Sample records for suzuki coupling reactions
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Nanocatalysts for Suzuki cross-coupling reactions
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.
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Nanocatalysts for Suzuki cross-coupling reactions
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
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Palladium supported on natural phosphate: Catalyst for Suzuki coupling reactions in water
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.
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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.
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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
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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.
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Suzuki-Miyaura cross-coupling reactions in aqueous media: Green and sustainable syntheses of biaryls
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.
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Suzuki-Miyaura cross-coupling reactions in aqueous media: Green and sustainable syntheses of biaryls
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
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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.
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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.…
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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.
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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
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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…
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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…
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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).
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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.
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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.
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Ruphus-mediated Suzuki cross-coupling of secondary alkyl trifluoroborates
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
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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…
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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.
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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.
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Preparation of Pd-Diimine@SBA-15 and Its Catalytic Performance for the Suzuki Coupling Reaction
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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.
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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.
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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.
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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.
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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…
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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An efficient protocol for the palladium-catalysed Suzuki-Miyaura cross-coupling
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.
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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.
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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.
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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.
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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.
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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
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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…
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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.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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Facile palladium catalyzed Suzuki-Miyaura coupling in air and water at ambient temperature
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.
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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.
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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
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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.
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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
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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
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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 ().
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Ligandless Suzuki-Miyaura reaction in neat water with or without native β-cyclodextrin as additive
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.
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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.
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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 ...
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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.
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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
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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.
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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).
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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
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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.
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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
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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 ...
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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.
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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.
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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.
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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.
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Suzuki ja Szilvay : meetodist ja individuaalsusest / Lembi Mets
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
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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...
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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.
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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.
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Monitoring chemical reactions by low-field benchtop NMR at 45 MHz: pros and cons.
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.
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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)
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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
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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.
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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
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Surface-Activated Coupling Reactions Confined on a Surface.
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
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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.)
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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.
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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.
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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.
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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...
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The Eschenmoser coupling reaction under continuous-flow conditions
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
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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.
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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...
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Palladium-catalyzed coupling reactions
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
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Powerful Learning Experiences and Suzuki Music Teachers
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…
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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
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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.
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Baran, Talat; Yılmaz Baran, Nuray; Menteş, Ayfer
2018-05-01
In this study, we reported production, characterization, and catalytic behavior of two novel heterogeneous palladium(II) and platinum(II) catalysts derived from cellulose biopolymer. In order to eliminate the use of toxic organic or inorganic solvents and to reduce the use of excess energy in the coupling reactions, we have developed a very simple, rapid, and eco-friendly microwave irradiation protocol. The developed microwave-assisted method of Suzuki cross coupling reactions produced excellent reaction yields in the presence of cellulose supported palladium and platinum (II) catalysts. Moreover, the catalysts easily regenerated after simple filtration, and they gave good reusability. This study revealed that the designed catalysts and method provide clean, simple, rapid, and impressive catalytic performance for Suzuki coupling reactions.
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High throughput reaction screening using desorption electrospray ionization mass spectrometry.
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.
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Polymer and Membrane Design for Low Temperature Catalytic Reactions
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.
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Polymer and Membrane Design for Low Temperature Catalytic Reactions
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.
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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.
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Palladium-Catalysed Coupling Reactions
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
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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…
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Autobiography: Kinuko Suzuki, MD.
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.
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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...
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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.
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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.
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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.
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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.
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Applications of Palladium-Catalyzed C-N Cross-Coupling Reactions.
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.
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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.
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Cu(I)/Diamine-catalyzed Aryl-alkyne Coupling Reactions
Institute of Scientific and Technical Information of China (English)
无
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.
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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.
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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
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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 ...
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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
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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) + ...
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What Is the Structure of the Antitubercular Natural Product Eucapsitrione?
Pullella, Glenn A; Wild, Duncan A; Nealon, Gareth L; Elyashberg, Mikhail; Piggott, Matthew J
2017-07-21
1,5,7-Trihydroxy-6H-indeno[1,2-b]anthracene-6,11,13-trione (1), proposed to be the antitubercular natural product eucapsitrione, has been synthesized in 43% overall yield and six steps, including a key Suzuki-Miyaura biaryl coupling and a directed remote metalation (DReM)-initiated cyclization. The physical and spectroscopic properties of 1 do not match the data reported for the natural product. At this time there is insufficient information available to enable a structure reassignment. During the optimization of the Suzuki-Miyaura coupling, an unprecedented biaryl coupling ortho to the borono group was observed. The scope of this unusual reaction has been investigated.
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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.
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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
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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.
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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
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Regioselectivity and Enantioselectivity in Nickel-Catalysed Reductive Coupling Reactions of Alkynes
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
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Learning with Sound Recordings: A History of Suzuki's Mediated Pedagogy
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…
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Journal of Chemical Sciences | Indian Academy of Sciences
Indian Academy of Sciences (India)
... 4' -methylenedioxyphenyl)-5,6,7-trimethoxyisoflavone] derivatives, structurally similar to glaziovianin A, a known cytotoxic substance, has been described. The key steps in the synthesis are site selective bromination reaction followed by Suzuki coupling reaction in very good yield. The structural assignment of the bromo ...
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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...
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The Conservation of Rhythm in Suzuki Violin Students: A Task Validation Study.
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)
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76 FR 4991 - Petition for Exemption From the Vehicle Theft Prevention Standard; Suzuki
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...
