because of its enhanced B(E2;5 - to 31 - ) value, was observed to be one of the strongest peaks in the spectrum, and is reassigned as the s1/2 otimes h11/2 two-quasineutron configuration.

  14. Electrochemical reactions of the Th4+/Th couple on the tungsten, aluminum and bismuth electrodes in chloride molten salt

    International Nuclear Information System (INIS)

    Liu, Kui; Yuan, Li-Yong; Liu, Ya-Lan; Zhao, Xiu-Liang; He, Hui; Ye, Guo-An; Chai, Zhi-Fang; Shi, Wei-Qun

    2014-01-01

    This work concerns the electrochemical behaviors of Th 4+ on the tungsten, aluminum and bismuth electrodes in the LiCl-KCl eutectic, respectively, at 773 K. Cyclic voltammetry and square wave voltammetry were employed to investigate the cathodic reduction of Th 4+ . The results demonstrate that the reduction of Th 4+ is a one step process with a transfer of 4 electrons. The reversibility of the Th 4+ /Th couple on the bismuth film and tungsten electrodes is directly confirmed by the CV. The diffusion coefficient is also calculated to be (2.23 ± 0.16) × 10 −5 and (7.19 ± 0.12) × 10 −5 cm 2 /s by applying both cyclic voltammetry and chronopotentiometry, respectively. A series of redox couples were confirmed to be associated with the formation of different kinds of Al-Th intermetallic compounds. Compared to Al electrode, a cathodic shift of the reduction potential of the Th 4+ is observed on the Al film electrode which is not conducive for the potentiostatic extraction of thorium. The cathodic depolarization gives a shift of 420 mV on the Al electrode, while 490 mV on the Bi film electrode for the reduction of Th 4+ compared to the inert W electrode. The reduction potential of Th 4+ on the Bi film electrode is 70 mV more anodic than that on the Al electrode. Potentiostatic electrolyses were carried out on an Al plate and Bi liquid electrode to confirm the formation of the Th alloys. Two Al-Th alloys (Al 3 Th and Al 2 Th) and one Bi-Th alloy (Bi 2 Th) were obtained, respectively

  15. A Coupled Model for Solution Flow and Bioleaching Reaction Based on the Evolution of Heap Pore Structure

    Directory of Open Access Journals (Sweden)

    Shenghua Yin

    2014-01-01

    Full Text Available Based on the basic seepage law, equations have been derived to descript the solution flow within the copper ore heap which is treated as anisotropy porous media. The relationship between heap permeability and pore ratio has been revealed. Given the consideration of cover pressure and particle dissolution, pore evolution model has been set up. The pore evolution mechanism, due to the process of dissolution, precipitation, blockage, collapse, and caking, has been investigated. The comprehensive model for pore evolution and solution flow under the effect of solute transport and leaching reaction has been established. A trapezoidal heap was calculated, and the estimated results show that permeability decreases with the decreasing of pore ratio. Therefore, the permeability of the heap with small particles is relatively low because of its low pore ratio. Furthermore, permeability and height are found to be the two main factors influencing the solution flow.

  16. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation

    KAUST Repository

    Minenkov, Yury

    2017-03-07

    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (<2 kcal mol-1) for some reactions of Na, Mg, Ca, Sr, Ba and Pb, while for a few reactions of Ca and Ba deviations up to 40 kcal mol-1 have been obtained. Large errors are both due to artificial mixing of the core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens in the molecular orbitals treated as core, and due to neglecting core-core and core-valence correlation effects. These large errors are reduced to a few kcal mol-1 if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol-1, indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.

  17. Numerical Simulation of Desulfurization Behavior in Gas-Stirred Systems Based on Computation Fluid Dynamics-Simultaneous Reaction Model (CFD-SRM) Coupled Model

    Science.gov (United States)

    Lou, Wentao; Zhu, Miaoyong

    2014-10-01

    A computation fluid dynamics-simultaneous reaction model (CFD-SRM) coupled model has been proposed to describe the desulfurization behavior in a gas-stirred ladle. For the desulfurization thermodynamics, different models were investigated to determine sulfide capacity and oxygen activity. For the desulfurization kinetic, the effect of bubbly plume flow, as well as oxygen absorption and oxidation reactions in slag eyes are considered. The thermodynamic and kinetic modification coefficients are proposed to fit the measured data, respectively. Finally, the effects of slag basicity and gas flow rate on the desulfurization efficiency are investigated. The results show that as the interfacial reactions (Al2O3)-(FeO)-(SiO2)-(MnO)-[S]-[O] simultaneous kinetic equilibrium is adopted to determine the oxygen activity, and the Young's model with the modification coefficient R th of 1.5 is adopted to determine slag sulfide capacity, the predicted sulfur distribution ratio LS agrees well with the measured data. With an increase of the gas blowing time, the predicted desulfurization rate gradually decreased, and when the modification parameter R k is 0.8, the predicted sulfur content changing with time in ladle agrees well with the measured data. If the oxygen absorption and oxidation reactions in slag eyes are not considered in this model, then the sulfur removal rate in the ladle would be overestimated, and this trend would become more obvious with an increase of the gas flow rate and decrease of the slag layer height. With the slag basicity increasing, the total desulfurization ratio increases; however, the total desulfurization ratio changes weakly as the slag basicity exceeds 7. With the increase of the gas flow rate, the desulfurization ratio first increases and then decreases. When the gas flow rate is 200 NL/min, the desulfurization ratio reaches a maximum value in an 80-ton gas-stirred ladle.

  18. Redox zone II. Coupled modeling of groundwater flow, solute transport, chemical reactions and microbial processes in the Aespoe island

    Energy Technology Data Exchange (ETDEWEB)

    Samper, Javier; Molinero, Jorge; Changbing Yang; Guoxiang Zhang [Univ. Da Coruna (Spain)

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behaviour and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by Banwart et al. Later, Banwart presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by Molinero who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulphate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of Molinero and extends the preliminary microbial model of Zhang by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfaphe concentration, thus adding additional evidence for the possibility

  19. Redox zone II. Coupled modeling of groundwater flow, solute transport, chemical reactions and microbial processes in the Aespoe island

    International Nuclear Information System (INIS)

    Samper, Javier; Molinero, Jorge; Changbing Yang; Guoxiang Zhang

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behaviour and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by Banwart et al. Later, Banwart presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by Molinero who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulphate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of Molinero and extends the preliminary microbial model of Zhang by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfaphe concentration, thus adding additional evidence for the possibility

  20. Coupled modeling of groundwater flow solute transport, chemical reactions and microbial processes in the 'SP' island

    Energy Technology Data Exchange (ETDEWEB)

    Samper, Javier; Molinero, Jorg; Changbing, Yang; Zhang, Guoxiang

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behavior and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by /Banwart et al, 1995/. Later, /Banwart et al, 1999/ presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by /Molinero, 2000/ who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulfate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of /Molinero, 2000/ and extends the preliminary microbial model of /Zhang, 2001/ by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfate concentration, thus

  1. Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Nesreen S. [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia); Menzel, Robert [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Bio Nano Consulting, The Gridiron Building, One Pancras Square, London N1C 4AG (United Kingdom); Wang, Yifan [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Garcia-Gallastegui, Ainara [Bio Nano Consulting, The Gridiron Building, One Pancras Square, London N1C 4AG (United Kingdom); Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N. [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia); Mokhtar, Mohamed, E-mail: mmokhtar2000@yahoo.com [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia)

    2017-02-15

    Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH. - Graphical abstract: CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary, two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. - Highlights: • CuAl LDH/GO and CoAl LDH/GO hybrid materials with different LDH compositions were prepared. • Hybrids were fully characterised and their catalytic efficiency over the Classic Ullman Reaction was studied. • CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) in 25 min reaction times. • GO provides a light-weight, charge complementary, two-dimensional material that interacts effectively with the 2D LDHs. • After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

  2. Optimization of an Efficient and Sustainable Sonogashira Cross-Coupling Protocol

    KAUST Repository

    Walter, Philipp E.

    2012-12-01

    Cross coupling reactions are a well-established tool in modern organic synthesis and play a crucial role in the synthesis of a high number of organic compounds. Their importance is highlighted by the Nobel Prize in chemistry to Suzuki, Heck and Negishi in 2010. The increasing importance of sustainability requirements in chemical production has furthermore promoted the development of cross-coupling protocols that comply with the principles of “Green Chemistry”1. The Sonogashira reaction is today the most versatile and powerful way to generate aryl alkynes, a moiety recurring in many pharmaceutical and natural products. Despite many improvements to the original reaction, reports on generally applicable protocols that work under sustainable conditions are scarce. Our group recently reported an efficient protocol for a copperfree Sonogashira cross-coupling at low temperature, in aqueous medium and with no addition of organic solvents or additives2. The goal of this work was to further investigate the effects of different reaction parameters on the catalytic activity in order to optimize the protocol. Limitations of the protocol were tested in respect to reaction temperature, heating method, atmosphere, base type and amount, catalyst loading, reaction time and work up procedure. The reaction worked successfully under air and results were not affected by the presence of oxygen in the water phase. Among a variety of bases tested, triethylamine was confirmed to give the best results and its required excess could be reduced from nine to four equivalents. Catalyst loading could also be reduced by up to 90%: Good to near quantitative yields for a broad range of substrates were achieved using a catalyst concentration of 0.25mol% and 5 eq of Et3N at 50°C while more reactive substrates could be coupled with a catalyst concentration as low as 0.025mol%. Filtration experiments showed the possibility of a simplified work up procedure and a protocol completely free of organic

  3. Coupled transport-reaction pathways and distribution patterns between siliciclastic-carbonate sediments at the Ria de Vigo

    Science.gov (United States)

    García, T.; Velo, A.; Fernandez-Bastero, S.; Gago-Duport, L.; Santos, A.; Alejo, I.; Vilas, F.

    2005-02-01

    This paper examines the linkages between the space-distribution of grain sizes and the relative percentage of the amount of mineral species that result from the mixing process of siliciclastic and carbonate sediments at the Ria de Vigo (NW of Spain). The space-distribution of minerals was initially determined, starting from a detailed mineralogical study based on XRD-Rietveld analysis of the superficial sediments. Correlations between the maps obtained for grain sizes, average fractions of either siliciclastic or carbonates, as well as for individual-minerals, were further stabilised. From this analysis, spatially organized patterns were found between carbonates and several minerals involved in the siliciclastic fraction. In particular, a coupled behaviour is observed between plagioclases and carbonates, in terms of their relative percentage amounts and the grain size distribution. In order to explain these results a conceptual model is proposed, based on the interplay between chemical processes at the seawater-sediment interface and hydrodynamical factors. This model suggests the existence of chemical control mechanisms that, by selective processes of dissolution-crystallization, constrain the mixed environment's long-term evolution, inducing the formation of self-organized sedimentary patterns.

  4. Synthesis of palladium nanoparticles with leaf extract of Chrysophyllum cainito (Star apple) and their applications as efficient catalyst for C-C coupling and reduction reactions

    Science.gov (United States)

    Majumdar, Rakhi; Tantayanon, Supawan; Bag, Braja Gopal

    2017-10-01

    A simple green chemical method for the one-step synthesis of palladium nanoparticles (PdNPs) has been described by reducing palladium (II) chloride with the leaf extract of Chrysophyllum cainito in aqueous medium. The synthesis of the palladium nanoparticles completed within 2-3 h at room temperature, whereas on heat treatment (70-80 °C), the synthesis of colloidal PdNPs completed almost instantly. The stabilized PdNPs have been characterized in detail by spectroscopic, electron microscopic and light scattering measurements. The synthesized PdNPs have been utilized as a green catalyst for C-C coupling reactions under aerobic and phosphine-free conditions in aqueous medium. In addition, the synthesized PdNPs have also been utilized as a catalyst for a very efficient sodium borohydride reduction of 3- and 4-nitrophenols. The synthesized PdNPs can retain their catalytic activity for several months.

  5. Recent Advances in the Synthesis of N-Containing Heteroaromatics via Heterogeneously Transition Metal Catalysed Cross-Coupling Reactions

    Directory of Open Access Journals (Sweden)

    Laurent Djakovitch

    2011-06-01

    Full Text Available N-containing heteroaromatics are important substructures found in numerous natural or synthetic alkaloids. The diversity of the structures encountered, as well as their biological and pharmaceutical relevance, have motivated research aimed at the development of new economical, efficient and selective synthetic strategies to access these compounds. Over more than 100 years of research, this hot topic has resulted in numerous so-called “classical synthetic methods” that have really contributed to this important area. However, when the selective synthesis of highly functional heteroaromatics like indoles, quinolones, indoxyls, etc. is considered these methods remain limited. Recently transition metal-catalysed (TM-catalysed procedures for the synthesis of such compounds and further transformations, have been developed providing increased tolerance toward functional groups and leading generally to higher reaction yields. Many of these methods have proven to be the most powerful and are currently applied in target- or diversity-oriented syntheses. This review article aims at reporting the recent developments devoted to this important area, focusing on the use of heterogeneous catalysed procedures that include either the formation of the heterocyclic ring towards the nuclei or their transformations to highly substituted compounds.

  6. Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

    Directory of Open Access Journals (Sweden)

    Ruth Gomes

    2014-11-01

    Full Text Available A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state 13C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N2 sorption, HR-TEM, and NH3 temperature programmed desorption-thermal conductivity detector (TPD-TCD analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, β-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

  7. A coupled transport and solid mechanics formulation with improved reaction kinetics parameters for modeling oxidation and decomposition in a uranium hydride bed.

    Energy Technology Data Exchange (ETDEWEB)

    Salloum, Maher N.; Shugard, Andrew D.; Kanouff, Michael P.; Gharagozloo, Patricia E.

    2013-03-01

    Modeling of reacting flows in porous media has become particularly important with the increased interest in hydrogen solid-storage beds. An advanced type of storage bed has been proposed that utilizes oxidation of uranium hydride to heat and decompose the hydride, releasing the hydrogen. To reduce the cost and time required to develop these systems experimentally, a valid computational model is required that simulates the reaction of uranium hydride and oxygen gas in a hydrogen storage bed using multiphysics finite element modeling. This SAND report discusses the advancements made in FY12 (since our last SAND report SAND2011-6939) to the model developed as a part of an ASC-P&EM project to address the shortcomings of the previous model. The model considers chemical reactions, heat transport, and mass transport within a hydride bed. Previously, the time-varying permeability and porosity were considered uniform. This led to discrepancies between the simulated results and experimental measurements. In this work, the effects of non-uniform changes in permeability and porosity due to phase and thermal expansion are accounted for. These expansions result in mechanical stresses that lead to bed deformation. To describe this, a simplified solid mechanics model for the local variation of permeability and porosity as a function of the local bed deformation is developed. By using this solid mechanics model, the agreement between our reacting bed model and the experimental data is improved. Additionally, more accurate uranium hydride oxidation kinetics parameters are obtained by fitting the experimental results from a pure uranium hydride oxidation measurement to the ones obtained from the coupled transport-solid mechanics model. Finally, the coupled transport-solid mechanics model governing equations and boundary conditions are summarized and recommendations are made for further development of ARIA and other Sandia codes in order for them to sufficiently implement the model.

  8. Degradation of a cationic dye (Rhodamine 6G) using hydrodynamic cavitation coupled with other oxidative agents: Reaction mechanism and pathway.

    Science.gov (United States)

    Rajoriya, Sunil; Bargole, Swapnil; Saharan, Virendra Kumar

    2017-01-01

    In the present study, decolorization and mineralization of a cationic dye, Rhodamine 6G (Rh6G), has been carried out using hydrodynamic cavitation (HC). Two cavitating devices such as slit and circular venturi were used to generate cavitation in HC reactor. The process parameters such as initial dye concentration, solution pH, operating inlet pressure, and cavitation number were investigated in detail to evaluate their effects on the decolorization efficiency of Rh6G. Decolorization of Rh6G was marginally higher in the case of slit venturi as compared to circular venturi. The kinetic study showed that decolorization and mineralization of the dye fitted first-order kinetics. The loadings of H 2 O 2 and ozone have been optimized to intensify the decolorization and mineralization efficiency of Rh6G using HC. Nearly 54% decolorization of Rh6G was obtained using a combination of HC and H 2 O 2 at a dye to H 2 O 2 molar ratio of 1:30. The combination of HC with ozone resulted in 100% decolorization in almost 5-10min of processing time depending upon the initial dye concentration. To quantify the extent of mineralization, total organic carbon (TOC) analysis was also performed using various processes and almost 84% TOC removal was obtained using HC coupled with 3g/h of ozone. The degradation by-products formed during the complete degradation process were qualitatively identified by liquid chromatography-mass spectrometry (LC-MS) and a detailed degradation pathway has been proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Simple synthesis of P(Cbz-alt-TBT) and PCDTBT by combining direct arylation with suzuki polycondensation of heteroaryl chlorides.

    Science.gov (United States)

    Lombeck, Florian; Matsidik, Rukiya; Komber, Hartmut; Sommer, Michael

    2015-01-01

    Direct arylation (DA) of 2-chlorothiophene and 2-chloro-3-hexylthiophene with 4,7-dibromo-2,1,3-benzothiadiazole is used to synthesize 4,7-bis(5-chloro-2-thienyl)-2,1,3-benzothiadiazole (TBTCl2) and 4,7-bis(5-chloro-4-hexyl-2-thienyl)-2,1,3-benzothiadiazole (DH-TBTCl2) in one step. Suitable conditions of the Suzuki polycondensations (SPC) of TBTCl2 and DH-TBTCl2 with the carbazole comonomer CbzPBE2 are established, furnishing PCDTBT and P(Cbz-alt-TBT) with high molecular weight and yield. Compared with control samples made from the corresponding dibromides, high-temperature NMR and UV-vis spectroscopy indicate similar properties for PCDTBT but an increased content of Cbz-Cbz homocouplings for P(Cbz-alt-TBT). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Preventive Effect of Pine Bark Extract (Flavangenol on Metabolic Disease in Western Diet-Loaded Tsumura Suzuki Obese Diabetes Mice

    Directory of Open Access Journals (Sweden)

    Tsutomu Shimada

    2011-01-01

    Full Text Available It is known that the metabolic syndrome has a multi-factorial basis involving both genetic and environmental risk factors. In this study, Tsumura Suzuki Obese Diabetes (TSOD mice, a mouse model of multi-factorial, hereditary, obese type II diabetes, were given a Western diet (WTD as an environmental factor to prepare a disease model (TSOD-WTD and to investigate the preventive effects of Pine bark extract (Flavangenol against obesity and various features of metabolic disease appearing in this animal model. In contrast to control Tsumura Suzuki Non-obesity (TSNO mice, TSOD mice were obese and suffered from other metabolic complications. WTD-fed TSOD mice developed additional features such as hyperinsulinemia, abnormal glucose/lipid metabolism and fatty liver. The treatment with Flavangenol had a suppressive effect on increase in body weight and accumulation of visceral and subcutaneous fat, and also showed preventive effects on symptoms related to insulin resistance, abnormal glucose/lipid metabolism and hypertension. Flavangenol also increased the plasma concentration of adiponectin and decreased the plasma concentration of TNF-α. We next investigated the effect of Flavangenol on absorption of meal-derived lipids. Flavangenol suppressed absorption of neutral fat in an olive-oil-loading test (in vivo and showed an inhibitory effect on pancreatic lipase (in vitro. The above results suggest that Flavangenol has a preventive effect on severe metabolic disease due to multiple causes that involve both genetic and environmental risk factors. The mechanism of action might involve a partial suppressive effect of meal-derived lipids on absorption.

  11. The mediation reaction between the external couple Ferri/Ferrocyanide and Os(II) bipyridile poly-vinylpyridile films coated onto glassy carbon electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Ybarra, Gabriel; Moina, Carlos [Centro de Investigacion sobre Electrodeposicion y Procesos Superficiales, Instituto Nacional de Tecnologia Industrial, CC 157, 1650 San Martin (Argentina); Florit, M. Ines [INIFTA, Facultad de Ciencias Exactas, UNLP, Suc. 4, CC 16, 1900 La Plata (Argentina); Posadas, Dionisio [INIFTA, Facultad de Ciencias Exactas, UNLP, Suc. 4, CC 16, 1900 La Plata (Argentina)], E-mail: dposadas@inifta.unlp.edu.ar

    2008-05-30

    The oxidation-reduction of the Ferri/Ferrocyanide couple in solution onto modified glassy carbon Rotating Disk Electrodes (RDE) covered by Os(II) bipyridile poly-vinylpyridile (OsBPP) polymer was studied at room temperature. Steady state polarization curves were carried out as a function of the rotation speed, the polymer thickness and the concentration of redox centers within the polymer. This system has the characteristic that the formal redox potentials of both the external redox couple (E{sup 0}'(Fe(CN){sub 6}{sup 3-/4-}) = + 0.225 V vs. SCE) and the mediator polymer (E{sup 0}'(OsBPP) = 0.260 V vs. SCE) lie very close. It is demonstrated that diffusion of the Ferri/Ferrocyanide inside the polymer can be ruled out. Since the processes of charge transfer at the metal/polymer and the mediating reaction are fast, the experimental results can be interpreted in terms of a kinetics in which the charge transport in the polymer or the diffusion in the solution may be the rate determining step, according to the experimental conditions. A simple model is considered that allows interpreting the experimental results quantitatively. Application of this model allows the determination of the diffusion coefficient of the electrons within the film, D{sub e} {approx} 10{sup -10} cm{sup 2} s{sup -1}.

  12. Comparison of standard and reaction cell inductively coupled plasma mass spectrometry in the determination of chromium and selenium species by HPLC-ICP-MS

    International Nuclear Information System (INIS)

    Bednar, A.J.; Kirgan, R.A.; Jones, W.T.

    2009-01-01

    Elemental speciation is becoming a common analytical procedure for geochemical investigations. The various redox species of environmentally relevant metals can have vastly different biogeochemical properties, including sorption, solubility, bioavailability, and toxicity. The use of high performance liquid chromatography (HPLC) coupled to elemental specific detectors, such as inductively coupled plasma mass spectrometry (ICP-MS), has become one of the most important speciation methods employed. This is due to the separation versatility of HPLC and the sensitive and selective detection capabilities of ICP-MS. The current study compares standard mode ICP-MS to recently developed reaction cell (RC) ICP-MS, which has the ability to remove or reduce many common polyatomic interferences that can limit the ability of ICP-MS to quantitate certain analytes in complex matrices. Determination of chromium and selenium redox species is achieved using ion-exchange chromatography with elemental detection by standard and RC-ICP-MS, using various chromium and selenium isotopes. In this study, method performance and detection limits for the various permutations of the method (isotope monitored or ICP-MS detection mode) were found to be comparable and generally less than 1 μg L -1 . The method was tested on synthetic laboratory samples, surface water, groundwater, and municipal tap water matrices

  13. Study of W boson polarisations and Triple Gauge boson Couplings in the reaction $e^{+}e^{-} \\to W^{+}W^{-}$ at LEP 2

    CERN Document Server

    Abdallah, J.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P.P.; Amaldi, U.; Amapane, N.; Amato, Sandra F.; Anashkin, E.; Andreazza, A.; Andringa, Sofia; Anjos, N.; Antilogus, Pierre; Apel, W-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, Jean-Eudes; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G.J.; Baroncelli, Antonio; Battaglia, Marco; Baubillier, M.; Becks, K-H.; Begalli, M.; Behrmann, A.; Ben-Haim, Eli; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, Mikael; Bertrand, D.; Besancon, Marc; Besson, N.; Bloch, Daniel; Blom, M.; Bluj, Michal; Bonesini, Maurizio; Boonekamp, M.; Booth, P.S.L.; Borisov, G.; Botner, Olga; Bouquet, B.; Bowcock, T.J.V.; Boyko, I.; Bracko, Marko; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J.M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, Tiziano; Canale, V.; Carena, F.; Castro, Nuno Filipe; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, Paolo; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, Suh-Urk; Cieslik, K.; Collins, P.; Contri, Roberto; Cosme, G.; Cossutti, Fabio; Costa, M.J.; Crennell, D.; Cuevas, Javier; D'Hondt, J.; da Silva, T.; Da Silva, W.; Della Ricca, Giuseppe; De Angelis, Alessandro; De Boer, W.; De Clercq, C.; De Lotto, Barbara; De Maria, N.; De Min, A.; de Paula, L.; Di Ciaccio, L.; Di Simone, A.; Doroba, K.; Eigen, G.; Ekelof, Tord; Ellert, Mattias; Elsing, M.; Espirito Santo, Maria Catarina; Fanourakis, George K.; Feindt, Michael; Fernandez, J.; Ferrer, Antonio; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, Miriam; Garcia, C.; Gavillet, Philippe; Gazis, Evangelos; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, Klaus; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, Vincent; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S-O.; Holt, P.J.; Houlden, M.A.; Jackson, John Neil; Jarlskog, Goran; Jarry, P.; Jeans, D.; Johansson, E.K.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, Frederic; Katsanevas, S.; Katsoufis, E.; Kernel, Gabrijel; Kerzel, U.; King, B.T.; Kjaer, N.J.; Kluit, Peter; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, Jacques; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J.H.; Lopez, J.M.; Loukas, D.; Lutz, Pierre; Lyons, Louis; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Nulty, R.Mc; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Muller, Ulrich; Muenich, K.; Mulders, M.; Mundim Filho, Luiz Martins; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J.P.; Palka, Henryk; Papadopoulou, Th.D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, Andrea; Petrolini, Alessandro; Piedra, Jonatan; Pieri, L.; Pierre, Francois; Pimenta, M.; Piotto, E.; Poireau, V.; Pol, M.E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Radojicic, D.; Rames, J.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, Peter; Richard, F.; Ridky, Jan; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, Paolo; Roudeau, P.; Rovelli, T.; Ruhlmann, Vanina; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Segar, A.; Sekulin, R.; Siebel, Martin; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, Andrei Valerevich; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli de Fatis, T.; Taffard, A.C.; Tegenfeldt, F.; Timmermans, Jan; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, Petr; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, Clara; Turluer, M-L.; Tyapkin, I.A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, Giovanni; Van Dam, P.; Van Eldik, J.; Van Lysebetten, A.; van Remortel, N.; Van Vulpen, I.; Vegni, G.; Veloso, Filipe; Venus, W.; Verdier, Patrice; Verzi, V.; Vilanova, D.; Vitale, Lorenzo; Vrba, V.; Wahlen, H.; Washbrook, A.J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, Danilo; Zhuravlov, V.; Zimine, N.I.; Zintchenko, Alexandre

    2008-01-01

    A determination of the single W Spin Density Matrix (SDM) elements in the reaction e+e- -> W+W- -> l nu q qbar (l=e/mu) is reported at centre-of-mass energies between 189 and 209 GeV. The data sample used corresponds to an integrated luminosity of 520 pb^{-1} taken by DELPHI between 1998 and 2000. The single W SDM elements, rho_{tau tau'}^{W+-} (tau,tau' = +/-1 or 0), are determined as a function of the W- production angle with respect to the e- beam direction and are obtained from measurements of the W decay products by the application of suitable projection operators, Lambda_{tau tau'}, which assume the V-A coupling of the W boson to fermions. The measured SDM elements are used to obtain the fraction of longitudinally polarised Ws, with the result: sigma_L/sigma_tot = 24.9 +/- 4.5(stat) +/- 2.2(syst) % at a mean energy of 198 GeV. The SDM elements are also used to determine the Triple Gauge Couplings Delta g_1^Z, Delta kappa_gamma, lambda_gamma and g_4^Z, ~kappa_Z and ~lambda_Z. For the CP-violating couplin...

  14. Effect of a weak magnetic field on the Mizoroki–Heck coupling reaction in the presence of wicker-like palladium-poly(N-vinylpyrrolidone)-iron nanocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Rafiee, Ezzat, E-mail: ezzat_rafiee@yahoo.com [Department of Inorganic Chemistry, Faculty of Chemistry, Razi University, Kermanshah 67149 (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, Razi University, Kermanshah 67149 (Iran, Islamic Republic of); Joshaghani, Mohammad [Department of Inorganic Chemistry, Faculty of Chemistry, Razi University, Kermanshah 67149 (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, Razi University, Kermanshah 67149 (Iran, Islamic Republic of); Abadi, Parvaneh Ghaderi-Shekhi [Institute of Nano Science and Nano Technology, Razi University, Kermanshah 67149 (Iran, Islamic Republic of)

    2016-06-15

    The wicker-like Pd-PVP-Fe (palladium-poly(N-vinylpyrrolidone)-iron) was synthesized by the external magnetic field (EMF). The Pd-based catalyst with nano and the face-centered cubic (fcc) structure was obtained at room temperature without using any additive. The resulting composite was characterized. The results show that EMF has a great influence on morphology, particle size, and crystalline structure of the Pd-PVP-Fe composite. The resulting composite (Pd-PVP-Fe), was found to be an effective catalyst for the Mizoroki–Heck reaction while is exposed to EMF with the intensity at 486 µT. The reused catalyst for at least five repeating cycles, shows excellent activity. - Highlights: • The wicker-like Pd-PVP-Fe nanocatalyst was synthesized via external magnetic field. • The resulting catalyst composite was characterized. • The C–C coupling reaction was carried out at magnetic field and room temperature. • Magnetic field affects on the morphology and size of the catalyst. • The catalyst could be reused without significant degradation in activity.

  15. Pair natural orbital and canonical coupled cluster reaction enthalpies involving light to heavy alkali and alkaline earth metals: the importance of sub-valence correlation.

    Science.gov (United States)

    Minenkov, Yury; Bistoni, Giovanni; Riplinger, Christoph; Auer, Alexander A; Neese, Frank; Cavallo, Luigi

    2017-04-05

    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (correlation effects. These large errors are reduced to a few kcal mol -1 if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol -1 , indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.

  16. Atypical McMurry Cross-Coupling Reactions Leading to a New Series of Potent Antiproliferative Compounds Bearing the Key [Ferrocenyl-Ene-Phenol] Motif

    Directory of Open Access Journals (Sweden)

    Pascal Pigeon

    2014-07-01

    Full Text Available In the course of the preparation of a series of ferrocenyl derivatives of diethylstilbestrol (DES, in which one of the 4-hydroxyphenyl moieties was replaced by a ferrocenyl group, the McMurry reaction of chloropropionylferrocene with a number of mono-aryl ketones unexpectedly yielded the hydroxylated ferrocenyl DES derivatives, 5a–c, in poor yields (10%–16%. These compounds showed high activity on the hormone-independent breast cancer cell line MDA-MB-231 with IC50 values ranging from 0.14 to 0.36 µM. Surprisingly, non-hydroxylated ferrocenyl DES, 4, showed only an IC50 value of 1.14 µM, illustrating the importance of the hydroxyethyl function in this promising new series. For comparison, McMurry reactions of the shorter chain analogue chloroacetylferrocene were carried out to see the difference in behaviour with mono-aryl ketones versus a diaryl ketone. The effect of changing the length of the alkyl chain adjacent to the phenolic substituent of the hydroxylated ferrocenyl DES was studied, a mechanistic rationale to account for the unexpected products is proposed, and the antiproliferative activities of all of these compounds on MDA-MB-231 cells lines were measured and compared. X-ray crystal structures of cross-coupled products and of pinacol-pinacolone rearrangements are reported.

  17. Dinuclear NHC-palladium complexes containing phosphine spacers: synthesis, X-ray structures and their catalytic activities towards the Hiyama coupling reaction.

    Science.gov (United States)

    Yang, Jin; Li, Pinhua; Zhang, Yicheng; Wang, Lei

    2014-05-21

    Six dinuclear N-heterocyclic carbene (NHC) palladium complexes, [PdCl2(IMes)]2(μ-dppe) (1), [PdCl2(IPr)]2(μ-dppe) (2), [PdCl2(IMes)]2(μ-dppb) (3), [PdCl2(IPr)]2(μ-dppb) (4), [PdCl2(IMes)]2(μ-dpph) (5), and [PdCl2(IPr)]2(μ-dpph) (6) [IMes = N,N'-bis-(2,4,6-trimethylphenyl)imidazol-2-ylidene; IPr = N,N'-bis-(2,6-di(iso-propyl)phenyl)imidazol-2-ylidene; dppe = 1,2-bis(diphenylphosphino)ethane, dppb = 1,4-bis(diphenylphosphino)butane; and dpph = 1,6-bis(diphenylphosphino)hexane], have been synthesized through bridge-cleavage reactions of chloro-bridged dimeric compounds, [Pd(μ-Cl)(Cl)(NHC)]2, with the corresponding diphosphine ligands. The obtained compounds were fully characterized by (1)H NMR, (13)C NMR and (31)P NMR spectroscopy, FT-IR, elemental analysis and single-crystal X-ray crystallography. Moreover, further explorations of the catalytic potential of the dinuclear carbene palladium complexes as catalysts for the Pd-catalyzed transformations have been performed under microwave irradiation conditions, and the complexes exhibited moderate to good catalytic activity in the Hiyama coupling reaction of trimethoxyphenylsilane with aryl chlorides.

  18. The dependence of the electronic coupling on energy gap and bridge conformation - Towards prediction of the distance dependence of electron transfer reactions

    International Nuclear Information System (INIS)

    Eng, Mattias P.; Albinsson, Bo

    2009-01-01

    The attenuation factor, β, for the distance dependence of electron exchange reactions is a sensitive function of the donor-bridge energy gap and bridge conformation. In this work the electronic coupling for electron and triplet excitation energy transfer has been investigated for five commonly used repeating bridge structures. The investigated bridge structures are OF (oligo fluorene), OP (oligo phenylene), OPE (oligo p-phenyleneethynylene), OPV (oligo phenylenevinylene), and OTP (oligo thiophene). Firstly, the impact of the donor-bridge energy gap was investigated by performing calculations with a variety of donors appended onto bridges that were kept in a planar conformation. This resulted in, to our knowledge, the first presented sets of bridge specific parameters to be inserted into the commonly used McConnell model. Secondly, since at experimental conditions large conformational flexibility is expected, a previously developed model that takes conformational disorder of the bridge into account has been applied to the investigated systems [M.P. Eng, T. Ljungdahl, J. Martensson, B. Albinsson, J. Phys. Chem. B 110 (2006) 6483]. This model is based on Boltzmann averaging and has been shown to describe the temperature dependence of the attenuation factor through OPE-bridges. Together, the parameters describing the donor-bridge energy gap dependence, for planar bridge structures, and the Boltzmann averaging procedure, describing the impact of rotational disorder, have the potential to a priori predict attenuation factors for electron and excitation energy transfer reactions through bridged donor-acceptor systems

  19. Nickel-catalyzed coupling reaction of alkyl halides with aryl Grignard reagents in the presence of 1,3-butadiene: mechanistic studies of four-component coupling and competing cross-coupling reactions† †Electronic supplementary information (ESI) available: Detailed experimental and computational results, procedures, characterization data, copies of NMR charts, and crystallographic data. CCDC 1572238. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc04675h

    Science.gov (United States)

    Fukuoka, Asuka; Yokoyama, Wataru; Min, Xin; Hisaki, Ichiro; Kuniyasu, Hitoshi

    2018-01-01

    We describe the mechanism, substituent effects, and origins of the selectivity of the nickel-catalyzed four-component coupling reactions of alkyl fluorides, aryl Grignard reagents, and two molecules of 1,3-butadiene that affords a 1,6-octadiene carbon framework bearing alkyl and aryl groups at the 3- and 8-positions, respectively, and the competing cross-coupling reaction. Both the four-component coupling reaction and the cross-coupling reaction are triggered by the formation of anionic nickel complexes, which are generated by the oxidative dimerization of two molecules of 1,3-butadiene on Ni(0) and the subsequent complexation with the aryl Grignard reagents. The C–C bond formation of the alkyl fluorides with the γ-carbon of the anionic nickel complexes leads to the four-component coupling product, whereas the cross-coupling product is yielded via nucleophilic attack of the Ni center toward the alkyl fluorides. These steps are found to be the rate-determining and selectivity-determining steps of the whole catalytic cycle, in which the C–F bond of the alkyl fluorides is activated by the Mg cation rather than a Li or Zn cation. ortho-Substituents of the aryl Grignard reagents suppressed the cross-coupling reaction leading to the selective formation of the four-component products. Such steric effects of the ortho-substituents were clearly demonstrated by crystal structure characterizations of ate complexes and DFT calculations. The electronic effects of the para-substituent of the aryl Grignard reagents on both the selectivity and reaction rates are thoroughly discussed. The present mechanistic study offers new insight into anionic complexes, which are proposed as the key intermediates in catalytic transformations even though detailed mechanisms are not established in many cases, and demonstrates their synthetic utility as promising intermediates for C–C bond forming reactions, providing useful information for developing efficient and straightforward

  20. Intermolecular Dehydrative Coupling Reaction of Arylketones with Cyclic Alkenes Catalyzed by a Well-Defined Cationic Ruthenium-Hydride Complex: A Novel Ketone Olefination Method via Vinyl C–H Bond Activation

    Science.gov (United States)

    Yi, Chae S.; Lee, Do W.

    2010-01-01

    Summary The cationic ruthenium-hydride complex [(η6-C6H6)(PCy3)(CO)RuH]+BF4− was found to be a highly effective catalyst for the intermolecular olefination reaction of arylketones with cycloalkenes. The preliminary mechanistic analysis revealed that electrophilic ruthenium-vinyl complex is the key species for mediating both vinyl C–H bond activation and the dehydrative olefination steps of the coupling reaction. PMID:20567607

  1. Exploiting dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) for sequential determination of trace elements in blood using a dilute-and-shoot procedure

    International Nuclear Information System (INIS)

    Lemos Batista, Bruno; Lisboa Rodrigues, Jairo; Andrade Nunes, Juliana; Oliveira Souza, Vanessa Cristina de; Barbosa, Fernando

    2009-01-01

    Inductively coupled plasma mass spectrometry with quadrupole (q-ICP-MS) and dynamic reaction cell (DRC-ICP-MS) were evaluated for sequential determination of As, Cd, Co, Cr, Cu, Mn, Pb, Se, Tl, V and Zn in blood. The method requires as little as 100 μL of blood. Prior to analysis, samples (100 μL) were diluted 1:50 in a solution containing 0.01% (v/v) Triton X-100 and 0.5% (v/v) nitric acid. The use of the DRC was only mandatory for Cr, Cu, V and Zn. For the other elements the equipment may be operated in a standard mode (q-ICP-MS). Ammonia was used as reaction gas. Selection of best flow rate of ammonium gas and optimization of the quadrupole dynamic band-pass tuning parameter (RPq) were carried out, using a ovine base blood for Cr and V and a synthetic matrix solution (SMS) for Zn and Cu diluted 1:50 and spiked to contain 1 μg L -1 of each element. Method detection limits (3 s) for 75 As, 114 Cd, 59 Co, 51 Cr, 63 Cu 55 Mn, 208 Pb, 82 Se, 205 Tl, 51 V, and 64 Zn were 14.0, 3.0, 11.0, 7.0, 280, 9.0, 3.0, 264, 0.7, 6.0 and 800 ng L -1 , respectively. Method validation was accomplished by the analysis of blood Reference Materials produced by the L'Institut National de Sante Publique du Quebec (Canada).

  2. Label-free and sensitive detection of T4 polynucleotide kinase activity via coupling DNA strand displacement reaction with enzymatic-aided amplification.