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Optimization of an Efficient and Sustainable Sonogashira Cross-Coupling Protocol
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
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Rhodium-Catalyzed Dehydrogenative Borylation of Cyclic Alkenes
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
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Coupled-channels analyses for 9,11Li + 208Pb fusion reactions with multi-neutron transfer couplings
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.
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Micro-coulometric study of bioelectrochemical reaction coupled with TCA cycle.
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.
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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
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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
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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
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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.
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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.
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Journal of Chemical Sciences | Indian Academy of Sciences
Indian Academy of Sciences (India)
The bisphosphomide-based pincer complex [PdBr{2,6-{Ph2PC(O)}2(C6H3)}] (2) has shown very high catalytic activity in Suzuki-Miyaura cross coupling reaction under microwave irradiation for a variety of aryl bromides and aryl boronic acids. The complex showed the same efficiency for gram scale reactions.
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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…
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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.
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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.
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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.
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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
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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.
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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.
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Library of biphenyl privileged substructures using a safety-catch linker approach
DEFF Research Database (Denmark)
Severinsen, Rune; Bourne, Gregory T; Tran, Tran T
2008-01-01
A biphenyl privileged structure library containing three attachment points were synthesized using a catechol-based safety-catch linker strategy. The method requires the attachment of a bromo-acid to the linker, followed by a Pd-catalyzed Suzuki cross-coupling reaction. Further derivatization...
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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...
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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.
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Journal of Chemical Sciences | Indian Academy of Sciences
Indian Academy of Sciences (India)
Pd immobilized on modified magnetic Fe₃O₄ nanoparticles: Magnetically recoverable and reusable Pd nanocatalyst for Suzuki-Miyaura coupling reactions and Ullmann-type N-arylation of indoles. RAMIN GHORBANI-VAGHEI SABA HEMMATI MALAK HEKMATI. Regular Article Volume 128 Issue 7 July 2016 pp 1157- ...
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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
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Journal of Chemical Sciences | Indian Academy of Sciences
Indian Academy of Sciences (India)
The analysis revealed that the complexes possess a distorted octahedral geometry with the ligand coordinating in a uni-negative tridentate ONS fashion. The catalytic activity of complexes towards some C–C coupling reactions (viz., Kumada-Corriu, Suzuki-Miyaura and Sonogashira) has been examined. The complexes ...
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Goh, Li Min Serena; Hogerl, Manuel Peter; Jokic̈, Nadežda B.; Tanase, Alexandrina D.; Bechlars, Bettina; Baratta, Walter; Mí nk, Já nos; Kü hn, Fritz
2014-01-01
A cationic phthalimido-functionalized N-heterocyclic carbene (NHC) palladium(II) complex has been synthesized from [3-methyl-1-(2′- phthalimidoethyl)imidazolium] hexafluorophosphate ([NHCMe,PhtH] PF6) by transmetalation and isolated in 67 % yield. The title complex has been applied as catalyst in the Suzuki-Miyaura cross-coupling reaction under benign aqueous conditions. The catalyst is active without any observable initiation period. High average turnover frequencies (TOFs) of up to 55000 h-1 have been reached with catalyst concentrations as low as 0.01 mol-%. A cationic phthalimido-functionalized N-heterocyclic carbene (NHC) palladium(II) complex has been prepared in high yield. The complex was activated instantly, without an initiation period, in the Suzuki-Miyaura cross-coupling reaction under benign aqueous aerobic conditions. Turnover frequencies (TOFs) up to 55000 h-1, were achieved with 0.01 mol-% of the complex. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Goh, Li Min Serena
2014-01-29
A cationic phthalimido-functionalized N-heterocyclic carbene (NHC) palladium(II) complex has been synthesized from [3-methyl-1-(2′- phthalimidoethyl)imidazolium] hexafluorophosphate ([NHCMe,PhtH] PF6) by transmetalation and isolated in 67 % yield. The title complex has been applied as catalyst in the Suzuki-Miyaura cross-coupling reaction under benign aqueous conditions. The catalyst is active without any observable initiation period. High average turnover frequencies (TOFs) of up to 55000 h-1 have been reached with catalyst concentrations as low as 0.01 mol-%. A cationic phthalimido-functionalized N-heterocyclic carbene (NHC) palladium(II) complex has been prepared in high yield. The complex was activated instantly, without an initiation period, in the Suzuki-Miyaura cross-coupling reaction under benign aqueous aerobic conditions. Turnover frequencies (TOFs) up to 55000 h-1, were achieved with 0.01 mol-% of the complex. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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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
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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.
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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...
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Diversification of indoles via microwave-assisted ligand-free copper-catalyzed N-arylation
Energy Technology Data Exchange (ETDEWEB)
Kwon, Jae Kwan; Lee, Jin Hee; Kim, Tae Sung; Yum, Eul Kgun [Dept. of Chemistry, Chu ngnam National University, Daejon (Korea, Republic of); Park, Jee Jung [Western Seoul Center Korea Basic Science Institute, Seoul (Korea, Republic of)
2016-12-15
A simple, efficient Cu{sub 2}O catalyst system under microwave irradiation was developed for N-arylation of various indoles without ligands and additives. Diverse N-heteroarylated indoles were prepared by coupling indoles with various heteroaryl halides within 1 h. The selective reactivity of bromoindole with aryl iodide provided N-aryl bromoindoles, which could be useful intermediates for palladium-catalyzed Heck and Suzuki coupling reactions.