    Science.gov (United States)

    Cheng, Rui; Tao, Mangjuan; Shi, Zhilu; Zhang, Xiafei; Jin, Yan; Li, Baoxin

    2015-11-15

    Several fluorescence signal amplification strategies have been developed for sensitive detection of T4 polynucleotide kinase (T4 PNK) activity, but they need fluorescence dye labeled DNA probe. We have addressed the limitation and report here a label-free strategy for sensitive detection of PNK activity by coupling DNA strand displacement reaction with enzymatic-aided amplification. A hairpin oligonucleotide (hpDNA) with blunt ends was used as the substrate for T4 PNK phosphorylation. In the presence of T4 PNK, the stem of hpDNA was phosphorylated and further degraded by lambda exonuclease (λ exo) from 5' to 3' direction to release a single-stranded DNA as a trigger of DNA strand displacement reaction (SDR). The trigger DNA can continuously displace DNA P2 from P1/P2 hybrid with the help of specific cleavage of nicking endonuclease (Nt.BbvCI). Then, DNA P2 can form G-quadruplex in the presence of potassium ions and quadruplex-selective fluorphore, N-methyl mesoporphyrin IX (NMM), resulting in a significant increase in fluorescence intensity of NMM. Thus, the accumulative release of DNA P2 led to fluorescence signal amplification for determining T4 PNK activity with a detection limit of 6.6×10(-4) U/mL, which is superior or comparative with established approaches. By ingeniously utilizing T4 PNK-triggered DNA SDR, T4 PNK activity can be specifically and facilely studied in homogeneous solution containing complex matrix without any external fluorescence labeling. Moreover, the influence of different inhibitors on the T4 PNK activity revealed that it also can be explored to screen T4 PNK inhibitors. Therefore, this label-free amplification strategy presents a facile and cost-effective approach for nucleic acid phosphorylation related research. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Enhanced removal of aqueous acetaminophen by a laccase-catalyzed oxidative coupling reaction under a dual-pH optimization strategy.

    Science.gov (United States)

    Wang, Kaidong; Huang, Ke; Jiang, Guoqiang

    2018-03-01

    Acetaminophen is one kind of pharmaceutical contaminant that has been detected in municipal water and is hard to digest. A laccase-catalyzed oxidative coupling reaction is a potential method of removing acetaminophen from water. In the present study, the kinetics of radical polymerization combined with precipitation was studied, and the dual-pH optimization strategy (the enzyme solution at pH7.4 being added to the substrate solution at pH4.2) was proposed to enhance the removal efficiency of acetaminophen. The reaction kinetics that consisted of the laccase-catalyzed oxidation, radical polymerization and precipitation were studied by UV in situ, LC-MS and DLS (dynamic light scattering) in situ. The results showed that the laccase-catalyzed oxidation is the rate-limiting step in the whole process. The higher rate of enzyme-catalyzed oxidation under a dual-pH optimization strategy led to much faster formation of the dimer, trimer and tetramer. Similarly, the formation of polymerized products that could precipitate naturally from water was faster. Under the dual-pH optimization strategy, the initial laccase activity was increased approximately 2.9-fold, and the activity remained higher for >250s, during which approximately 63.7% of the total acetaminophen was transformed into biologically inactive polymerized products, and part of these polymerized products precipitated from the water. Laccase belongs to the family of multi-copper oxidases, and the present study provides a universal method to improve the activity of multi-copper oxidases for the high-performance removal of phenol and its derivatives. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. FAKTOR PSIKOLOGIS, LINGKUNGAN DAN BAURAN PEMASARAN YANG MEMPENGARUHI PEMBELIAN SEPEDA MOTOR Studi Pada Konsumen Sepeda Motor Bebek 4-tak Merk Suzuki dan Honda di Kota Banjarmasin

    Directory of Open Access Journals (Sweden)

    Taufiq Adi Rahmanie

    2012-05-01

    Full Text Available ABSTRAK Penelitian ini dilakukan untuk mengetahui faktor psikologis, lingkungan dan bauran pemasaran yang mempengaruhi pembelian sepeda motor bebek 4-tak merk Suzuki dan Honda di Kota Banjarmasin, dan untuk mengetahui variabel yang dominan terhadap keputusan pembelian. Penelitian ini dilakukan di Kota Banjarmasin. Pengambilan sampel dilakukan dengan teknik non random sampling dengan motode convenience sampling, dengan jumlah sampel 706 responden (355 konsumen Suzuki dan  351 konsumen Honda. Tingkat signifikansi yang ditetapkan dalam penelitian ini adalah 5%. Sebanyak 49 item dalam daftar pertanyaan yang diuraikan dalam 12 variabel dalam faktor psikologis, lingkungan dan bauran pemasaran. Pengujian terhadap semua instrumen penelitian menunjukkan tingkat reliabilitas dan validitas yang tinggi. Hasil penelitian ini semua variabel bebas yaitu persepsi (X1, sikap (X2, gaya hidup (X3, kepribadian (X4, budaya (X5, kelas sosial (X6, kelompok referensi (X7, situasi penentu (X8, produk (X9, harga (X10, promosi (X11 dan distribusi (X12 mempunyai korelasi yang signifikan terhadap keputusan pembelian sepeda motor bebek 4-tak merk Suzuki dan Honda. Diantara keduabelas variabel tersebut, variabel persepsi (X1, sikap (X2, gaya hidup (X3, kelompok referensi (X7, situasi penentu (X8 dan produk (X9 berpengaruh secara nyata terhadap keputusan pembelian sepeda motor bebek 4-tak merk Suzuki dan Honda di Kota Banjarmasin. Koefisien determinasi (R2 sebesar 0.591 menunjukkan kontribusi variabel-variabel independen untuk menjelaskan variabel dependen sebesar 59.1%. Sedangkan variabel yang paling dominan pengaruhnya adalah sikap sebesar 39.6%.   Kata kunci: pemasaran, bauran, psikologis ABSTRACT This research has been done to know psychological, environmental, marketing mix to influence 4 stroke bebek motorcycle (Honda and Suzuki buying in Banjarmasin, and also to know the dominant variable on buying decision. This research has been done in Banjarmasin. Writer uses non

  5. DNA-binding, catalytic oxidation, C—C coupling reactions and antibacterial activities of binuclear Ru(II thiosemicarbazone complexes: Synthesis and spectral characterization

    Directory of Open Access Journals (Sweden)

    Arumugam Manimaran

    2012-07-01

    Full Text Available New hexa-coordinated binuclear Ru(II thiosemicarbazone complexes of the type {[(B(EPh3(COClRu]2L} (where, E = P or As; B = PPh3 or AsPh3 or pyridine; L = mononucleating NS donor of N-substituted thiosemicarbazones have been synthesized and characterized by elemental analysis, FT-IR, UV–vis and 31P{1H} NMR cyclic voltammetric studies. The DNA-binding studies of Ru(II complexes with calf thymus DNA (CT-DNA were investigated by UV–vis, viscosity measurements, gel-electrophoresis and fluorescence spectroscopy. The new complexes have been used as catalysts in C—C coupling reaction and in the oxidation of alcohols to their corresponding carbonyl compounds by using NMO as co-oxidant and molecular oxygen (O2 atmosphere at ambient temperature. Further, the new binucleating thiosemicarbazone ligands and their Ru(II complexes were also screened for their antibacterial activity against Klebsiella pneumoniae, Shigella sp., Micrococcus luteus, Escherichia coli and Salmonella typhi. From this study, it was found out that the activity of the complexes almost reaches the effectiveness of the conventional bacteriocide.

  6. Coupling between solute transport and chemical reactions models. Acoplamiento de modelos de transporte de solutos y de modelos de reacciones quimicas

    Energy Technology Data Exchange (ETDEWEB)

    Samper, J.; Ajora, C. (Instituto de Ciencias de la Tierra, CSIC, Barcerlona (Spain))

    1993-01-01

    During subsurface transport, reactive solutes are subject to a variety of hydrodynamic and chemical processes. The major hydrodynamic processes include advection and convection, dispersion and diffusion. The key chemical processes are complexation including hydrolysis and acid-base reactions, dissolution-precipitation, reduction-oxidation, adsorption and ion exchange. The combined effects of all these processes on solute transport must satisfy the principle of conservation of mass. The statement of conservation of mass for N mobile species leads to N partial differential equations. Traditional solute transport models often incorporate the effects of hydrodynamic processes rigorously but oversimplify chemical interactions among aqueous species. Sophisticated chemical equilibrium models, on the other hand, incorporate a variety of chemical processes but generally assume no-flow systems. In the past decade, coupled models accounting for complex hydrological and chemical processes, with varying degrees of sophistication, have been developed. The existing models of reactive transport employ two basic sets of equations. The transport of solutes is described by a set of partial differential equations, and the chemical processes, under the assumption of equilibrium, are described by a set of nonlinear algebraic equations. An important consideration in any approach is the choice of primary dependent variables. Most existing models cannot account for the complete set of chemical processes, cannot be easily extended to include mixed chemical equilibria and kinetics, and cannot handle practical two and three dimensional problems. The difficulties arise mainly from improper selection of the primary variables in the transport equations. (Author) 38 refs.

  7. Ultrasensitive electrochemical detection of avian influenza A (H7N9) virus DNA based on isothermal exponential amplification coupled with hybridization chain reaction of DNAzyme nanowires.

    Science.gov (United States)

    Yu, Yanyan; Chen, Zuanguang; Jian, Wensi; Sun, Duanping; Zhang, Beibei; Li, Xinchun; Yao, Meicun

    2015-02-15

    In this work, a simple and label-free electrochemical biosensor with duel amplification strategy was developed for DNA detection based on isothermal exponential amplification (EXPAR) coupled with hybridization chain reaction (HCR) of DNAzymes nanowires. Through rational design, neither the primer nor the DNAzymes containing molecular beacons (MBs) could react with the duplex probe which were fixed on the electrode surface. Once challenged with target, the duplex probe cleaved and triggered the EXPAR mediated target recycle and regeneration circles as well as the HCR process. As a result, a greater amount of targets were generated to cleave the duplex probes. Subsequently, the nanowires consisting of the G-quadruplex units were self-assembled through hybridization with the strand fixed on the electrode surface. In the presence of hemin, the resulting catalytic G-quadruplex-hemin HRP-mimicking DNAzymes were formed. Electrochemical signals can be obtained by measuring the increase in reduction current of oxidized 3.3',5.5'-tetramethylbenzidine sulfate (TMB), which was generated by DNAzyme in the presence of H2O2. This method exhibited ultrahigh sensitivity towards avian influenza A (H7N9) virus DNA sequence with detection limits of 9.4 fM and a detection range of 4 orders of magnitude. The biosensor was also capable of discriminating single-nucleotide difference among concomitant DNA sequences and performed well in spiked cell lysates. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. A method of coupling the Paternò-Büchi reaction with direct infusion ESI-MS/MS for locating the C[double bond, length as m-dash]C bond in glycerophospholipids.

    Science.gov (United States)

    Stinson, Craig A; Xia, Yu

    2016-06-21

    Tandem mass spectrometry (MS/MS) coupled with soft ionization is established as an essential platform for lipid analysis; however, determining high order structural information, such as the carbon-carbon double bond (C[double bond, length as m-dash]C) location, remains challenging. Recently, our group demonstrated a method for sensitive and confident lipid C[double bond, length as m-dash]C location determination by coupling online the Paternò-Büchi (PB) reaction with nanoelectrospray ionization (nanoESI) and MS/MS. Herein, we aimed to expand the scope of the PB reaction for lipid analysis by enabling the reaction with infusion ESI-MS/MS at much higher flow rates than demonstrated in the nanoESI setup (∼20 nL min(-1)). In the new design, the PB reaction was effected in a fused silica capillary solution transfer line, which also served as a microflow UV reactor, prior to ESI. This setup allowed PB reaction optimization and kinetics studies. Under optimized conditions, a maximum of 50% PB reaction yield could be achieved for a standard glycerophosphocholine (PC) within 6 s of UV exposure over a wide flow rate range (0.1-10 μL min(-1)). A solvent composition of 7 : 3 acetone : H2O (with 1% acid or base modifier) allowed the highest PB yields and good lipid ionization, while lower yields were obtained with an addition of a variety of organic solvents. Radical induced lipid peroxidation was identified to induce undesirable side reactions, which could be effectively suppressed by eliminating trace oxygen in the solution via N2 purge. Finally, the utility of coupling the PB reaction with infusion ESI-MS/MS was demonstrated by analyzing a yeast polar lipid extract where C[double bond, length as m-dash]C bond locations were revealed for 35 glycerophospholipids (GPs).

  9. Synthesis of E-Alkyl Alkenes from Terminal Alkynes via Ni-Catalyzed Cross-Coupling of Alkyl Halides with B-Alkenyl-9-borabicyclo[3.3.1]nonanes.

    Science.gov (United States)

    Di Franco, Thomas; Epenoy, Alexandre; Hu, Xile

    2015-10-02

    The first Ni-catalyzed Suzuki-Miyaura coupling of alkyl halides with alkenyl-(9-BBN) reagents is reported. Both primary and secondary alkyl halides including alkyl chlorides can be coupled. The coupling method can be combined with hydroboration of terminal alkynes, allowing the expedited synthesis of functionalized alkyl alkenes from readily available alkynes with complete (E)-selectivity in one pot. The method was applied to the total synthesis of (±)-Recifeiolide, a natural macrolide.

  10. Ligand-Controlled Chemoselective C(acyl)–O Bond vs C(aryl)–C Bond Activation of Aromatic Esters in Nickel Catalyzed C(sp2)–C(sp3) Cross-Couplings

    KAUST Repository

    Chatupheeraphat, Adisak

    2018-02-20

    A ligand-controlled and site-selective nickel catalyzed Suzuki-Miyaura cross-coupling reaction with aromatic esters and alkyl organoboron reagents as coupling partners was developed. This methodology provides a facile route for C(sp2)-C(sp3) bond formation in a straightforward fashion by successful suppression of the undesired β-hydride elimination process. By simply switching the phosphorus ligand, the ester substrates are converted into the alkylated arenes and ketone products, respectively. The utility of this newly developed protocol was demonstrated by its wide substrate scope, broad functional group tolerance and application in the synthesis of key intermediates for the synthesis of bioactive compounds. DFT studies on the oxidative addition step helped rationalizing this intriguing reaction chemoselectivity: whereas nickel complexes with bidentate ligands favor the C(aryl)-C bond cleavage in the oxidative addition step leading to the alkylated product via a decarbonylative process, nickel complexes with monodentate phosphorus ligands favor activation of the C(acyl)-O bond, which later generates the ketone product.

  11. Multi-scale modelling of Suzuki segregation in γ′ precipitates in Ni and Co-base superalloys

    Directory of Open Access Journals (Sweden)

    Srimannarayana P.

    2014-01-01

    Full Text Available The high temperature strength of alloys with (γ + γ′ microstructure is primarily due to the resistance of the ordered precipitate to cutting by matrix dislocations. Such shearing requires higher stresses since it involves the creation of a planar fault. Planar fault energy is known to be dependent on composition. This implies that the composition on the fault may be different from that in the bulk for energetic reasons. Such segregation (or desegregation of specific alloying elements to the fault may result in Suzuki strengthening which has not been explored extensively in these systems. In this work, segregation (or desegregation of alloying elements to planar faults was studied computationally in Ni3(Al,Ti and Co3(W,Al type γ′ precipitates. The composition dependence of APB energy and heat of mixing were evaluated from first principle electronic structure calculations. A phase field model incorporating the first principles results, was used to simulate the motion of an extended superdislocation under stress concurrently with composition evolution. Results reveal that in both systems, significant (desegregation occurs on equilibration. On application of stress, solutes were dragged along with the APB in some cases. Additionally, it was also noted the velocity of the superdislocation under an applied stress is strongly dependent on atomic mobility (i.e. diffusivity.

  12. Laser ablation-inductively coupled plasma-dynamic reaction cell-mass spectrometry for the multi-element analysis of polymers

    International Nuclear Information System (INIS)

    Resano, M.; Garcia-Ruiz, E.; Vanhaecke, F.

    2005-01-01

    In this work, the potential of laser ablation-inductively coupled plasma-mass spectrometry for the fast analysis of polymers has been explored. Different real-life samples (polyethylene shopping bags, an acrylonitrile butadiene styrene material and various plastic bricks) as well as several reference materials (VDA 001 to 004, Cd in polyethylene) have been selected for the study. Two polyethylene reference materials (ERM-EC 680 and 681), for which a reference or indicative value for the most relevant metals is available, have proved their suitability as standards for calibration. Special attention has been paid to the difficulties expected for the determination of Cr at the μg g -1 level in this kind of materials, due to the interference of ArC + ions on the most abundant isotopes of Cr. The use of ammonia as a reaction gas in a dynamic reaction cell is shown to alleviate this problem, resulting in a limit of detection of 0.15 μg g -1 for this element, while limiting only modestly the possibilities of the technique for simultaneous multi-element analysis. In this regard, As is the analyte most seriously affected by the use of ammonia, and its determination has to be carried out in vented mode, at the expense of measuring time. In all cases studied, accurate results could be obtained for elements ranging in content from the sub-μg g -1 level to tens of thousands of μg g -1 . However, the use of an element of known concentration as internal standard may be needed for materials with a matrix significantly different from that of the standard (polyethylene in this work). Precision ranged between 5% and 10% RSD for elements found at the 10 μg g -1 level or higher, while this value could deteriorate to 20% for analytes found at the sub-μg g -1 level. Overall, the technique evaluated presents many advantages for the fast and accurate multi-element analysis of these materials, avoiding laborious digestion procedures and minimizing the risk of analyte losses due to the

  13. Computational Study of Pincer Iridium Catalytic Systems: C-H, N-H, and C-C Bond Activation and C-C Coupling Reactions

    Science.gov (United States)

    Zhou, Tian

    Computational chemistry has achieved vast progress in the last decades in the field, which was considered to be only experimental before. DFT (density functional theory) calculations have been proven to be able to be applied to large systems, while maintaining high accuracy. One of the most important achievements of DFT calculations is in exploring the mechanism of bond activation reactions catalyzed by organometallic complexes. In this dissertation, we discuss DFT studies of several catalytic systems explored in the lab of Professor Alan S. Goldman. Headlines in the work are: (1) (R4PCP)Ir alkane dehydrogenation catalysts are highly selective and different from ( R4POCOP)Ir catalysts, predicting different rate-/selectivity-determining steps; (2) The study of the mechanism for double C-H addition/cyclometalation of phenanthrene or biphenyl by (tBu4PCP)Ir(I) and ( iPr4PCP)Ir illustrates that neutral Ir(III) C-H addition products can undergo a very facile second C-H addition, particularly in the case of sterically less-crowded Ir(I) complexes; (3) (iPr4PCP)Ir pure solid phase catalyst is highly effective in producing high yields of alpha-olefin products, since the activation enthalpy for dehydrogenation is higher than that for isomerization via an allyl pathway; higher temperatures favor the dehydrogenation/isomerization ratio; (4) (PCP)Ir(H)2(N2H4) complex follows a hydrogen transfer mechanism to undergo both dehydrogenation to form N 2 and H2, as well as hydrogen transfer followed by N-N bond cleavage to form NH3, N2, and H2; (5) The key for the catalytic effect of solvent molecule in CO insertion reaction for RMn(CO)5 is hydrogen bond assisted interaction. The basicity of the solvent determines the strength of the hydrogen bond interaction during the catalytic path and determines the catalytic power of the solvent; and (6) Dehydrogenative coupling of unactivated C-H bonds (intermolecular vinyl-vinyl, intramolecular vinyl-benzyl) is catalyzed by precursors of the

  14. Orbital-optimized coupled-electron pair theory and its analytic gradients: Accurate equilibrium geometries, harmonic vibrational frequencies, and hydrogen transfer reactions

    Science.gov (United States)

    Bozkaya, Uǧur; Sherrill, C. David

    2013-08-01

    Orbital-optimized coupled-electron pair theory [or simply "optimized CEPA(0)," OCEPA(0), for short] and its analytic energy gradients are presented. For variational optimization of the molecular orbitals for the OCEPA(0) method, a Lagrangian-based approach is used along with an orbital direct inversion of the iterative subspace algorithm. The cost of the method is comparable to that of CCSD [O(N6) scaling] for energy computations. However, for analytic gradient computations the OCEPA(0) method is only half as expensive as CCSD since there is no need to solve the λ2-amplitude equation for OCEPA(0). The performance of the OCEPA(0) method is compared with that of the canonical MP2, CEPA(0), CCSD, and CCSD(T) methods, for equilibrium geometries, harmonic vibrational frequencies, and hydrogen transfer reactions between radicals. For bond lengths of both closed and open-shell molecules, the OCEPA(0) method improves upon CEPA(0) and CCSD by 25%-43% and 38%-53%, respectively, with Dunning's cc-pCVQZ basis set. Especially for the open-shell test set, the performance of OCEPA(0) is comparable with that of CCSD(T) (ΔR is 0.0003 Å on average). For harmonic vibrational frequencies of closed-shell molecules, the OCEPA(0) method again outperforms CEPA(0) and CCSD by 33%-79% and 53%-79%, respectively. For harmonic vibrational frequencies of open-shell molecules, the mean absolute error (MAE) of the OCEPA(0) method (39 cm-1) is fortuitously even better than that of CCSD(T) (50 cm-1), while the MAEs of CEPA(0) (184 cm-1) and CCSD (84 cm-1) are considerably higher. For complete basis set estimates of hydrogen transfer reaction energies, the OCEPA(0) method again exhibits a substantially better performance than CEPA(0), providing a mean absolute error of 0.7 kcal mol-1, which is more than 6 times lower than that of CEPA(0) (4.6 kcal mol-1), and comparing to MP2 (7.7 kcal mol-1) there is a more than 10-fold reduction in errors. Whereas the MAE for the CCSD method is only 0.1 kcal

  15. Multi-element analysis of urine using dynamic reaction cell inductively coupled plasma mass spectrometry (ICP-DRC-MS — A practical application

    Directory of Open Access Journals (Sweden)

    Renata Brodzka

    2013-04-01

    Full Text Available Objectives: The method for the determination of As, Al, Cd, Ni, Pb (toxic elements and Cr, Co, Cu, Fe, Mn, Zn (essential elements in human urine by the use of Inductively Coupled Plasma Mass Spectrometry (quadrupole ICP-MS DRCe Elan, Perkin Elmer with the dynamic reaction cell (DRC was developed. Materials and Methods: The method has been applied for multi-element analysis of the urine of 16 non-exposed healthy volunteers and 27 workers employed in a copper smelter. The analysis was conducted after initial 10-fold dilution of the urine samples with 0,1% nitric acid. Rhodium was used as an internal standard. The method validation parameters such as detection limit, sensitivity, precision were described for all elements. Accuracy of the method was checked by the regular use of certified reference materials ClinCheck®-Control Urine (Recipe as well as by participation of the laboratory in the German External Quality Assessment Scheme (G-EQUAS. Results: The detection limits (DL 3s of the applied method were 0.025, 0.007, 0.002, 0.004, 0.004, 0.086, 0.037, 0.009, 0.016, 0.008, 0.064 (μg/l for Al, As, Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, Zn in urine, respectively. For each element linearity with correlation coefficient of at least 0.999 was determined. Spectral interferences from some of the ions were removed using DRC-e with addition of alternative gas: methane for cobalt, copper, cadmium, chromium, iron, manganese, nickel and rhodium, and oxygen for arsenic. Conclusions: The developed method allows to determine simultaneously eleven elements in the urine with low detection limits, high sensitivity and good accuracy. Moreover, the method is appropriate for the assessment of both environmental and occupational exposure.

  16. Determination of Cd, Cr, Hg and Pb in plastics from waste electrical and electronic equipment by inductively coupled plasma mass spectrometry with collision-reaction interface technology.

    Science.gov (United States)

    Santos, Mirian C; Nóbrega, Joaquim A; Cadore, Solange

    2011-06-15

    A procedure based on the use of a quadrupole inductively coupled plasma-mass spectrometer equipped with a collision-reaction interface (CRI) for control of spectral overlap interferences was developed for simultaneous determination of Cd, Cr, Hg, and Pb in plastics from waste electrical and electronic equipment (WEEE). The injection of H(2) and He (80 and 60 mL min(-1), respectively) into the sampled plasma, colliding and reacting with potentially interfering polyatomic ions, allows interference-free determination of chromium via its isotopes (52)Cr and (53)Cr that are freed from overlap due to the occurrence of (40)Ar(12)C(+), (40)Ar(12)C(1)H(+), (36)S(16)O(+) or (1)H(36)S(16)O(+). Cadmium, Hg and Pb were directly determined via their isotopes (110)Cd, (111)Cd, (112)Cd, (199)Hg, (200)Hg, (201)Hg, (202)Hg, (206)Pb, (207)Pb, and (208)Pb, without using CRI. The CRI can be quickly activated or deactivated before each analyte measurement. Limits of detection for (52)Cr were 0.04 or 0.14 μg L(-1) with He or H(2) injected in CRI. Cadmium and Pb have LODs between 0.02 and 0.08 μg L(-1) and Hg had 0.93-0.98 μg L(-1), without using CRI. Analyte concentrations for samples varied from 16 to 43, 1 to 11, 4 to 12, and 5 to 13 mg kg(-1) for Cr, Cd, Hg and Pb, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Emerging Roles for MAS-Related G Protein-Coupled Receptor-X2 in Host Defense Peptide, Opioid, and Neuropeptide-Mediated Inflammatory Reactions.

    Science.gov (United States)

    Ali, Hydar

    2017-01-01

    Mast cells (MCs) are tissue-resident immune cells that contribute to host defense but are best known for their roles in allergic and inflammatory diseases. In humans, MCs are divided into two subtypes based on the protease content of their secretory granules. Thus, human lung MCs contain only tryptase and are known as MC T , whereas skin MCs contain both tryptase and chymase and are known as MC TC . Patients with severe asthma display elevated MCs in the lung, which undergo phenotypic change from MC T to MC TC . Although the human genome contains four Mas related G protein coupled receptor X (MRGPRX) genes, an important feature of MC TC is that they selectively express MRGPRX2. It is activated by antimicrobial host defense peptides such as human β-defensins and the cathelicidin LL-37 and likely contributes to host defense. MRGPRX2 is also a receptor for the neuropeptide substance P, major basic protein, eosinophil peroxidase, opioids, and many FDA-approved cationic drugs. Increased expression of MRGPRX2 or enhanced downstream signaling likely contributes to chronic inflammatory diseases such as rosacea, atopic dermatitis, chronic urticaria, and severe asthma. In this chapter, I will discuss the expression profile and function of MRGPRX1-4 and review the emerging roles of MRGPRX2 on host defense, chronic inflammatory diseases, and drug-induced pseudoallergic reactions. I will also examine the novel aspects of MRGPRX2 signaling in MCs as it related to degranulation and review the mechanisms of its regulation. © 2017 Elsevier Inc. All rights reserved.

  18. Crystal structures of three 4-substituted-2,2′-bipyridines synthesized by Sonogashira and Suzuki–Miyaura cross-coupling reactions

    Directory of Open Access Journals (Sweden)

    Thuy Luong Thi Thu

    2017-04-01

    Full Text Available Facile synthetic routes for three 4-substituted 2,2′-bipyridine derivatives, 4-[2-(4-methylphenylethynyl]-2,2′-bipyridine, C19H14N2, (I, 4-[2-(pyridin-3-ylethynyl]-2,2′-bipyridine, C17H11N3, (II, and 4-(indol-4-yl-2,2′-bipyridine, C18H13N3, (III, via Sonogashira and Suzuki–Miyaura cross-coupling reactions, respectively, are described. As indicated by X-ray analysis, the 2,2′-bipyridine core, the ethylene linkage and the substituents of (I and (II are almost planar [dihedral angles between the two ring systems: 8.98 (5 and 9.90 (6° for the two molecules of (I in the asymmetric unit and 2.66 (14° for (II], allowing π-conjugation. On the contrary, in (III, the indole substituent ring is rotated significantly out of the bipyridine plane [dihedral angle = 55.82 (3°], due to steric hindrance. The crystal packings of (I and (II are dominated by π–π interactions, resulting in layers of molecules parallel to (30-2 in (I and columns of molecules along the a axis in (II. The packing of (III exhibits zigzag chains of molecules along the c axis interacting through N—H...N hydrogen bonds and π–π interactions. The contributions of unknown disordered solvent molecules to the diffraction intensities in (II were removed with the SQUEEZE [Spek (2015. Acta Cryst. C71, 9–18] algorithm of PLATON. The given chemical formula and other crystal data do not take into account these solvent molecules.

  19. Study for the charge symmetric systems, 12C+13N and 12C+13C with the orthogonalized coupled-reaction-channel method

    International Nuclear Information System (INIS)

    Imanishi, B.; Denisov, V.; Motobayashi, T.

    1996-10-01

    The charge-symmetric scattering systems, 12 C+ 13 N and 12 C+ 13 C have been investigated by using the orthogonalized coupled-reaction-channel (OCRC) method with the basis functions of the elastic, inelastic and transfer channels defined by the single-particle states, 1p1/2, 2s1/2, 1d5/2 and 1d3/2 of the valence nucleon in 13 N or 13 C. The data of the elastic scattering of 13 N on 12 C measured by Lienard et al. have been explained consistently with the data of the elastic and inelastic scattering of the 12 C+ 13 C system. The CRC effects both on the above systems are very strong, although those on the 12 C+ 13 N system are fairly weaker than the 12 C+ 13 C system. The role of the highly excited single-particle states 1d3/2 is particularly important in the formation of a specific CRC scheme, i.e., the formation of the covalent molecules due to the hybridization caused by the mixing of the different parity single-particle states. The fusion cross sections of the 12 C+ 13 C system at energies below the Coulomb barrier are strongly enhanced as a result of the strong CRC effects as compared with those of the 12 C+ 12 C system, while in 12 C+ 13 N system the enhancement of the sub-barrier fusion has not been observed. The above absorption mechanism for the 12 C+ 13 C system explains the lack of the molecular-resonance phenomena observed in the 12 C+ 12 C system. We check the effects of the dipole (E1) transition of the valence nucleon in 13 N (and also in 13 C) due to the core-core Coulomb interaction in the scattering at sub-barrier energies. The effects are not appreciable. (author)

  20. An electrochemical impedance biosensor for Hg2+ detection based on DNA hydrogel by coupling with DNAzyme-assisted target recycling and hybridization chain reaction.

    Science.gov (United States)

    Cai, Wei; Xie, Shunbi; Zhang, Jin; Tang, Dianyong; Tang, Ying

    2017-12-15

    In this work, an electrochemical impedance biosensor for high sensitive detection of Hg 2+ was presented by coupling with Hg 2+ -induced activation of Mg 2+ -specific DNAzyme (Mg 2+ -DNAzyme) for target cycling and hybridization chain reaction (HCR) assembled DNA hydrogel for signal amplification. Firstly, we synthesized two different copolymer chains P1 and P2 by modifying hairpin DNA H3 and H4 with acrylamide polymer, respectively. Subsequently, Hg 2+ was served as trigger to activate the Mg 2+ -DNAzyme for selectively cleavage ribonucleobase-modified substrate in the presence of Mg 2+ . The partial substrate strand could dissociate from DNAzyme structure, and hybridize with capture probe H1 to expose its concealed sequence for further hybridization. With the help of the exposed sequence, the HCR between hairpin DNA H3 and H4 in P1 and P2 was initiated, and assembled a layer of DNA cross-linked hydrogel on the electrode surface. The formed non-conductive DNA hydrogel film could greatly hinder the interfacial electronic transfer which provided a possibility for us to construct a high sensitive impedance biosensor for Hg 2+ detection. Under the optimal conditions, the impedance biosensor showed an excellent sensitivity and selectivity toward Hg 2+ in a concentration range of 0.1pM - 10nM with a detection limit of 0.042pM Moreover, the real sample analysis reveal that the proposed biosensor is capable of discriminating Hg 2+ ions in reliable and quantitative manners, indicating this method has a promising potential for preliminary application in routine tests. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Coupled transport/reaction modelling with ion-exchange: Study of the long-term properties of bentonite buffer in a final repository

    International Nuclear Information System (INIS)

    Liu Jinsong; Neretnieks, I.

    1997-05-01

    Possible transformation of Na-montmorillonite to Ca-montmorillonite, by ion exchange, in the bentonite buffer in a final repository for spent nuclear fuel can lead to a drastic decrease in the swelling capacity and a significant increase in the permeability of the bentonite. The ion exchange mechanism has been studied, by using the coupled transport/reaction model. In most typical sites of the granite bedrock where there are no large fractures, groundwater flow is limited. The results of this study show that the ion-exchange process will be very slow in this case. Only a few percent of the total Na-montmorillonite is exchanged within 1 to 10 thousand years. When the groundwater flow in the bedrock is assumed to be unlimited, an upper bound of the conditions of the water flow, a sharp ion-exchange front can be formed and propagate within the bentonite buffer. When the groundwater is assumed to be the Aespoe water, with a high Ca concentration, the break-through time of the ion-exchange front can be a few thousand years. When the water is assumed to be Allard water with low Ca concentration, the break-through time can be as long as 10 5 to 10 6 years. When a canister has manufacturing defects, both the pyrite oxidation and the ion-exchange processes can occur simultaneously. A redox front and an ion-exchange front develop from both sides of the bentonite buffer. before the two fronts meet, they travel relatively independently in the bentonite. After they have met, they interact only marginally. Even if a large scale ion-exchange happens, the release of the dissolved uranium species from the bentonite to the rock can still be extremely small. The release is mainly controlled by the redox potential of pyrite oxidation

  2. Design, synthesis and characterization of 1H-pyridin-4-yl-3,5 ...

    Indian Academy of Sciences (India)

    Keywords. 1H-pyridin-4-yl-3,5-disubstituted indazoles; Suzuki reaction; Akt kinase activity. 1. Introduction. In organic synthesis, Palladium-catalysed new carbon– carbon bond formation from aryl halides with organo boronic acids via Suzuki coupling reaction has been proved to be an important method. The 2010 Nobel.

  3. Detection of influenza viruses by coupling multiplex reverse-transcription loop-mediated isothermal amplification with cascade invasive reaction using nanoparticles as a sensor

    Directory of Open Access Journals (Sweden)

    Ge Y

    2017-04-01

    Full Text Available Yiyue Ge,1 Qiang Zhou,2 Kangchen Zhao,1 Ying Chi,1 Bin Liu,3 Xiaoyan Min,4 Zhiyang Shi,1 Bingjie Zou,2 Lunbiao Cui1 1Institute of Pathogenic Microbiology, Key Laboratories of Enteric Pathogenic Microbiology (Ministry of Health, Jiangsu Provincial Center for Disease Control and Prevention, 2Department of Pharmacology, Jinling Hospital, Medical School of Nanjing University, 3Department of Biomedical Engineering, Nanjing Medical University, 4Department of Geriatrics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China Abstract: Influenza virus infections represent a worldwide public health and economic problem due to the significant morbidity and mortality caused by seasonal epidemics and pandemics. Sensitive and convenient methodologies for detection of influenza viruses are essential for further disease control. Loop-mediated isothermal amplification (LAMP is the most commonly used method of nucleic acid isothermal amplification. However, with regard to multiplex LAMP, differentiating the ladder-like LAMP products derived from multiple targets is still challenging today. The requirement of specialized instruments has further hindered the on-site application of multiplex LAMP. We have developed an integrated assay coupling multiplex reverse transcription LAMP with cascade invasive reaction using nanoparticles (mRT-LAMP-CIRN as a sensor for the detection of three subtypes of influenza viruses: A/H1N1pdm09, A/H3 and influenza B. The analytic sensitivities of the mRT-LAMP-CIRN assay were 101 copies of RNA for both A/H1N1pdm09 and A/H3, and 102 copies of RNA for influenza B. This assay demonstrated highly specific detection of target viruses and could differentiate them from other genetically or clinically related viruses. Clinical specimen analysis showed the mRT-LAMP-CIRN assay had an overall sensitivity and specificity of 98.3% and 100%, respectively. In summary, the mRT-LAMP-CIRN assay is

  4. Cross-coupling reactions of unprotected halopurine bases, nucleosides, nucleotides and nucleoside triphosphates with 4-boronophenylalanine in water. Synthesis of (purin-8-yl)- and (purin-6-yl)phenylalanines

    Czech Academy of Sciences Publication Activity Database

    Čapek, Petr; Pohl, Radek; Hocek, Michal

    2006-01-01

    Roč. 4, č. 11 (2006), s. 2278-2284 ISSN 1477-0520 R&D Projects: GA AV ČR(CZ) 1QS400550501; GA MŠk(CZ) 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : amino acids * purines * nucleosides * cross-coupling reactions Subject RIV: CC - Organic Chemistry Impact factor: 2.874, year: 2006

  5. Diversity Oriented Synthesis of Natural 2-Arylbenzofuran, Moracin F

    International Nuclear Information System (INIS)

    Yun, So-Ra; Jun, Jong-Gab

    2016-01-01

    Diversity oriented synthesis of natural 2-arylbenzofuran, moracin F (1) has been carried out from the commercially available starting materials using Sonogashira coupling, Suzuki coupling, neutral Al 2 O 3 mediated cyclization, and intramolecular Wittig reaction as key steps.

  6. The taxonomic implication of frontal tubercles in Polypedilum subgenera diagnoses, with re-description of Polypedilum isigabeceum Sasa & Suzuki (Diptera, Chironomidae).

    Science.gov (United States)

    Yamamoto, Nao; Yamamoto, Masaru

    2016-11-15

    Polypedilum isigabeceum Sasa et Suzuki, 2000 was described as belonging to subgenus Polypedilum s. str. However, if we accept the conclusion of Sæther et al. (2010), the species might be placed into Kribionympha with P. unagiquartum Sasa, 1985 because of the presence of distinct frontal tubercles in the adult males. However, other taxonomic characters do not support their treatment. P. isigabeceum is re-described and reconfirmed to be assigned to the subgenus Polypedilum s. str. The taxonomic meaning of frontal tubercles is discussed for defining the subgeneric rankings within genus Polypedilum.

  7. Combined effects of chemical reaction and temperature dependent heat source on MHD mixed convective flow of a couple-stress fluid in a vertical wavy porous space with travelling thermal waves

    Directory of Open Access Journals (Sweden)

    Muthuraj R.

    2012-01-01

    Full Text Available A mathematical model is developed to examine the effect of chemical reaction on MHD mixed convective heat and mass transfer flow of a couple-stress fluid in vertical porous space in the presence of temperature dependent heat source with travelling thermal waves. The dimensionless governing equations are assumed to be made up of two parts: a mean part corresponding to the fully developed mean flow, and a small perturbed part, using amplitude as a small parameter. The analytical solution of perturbed part have been carried out by using the long-wave approximation. The expressions for the zeroth-order and the first order solutions are obtained and the results of the heat and mass transfer characteristics are presented graphically for various values of parameters entering into the problem. It is noted that velocity of the fluid increases with the increase of the couple stress parameter and increasing the chemical reaction parameter leads suppress the velocity of the fluid. Cross velocity decreases with an increase of the phase angle. The increase of the chemical reaction parameter and Schmidt number lead to decrease the fluid concentration. The hydrodynamic case for a non-porous space in the absence of the temperature dependent heat source for Newtonian fluid can be captured as a limiting case of our analysis by taking, and α1→0, Da→∞, a→∞.