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Synthesis of novel kavain-like derivatives and evaluation of their cytotoxic activity
Energy Technology Data Exchange (ETDEWEB)
Amaral, Patricia de A.; Agustini, Taciane; Eifler-Lima, Vera L. [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre (Brazil). Faculdade de Farmacia. Lab. de Sintese Organica Medicinal; Petrignet, Julien; Cariou, Alexandre; Gree, Rene [Universite de Rennes 1, Rennes (France). Lab. de Chimie Therapeutique; Gouault, Nicolas; Lohezic-Ledevehat, Francoise; David, Michele [CNRS UMR, Universite de Rennes 1, Rennes (France). Lab. de Chimie et Photonique Moleculaires
2009-07-01
Palladium-catalyzed cross coupling reactions (Sonogashira-Hagihara, Suzuki-Miyaura, and Heck) coupling and nickel hydride-mediated tandem isomerization aldolisation have been used for the synthesis of three series of {delta}-valerolactones substituted in positions 3, 4, 5 and 6 of the lactone ring. The 26 kavaien-like derivatives were tested against three cell lines and five of them exhibited a weak cytotoxic activity. (author)
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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.
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[Production of sugar syrup containing rare sugar using dual-enzyme coupled reaction system].
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.
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A novel synthesis of hemispherands
Ostaszewski, Ryszard; Verboom, Willem; Reinhoudt, David
1992-01-01
A novel, flexible synthesis of hemispherands {2,5,8-trioxa[9](3,3″) m-terphenylophanes 5a-d} with different central aromatic groups is described. The key step comprises the introduction of the central aromatic ring in the last step of the synthesis via a Suzuki cross-coupling reaction using
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Synthesis of (+)-Antroquinonol: An Antihyperglycemic Agent.
Sulake, Rohidas S; Lin, Hsiao-Han; Hsu, Chia-Yu; Weng, Ching-Feng; Chen, Chinpiao
2015-06-19
The total synthesis of antroquinonol has been accomplished through Suzuki-Miyaura cross-coupling and Barton-McCombie reaction, and the α,β-unsaturation was achieved through selenylation and oxidation protocols. In vitro and in vivo studies on the glucose-lowering properties of antroquinonol indicate that it is a potential antidiabetic agent.
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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
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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
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DEFF Research Database (Denmark)
Kijima, Tetsushi; Javakhishvili, Irakli; Jankova Atanasova, Katja
2012-01-01
Fluoroalkyl end-capped betaine-type cooligomeric nanocomposites-immobilized palladium nanoparticles were prepared by the reactions of palladium chloride with sodium acetate in the presence of sodium chloride and the corresponding fluorinated cooligomers. Outer blocks of poly(2,3,4,5,6-pentafluoro....... These fluorinated nanocomposites-immobilized palladium nanoparticles were also applied to the catalysts for Suzuki-Miyaura cross-coupling reaction, and the different reactivity between these nanocomposites was observed....
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Pd-Catalyzed Cross-Coupling Reactions of Amides and Aryl Mesylates
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
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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.
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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.
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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
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Optical trapping via guided resonance modes in a Slot-Suzuki-phase photonic crystal lattice.
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.
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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
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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
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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)
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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.
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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.
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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)
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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.
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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.
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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.
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Visual monitoring of solid-phase extraction using chromogenic fluorous synthesis supports.
Blackburn, Christopher
2012-03-12
Reductive aminations and further transformations of an azo dye and fluorous tagged aldehyde are described. The intensely colored 2,4-dialkoxybenzyl protected amines undergo Fmoc-based peptide coupling, Suzuki reactions, and sulfonamide formation with product isolation facilitated by visual monitoring of fluorous solid phase extraction. Target compounds are released from the supports in high yields and purities by treatment with trifluoroacetic acid (TFA).
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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.
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Synthesis of Au-Pd Nanoflowers Through Nanocluster Assembly
Energy Technology Data Exchange (ETDEWEB)
Xu, Jianguang [Duke University; Howe, Jane Y [ORNL; Chi, Miaofang [ORNL; Wilson, Adria [Duke University; Rathmall, Aaron [Duke University; Wiley, Benjamin J [ORNL
2011-01-01
Reduction of Pd ions by hydroquinone in the presence of gold nanoparticles and polyvinylpyrrolidone resulted in the formation of nanoflowers with a Au core and Pd petals. Addition of HCl to the synthesis halted the reduction by hydroquinone and enabled the acquisition of snapshots of the nanoflowers at different stages of growth. TEM images of the reaction after 10 s show that the nanoflower morphology resulted from the homogeneous nucleation of Pd clusters in solution and their subsequent attachment to gold seeds coated with a thin (0.8 {+-} 0.1 nm) shell of Pd. UV-visible spectra also indicate Pd clusters formed in the early stages of the reaction and disappeared as the nanoflowers grew. The speed at which this reaction can be halted is useful not only for producing a variety of bimetallic nanostructures with precisely controlled dimensions and morphologies but also for understanding the growth mechanism of these structures. The ability of the AuPd core-shell structure to catalyze the Suzuki coupling reaction of iodobenzene to phenylboronic acid was probed and compared against the activity of Pd nanocubes and thin-shelled AuPd core-shell nanoparticles. The results of this study suggest that Suzuki coupling was not affected by the surface structure or subsurface composition of the nanoparticles, but instead was primarily catalyzed by molecular Pd species that leached from the nanostructures.