  8. Identification of a time-varying point source in a system of two coupled linear diffusion-advection- reaction equations: application to surface water pollution

    International Nuclear Information System (INIS)

    Hamdi, Adel

    2009-01-01

    This paper deals with the identification of a point source (localization of its position and recovering the history of its time-varying intensity function) that constitutes the right-hand side of the first equation in a system of two coupled 1D linear transport equations. Assuming that the source intensity function vanishes before reaching the final control time, we prove the identifiability of the sought point source from recording the state relative to the second coupled transport equation at two observation points framing the source region. Note that at least one of the two observation points should be strategic. We establish an identification method that uses these records to identify the source position as the root of a continuous and strictly monotonic function. Whereas the source intensity function is recovered using a recursive formula without any need of an iterative process. Some numerical experiments on a variant of the surface water pollution BOD–OD coupled model are presented

  9. Nuclear structure of weakly bound radioactive nuclei through elastic and and inelastic scattering on proton. Impacts of the couplings induced by these exotic nuclei on direct reactions

    International Nuclear Information System (INIS)

    Lapoux, V.

    2005-09-01

    Information on the structure, spectroscopy and target interaction potentials of exotic nuclei can be inferred by interpreting measured data from direct reactions on proton such as elastic or inelastic scattering of proton (p,p') or one-nucleon transfer reaction (p,d). A series of experimental results has been obtained at the GANIL facilities on the setting composed of the MUST telescope array used for the detection of light charged-particles and of CATS beam detectors. This setting aims at measuring reactions on light proton or deuteron targets through reverse kinematics. Particularly, results on C 10 , C 11 and on direct reactions with the He 8 beam of Spiral are presented. The first chapter is dedicated to the description of the most important theories concerning the nucleus. The experimental tools used to probe the nucleus are reported in the second chapter. The third and fourth chapters present the framework that has allowed us to analyse results from (p,p') and (p,d) reactions on weakly bound exotic nuclei. The last chapter is dedicated to the description of future experimental programs. (A.C.)

  10. The study of CaO and MgO heterogenic nano-catalyst coupling on transesterification reaction efficacy in the production of biodiesel from recycled cooking oil.

    Science.gov (United States)

    Tahvildari, Kambiz; Anaraki, Yasaman Naghavi; Fazaeli, Reza; Mirpanji, Sogol; Delrish, Elham

    2015-01-01

    Fossil fuels' pollution and their non-renewability have motivated the search for alternative fuels. Some common example of seed oils are sunflower oil, date seed oil, soy bean oil. For instance, soy methyl and soy-based biodiesel are the main biodiesel. Biodiesel is a clean diesel fuel that can be produced through transesterification reaction. Recycled cooking oil, on the other hand, is one of the inexpensive, easily available sources for producing biodiesel. This article is aimed at production of biodiesel via trans-esterification method, Nano CaO synthesis using sol-gel method, and Nano MgO synthesis using sol-gel self-combustion. Two catalysts' combination affecting the reaction's efficacy was also discussed. Optimum conditions for the reaction in the presence of Nano CaO are 1.5 % weight fracture, 1:7 alcohol to oil proportion and 6 h in which biodiesel and glycerin (the byproduct) are produced. Moreover, the optimum conditions for this reaction in the presence of Nano CaO and Nano MgO mixture are 3 % weight fracture (0.7 g of Nano CaO and 0.5 g of Nano MgO), 1:7 alcohols to oil proportion and 6 h. Nano MgO is not capable of catalyzing the transesterification by itself, because it has a much weaker basic affinity but when used with Nano CaO due to its surface structure, the basic properties increase and it becomes a proper base for the catalyst so that CaO contact surface increases and transesterification reaction yield significantly increases as well. This study investigates the repeatability of transesterification reaction in the presence of these Nano catalysts as well.

  11. Synthesis of 2'-deoxyadenosine nucleosides bearing bipyridine-type ligands and their Ru-complexes in position 8 through cross-coupling reactions

    Czech Academy of Sciences Publication Activity Database

    Vrábel, Milan; Pohl, Radek; Klepetářová, Blanka; Votruba, Ivan; Hocek, Michal

    2007-01-01

    Roč. 5, č. 17 (2007), s. 2849-2857 ISSN 1477-0520 R&D Projects: GA MŠk LC512; GA ČR GA203/05/0043 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleosides * purines * cross-coupling * ruthenium Subject RIV: CC - Organic Chemistry Impact factor: 3.167, year: 2007

  12. Oxidative Photoredox-Catalytic Activation of Aliphatic Nucleophiles for C(sp3)-C(sp2) Cross-Coupling Reactions

    Czech Academy of Sciences Publication Activity Database

    Jahn, Emanuela; Jahn, Ullrich

    2014-01-01

    Roč. 53, č. 49 (2014), s. 13326-13328 ISSN 1433-7851 Institutional support: RVO:61388963 Keywords : amino acids * cross - coupling * nickel * persistent radical effect * photoredox catalysis Subject RIV: CC - Organic Chemistry Impact factor: 11.261, year: 2014

  13. Quasielastic reactions

    International Nuclear Information System (INIS)

    Hansen, O.

    1983-01-01

    A brief review is presented of the experimental and theoretical situation regarding transfer reactions and inelastic scattering. In the first category there is little (very little) precision data for heavy projectiles and consequently almost no experience with quantitative theoretical analysis. For the inelastic scattering the rather extensive data strongly supports the coupled channels models with collective formfactors. At the most back angles, at intensities about 10 -5 of Rutherford scattering, a second, compound-like mechanism becomes dominant. The description of the interplay of these two opposite mechanisms provides a new challenge for our understanding

  14. Partial wave analysis of the reaction πN→Nππ and coupled channel analyses of the reactions πN in the CM energy range 1.38-1.74GeV

    International Nuclear Information System (INIS)

    Dolbeau, Jean.

    1976-01-01

    The partial wave analysis of 91314 π + -p→Nππ events at nine CM energies between 1.38 and 1.74GeV was performed using the generalized isobar model and assuming the coherent production of Δ, rho and sigma in the final state. A coupled channel analysis (K-matrix formalism) led to the determination of the arbitrary phase at each energy and to smooth the partial wave amplitudes. The paramaters (mass, total and partial widths, signs of coupling constants) of sixteen resonances, among which two new ones, are determined by two different methods. Those results help in classifying the lower-mass excited states of the nucleon in the frame of unitary symmetries, as SU6 [fr

  15. Efficient C-O and C-N bond forming cross-coupling reactions catalyzed by core-shell structured Cu/Cu2O nanowires

    KAUST Repository

    Elshewy, Ahmed M.

    2013-01-01

    linkages in organic molecules. Despite significant advancements in this field, the construction of C-O and C–N bonds is still a major challenge for organic chemists, due to the involvement of harsh reaction conditions or the use of expensive catalysts

  16. A study into Stille cross-coupling reaction mediated by palladium catalysts deposited over siliceous supports bearing N-donor groups at the surface

    Czech Academy of Sciences Publication Activity Database

    Semler, M.; Čejka, Jiří; Štěpnička, P.

    2013-01-01

    Roč. 27, č. 6 (2013), s. 353-360 ISSN 0268-2605 R&D Projects: GA ČR GA104/09/0561 Institutional support: RVO:61388955 Keywords : palladium * suppoerted catalysts * Stille reaction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.017, year: 2013

  17. Palladium-catalyzed aerobic regio- and stereo-selective olefination reactions of phenols and acrylates via direct dehydrogenative C(sp2)-O cross-coupling.

    Science.gov (United States)

    Wu, Yun-Bin; Xie, Dan; Zang, Zhong-Lin; Zhou, Cheng-He; Cai, Gui-Xin

    2018-04-26

    An efficient olefination protocol for the oxidative dehydrogenation of phenols and acrylates has been achieved using a palladium catalyst and O2 as the sole oxidant. This reaction exhibits high regio- and stereo-selectivity (E-isomers) with moderate to excellent isolated yields and a wide substrate scope (32 examples) including ethyl vinyl ketone and endofolliculina.

  18. Coupling between reactions and transport for the modelling and simulation of CO{sub 2} geological storage; Couplage reactions-transport pour la modelisation et la simulation du stockage geologique de CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Tillier, E

    2007-09-15

    In this work, we present some results about the coupling between transport and geochemistry for the modelling and the simulation of CO{sub 2} geological storage. We present a multiphase flow model and a geochemical model which enables to describe a coupled reactive multiphase flow problem. We then propose two methods of resolution, the first one is a global method, the other one is a splitting method which is used at the IFP in the software COORES. The splitting is based on physical assumptions. The coupling method used is a non iterative method, in which the splitting error is corrected by adding a penalization term. A convergence study shows that this scheme converges to the same solution as the global scheme. A part of this PhD is dedicated to diffusion and dispersion phenomena. We are interested in this term because it cannot be integrated easily in a splitting scheme, if the reactive transport is solved locally (which is necessary to use local time-step). After having highlighted the importance of this term on a representative test case, we show some difficulties encountered to integrate it in a splitting scheme. Finally, we study a miscible multiphase flow problem in 1D from a mathematical point of view. The difficulties arise with the non linearity due to the non zero gas solubility in water. We propose a definition for the weak solution of this problem and its existence is shown thanks to the convergence of a finite volume scheme. (O.M.)

  19. Inclusive Σp and pp reactions. How can one learn the nature of π, K, Λ, N exchanges and determine the coupling constants

    International Nuclear Information System (INIS)

    Vasylev, A.M.; Ginzburg, I.F.; Perlovskij, L.I.

    1977-01-01

    Inclusive experiments pp → π + +..., Σp → Λ +..., pp → K + +... are proposed in which it is possible to come very close to the π, K, N, Λ poles. In these experiments it is possible, in principle, to extract the most precise values of the coupling constants KNY, Σ π Λ,... and to state the problem which is the nature of the exchanges. A critical analysis of the pp → π + + ... data is carried out

  20. Efficient C-O and C-N bond forming cross-coupling reactions catalyzed by core-shell structured Cu/Cu2O nanowires

    KAUST Repository

    Elshewy, Ahmed M.

    2013-12-01

    Oxygen and Nitrogen containing compounds are of utmost importance due to their interesting and diverse biological activities. The construction of the C-O and C–N bonds is of significance as it opens avenues for the introduction of ether and amine linkages in organic molecules. Despite significant advancements in this field, the construction of C-O and C–N bonds is still a major challenge for organic chemists, due to the involvement of harsh reaction conditions or the use of expensive catalysts or ligands in many cases. Thus, it is a challenge to develop alternative, milder, cheaper and more reproducible methodologies for the construction of these types of bonds. Herein, we introduce a new efficient ligand free catalytic system for C-O and C-N bond formation reactions.

  1. Oxidative C-H/C-H Cross-Coupling Reactions between N-Acylanilines and Benzamides Enabled by a Cp*-Free RhCl3/TFA Catalytic System.

    Science.gov (United States)

    You, Jingsong; Shi, Yang; Zhang, Luoqiang; Lan, Jingbo; Zhang, Min; Zhou, Fulin; Wei, Wenlong

    2018-06-03

    Using the dual chelation-assisted strategy, a completely regiocontrolled oxidative C-H/C-H cross-coupling reaction between an N-acylaniline and a benzamide has been accomplished for the first time, which enables a step-economical and highly efficient pathway to 2-amino-2'-carboxybiaryl scaffolds from readily available substrates. A Cp*-free RhCl3/TFA catalytic system has been developed to replace the generally used [Cp*RhCl2]2/AgSbF6 (Cp* = pentamethyl cyclopentadienyl) in oxidative C-H/C-H cross-coupling reactions between two (hetero)arenes. The RhCl3/TFA system avoids the use of expensive Cp* ligand and AgSbF6. As an illustrative example, the protocol developed herein greatly streamlines access to naturally occurring benzo[c]phenanthridine alkaloid oxynitidine in an excellent overall yield. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Direct observation of dislocation dissociation and Suzuki segregation in a Mg–Zn–Y alloy by aberration-corrected scanning transmission electron microscopy

    International Nuclear Information System (INIS)

    Yang Zhiqing; Chisholm, Matthew F.; Duscher, Gerd; Ma Xiuliang; Pennycook, Stephen J.

    2013-01-01

    Crystal defects in a plastically deformed Mg–Zn–Y alloy have been studied on the atomic scale using aberration-corrected scanning transmission electron microscopy, providing important structural data for understanding the material’s deformation behavior and strengthening mechanisms. Atomic scale structures of deformation stacking faults resulting from dissociation of different types of dislocations have been characterized experimentally, and modeled. Suzuki segregation of Zn and Y along stacking faults formed through dislocation dissociation during plastic deformation at 300 °C is confirmed experimentally on the atomic level. The stacking fault energy of the Mg–Zn–Y alloy is evaluated to be in the range of 4.0–10.3 mJ m −2 . The newly formed nanometer-wide stacking faults with their Zn/Y segregation in Mg grains play an important role in the superior strength of this alloy at elevated temperatures.

  3. Role of self-assembly coated Er3+: YAlO3/TiO2 in intimate coupling of visible-light-responsive photocatalysis and biodegradation reactions

    International Nuclear Information System (INIS)

    Dong, Shanshan; Dong, Shuangshi; Tian, Xiadi; Xu, Zhengxue; Ma, Dongmei; Cui, Bin; Ren, Nanqi; Rittmann, Bruce E.

    2016-01-01

    Highlights: • First study on intimate coupling of photocatalysis & biodegradation by visible light. • Self-assembly was used to coat Er 3+ : YAlO 3 /TiO 2 on the sponge carriers. • Fewer accumulated intermediates & higher phenol removal for VPCB than VPC or B alone. • Self-regulation in VPCB contributes to the high degradation efficiency. - Abstract: Conventionally used ultraviolet light can result in dissolved organic carbon (DOC) increasing and biofilm damage in intimate coupling of photocatalysis and biodegradation (ICPB). Visible-light-responsive photocatalysis offers an alternative for achieving ICPB. In this study, composite-cubes were developed using self-assembly to coat a thin and even layer of visible-light-responsive photocatalyst (Er 3+ : YAlO 3 /TiO 2 ) on sponge-type carriers, followed by biofilm cultivation. The degradations of phenol (50 mg L −1 ) were compared for four protocols in circulating beds: adsorption (AD), visible-light-responsive photocatalysis (VPC), biodegradation (B), and intimately coupled visible-light-responsive photocatalysis and biodegradation (VPCB). The phenol and DOC removal efficiencies using VPCB in 16 h were 99.8% and 65.2%, respectively, i.e., higher than those achieved using VPC (71.6% and 50.0%) or B (99.4% and 58.2%). The phenol removal of 96.3% could be obtained even after 3 additional cycles. The 6.17-min intermediate detected by HPLC, continuously accumulated for VPC, appeared at 1–6 h and then was completely removed for VPCB in 10 h. ICPB was further illustrated in that most of the biofilm was protected in the carrier interiors, with less protection on the carrier exterior in VPCB. A self-regulation mechanism that helped photocatalyst exposure to visible-light irradiation was identified, promoting the combined photocatalysis and biodegradation.

  4. Mo-II Cluster Complex-Based Coordination Polymer as an Efficient Heterogeneous Catalyst in the Suzuki–Miyaura Coupling Reaction

    Czech Academy of Sciences Publication Activity Database

    Bůžek, Daniel; Hynek, Jan; Kučeráková, Monika; Kirakci, Kaplan; Demel, Jan; Lang, Kamil

    2016-01-01

    Roč. 2016, č. 28 (2016), s. 4668-4673 ISSN 1434-1948 R&D Projects: GA ČR GA13-05114S; GA ČR GA15-12653S EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:61388980 ; RVO:68378271 Keywords : C–C coupling * Heterogeneous catalysis * Molybdenum * Palladium * Polymers Subject RIV: CA - Inorganic Chemistry ; CF - Physical ; Theoretical Chemistry (FZU-D) Impact factor: 2.444, year: 2016

  5. Liquid-liquid transfer phenomena studies coupled with redox reactions: back-extraction of nitrous acid in the presence of scavengers in aqueous phase

    International Nuclear Information System (INIS)

    K'zerho, R.

    1998-01-01

    This work deals with the investigation of redox reaction contribution to the kinetics of liquid-liquid transfer, in relation with PUREX reprocessing of spent nuclear fuel. The chemical system chosen concerns the tripping of nitrous acid from tributylphosphate organic phase into a nitric acid aqueous solution containing an 'anti-nitrous' component, namely hydrazinium nitrate. According to the abundant literature, a major attention is devoted to the very important role of interfacial phenomena on the kinetics of solvent extraction with tributylphosphate. Although, a suitable experimental technique is chosen, using a constant interfacial area cell of the ARMOLLEX-type. Furthermore, the effects of the hydrodynamical and the physico-chemical parameters on the extraction rate led to the identification of the extraction regime nature: diffusional, then chemical limitation. When no 'anti-nitrous' component is used, the diffusional resistance is found to be mainly located in the aqueous diffusion layer. The presence of hydrazinium nitrate into the aqueous solution has an overall accelerating effect on the rate of extraction, related to both a complete suppression of the aqueous diffusional resistance, and a very significant enhancement of the interfacial transfer of the nitrous acid, as a function of hydrazinium concentration. If the first effect could be expected because of the well known fast redox reaction in aqueous phase, the second phenomenon represents a quite original and new result which has never been explored before, to the best of our knowledge. A reaction mechanism is postulated and validated, taking into account the reactive effect of hydrazinium on the interfacial step. In order to support the drawn general patterns, different complementary studies were attempted. When hydroxyl-ammonium nitrate is used, a surprising interfacial transfer blockage is observed, pointing out the extreme performance and specificity of the common hydrazinium component. (author)

  6. Direct production of D-arabinose from D-xylose by a coupling reaction using D-xylose isomerase, D-tagatose 3-epimerase and D-arabinose isomerase.

    Science.gov (United States)

    Sultana, Ishrat; Mizanur, Rahman Md; Takeshita, Kei; Takada, Goro; Izumori, Ken

    2003-01-01

    Klebsiella pneumoniae 40bXX, a mutant strain that constitutively produces D-arabinose isomerase (D-AI), was isolated through a series of repeated subcultures from the parent strain on a mineral salt medium supplemented with L-Xylose as the sole carbon source. D-AI could be efficiently immobilized on chitopearl beads. The optimum temperature for the activity of the immobilized enzyme was 40 degrees C and the enzyme was stable up to 50 degrees C. The D-Al was active at pH 10.0 and was stable in the range of pH 6.0-11.0. The enzyme required manganese ions for maximum activity. Three immobilized enzymes, D-xylose isomerase (D-XI), D-tagatose 3-epimerase (D-TE and D-AI were used for the preparation of D-arabinose from D-xylose in a coupling reaction. After completion of the reaction, degradation of D-xylulose was carried out by Saccharomyces cerevisiae. The reaction mixture containing D-Xylose, D-ribulose and the product was then separated by ion exchange column chromatography. After crystallization, the product was checked by HPLC, IR spectroscopy, NMR spectroscopy and optical rotation measurements. Finally, 2.0 g of D-arabinose could be obtained from 5 g of the substrate.

  7. Selective extraction by dissolvable (nitriloacetic acid-nickel)-layered double hydroxide coupled with reaction with potassium thiocyanate for sensitive detection of iron(III).

    Science.gov (United States)

    Tang, Sheng; Chang, Yuepeng; Shen, Wei; Lee, Hian Kee

    2016-07-01

    A highly selective method has been proposed for the determination of iron cation (Fe(3+)). (Nitriloacetic acid-nickel)-layered double hydroxide ((NTA-Ni)-LDH) was successfully synthesized and used as dissolvable sorbent in dispersive solid-phase extraction to pre-concentrate and separate Fe(3+) from aqueous phase. Since Fe(3+) has a larger formation constant with NTA compared to Ni(2+), subsequently ion exchange occurred when (NTA-Ni)-LDH was added to the sample solution. The resultant (NTA-Fe)-LDH sol was isolated and transferred in an acidic medium containing potassium thiocyanate (KSCN). Since (NTA-Fe)-LDH could be dissolved in acidic conditions, Fe(3+)was released and reacted with SCN(-) to form an Fe-SCN complex. The resulting product was measured by ultraviolet-visible spectrometry for quantitative detection of Fe(3+). Extraction factors, including sample pH, reaction pH, extraction temperature, extraction time, reaction time and concentration of KSCN were optimized. This method achieved a low limit of detection of 15.2nM and a good linear range from 0.05 to 50μM (r(2)=0.9937). A nearly 18-fold enhancement of signal intensity was achieved after selective extraction. The optimized conditions were validated by applying the method to determine Fe(3+) in seawater samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system

    International Nuclear Information System (INIS)

    Marty, N.

    2006-11-01

    The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

  9. Rhodium-Catalyzed Dehydrogenative Borylation of Cyclic Alkenes

    Science.gov (United States)

    Kondoh, Azusa; Jamison, Timothy F.

    2010-01-01

    A rhodium-catalyzed dehydrogenative borylation of cyclic alkenes is described. This reaction provides direct access to cyclic 1-alkenylboronic acid pinacol esters, useful intermediates in organic synthesis. Suzuki-Miyaura cross-coupling applications are also presented. PMID:20107646

  10. The $e^+ e^- \\to Z\\gamma\\gamma \\to q\\overline{q}\\gamma\\gamma$ Reaction at LEP and Constraints on Anomalous Quartic Gauge Boson Couplings

    CERN Document Server

    Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, Michael; Doria, A; Dova, M T; Duchesneau, D; Echenard, B; Eline, A; El-Mamouni, H; Engler, A; Eppling, F J; Ewers, A; Extermann, Pierre; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hakobyan, R S; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Latt, J; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Palomares, C; Pandoulas, D; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R P; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wallraff, W; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M

    2002-01-01

    The cross section of the process e^+ e^- -> Z \\gamma\\gamma -> qq~ \\gamma \\gamma is measured with 215 pb^-1 of data collected with the L3 detector during the final LEP run at centre-of-mass energies around 205 GeV and 207 GeV. No deviation from the Standard Model expectation is observed. The full data sample of 713 pb^-1, collected above the Z resonance, is used to constrain the coefficients of anomalous quartic gauge boson couplings to: -0.02 GeV^-2 < a_0/\\Lambda^2 < 0.03 GeV^-2 and -0.07 GeV^-2 < a_c/\\Lambda^2 < 0.05 GeV^-2, at 95% confidence level.

  11. Synthesis and characterization of para-pyridine linked NHC palladium complexes and their studies for the Heck-Mizoroki coupling reaction.

    Science.gov (United States)

    Liu, Ya-Ming; Lin, Yi-Chun; Chen, Wen-Ching; Cheng, Jen-Hao; Chen, Yi-Lin; Yap, Glenn P A; Sun, Shih-Sheng; Ong, Tiow-Gan

    2012-06-28

    This paper describes the synthesis of 1-(pyridine-4-ylmethyl) NHC and their Pd(II) and Ag(I) complexes, which are fully characterized. Interestingly, we have also synthesized a Pd complex 3a-CO(3) using a more direct treatment of K(2)CO(3) with PdCl(2). 3a-CO(3) represents the first reported solid structure of a Pd η(2)-carbonato complex stabilized by an NHC framework. 3a-CO(3) can be easily converted to a PdCl(2) derivative by treating it with chloroform. We have found these palladium complexes mediate the Heck-Mizoroki coupling with a low catalyst loading. Furthermore, we also expand such catalytic manifold toward constructing fused polyaromatic substrates, a highly useful class of compounds in optoelectronic chemistry.

  12. Coupled channel analysis of the 142Ce (α,α)142Ce* reaction: study of a vibrational-rotational transition nucleus

    International Nuclear Information System (INIS)

    Appoloni, C.R.

    1983-01-01

    The angular distribution of the elastic and inelastic scattering of a particles corresponding to the excitation of the low-lying collective states of 142 Ce were measured at an incident energy of 18.0 MeV. The angular distribution of the following excited states were obtained: 641, 1.219, 1.450, 1.536, 1.653, 1.742, 2.004, 2.043, 2.114, 2.125, 2.279, 2.364, 2.542, 2.604 e 3.067 MeV. The angular distributions of the ground state and the first six excited states were analysed within the flamework of the Anharmonic Vibrational and Symmetric Rotational Models, with the Coupled Channel Theory. The Anharmonic Vibrational Model gave the best and most complete description of the experimental data. The wave functions and the deformation parameters of the analysed states were determined. (Author) [pt

  13. Dealing with chemical reaction pathways and electronic excitations in molecular systems via renormalized and active-space coupled-cluster methods

    Energy Technology Data Exchange (ETDEWEB)

    Piecuch, Piotr; Li, Wei; Lutz, Jesse J. [Department of Chemistry, Michigan State University, East Lansing, MI 48824 (United States); Włoch, Marta [Department of Chemistry, Michigan Technological University, Houghton, Michigan 49931 (United States); Gour, Jeffrey R. [Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA and Department of Chemistry, Stanford University, Stanford, California 94305 (United States)

    2015-01-22

    Coupled-cluster (CC) theory has become the de facto standard for high-accuracy molecular calculations, but the widely used CC and equation-of-motion (EOM) CC approaches, such as CCSD(T) and EOMCCSD, have difficulties with capturing stronger electron correlations that characterize multi-reference molecular problems. This presentation demonstrates that many of these difficulties can be addressed by exploiting the completely renormalized (CR) CC and EOMCC approaches, such as CR-CC(2,3), CR-EOMCCSD(T), and CR-EOMCC(2,3), and their local correlation counterparts applicable to systems with hundreds of atoms, and the active-space CC/EOMCC approaches, such as CCSDt and EOMCCSDt, and their extensions to valence systems via the electron-attached and ionized formalisms.

  14. Determination of (90)Sr in soil samples using inductively coupled plasma mass spectrometry equipped with dynamic reaction cell (ICP-DRC-MS).

    Science.gov (United States)

    Feuerstein, J; Boulyga, S F; Galler, P; Stingeder, G; Prohaska, T

    2008-11-01

    A rapid method is reported for the determination of (90)Sr in contaminated soil samples in the vicinity of the Chernobyl Nuclear Power Plant by ICP-DRC-MS. Sample preparation and measurement procedures focus on overcoming the isobaric interference of (90)Zr, which is present in soils at concentrations higher by more than six orders of magnitude than (90)Sr. Zirconium was separated from strontium in two steps to reduce the interference by (90)Zr(+) ions by a factor of more than 10(7): (i) by ion exchange using a Sr-specific resin and (ii) by reaction with oxygen as reaction gas in a dynamic reaction cell (DRC) of a quadrupole ICP-MS. The relative abundance sensitivity of the ICP-MS was studied systematically and the peak tailing originating from (88)Sr on mass 90 u was found to be about 3 x 10(-9). Detection limits of 4 fg g(-1) (0.02 Bq g(-1)) were achieved when measuring Sr solutions containing no Zr. In digested uncontaminated soil samples after matrix separation as well as in a solution of 5 microg g(-1) Sr and 50 ng g(-1) Zr a detection limit of 0.2 pg g(-1) soil (1 Bq g(-1) soil) was determined. (90)Sr concentrations in three soil samples collected in the vicinity of the Chernobyl Nuclear Power Plant were 4.66+/-0.27, 13.48+/-0.68 and 12.9+/-1.5 pg g(-1) corresponding to specific activities of 23.7+/-1.3, 68.6+/-3.5 and 65.6+/-7.8 Bq g(-1), respectively. The ICP-DRC-MS results were compared to the activities measured earlier by radiometry. Although the ICP-DRC-MS is inferior to commonly used radiometric methods with respect to the achievable minimum detectable activity it represents a time- and cost-effective alternative technique for fast monitoring of high-level (90)Sr contamination in environmental or nuclear industrial samples down to activities of about 1 Bq g(-1).

  15. Determination of 90Sr in soil samples using inductively coupled plasma mass spectrometry equipped with dynamic reaction cell (ICP-DRC-MS)

    International Nuclear Information System (INIS)

    Feuerstein, J.; Boulyga, S.F.; Galler, P.; Stingeder, G.; Prohaska, T.

    2008-01-01

    A rapid method is reported for the determination of 90 Sr in contaminated soil samples in the vicinity of the Chernobyl Nuclear Power Plant by ICP-DRC-MS. Sample preparation and measurement procedures focus on overcoming the isobaric interference of 90 Zr, which is present in soils at concentrations higher by more than six orders of magnitude than 90 Sr. Zirconium was separated from strontium in two steps to reduce the interference by 90 Zr + ions by a factor of more than 10 7 : (i) by ion exchange using a Sr-specific resin and (ii) by reaction with oxygen as reaction gas in a dynamic reaction cell (DRC) of a quadrupole ICP-MS. The relative abundance sensitivity of the ICP-MS was studied systematically and the peak tailing originating from 88 Sr on mass 90 u was found to be about 3 x 10 -9 . Detection limits of 4 fg g -1 (0.02 Bq g -1 ) were achieved when measuring Sr solutions containing no Zr. In digested uncontaminated soil samples after matrix separation as well as in a solution of 5 μg g -1 Sr and 50 ng g -1 Zr a detection limit of 0.2 pg g -1 soil (1 Bq g -1 soil) was determined. 90 Sr concentrations in three soil samples collected in the vicinity of the Chernobyl Nuclear Power Plant were 4.66 ± 0.27, 13.48 ± 0.68 and 12.9 ± 1.5 pg g -1 corresponding to specific activities of 23.7 ± 1.3, 68.6 ± 3.5 and 65.6 ± 7.8 Bq g -1 , respectively. The ICP-DRC-MS results were compared to the activities measured earlier by radiometry. Although the ICP-DRC-MS is inferior to commonly used radiometric methods with respect to the achievable minimum detectable activity it represents a time- and cost-effective alternative technique for fast monitoring of high-level 90 Sr contamination in environmental or nuclear industrial samples down to activities of about 1 Bq g -1

  16. Determination of {sup 90}Sr in soil samples using inductively coupled plasma mass spectrometry equipped with dynamic reaction cell (ICP-DRC-MS)

    Energy Technology Data Exchange (ETDEWEB)

    Feuerstein, J.; Boulyga, S.F.; Galler, P.; Stingeder, G. [Department of Chemistry, Division of Analytical Chemistry-VIRIS Laboratory, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna (Austria); Prohaska, T. [Department of Chemistry, Division of Analytical Chemistry-VIRIS Laboratory, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna (Austria)], E-mail: thomas.prohaska@boku.ac.at

    2008-11-15

    A rapid method is reported for the determination of {sup 90}Sr in contaminated soil samples in the vicinity of the Chernobyl Nuclear Power Plant by ICP-DRC-MS. Sample preparation and measurement procedures focus on overcoming the isobaric interference of {sup 90}Zr, which is present in soils at concentrations higher by more than six orders of magnitude than {sup 90}Sr. Zirconium was separated from strontium in two steps to reduce the interference by {sup 90}Zr{sup +} ions by a factor of more than 10{sup 7}: (i) by ion exchange using a Sr-specific resin and (ii) by reaction with oxygen as reaction gas in a dynamic reaction cell (DRC) of a quadrupole ICP-MS. The relative abundance sensitivity of the ICP-MS was studied systematically and the peak tailing originating from {sup 88}Sr on mass 90 u was found to be about 3 x 10{sup -9}. Detection limits of 4 fg g{sup -1} (0.02 Bq g{sup -1}) were achieved when measuring Sr solutions containing no Zr. In digested uncontaminated soil samples after matrix separation as well as in a solution of 5 {mu}g g{sup -1} Sr and 50 ng g{sup -1} Zr a detection limit of 0.2 pg g{sup -1} soil (1 Bq g{sup -1} soil) was determined. {sup 90}Sr concentrations in three soil samples collected in the vicinity of the Chernobyl Nuclear Power Plant were 4.66 {+-} 0.27, 13.48 {+-} 0.68 and 12.9 {+-} 1.5 pg g{sup -1} corresponding to specific activities of 23.7 {+-} 1.3, 68.6 {+-} 3.5 and 65.6 {+-} 7.8 Bq g{sup -1}, respectively. The ICP-DRC-MS results were compared to the activities measured earlier by radiometry. Although the ICP-DRC-MS is inferior to commonly used radiometric methods with respect to the achievable minimum detectable activity it represents a time- and cost-effective alternative technique for fast monitoring of high-level {sup 90}Sr contamination in environmental or nuclear industrial samples down to activities of about 1 Bq g{sup -1}.

  17. Simultaneous determination of Cr(iii) and Cr(vi) using reversed-phased ion-pairing liquid chromatography with dynamic reaction cell inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Wolf, R.E.; Morrison, J.M.; Goldhaber, M.B.

    2007-01-01

    A method for the simultaneous determination of Cr(iii) and Cr(vi) species in waters, soil leachates and synthetic bio-fluids is described. The method uses reversed-phase ion-pairing liquid chromatography to separate the chromium species and a dynamic reaction cell (DRC??) equipped ICP-MS for detection of chromium. Separation of the chromium species is carried out in less than 2 min. Cr(iii) is complexed with ethylenediaminetetraacetic acid (EDTA) prior to separation by mixing samples with the mobile phase containing 2.0 mM tetrabutylammonium hydroxide (TBAOH), 0.5 mM EDTA (dipotassium salt), and 5% (vol/vol) methanol, adjusted to pH 7.6. The interfering 40Ar 12C+ background peak at mass 52 was reduced by over four orders of magnitude to less than 200 cps by using 0.65 mL min-1 ammonia as a reaction gas and an RPq setting on the DRC of 0.75. Method detection limits (MDLs) of 0.09 ??g L-1 for Cr(iii) and 0.06 ??g L-1 for Cr(vi) were obtained based on peak areas at mass 52 for 50 ??L injections of low level spikes. Reproducibility at 2 ??g L-1 was 3% RSD for 5 replicate injections. The tolerance of the method to various levels of common cations and anions found in natural waters and to matrix constituents found in soil leachates and simulated gastric and lung fluids was tested by performing spike recovery calculations for a variety of samples. ?? The Royal Society of Chemistry.

  18. Development of a method based on inductively coupled plasma-dynamic reaction cell-mass spectrometry for the simultaneous determination of phosphorus, calcium and strontium in bone and dental tissue

    International Nuclear Information System (INIS)

    De Muynck, David; Vanhaecke, Frank

    2009-01-01

    A method, based on the use of a quadrupole-based inductively coupled plasma-mass spectrometry instrument equipped with a quadrupole-based collision/reaction cell (dynamic reaction cell, DRC), was developed for the simultaneous determination of phosphorus, calcium and strontium in bone and dental (enamel and dentine) tissue. The use of NH 3 , introduced at a gas flow rate of 0.8 mL min -1 in the dynamic reaction cell, combined with a rejection parameter q (RPq) setting of 0.65, allows interference-free determination of calcium via its low-abundant isotopes 42 Ca, 43 Ca and 44 Ca, and of strontium via its isotopes 86 Sr and 88 Sr that are freed from overlap due to the occurrence of ArCa + and/or Ca 2 + ions. Also the determination of phosphorus ( 31 P, mono-isotopic) was shown to be achievable using the same dynamic reaction cell operating conditions. The bone certified reference materials NIST SRM 1400 Bone Ash and NIST SRM 1486 Bone Meal were used for validation of the measurement protocol that was shown capable of providing accurate and reproducible results. Detection limits of P, Ca and Sr in dental tissue digests were established as 3 μg L -1 for P, 2 μg L -1 for Ca and 0.2 μg L -1 for Sr. This method can be used to simultaneously (i) evaluate the impact of diagenesis on the elemental and isotopic composition of buried skeletal tissue via its Ca/P ratio and (ii) determine its Sr concentration. The measurement protocol was demonstrated as fit-for-purpose by the analysis of a set of teeth of archaeological interest for their Ca/P ratio and Sr concentration.

  19. New analytical methods for materials characterization using the techniques of nuclear activation reactions induced by thermal neutrons and accelerated ion beams, coupled to gamma-ray spectroscopy

    International Nuclear Information System (INIS)

    Cincu, Emanuela

    1999-01-01

    This thesis is a comprehensive collection of the author's works in the field of 'Nuclear Activation Techniques with accelerated Charged Particles and Thermal Neutrons' carried out within the framework of the research contracts the author initiated and performed in the period 1990 - 1999. The works objective was to achieve a consistent and complete methodological and instrumental assembly for accurate elemental analysis of technological samples of interest for industry, medicine, and monitoring of the environmental radioactivity. The experiments were carried out using the IFIN-HH facilities: U-120 Cyclotron, 8 MV Tandem Van de Graaff accelerator, and the WWR-S nuclear reactor. Part of the reported works were initiated and performed in collaboration with partners from the chemical industry and metallurgic industry, wishing to employ the sensitive nuclear analytical techniques, which are able to put in evidence simultaneously major, minor elements, and impurities in the investigated samples. The impact with the challenging topics and the characteristics of some investigated technological samples, generated the studies having both theoretical and experimental features, presented in this thesis, as well as the original analytical and methodological solutions. The thesis structure has two parts: The 1st part (Chapter 1) is a survey of the literature until 1999, that concerns the theory of nuclear activation reactions with accelerated charged particles (CPAA) and thermal neutrons (NAA), evidencing the analytical performance of both techniques; details are also given about the 'critical' phenomena encountered in CPAA, whose origin is still under discussion in the literature. The 2 nd part of the thesis contains the original contributions of the author in the theoretical, methodological, and software fields (Chapters 2-8), the experimental results obtained, and the nuclear database software based on the 'Fox-Pro' operation system, conceived for processing the experimental

  20. Synthetic and mechanistic study of oxycarbene-like coupling reaction patterns of actinide eta2-acyl complexes with carbon monoxide and isocyanides

    International Nuclear Information System (INIS)

    Moloy, K.G.; Fagan, P.J.; Manriquez, J.M.; Marks, T.J.

    1986-01-01

    This contribution reports the synthesis and characterization of the ylide complexes Cp' 2 Th[OC(CH 2 -t-Bu)C-(PR 3 )O[(Cl) (Cp' = eta 5 -C 5 Me 5 ; R = Me, Ph) formed by the carbonylation of Cp' 2 Th(Cl)(eta 2 -COCH 2 -t-Bu) (1) in the presence of phosphines. Isotopic tracer studies with 13 CO indicate that the labeled carbon atom is incorporated regiospecifically at the ylide α-carbon atom position. The carbonylation of 1 to yield the enedionediolate (Cp' 2 Th[OC(CH 2 -t-Bu)CO](Cl)] 2 (2) or the ylide complexes was found to obey a second-order rate law where rate = kP/sub CO/[1]; k = 1.50 (5) x 10 -5 min -1 torr -1 for both carbonylations at 30.8 0 C. The rate of formation of the ylide complexes was also found to be independent of solvent, phosphine concentration, and type of phosphine used. The carbonylation of 1 is therefore inferred to involve a rate-determining coupling of CO with the acyl to yield an intermediate ketene or ketene-like complex. 51 references, 4 figures, 3 tables

  1. Beyond Born-Oppenheimer theory for ab initio constructed diabatic potential energy surfaces of singlet H3+ to study reaction dynamics using coupled 3D time-dependent wave-packet approach.