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Synthesis and Catalytic Properties of Au Pd Nanoflowers
Energy Technology Data Exchange (ETDEWEB)
Xu, Jianguang [Department of Chemistry, Duke University; Wilson, Adria [Duke University; Howe, Jane Y [ORNL; Chi, Miaofang [ORNL; Wiley, Benjamin J [Duke University
2011-01-01
Reduction of Pd ions by hydroquinone in the presence of gold nanoparticles and polyvinylpyrrolidone resulted in the formation of nanoflowers with a Au core and Pd petals. Addition of HCl to the synthesis halted the reduction by hydroquinone and enabled the acquisition of snapshots of the nanoflowers at different stages of growth. TEM images of the reaction after 10 s show that the nanoflower morphology resulted from the homogeneous nucleation of Pd clusters in solution and their subsequent attachment to gold seeds coated with a thin (0.8 0.1 nm) shell of Pd. UV visible spectra also indicate Pd clusters formed in the early stages of the reaction and disappeared as the nanoflowers grew. The speed at which this reaction can be halted is useful not only for producing a variety of bimetallic nanostructures with precisely controlled dimensions and morphologies but also for understanding the growth mechanism of these structures. The ability of the AuPd core shell structure to catalyze the Suzuki coupling reaction of iodobenzene to phenylboronic acid was probed and compared against the activity of Pd nanocubes and thin-shelled AuPd core shell nanoparticles. The results of this study suggest that Suzuki coupling was not affected by the surface structure or subsurface composition of the nanoparticles, but instead was primarily catalyzed by molecular Pd species that leached from the nanostructures.
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Synthesis and catalytic properties of Au-Pd nanoflowers.
Xu, Jianguang; Wilson, Adria R; Rathmell, Aaron R; Howe, Jane; Chi, Miaofang; Wiley, Benjamin J
2011-08-23
Reduction of Pd ions by hydroquinone in the presence of gold nanoparticles and polyvinylpyrrolidone resulted in the formation of nanoflowers with a Au core and Pd petals. Addition of HCl to the synthesis halted the reduction by hydroquinone and enabled the acquisition of snapshots of the nanoflowers at different stages of growth. TEM images of the reaction after 10 s show that the nanoflower morphology resulted from the homogeneous nucleation of Pd clusters in solution and their subsequent attachment to gold seeds coated with a thin (0.8 ± 0.1 nm) shell of Pd. UV-visible spectra also indicate Pd clusters formed in the early stages of the reaction and disappeared as the nanoflowers grew. The speed at which this reaction can be halted is useful not only for producing a variety of bimetallic nanostructures with precisely controlled dimensions and morphologies but also for understanding the growth mechanism of these structures. The ability of the AuPd core-shell structure to catalyze the Suzuki coupling reaction of iodobenzene to phenylboronic acid was probed and compared against the activity of Pd nanocubes and thin-shelled AuPd core-shell nanoparticles. The results of this study suggest that Suzuki coupling was not affected by the surface structure or subsurface composition of the nanoparticles, but instead was primarily catalyzed by molecular Pd species that leached from the nanostructures. © 2011 American Chemical Society
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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.
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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.
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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...
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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.
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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)
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Synthesis and Characterization of New Thieno[3,2-b]thiophene Derivatives
Directory of Open Access Journals (Sweden)
Wojciech Pisula
2012-10-01
Full Text Available Three derivatives of thieno[3,2-b]thiophene end-capped with phenyl units have been synthesized and characterized by MALDI TOF mass spectroscopy, elemental analysis, UV-vis absorption spectroscopy and thermogravimetric analysis (TGA. All compounds were prepared using Pd-catalyzed Stille or Suzuki coupling reactions. Optical measurements and thermal analysis revealed that these compounds are promising candidates for p-type organic semiconductor applications.
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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.
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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.
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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.)
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DEFF Research Database (Denmark)
Hansen, Casper Lykke; Clausen, Janie Regitse Waël; Ohm, Ragnhild Gaard
2013-01-01
This paper describes an efficient tandem sequence for the synthesis of 1,2,3,4-tetrahydro-β-carbolines (THBCs) relying on a ruthenium hydride/Brønsted acid- catalyzed isomerization of allylic amides to N-acyliminium ion intermediates which are trapped by a tethered indolenucleophile. The methodol...... the Suzuki cross-coupling reaction to the isomerization/N-acyliminium cyclization sequence. Finally, diastereo- and enantioselective versions of the title reaction have been examined using substrate control (with dr >15: 1) and asymmetric catalysis (ee up to 57%), respectively...
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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.
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Bite angle effects of diphosphines in C-C and C-X bond forming cross coupling reactions
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
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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.
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Antioxidant study of biaryls synthesized in the presence of Aliquat-336 activated by ultrasound
Directory of Open Access Journals (Sweden)
khemais Said
2016-05-01
Full Text Available In this work we describe the study of some Suzuki coupling reactions of an aryl halide with arylboronic acids. The reaction yields obtained were increased through sonochemical activation and in the presence of a phase transfer catalyst for a very short period of time. The isolated products obtained are of a high purity. In this context, we propose the reaction mechanisms for these reactions in the presence of a catalyst. Synthesized compounds were screened for theirantioxidant activity with 1,1-diphenyl-2-picrylhydrazyl (DPPH, ferric reducing power (FRP assay and ferrous ion chelating (FIC methods. It was found that Biaryls synthesized compounds showed appreciate antioxidant activity.
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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.)
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Directory of Open Access Journals (Sweden)
Mi-Seon Song
2013-11-01
Full Text Available A series of green dopants based on 2,2-diphenylvinyl end-capped bithiophene and three different arylamine moieties (9-phenylcarbazole, triphenylamine, and N,N’-di-(p-tolylbenzeneamine were successfully synthesized by the Suzuki and Wittig coupling reactions. The photophysical properties of these compounds are reported. The strongest PL emitting compound with the 9-phenylcarbazole moiety has been used for fabricating an OLED device with good overall performance.
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The First Total Synthesis of Dragmacidin D
Garg, Neil K.; Sarpong, Richmond; Stoltz, Brian M.
2002-01-01
The first total synthesis of the biologically significant bis-indole alkaloid dragmacidin D (5) has been achieved. Thermal and electronic modulation provides the key for a series of palladium-catalyzed Suzuki cross-coupling reactions that furnished the core structure of the complex guanidine- and aminoimidazole-containing dragmacidins. Following this crucial sequence, a succession of meticulously controlled final events was developed leading to the completion of the natural product.
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Solid-phase synthesis of isoxazoles using vinyl ethers as chameleon catches.
Barrett, A G; Procopiou, P A; Voigtmann, U
2001-10-04
[reaction: see text] Regioselective 1,3-dipolar cycloadditions of supported vinyl ethers R(1)C(=CH(2))O-CH(2)-polymer, prepared by the Tebbe olefination of R(1)CO(2)-CH(2)-polymer, with ethyl cyanoformate N-oxide gave supported isoxazoline derivatives. Release from the support under mild acidic conditions gave the isoxazoles ethyl 5-R(1)-isoxazole-3-carboxylates. Alternatively, further on-resin functionalization of the R(1) substituent using Suzuki coupling reactions and release from the support under acidic conditions gave more structurally diverse isoxazoles.
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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.
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Rapid syntheses of dehydrodiferulates via biomimetic radical coupling reactions of ethyl ferulate.
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.
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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
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Synthesis of Functionalized Arylaziridines as Potential Antimicrobial Agents
Directory of Open Access Journals (Sweden)
Arianna Giovine
2014-08-01
Full Text Available By using the Suzuki-Miyaura protocol, a simple straightforward synthesis of functionalized 2-arylaziridines has been developed. By means of this synthetic strategy from readily available ortho-, meta- and para-bromophenylaziridines and aryl- or heteroarylboronic acids, new aziridines could be obtained. The cross-coupling reactions occurred without ring opening of the three membered ring. Preliminary results on the antimicrobial activity of the heterosubstituted biaryl compounds have been also included.
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Cross-Dehydrogenative Coupling Reactions Between P(O)-H and X-H (X = S, N, O, P) Bonds.
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.
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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
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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.
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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
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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.
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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.
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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
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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
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Directory of Open Access Journals (Sweden)
Mohsine Driowya
2016-08-01
Full Text Available This review describes the recent advances in the microwave-assisted synthesis of 7-membered and larger heterocyclic compounds. Several types of reaction for the cyclization step are discussed: Ring Closing Metathesis (RCM, Heck and Sonogashira reactions, Suzuki-Miyaura cross-coupling, dipolar cycloadditions, multi-component reactions (Ugi, Passerini, etc. Green syntheses and solvent-free procedures have been introduced whenever possible. The syntheses discussed herein have been selected to illustrate the huge potential of microwave in the synthesis of highly functionalized molecules with potential therapeutic applications, in high yields, enhanced reaction rates and increased chemoselectivity, compared to conventional methods. More than 100 references from the recent literature are listed in this review.
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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
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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
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Hiebler, Katharina; Lichtenegger, Georg J; Maier, Manuel C; Park, Eun Sung; Gonzales-Groom, Renie; Binks, Bernard P; Gruber-Woelfler, Heidrun
2018-01-01
Within the "compartmentalised smart factory" approach of the ONE-FLOW project the implementation of different catalysts in "compartments" provided by Pickering emulsions and their application in continuous flow is targeted. We present here the development of heterogeneous Pd catalysts that are ready to be used in combination with biocatalysts for catalytic cascade synthesis of active pharmaceutical ingredients (APIs). In particular, we focus on the application of the catalytic systems for Suzuki-Miyaura cross-coupling reactions, which is the key step in the synthesis of the targeted APIs valsartan and sacubitril. An immobilised enzyme will accomplish the final product formation via hydrolysis. In order to create a large interfacial area for the catalytic reactions and to keep the reagents separated until required, the catalyst particles are used to stabilise Pickering emulsions of oil and water. A set of Ce-Sn-Pd oxides with the molecular formula Ce 0.99- x Sn x Pd 0.01 O 2-δ ( x = 0-0.99) has been prepared utilising a simple single-step solution combustion method. The high applicability of the catalysts for different functional groups and their minimal leaching behaviour is demonstrated with various Suzuki-Miyaura cross-coupling reactions in batch as well as in continuous flow employing the so-called "plug & play reactor". Finally, we demonstrate the use of these particles as the sole emulsifier of oil-water emulsions for a range of oils.