    Science.gov (United States)

    Ghosh, Sandip; Mukherjee, Saikat; Mukherjee, Bijit; Mandal, Souvik; Sharma, Rahul; Chaudhury, Pinaki; Adhikari, Satrajit

    2017-08-21

    The workability of beyond Born-Oppenheimer theory to construct diabatic potential energy surfaces (PESs) of a charge transfer atom-diatom collision process has been explored by performing scattering calculations to extract accurate integral cross sections (ICSs) and rate constants for comparison with most recent experimental quantities. We calculate non-adiabatic coupling terms among the lowest three singlet states of H 3 + system (1 1 A ' , 2 1 A ' , and 3 1 A ' ) using MRCI level of calculation and solve the adiabatic-diabatic transformation equation to formulate the diabatic Hamiltonian matrix of the same process [S. Mukherjee et al., J. Chem. Phys. 141, 204306 (2014)] for the entire region of nuclear configuration space. The nonadiabatic effects in the D + + H 2 reaction has been studied by implementing the coupled 3D time-dependent wave packet formalism in hyperspherical coordinates [S. Adhikari and A. J. C. Varandas, Comput. Phys. Commun. 184, 270 (2013)] with zero and non-zero total angular momentum (J) on such newly constructed accurate (ab initio) diabatic PESs of H 3 + . We have depicted the convergence profiles of reaction probabilities for the reactive non-charge transfer, non-reactive charge transfer, and reactive charge transfer processes for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. Finally, total and state-to-state ICSs are calculated as a function of collision energy for the initial rovibrational state (v = 0, j = 0) of the H 2 molecule, and consequently, those quantities are compared with previous theoretical and experimental results.

  2. A new, fully coupled, reaction-transport-mechanical approach to modeling the evolution of natural gas reservoirs in the Piceance Basin

    Science.gov (United States)

    Payne, Dorothy Frances

    The Piceance Basin is highly compartmented, and predicting the location and characteristics of producible reservoirs is difficult. Gas generation is an important consideration in quality and size of natural gas reserves, but it also may contribute to fracturing, and hence the creation of the reservoirs in which it is contained. The purpose of this dissertation is to use numerical modeling to study the evolution of these unconventional natural gas reservoirs in the Piceance Basin. In order to characterize the scale and structure of compartmentation in the Piceance Basin, a set of in-situ fluid pressure data were interpolated across the basin and the resulting fluid pressure distribution was analyzed. Results show complex basin- and field-scale compartmentation in the Upper Cretaceous units. There are no simple correlations between compartment location and such factors as stratigraphy, basin structure, or coal thickness and maturity. To account for gas generation in the Piceance Basin, a new chemical kinetic approach to modeling lignin maturation is developed, based primarily on structural transformations of the lignin molecule observed in naturally matured samples. This model calculates mole fractions of all species, functional group fractions, and elemental weight percents. Results show reasonable prediction of maturities at other sites in the Piceance Basin for vitrinite reflectance up to about 1.7 %Ro. The flexible design of the model allows it to be modified to account for compositionally heterogeneous source material. To evaluate the role of gas generation in this dynamical system, one-dimensional simulations have been performed using the CIRFB reaction-transport-mechanical (RTM) simulator. CIRFB accounts for compaction, fracturing, hydrocarbon generation, and multi-phase flow. These results suggest that by contributing to overpressure, gas generation has two important implications: (1) gas saturation in one unit affects fracturing in other units, thereby

  3. Determination of low concentrations of iron, arsenic, selenium, cadmium, and other trace elements in natural samples using an octopole collision/reaction cell equipped quadrupole-inductively coupled plasma mass spectrometer.

    Science.gov (United States)

    Dial, Angela R; Misra, Sambuddha; Landing, William M

    2015-04-30

    Accurate determination of trace metals has many applications in environmental and life sciences, such as constraining the cycling of essential micronutrients in biological production and employing trace metals as tracers for anthropogenic pollution. Analysis of elements such as Fe, As, Se, and Cd is challenged by the formation of polyatomic mass spectrometric interferences, which are overcome in this study. We utilized an Octopole Collision/Reaction Cell (CRC)-equipped Quadrupole-Inductively Coupled Plasma Mass Spectrometer for the rapid analysis of small volume samples (~250 μL) in a variety of matrices containing HNO3 and/or HCl. Efficient elimination of polyatomic interferences was demonstrated by the use of the CRC in Reaction Mode (RM; H2 gas) and in Collision-Reaction Mode (CRM; H2 and He gas), in addition to hot plasma (RF power 1500 W) and cool plasma (600 W) conditions. It was found that cool plasma conditions with RM achieved the greatest signal sensitivity while maintaining low detection limits (i.e. (56) Fe in 0.44 M HNO3 has a sensitivity of 160,000 counts per second (cps)-per-1 µg L(-1) and a limit of detection (LoD) of 0.86 ng L(-1) ). The average external precision was ≤ ~10% for minor (≤10 µg L(-1) ) elements measured in a 1:100 dilution of NIST 1643e and for iron in rainwater samples under all instrumental operating conditions. An improved method has been demonstrated for the rapid multi-element analysis of trace metals that are challenged by polyatomic mass spectrometric interferences, with a focus on (56) Fe, (75) As, (78) Se and (111) Cd. This method can contribute to aqueous environmental geochemistry and chemical oceanography, as well as other fields such as forensic chemistry, agriculture, food chemistry, and pharmaceutical sciences. Copyright © 2015 John Wiley & Sons, Ltd.

  4. Studies of the thermal dissolution process of the Suzuki phase of the Eu2+ ion in KBr single crystals by analysis of photoacoustic signals

    International Nuclear Information System (INIS)

    MejIa-Uriarte, E V; Castaneda-Guzman, R; Villagran-Muniz, M; Camarillo, E; A, J Hernandez; S, H Murrieta; Navarrete, M

    2003-01-01

    An experimental investigation of the thermal behaviour of the dissolution process of the Suzuki phase (SP) by continuous heating (1 deg. C min -1 ) of KBr:Eu 2+ crystals is reported in this work. The thermal profiles were determined by the correlation functions between subsequent photoacoustic (PA) signals registered during the dissolution process. The behaviour of the thermal profile is directly related to the absorption coefficient of the Eu 2+ ion in precipitated states that are present in the crystal. The PA signal is detected as a consequence of the non-radiative processes that take place after the excitation of the low-energy band of the Eu 2+ ion by means of a focused laser pulse at 355 nm. The results obtained by this method are compared with those simultaneously obtained by the photoluminescence (PL) technique. The samples were heated from room temperature to 205 deg. C. The PA signal and PL spectrum were obtained every 6 deg. C. The temperature range of the SP dissolution process was from 77 to 115 deg. C. These results are in agreement with those obtained by the PL technique and with the data reported in the literature

  5. Action-Perception Coupling in Violinists

    Directory of Open Access Journals (Sweden)

    Lauren eStewart

    2013-07-01

    Full Text Available The current study investigates auditory-motor coupling in musically trained participants using a Stroop-type task that required the execution of simple finger sequences according to aurally presented number sequences (e.g. ‘2’, ‘4’, ‘5’, ‘3’, ‘1’. Digital remastering was used to manipulate the pitch contour of the number sequences such that they were either congruent or incongruent with respect to the resulting action sequence. Conservatoire-level violinists showed a strong effect of congruency manipulation (increased response time for incongruent versus congruent trials, in comparison to a control group of non-musicians. In experiment 2, this paradigm was used to determine whether pedagogical background would influence this effect in a group of young violinists. Suzuki trained violinists differed significantly from those with no musical background, while traditionally trained violinists did not. The findings extend previous research in this area by demonstrating that obligatory audio-motor coupling is directly related to a musicians’ expertise on their instrument of study and is influenced by pedagogy.

  6. Optimization of collision/reaction gases for determination of 90Sr in atmospheric particulate matter by inductively coupled plasma tandem mass spectrometry after direct introduction of air via a gas-exchange device

    Science.gov (United States)

    Suzuki, Yoshinari; Ohara, Ryota; Matsunaga, Kirara

    2017-09-01

    Nuclear power plant accidents release radioactive strontium 90 (90Sr) into the environment. Monitoring of 90Sr, although important, is difficult and time consuming because it emits only beta radiation. We have developed a new analytical system that enables real-time analysis of 90Sr in atmospheric particulate matter with an analytical run time of only 10 min. Briefly, after passage of an air sample through an impactor, a small fraction of the sample is introduced into a gas-exchange device, where the air is replaced by Ar. Then the sample is directly introduced into an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) system equipped with a collision/reaction cell to eliminate isobaric interferences on 90Sr from 90Zr+, 89Y1H+, and 90Y+. Experiments with various reaction gas conditions revealed that these interferences could be minimized under the following optimized conditions: 1.0 mL min- 1 O2, 10.0 mL min- 1 H2, and 1.0 mL min- 1 NH3. The estimated background equivalent concentration and estimated detection limit of the system were 9.7 × 10- 4 and 3.6 × 10- 4 ng m- 3, respectively, which are equivalent to 4.9 × 10- 6 and 1.8 × 10- 6 Bq cm- 3. Recoveries of Sr in PM2.5 measured by real-time analysis compared to those obtained by simultaneously collection on filter was 53 ± 23%, and using this recovery, the detection limit as PM2.5 was estimated to be 3.4 ± 1.5 × 10- 6 Bq cm- 3. That is, this system enabled detection of 90Sr at concentrations < 5 × 10- 6 Bq cm- 3 even considering the insufficient fusion/vaporization/ionization efficiency of Sr in PM2.5.

  7. Coupled diffusion systems with localized nonlinear reactions

    DEFF Research Database (Denmark)

    Pedersen, M.; Lin, Zhigui

    2001-01-01

    This paper deals with the blowup rate and profile near the blowup time for the system of diffusion equations uit - δui = ui+1Pi(x0, t), (i = 1,...,k, uk+1 := uu) in Ω × (0, T) with boundary conditions ui = 0 on ∂Ω × [0, T). We show that the solution has a global blowup. The exact rate...

  8. Extensive regularization of the coupled cluster methods based on the generating functional formalism: Application to gas-phase benchmarks and to the SN2 reaction of CHCl3 and OH- in water

    International Nuclear Information System (INIS)

    Kowalski, Karol; Valiev, Marat

    2009-01-01

    The recently introduced energy expansion based on the use of generating functional (GF) [K. Kowalski and P. D. Fan, J. Chem. Phys. 130, 084112 (2009)] provides a way of constructing size-consistent noniterative coupled cluster (CC) corrections in terms of moments of the CC equations. To take advantage of this expansion in a strongly interacting regime, the regularization of the cluster amplitudes is required in order to counteract the effect of excessive growth of the norm of the CC wave function. Although proven to be efficient, the previously discussed form of the regularization does not lead to rigorously size-consistent corrections. In this paper we address the issue of size-consistent regularization of the GF expansion by redefining the equations for the cluster amplitudes. The performance and basic features of proposed methodology are illustrated on several gas-phase benchmark systems. Moreover, the regularized GF approaches are combined with quantum mechanical molecular mechanics module and applied to describe the S N 2 reaction of CHCl 3 and OH - in aqueous solution.

  9. Ultra-trace determination of Strontium-90 in environmental soil samples from Qatar by collision/reaction cell-inductively coupled plasma mass spectrometry (CRC-ICP-MS/MS)

    Energy Technology Data Exchange (ETDEWEB)

    Al-Meer, S. H.; Amr, M. A. [Central Laboratories Unit, Qatar University, Doha (Qatar); Helal, A.I. [Atomic Energy Authority, Cairo (Egypt); Al-Kinani, A.T. [Minstery of Environment, Doha (Qatar)

    2013-07-01

    Because of the very low level of {sup 90}Sr in the environmental soil samples and its determination by beta counting may take several weeks, we developed a procedure for ultra-trace determination of {sup 90}Sr using collision reaction cell-inductively coupled plasma tandem mass spectrometry (CRC-ICP-MS/MS, Agilent 8800). Soil samples were dried at 105 deg. C and then heated in a furnace at 550 deg. C to remove any organics present. 500 g of each soil samples were aliquoted into 2000 ml glass beakers. Each Soils samples were soaked in 2 ppm Sr solution carrier to allow determination of chemical yield. The solid to liquid ratio was 1:1. Finally the soil samples were dried at 105 deg. C. Five hundred milliliters concentrated nitric acid and 250 ml hydrochloric acid volumes were added on 500 g soil samples. The samples were digested on hot plate at 80 deg. C to prevent spraying with continuous manual mixing. The leachate solution was separated. The solids were rinsed with 500 ml deionized water, warmed on a hot plate and the leachate plus previous leachate were filtered and the total volume was reduced to 500 ml by evaporation. Final leachate volume was transferred to a centrifuge tubes. The centrifuge tubes were centrifuged at 3,500 rpm for 10 min. The leachate was transferred to a 1 L beaker and heated on a hot plate to evaporate the leachate to dryness. The reside was re-dissolved in 100 ml of 2% HNO{sub 3} and reduced by evaporation to 10 mL. The solution was measured directly by CRC-ICP-MS/MS by setting the first quadruple analyzer to m/z 90 and introducing oxygen gas into the reaction cell for elimination isobar interference from zirconium-90. The method was validated by measurements of standard reference materials and applied on environmental soil samples. The overall time requirement for the measurement of strontium-90 by CRC-ICP-MS/MS is 2 days, significantly shorter than any radioanalytical protocol currently available. (authors)

  10. Vibronic coupling density and related concepts

    International Nuclear Information System (INIS)

    Sato, Tohru; Uejima, Motoyuki; Iwahara, Naoya; Haruta, Naoki; Shizu, Katsuyuki; Tanaka, Kazuyoshi

    2013-01-01

    Vibronic coupling density is derived from a general point of view as a one-electron property density. Related concepts as well as their applications are presented. Linear and nonlinear vibronic coupling density and related concepts, orbital vibronic coupling density, reduced vibronic coupling density, atomic vibronic coupling constant, and effective vibronic coupling density, illustrate the origin of vibronic couplings and enable us to design novel functional molecules or to elucidate chemical reactions. Transition dipole moment density is defined as an example of the one-electron property density. Vibronic coupling density and transition dipole moment density open a way to design light-emitting molecules with high efficiency.

  11. The Glaser–Hay reaction

    DEFF Research Database (Denmark)

    Vilhelmsen, Mie Højer; Jensen, Jonas; Tortzen, Christian

    2013-01-01

    The oxidative Glaser–Hay coupling of two terminal alkynes to furnish a butadiyne is a key reaction for acetylenic scaffolding. Although the reaction is performed under rather simple conditions [CuCl/TMEDA/O2 (air)], the mechanism is still under debate. Herein we present detailed studies...... on the scope of this reaction by using both 13C NMR and UV/Vis spectroscopic methods. The former method was used to study the kinetics of the coupling of aryl-substituted alkynes as the aryl carbon resonances of the reactants and products have similar NOEs and relaxation times. The reaction was found...... to be zero-order with respect to the terminal alkyne reactant under standard preparative conditions. Moreover, as the reaction proceeded, a clear change to slower reaction kinetics was observed, but it was still apparently zero-order. The onset of this change was found to depend on the catalyst loading...

  12. Sea-to-air flux of dimethyl sulfide in the South and North Pacific Ocean as measured by proton transfer reaction-mass spectrometry coupled with the gradient flux technique

    Science.gov (United States)

    Omori, Yuko; Tanimoto, Hiroshi; Inomata, Satoshi; Ikeda, Kohei; Iwata, Toru; Kameyama, Sohiko; Uematsu, Mitsuo; Gamo, Toshitaka; Ogawa, Hiroshi; Furuya, Ken

    2017-07-01

    Exchange of dimethyl sulfide (DMS) between the surface ocean and the lower atmosphere was examined by using proton transfer reaction-mass spectrometry coupled with the gradient flux (PTR-MS/GF) system. We deployed the PTR-MS/GF system and observed vertical gradients of atmospheric DMS just above the sea surface in the subtropical and transitional South Pacific Ocean and the subarctic North Pacific Ocean. In total, we obtained 370 in situ profiles, and of these we used 46 data sets to calculate the sea-to-air flux of DMS. The DMS flux determined was in the range from 1.9 to 31 μmol m-2 d-1 and increased with wind speed and biological activity, in reasonable accordance with previous observations in the open ocean. The gas transfer velocity of DMS derived from the PTR-MS/GF measurements was similar to either that of DMS determined by the eddy covariance technique or that of insoluble gases derived from the dual tracer experiments, depending on the observation sites located in different geographic regions. When atmospheric conditions were strongly stable during the daytime in the subtropical ocean, the PTR-MS/GF observations captured a daytime versus nighttime difference in DMS mixing ratios in the surface air overlying the ocean surface. The difference was mainly due to the sea-to-air DMS emissions and stable atmospheric conditions, thus affecting the gradient of DMS. This indicates that the DMS gradient is strongly controlled by diurnal variations in the vertical structure of the lower atmosphere above the ocean surface.

  13. Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling

    KAUST Repository

    Takanabe, Kazuhiro

    2012-01-01

    and the oxidative coupling of methane. These two reactions have tremendous technological significance for practical application in industry. An understanding of the fundamental aspects and reaction mechanisms of the catalytic reactions reviewed in this study would

  14. Nuclear reactions

    International Nuclear Information System (INIS)

    Lane, A.M.

    1980-01-01

    In reviewing work at Harwell over the past 25 years on nuclear reactions it is stated that a balance has to be struck in both experiment and theory between work on cross-sections of direct practical relevance to reactors and on those relevant to an overall understanding of reaction processes. The compound nucleus and direct process reactions are described. Having listed the contributions from AERE, Harwell to developments in nuclear reaction research in the period, work on the optical model, neutron capture theory, reactions at doorway states with fine structure, and sum-rules for spectroscopic factors are considered in more detail. (UK)

  15. Heavy ion transfer reactions

    International Nuclear Information System (INIS)

    Weisser, D.C.

    1977-06-01

    To complement discussions on the role of γ rays in heavy ion induced reactions, the author discusses the role played by particle detection. Transfer reactions are part of this subject and are among those in which one infers the properties of the residual nucleus in a reaction by observing the emerging light nucleus. Inelastic scattering ought not be excluded from this subject, although no particles are transferred, because of the role it plays in multistep reactions and in fixing O.M. parameters describing the entrance channel of the reaction. Heavy ion transfer reaction studies have been under study for some years and yet this research is still in its infancy. The experimental techniques are difficult and the demands on theory rigorous. One of the main products of heavy ion research has been the thrust to re-examine the assumptions of reaction theory and now include many effects neglected for light ion analysis. This research has spurred the addition of multistep processes to simple direct processes and coupled channel calculations. (J.R.)

  16. Incorporating drug delivery into an imaging-driven, mechanics-coupled reaction diffusion model for predicting the response of breast cancer to neoadjuvant chemotherapy: theory and preliminary clinical results

    Science.gov (United States)

    Jarrett, Angela M.; Hormuth, David A.; Barnes, Stephanie L.; Feng, Xinzeng; Huang, Wei; Yankeelov, Thomas E.