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Analysis of coupled mass transfer and sol-gel reaction in a two-phase system
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
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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.
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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
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Radzuan, Nuur Haziqah Mohd; Hassan, Nurul Izzaty; Bakar, Muntaz Abu
2018-04-01
The building blocks for synthesis of light harvesting antenna which are 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)-10,20-diphenylporphyrin, 5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolane)-10,20-dihexylporphyrin and 5,10,15,20-tetra-(bromophenyl)porphyrin were synthesized. Borylated porphyrin was synthesized by Suzuki coupling reaction between A2BC bromo-porphyrin and pinacolborane. Whereas 5,10,15,20-tetra-(bromophenyl) porphyrin was synthesized by Lindsey condensation reaction between pyrrole and 4-bromobenzaldehyde. 1H-NMR, 13C-NMR spectroscopy and UV-visible spectroscopy confirmed the successful formation of all compounds.
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Potassium 3-formyl-[1,1′-biphenyl]-4-olate monohydrate
Directory of Open Access Journals (Sweden)
Ryoji Moriwaki
2017-09-01
Full Text Available The title salt, K+·C13H9O2−·H2O, was synthesized from 5-bromosalicylaldehyde and a phenylboronic acid derivative using the Suzuki–Miyaura cross-coupling reaction (Miyaura & Suzuki, 1979. In addition to the intermolecular interactions between the charged species, two O—H...O hydrogen bonds involving the isolated water molecules further stabilize the crystal packing of the title salt leading to the formation of a three-dimensional framework structure.
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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.
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A two-dimensional conjugated aromatic polymer via C-C coupling reaction
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.
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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.
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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.
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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.
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Mechanism of the Suzuki–Miyaura Cross-Coupling Reaction Mediated by [Pd(NHC)(allyl)Cl] Precatalysts
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
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Wu, Kevin; Doyle, Abigail G.
2017-08-01
The field of Ni-catalysed cross-coupling has seen rapid recent growth because of the low cost of Ni, its earth abundance, and its ability to promote unique cross-coupling reactions. Whereas advances in the related field of Pd-catalysed cross-coupling have been driven by ligand design, the development of ligands specifically for Ni has received minimal attention. Here, we disclose a class of phosphines that enable the Ni-catalysed Csp3 Suzuki coupling of acetals with boronic acids to generate benzylic ethers, a reaction that failed with known ligands for Ni and designer phosphines for Pd. Using parameters to quantify phosphine steric and electronic properties together with regression statistical analysis, we identify a model for ligand success. The study suggests that effective phosphines feature remote steric hindrance, a concept that could guide future ligand design tailored to Ni. Our analysis also reveals that two classic descriptors for ligand steric environment—cone angle and % buried volume—are not equivalent, despite their treatment in the literature.
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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.
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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.
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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...
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A general synthesis of C8-arylpurine phosphoramidites.
Vongsutilers, Vorasit; Daft, Jonathan R; Shaughnessy, Kevin H; Gannett, Peter M
2009-09-02
A general scheme for the synthesis of C8-arylpurine phosphoramidites has been developed. C8-Arylation of C8-bromo-2'-deoxyguanosine is the key step and has been achieved through the use of a Suzuki coupling. Since the coupling reaction is conducted under aqueous conditions, it is unnecessary to protect and then deprotect the hydroxyl groups, thus saving several steps and improving overall yields. Once the C8-arylgroup is introduced, the glycosidic bond becomes very sensitive to acid catalyzed cleavage. Protection of the amino groups as the corresponding N,N-dimethylformamidine derivative improves stability of the derivatives. Synthetic C8-arylpurines were successfully used to prepare synthetic oligonucleotides.
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Makarov, Vadim A; Riabova, Olga B; Granik, Vladimir G; Wutzler, Peter; Schmidtke, Michaela
2005-04-01
During this study, novel biphenyl derivatives were synthesized and tested for antiviral activity. A new method based on the Suzuki coupling reaction has been established for the synthesis of these polysubstituted chain systems. In parallel with cytotoxicity, the antiviral activity of biphenyl derivatives has been determined in cytopathic effect (CPE)-inhibitory assays with the pleconaril-resistant coxsackievirus B3 (CVB3) strain Nancy, human rhinovirus 2 (HRV-2) and 14 (HRV-14) and in plaque reduction assays with the pleconaril-sensitive human isolate CVB3 97-927 in HeLa cells. Based on the results from these investigations the selectivity index (SI) was determined as the ratio of the 50% cytotoxic concentration to the 50% inhibitory concentration. The new method based on the Suzuki coupling reaction includes the condensation of 2,6-dimethyl-4-bromophenol with pentyne chloride by means of potassium carbonate and potassium iodide in N-methylpyrrolidone-2 and yields 5-bromo-1,3-dimethyl-2-(4-pentynyloxy)benzene. Its condensation with methylacetaldoxime results in 3-methylisoxazole derivatives. The following reaction with different benzeneboronic acids by means of tetrakis(triphenylphosphine)-palladium(0) finally yields the corresponding derivatives. Several of the novel synthesized derivatives demonstrated a good antiviral activity on CVB3 (SI > 2 to > 37.5) and a strong anti-HRV-2 activity (SI > 50 to > 200). In contrast, none of the compounds inhibited the HRV-14-induced CPE. These results indicate that [(biphenyloxy)propyl]isoxazole derivatives are potential inhibitors of HRV-2 and CVB3 replication, and make them promising agents for the specific treatment of these virus infections.
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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
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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.
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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.
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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.
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How low does iron go? Chasing the active species in fe-catalyzed cross-coupling reactions.
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
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Wang, Xinbo; Min, Shixiong; Das, Swapan Kumar; Fan, Wei; Huang, Kuo-Wei; Lai, Zhiping
2017-01-01
We report here a direct knitting Method for preparation of highly robust, effective while air- and moisture-tolerant, and readily recyclable three-dimensional (3D) porous polymer-Pd network (PPPd) from the widely used Pd(PPh3)4. Electro-beam induced Pd atom crystallization was observed for the first time in organic polymer and revealed the ultrafine dispersion of palladium atoms. Challenging types of Suzuki-Miyaura couplings, reductive coupling of aryl halides and oxidative coupling of arylboronic acid were successively catalyzed by PPPd in aqueous media. Also catalytically selective CH functionalization reactions were achieved with orders of magnitude more efficient than conventional Pd homogeneous catalysts. The strategy developed here provides a practical method for easy-to-make yet highly efficient heterogeneous catalysis.
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Wang, Xinbo
2017-10-03
We report here a direct knitting Method for preparation of highly robust, effective while air- and moisture-tolerant, and readily recyclable three-dimensional (3D) porous polymer-Pd network (PPPd) from the widely used Pd(PPh3)4. Electro-beam induced Pd atom crystallization was observed for the first time in organic polymer and revealed the ultrafine dispersion of palladium atoms. Challenging types of Suzuki-Miyaura couplings, reductive coupling of aryl halides and oxidative coupling of arylboronic acid were successively catalyzed by PPPd in aqueous media. Also catalytically selective CH functionalization reactions were achieved with orders of magnitude more efficient than conventional Pd homogeneous catalysts. The strategy developed here provides a practical method for easy-to-make yet highly efficient heterogeneous catalysis.
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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.
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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.
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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.
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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.
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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.
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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
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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.
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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...
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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
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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.
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A General Synthesis of C8-Arylpurine Phosphoramidites
Directory of Open Access Journals (Sweden)
Vorasit Vongsutilers
2009-09-01
Full Text Available A general scheme for the synthesis of C8-arylpurine phosphoramidites has been developed. C8-Arylation of C8-bromo-2′-deoxyguanosine is the key step and has been achieved through the use of a Suzuki coupling. Since the coupling reaction is conducted under aqueous conditions, it is unnecessary to protect and then deprotect the hydroxyl groups, thus saving several steps and improving overall yields. Once the C8-arylgroup is introduced, the glycosidic bond becomes very sensitive to acid catalyzed cleavage. Protection of the amino groups as the corresponding N,N-dimethylformamidine derivative improves stability of the derivatives. Synthetic C8-arylpurines were successfully used to prepare synthetic oligonucleotides.
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Liang, Yen-Peng; He, Yun-Jui; Lee, Yin-Hsuan; Chan, Yi-Tsu
2015-03-21
Three unsymmetrical, 60°-bended bisterpyridine ligands with varying phenylene spacer lengths have been synthesized via the Suzuki-Miyaura coupling reactions. Their self-assembly processes were found to be strongly dependent on the ligand geometry. Upon complexation with Zn(II) ions, only 2,4''-di(4'-terpyridinyl)-1,1':4',1''-terphenyl underwent self-selection to give a trinuclear metallomacrocycle with perfect heteroleptic connectivity and the other two afforded a mixture of constitutional isomers. The metallosupramolecular assemblies were characterized by NMR spectroscopy, electrospray mass spectrometry (ESI MS), and single-crystal X-ray diffraction. In particular, the identification of isomeric architecture was accomplished using tandem mass spectrometry (MS(2)) coupled with traveling wave ion mobility mass spectrometry (TWIM MS).
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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...
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5-Bromo-4′,5′-bis(dimethylaminofluorescein: Synthesis and Photophysical Studies
Directory of Open Access Journals (Sweden)
Jun Yeon Hwang
2018-01-01
Full Text Available In this study, three new fluorescein derivatives—5-bromo-4′,5′-dinitrofluorescein (BDNF, 5-bromo-4′,5′-diaminofluorescein (BDAF, and 5-bromo-4′,5′-bis(dimethylaminofluorescein (BBDMAF—were synthesized and their pH-dependent protolytic equilibria were investigated. In particular, BBDMAF exhibited pH-dependent fluorescence, showing strong emission only at pH 3–6. BBDMAF bears a bromine moiety and thus, can be used in various cross-coupling reactions to prepare derivatives and take advantage of its unique emission properties. To confirm this, the Suzuki and Sonogashira reactions of BBDMAF with phenylboronic acid and phenylacetylene, respectively, were performed, and the desired products were successfully obtained.
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Lehnherr, Dan; Chen, Chen; Pedramrazi, Zahra; DeBlase, Catherine R.; Alzola, Joaquin M.; Keresztes, Ivan; Lobkovsky, Emil B.