    2018-05-01

    Clinical methods for assessing tumor response to therapy are largely rudimentary, monitoring only temporal changes in tumor size. Our goal is to predict the response of breast tumors to therapy using a mathematical model that utilizes magnetic resonance imaging (MRI) data obtained non-invasively from individual patients. We extended a previously established, mechanically coupled, reaction-diffusion model for predicting tumor response initialized with patient-specific diffusion weighted MRI (DW-MRI) data by including the effects of chemotherapy drug delivery, which is estimated using dynamic contrast-enhanced (DCE-) MRI data. The extended, drug incorporated, model is initialized using patient-specific DW-MRI and DCE-MRI data. Data sets from five breast cancer patients were used—obtained before, after one cycle, and at mid-point of neoadjuvant chemotherapy. The DCE-MRI data was used to estimate spatiotemporal variations in tumor perfusion with the extended Kety–Tofts model. The physiological parameters derived from DCE-MRI were used to model changes in delivery of therapy drugs within the tumor for incorporation in the extended model. We simulated the original model and the extended model in both 2D and 3D and compare the results for this five-patient cohort. Preliminary results show reductions in the error of model predicted tumor cellularity and size compared to the experimentally-measured results for the third MRI scan when therapy was incorporated. Comparing the two models for agreement between the predicted total cellularity and the calculated total cellularity (from the DW-MRI data) reveals an increased concordance correlation coefficient from 0.81 to 0.98 for the 2D analysis and 0.85 to 0.99 for the 3D analysis (p  <  0.01 for each) when the extended model was used in place of the original model. This study demonstrates the plausibility of using DCE-MRI data as a means to estimate drug delivery on a patient-specific basis in predictive models and

  17. Multi-elemental characterization of tunnel and road dusts in Houston, Texas using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry: Evidence for the release of platinum group and anthropogenic metals from motor vehicles

    International Nuclear Information System (INIS)

    Spada, Nicholas; Bozlaker, Ayse; Chellam, Shankararaman

    2012-01-01

    Highlights: ► Analytical method for PGEs, main group, transition and rare earth metals developed. ► Comprehensive characterization of road and tunnel dust samples was accomplished. ► PGEs in dusts arise from autocatalyst attrition. ► Mobile sources also contributed to Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. ► All other elements, including rare earths arose from crustal sources. - Abstract: Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry (DRC-q-ICP–MS). Average Rh, Pd and Pt concentrations were 152 ± 52, 770 ± 208 and 529 ± 130 ng g −1 respectively in tunnel dusts while they varied between 6 and 8 ng g −1 , 10 and 88 ng g −1 and 35 and 131 ng g −1 in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However

  18. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    2015-01-01

    We study possible motivations for co-entreprenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes...

  19. HandaPhos

    DEFF Research Database (Denmark)

    Handa, Sachin; Andersson, Martin Peter; Gallou, Fabrice

    2016-01-01

    The new monophosphine ligand HandaPhos has been identified such that when complexed in a 1:1 ratio with Pd(OAc)2, enables Pd-catalyzed cross-couplings to be run using ≤1000 ppm of this pre-catalyst. Applications to Suzuki-Miyaura reactions involving highly funtionalized reaction partners are demo......The new monophosphine ligand HandaPhos has been identified such that when complexed in a 1:1 ratio with Pd(OAc)2, enables Pd-catalyzed cross-couplings to be run using ≤1000 ppm of this pre-catalyst. Applications to Suzuki-Miyaura reactions involving highly funtionalized reaction partners...

  20. Aminoarenethiolato-copper(I) as (pre-)catalyst for the synthesis of diaryl ethers from aryl bromides and sequential C-O/C-S and C-N/C-S cross coupling reactions

    NARCIS (Netherlands)

    Sperotto, Elena; Klink, Gerard P.M. van; Vries, Johannes G. de; Koten, Gerard van

    2010-01-01

    A small library of 2-aminoarenethiolato-copper(I) (CuSAr) complexes was tested as (pre-)catalysts in the arylation reaction of phenols with aryl bromides. These copper(I) (pre-)catalysts are thermally stable, soluble in common organic solvents, and allow reactions of 6 h at 160 °C with low catalyst

  1. Synthesis and biological evaluation of flexible and conformationally constrained LpxC inhibitors

    DEFF Research Database (Denmark)

    Löppenberg, Marius; Müller, Hannes; Pulina, Carla

    2013-01-01

    , conformationally constrained C-glycosidic as well as open chained hydroxamic acids with a defined stereochemistry were prepared. Diversity was introduced by performing C–C coupling reactions like the Sonogashira and Suzuki cross-coupling reactions. The biological evaluation of the synthesized compounds revealed...

  2. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse – most commonly the female – has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female......We study possible motivations for co-entrepenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and postdissolution private and financial outcomes......, are larger in co-entrepreneurial firms, both during the life of the business and post-dissolution. The start-up of co-entrepreneurial firms seems therefore a sound investment in the human capital of both spouses as well as in the reduction of income inequality in the household. We find no evidence of non...

  3. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse - most commonly the female - has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female......We study possible motivations for co-entrepenurial couples to start up a joint firm, us-ing a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes......, are larger in co-entrepreneurial firms, both during the life of the business and post-dissolution. The start-up of co-entrepreneurial firms seems therefore a sound in-vestment in the human capital of both spouses as well as in the reduction of income inequality in the household. We find no evidence of non...

  4. Spatial coupling in heterogeneous catalysis

    Science.gov (United States)

    Yamamoto, S. Y.; Surko, C. M.; Maple, M. B.

    1995-11-01

    Spatial coupling mechanisms are studied in the heterogeneous catalytic oxidation of carbon monoxide over platinum at atmospheric pressure under oscillatory conditions. Experiments are conducted in a continuous flow reactor, and the reaction rate is monitored using both infrared imaging and thermocouples. The catalysts are in the form of platinum annular thin films on washer-shaped quartz substrates, and they provide highly repeatable oscillatory behavior. Oscillations are typically spatially synchronized with the entire catalyst ``flashing'' on and off uniformly. Spatial coupling is investigated by introducing various barriers which split the annular ring in half. Infrared images show that coupling through the gas phase dominates coupling via the diffusion of CO on the surface or heat diffusion through the substrate. The introduction of a localized heat perturbation to the catalyst surface does not induce a transition in the reaction rate. Thus, it is likely that the primary mode of communication is through the gas-phase diffusion of reactants.

  5. Quasielastic reactions

    International Nuclear Information System (INIS)

    Henning, W.

    1979-01-01

    Quasielastic reaction studies, because of their capability to microscopically probe nuclear structure, are still of considerable interest in heavy-ion reactions. The recent progress in understanding various aspects of the reaction mechanism make this aim appear closer. The relation between microscopic and macroscopic behavior, as suggested, for example, by the single proton transfer data to individual final states or averaged excitation energy intervals, needs to be explored. It seems particularly useful to extend measurements to higher incident energies, to explore and understand nuclear structure aspects up to the limit of the energy range where they are important

  6. Determination of As and Se in crude oil diluted in xylene by inductively coupled plasma mass spectrometry using a dynamic reaction cell for interference correction on {sup 80}Se

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Fernanda Inda de [Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil); Duyck, Christiane B., E-mail: cbduyck@vm.uff.br [Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil); Departamento de Quimica, Universidade Federal Fluminense (UFF), Outeiro Sao Joao Batista s/n, Centro, 24020-150, Niteroi, RJ (Brazil); Fonseca, Teresa Cristina O. [Centro de Pesquisas Leopoldo A. Miguez de Mello da Petrobras (CENPES) (Brazil); Saint' Pierre, Tatiana D. [Departamento de Quimica, Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rua Marques de Sao Vicente 225, 22451-900 Rio de Janeiro, RJ (Brazil)

    2012-05-15

    Arsenic and selenium can be found in crude oils and represent an important source of pollution when released to the environment during any stage of extraction or refinery. These elements present low sensitivity in the direct determination by inductively coupled plasma mass spectrometry (ICP-MS), due to their high ionization potential, and are also prone to spectral interferences. Hydride generation (HG) can be alternatively employed for the separation of these analytes from the sample matrix and introduction into the instrument. However, the required sample preparation usually increases the analysis time. In this work, a method was developed for the determination of As and Se in crude oil by ICP-MS, after sample dilution in xylene. The use of a dynamic reaction cell (DRC) allowed for the overcoming of Ar{sub 2}{sup +} interference on {sup 80}Se, but was not necessary for As, since interference on m/z 75 was not observed. The optimized operational conditions for {sup 75}As and {sup 80}Se were: 1350 W of RF power, 0.4 L min{sup -1} of Ar nebulizer and 0.7 L min{sup -1} of Ar auxiliary flow rates. The DRC conditions for {sup 80}Se were 0.5 L min{sup -1} of methane and rejection parameter q (Rpq) of 0.2. The analyses were carried out by analyte addition and the limits of detection (LOD) were 0.04 {mu}g kg{sup -1} for As and 0.1 {mu}g kg{sup -1} for Se. The accuracy was verified by the analysis of residual fuel oil certified material, with agreement at a 95% confidence level. Nine Brazilian crude oil samples were analyzed and the results compared to those obtained by hydride generation ICP-MS. In this case, samples were decomposed with nitric acid in a digester block, the analytes pre-reduced with HCl 6 mol L{sup -1} and the determination carried out by external calibration. Although better instrumental LODs were obtained by HG (0.002 {mu}g kg{sup -1} of As and 0.04 {mu}g kg{sup -1} of Se), the direct determination of As and Se in crude oil diluted in xylene by DRC

  7. Statistical theory of breakup reactions

    International Nuclear Information System (INIS)

    Bertulani, Carlos A.; Descouvemont, Pierre; Hussein, Mahir S.

    2014-01-01

    We propose an alternative for Coupled-Channels calculations with loosely bound exotic nuclei (CDCC), based on the the Random Matrix Model of the statistical theory of nuclear reactions. The coupled channels equations are divided into two sets. The first set, described by the CDCC, and the other set treated with RMT. The resulting theory is a Statistical CDCC (CDCC s ), able in principle to take into account many pseudo channels. (author)

  8. Statistical theory of breakup reactions

    Energy Technology Data Exchange (ETDEWEB)

    Bertulani, Carlos A., E-mail: carlos.bertulani@tamuc.edu [Department of Physics and Astronomy, Texas A and M University-Commerce, Commerce, TX (United States); Descouvemont, Pierre, E-mail: pdesc@ulb.ac.be [Physique Nucleaire Theorique et Physique Mathematique, Universite Libre de Bruxelles (ULB), Brussels (Belgium); Hussein, Mahir S., E-mail: hussein@if.usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Estudos Avancados

    2014-07-01

    We propose an alternative for Coupled-Channels calculations with loosely bound exotic nuclei (CDCC), based on the the Random Matrix Model of the statistical theory of nuclear reactions. The coupled channels equations are divided into two sets. The first set, described by the CDCC, and the other set treated with RMT. The resulting theory is a Statistical CDCC (CDCC{sub s}), able in principle to take into account many pseudo channels. (author)

  9. Insights into Sonogashira cross-coupling by high-throughput kinetics and descriptor modeling

    NARCIS (Netherlands)

    an der Heiden, M.R.; Plenio, H.; Immel, S.; Burello, E.; Rothenberg, G.; Hoefsloot, H.C.J.

    2008-01-01

    A method is presented for the high-throughput monitoring of reaction kinetics in homogeneous catalysis, running up to 25 coupling reactions in a single reaction vessel. This method is demonstrated and validated on the Sonogashira reaction, analyzing the kinetics for almost 500 coupling reactions.

  10. Neuron-glia metabolic coupling: Role in plasticity and neuroprotection

    KAUST Repository

    Magistretti, Pierre J.

    2017-12-02

    A tight metabolic coupling between astrocytes and neurons is a key feature of brain energy metabolism (Magistretti and Allaman, Neuron, 2015). Over the years we have described two basic mechanisms of neurometabolic coupling. First the glycogenolytic effect of VIP and of noradrenaline indicating a regulation of brain homeostasis by neurotransmitters acting on astrocytes, as glycogen is exclusively localized in these cells. Second, the glutamate-stimulated aerobic glycolysis in astrocytes. Both the VIP-and noradrenaline-induced glycogenolysis and the glutamate-stimulated aerobic glycolysis result in the release of lactate from astrocytes as an energy substrate for neurons (Magistretti and Allaman, Neuron, 2015). We have recently shown that lactate is necessary not only as an energy substrate but is also a signaling molecule for long-term memory consolidation and for maintenance of LTP (Suzuki et al, Cell, 2011). At the molecular level we have found that L-lactate stimulates the expression of synaptic plasticity-related genes such as Arc, Zif268 and BDNF through a mechanism involving NMDA receptor activity and its downstream signaling cascade Erk1/2 (Yang et al, PNAS, 2014). L-lactate potentiates NMDA receptor-mediated currents and the ensuing increases in intracellular calcium. These results reveal a novel action of L-lactate as a signaling molecule for neuronal plasticity. We have also recently shown that peripheral administration of lactate exerts antidepressant-like effects in three animal models of depression (Carrard et al, Mol.Psy., 2016).

  11. cycloaddition reactions

    Indian Academy of Sciences (India)

    Unknown

    Molecular Modeling Group, Organic Chemical Sciences, Indian Institute of Chemical Technology,. Hyderabad ... thus obtained are helpful to model the regioselectivity ... compromise to model Diels–Alder reactions involving ...... acceptance.

  12. Direct Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Austern, N. [University of Pittsburgh, Pittsburgh, PA (United States)

    1963-01-15

    In order to give a unified presentation of one point of view, these lectures are devoted only to a detailed development of the standard theories of direct reactions, starting from basic principles. Discussion is given of the present status of the theories, of the techniques used for practical calculation, and of possible future developments. The direct interaction (DI) aspects of a reaction are those which involve only a few of the many degrees of freedom of a nucleus. In fact the minimum number of degrees of freedom which must be involved in a reaction are those required to describe the initial and final channels, and DI studies typically consider these degrees of freedom and no others. Because of this simplicity DI theories may be worked out in painstaking detail. DI processes concern only part of the wave function for a problem. The other part involves complicated excitations of many degrees of freedom, and gives the compound nucleus (CN) effects. While it is extremely interesting to learn how to separate DI and CN effects in an orderly manner, if they are both present in a reaction, no suitable method has yet been found. Instead, current work stresses the kinds of reactions and the kinds of final states in which DI effects dominate and in which CN effects may almost be forgotten. The DI cross-sections which are studied are often extremely large, comparable to elastic scattering cross-sections. (author)

  13. A Green Multicomponent Reaction for the Organic Chemistry Laboratory: The Aqueous Passerini Reaction

    Science.gov (United States)

    Hooper, Matthew M.; DeBoef, Brenton

    2009-01-01

    Water is the ideal green solvent for organic reactions. However, most organic molecules are insoluble in it. Herein, we report a laboratory module that takes advantage of this property. The Passerini reaction, a three-component coupling involving an isocyanide, aldehyde, and carboxylic acid, typically requires [similar to] 24 h reaction times in…

  14. Catalytic Organometallic Reactions of Ammonia

    Science.gov (United States)

    Klinkenberg, Jessica L.

    2012-01-01

    Until recently, ammonia had rarely succumbed to catalytic transformations with homogeneous catalysts, and the development of such reactions that are selective for the formation of single products under mild conditions has encountered numerous challenges. However, recently developed catalysts have allowed several classes of reactions to create products with nitrogen-containing functional groups from ammonia. These reactions include hydroaminomethylation, reductive amination, alkylation, allylic substitution, hydroamination, and cross-coupling. This Minireview describes examples of these processes and the factors that control catalyst activity and selectivity. PMID:20857466

  15. Reaction mechanisms

    International Nuclear Information System (INIS)

    Nguyen Trong Anh

    1988-01-01

    The 1988 progress report of the Reaction Mechanisms laboratory (Polytechnic School, France), is presented. The research topics are: the valence bond methods, the radical chemistry, the modelling of the transition states by applying geometric constraints, the long range interactions (ion - molecule) in gaseous phase, the reaction sites in gaseous phase and the mass spectroscopy applications. The points of convergence between the investigations of the mass spectroscopy and the theoretical chemistry teams, as well as the purposes guiding the research programs, are discussed. The published papers, the conferences, the congress communications and the thesis, are also reported [fr

  16. Extent of reaction in open systems with multiple heterogeneous reactions

    Science.gov (United States)

    Friedly, John C.

    1991-01-01

    The familiar batch concept of extent of reaction is reexamined for systems of reactions occurring in open systems. Because species concentrations change as a result of transport processes as well as reactions in open systems, the extent of reaction has been less useful in practice in these applications. It is shown that by defining the extent of the equivalent batch reaction and a second contribution to the extent of reaction due to the transport processes, it is possible to treat the description of the dynamics of flow through porous media accompanied by many chemical reactions in a uniform, concise manner. This approach tends to isolate the reaction terms among themselves and away from the model partial differential equations, thereby enabling treatment of large problems involving both equilibrium and kinetically controlled reactions. Implications on the number of coupled partial differential equations necessary to be solved and on numerical algorithms for solving such problems are discussed. Examples provided illustrate the theory applied to solute transport in groundwater flow.

  17. Exchange effects in direct reactions

    International Nuclear Information System (INIS)

    LeMere, M.; Kanellopoulos, E.J.; Suenkel, W.; Tang, Y.C.

    1979-01-01

    The effect of antisymmetrization in direct reactions is examined by studying the properties of the coupling-normalization kernel function occurring in a resonating-group formulation. From this study, one obtains useful information concerning the general behavior of direct-reactiion processes and some justification for the use of three-body models in phenomenological analyses

  18. Characterisation of Maillard reaction products derived from LEKFD--a pentapeptide found in β-lactoglobulin sequence, glycated with glucose--by tandem mass spectrometry, molecular orbital calculations and gel filtration chromatography coupled with continuous photodiode array.

    Science.gov (United States)

    Yamaguchi, Keiko; Homma, Takeshi; Nomi, Yuri; Otsuka, Yuzuru

    2014-02-15

    Maillard reaction peptides (MRPs) contribute to taste, aroma, colour, texture and biological activity. However, peptide degradation or the cross-linking of MRPs in the Maillard reaction has not been investigated clearly. A peptide of LEKFD, a part of β-lactoglobulin, was heated at 110 °C for 24h with glucose and the reaction products were analysed by HPLC with ODS, ESI-MS, ESI-MS/MS and HPLC with gel-filtration column and DAD detector. In the HPLC fractions, an imminium ion of LEK*FD, a pyrylium ion or a hydroxymethyl furylium ion of LEK*FD, and KFD and EK were detected by ESI-MS. Therefore, those products may be produced by the Maillard reaction. The molecular orbital of glycated LEKFD at the lysine epsilon-amino residue with Schiff base form was calculated by MOPAC. HPLC with gel-filtration column showed cross-linking and degradation of peptides. Copyright © 2013 Elsevier Ltd. All rights reserved.

  19. Allergic reactions

    Science.gov (United States)

    ... that don't bother most people (such as venom from bee stings and certain foods, medicines, and pollens) can ... person. If the allergic reaction is from a bee sting, scrape the ... more venom. If the person has emergency allergy medicine on ...

  20. Evidence for highly localized damage in internal tin and powder-in-tube Nb{sub 3}Sn strands rolled before reaction obtained from coupled magneto-optical imaging and confocal laser scanning microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Polyanskii, A A; Lee, P J; Jewell, M C; Larbalestier, D C [Applied Superconductivity Center, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310 (United States); Barzi, E; Turrioni, D; Zlobin, A V [Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

    2009-09-15

    Nb{sub 3}Sn strands for high-current, high-field magnets must be cabled before reaction while the conductor is still composed of ductile components. Even though still in the ductile, deformable state, significant damage can occur in this step, which expresses itself by inhomogeneous A15 formation, Sn leakage or even worse effects during later reaction. In this study, we simulate cabling damage by rolling recent high performance powder-in-tube (PIT) and internal tin (IT) strands in controlled increments, applying standard Nb{sub 3}Sn reaction heat treatments, and then examining the local changes using magneto-optical imaging (MOI), scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). These combined characterizations allow any local damage to the filament architecture to be made clear. MOI directly reveals the local variation of superconductivity while CLSM is extremely sensitive in revealing Sn leakage beyond the diffusion barrier into the stabilizing Cu. These techniques reveal a markedly different response to deformation by the PIT and IT strands. The study demonstrates that these tools can provide a local, thorough, and detailed view of how strands degrade and thus complement more complex extracted strand studies.