2016-01-01
A Cu-catalyzed benzannulation reaction transforms ortho(arylene ethynylene) oligomers into ortho-arylenes. This approach circumvents iterative Suzuki cross-coupling reactions previously used to assemble hindered ortho-arylene backbones. These derivatives form helical folded structures in the solid-state and in solution, as demonstrated by X-ray crystallography and solution-state NMR analysis. DFT calculations of misfolded conformations are correlated with variable-temperature 1H and EXSY NMR to reveal that folding is cooperative and more favorable in halide-substituted naphthalenes. Helical ortho-arylene foldamers with specific aromatic sequences organize functional π-electron systems into arrangements ideal for ambipolar charge transport and show preliminary promise for the surface-mediated synthesis of structurally defined graphene nanoribbons. PMID:28567248
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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.
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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.
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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.
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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
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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
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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.
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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.
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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.
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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).
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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 ...
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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.
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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.
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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
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Tang, Shi; Liu, Meirong; Gu, Cheng; Zhao, Yang; Lu, Ping; Lu, Dan; Liu, Linlin; Shen, Fangzhong; Yang, Bing; Ma, Yuguang
2008-06-06
A facile approach for synthesis of spirobifluorene trimers with peripheral carbazole functional groups by utilizing Suzuki coupling as the key reaction has been developed. These novel compounds exhibit blue emission with high quantum yields in solution and thin films, and excellent spectral stability upon photoirradiation and annealing in air. By the introduction of carbazole groups, the oxidation potentials of spirobifluorene trimers S TCPC-6 and STCPC-4 were significantly lower than that of model compound STHPH without peripheral carbazole groups, which reflect that the title compounds process higher HOMO energy level and better hole-injection ability. Highly luminescent films were obtained by electrochemical coupling between carbazole units. Pure blue-emission single-layer LEDs based on electrochemical deposition films as light emitting layers were achieved.
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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.
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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.
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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.
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DEFF Research Database (Denmark)
Petersen, Martin Helgesen; Krebs, Frederik C
2010-01-01
Thermocleavable low-band-gap polymers based on dithienylthienopyrazines were prepared and copolymerized with different donor units like dialkoxybenzene, fluorene, thiophene, and cyclopentadithiophene (CPDT) using both Stille and Suzuki cross-coupling reactions. In the solid state the band gaps...... are in the range of 1.17−1.37 eV. The polymers were explored as donor materials in bulk heterojunction solar cells together with PCBM as the acceptor material where they were shown to exhibit a photoresponse in the full absorption range up to 900 nm and power conversion efficiencies of up to 1.21% under 1 sun...
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Dang, Yizhe; Chen, Yi
2007-08-31
A class of 3,4-diaryl-2,5-dibromothiophenes (1b-5b) was synthesized by a one-pot reaction of 3,4-diaryl-2,5-dihydrothiophenes with Br2 reagent in excellent yield (83-92%). It was found that Br2 performed a double function (oxidation and bromination) during the conversion of 3,4-diaryl-2,5-dihydrothiophenes to 3,4-diaryl-2,5-dibromothiophenes. The application of 3,4-diaryl-2,5-dibromothiophenes used as building blocks was also investigated. Employing 3,4-diphenyl-2,5-dibromothiophene (1b) as a template, a class of 2,3,4,5-tetraarylthiophenes was prepared by the Suzuki coupling reaction. This provided a new and simple approach to the preparation of 2,3,4,5-tetraarylthiophenes.
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Synthesis of enyne and aryl vinyl sulfoxides: functionalization via Pummerer rearrangement.
Souza, Frederico B; Shamim, Anwar; Argomedo, Luiz M Z; Pimenta, Daniel C; Stefani, Hélio A
2015-11-01
An efficient methodology for the synthesis of aryl-substituted vinyl sulfoxides through direct substitution of aryl-substituted alkynyl grignard reagents on menthyl-p-toluenesulfinate followed by Suzuki-Miyaura cross-coupling reaction has been developed. It has also been described that the reaction of alkyl-substituted and cycloalkyl-substituted alkynyl grignard reagents with menthyl-p-toluenesulfinate led to two products, i.e., alkynyl sulfoxide derivatives, as a result of substitution, and enyne sulfoxide derivatives, which resulted from substitution followed by Michael type addition. It was possible to selectively synthesize the enyne sulfoxide derivatives by changing the concentration of the grignard reagent. These alkenyl sulfoxides were transformed into the corresponding [Formula: see text]-thio aldehydes in high yields via additive Pummerer rearrangement.
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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.
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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
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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
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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
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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.
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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.
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New Cu-based catalysts supported on TiO2 films for Ullmann SnAr-type C-O coupling reactions
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,
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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
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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...
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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.
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Zhang, Junxiang; Kang, Lauren J; Parker, Timothy C; Blakey, Simon B; Luscombe, Christine K; Marder, Seth R
2018-04-16
Abstract : Organic electronics is a rapidly growing field driven in large part by the synthesis of ∏-conjugated molecules and polymers. Traditional aryl cross-coupling reactions such as the Stille and Suzuki have been used extensively in the synthesis of ∏-conjugated molecules and polymers, but the synthesis of intermediates necessary for traditional cross-couplings can include multiple steps with toxic and hazardous reagents. Direct arylation through C-H bond activation has the potential to reduce the number of steps and hazards while being more atom-economical. Within the Center for Selective C-H Functionalization (CCHF), we have been developing C-H activation methodology for the synthesis of ∏-conjugated materials of interest, including direct arylation of difficult-to-functionalize electron acceptor intermediates and living polymerization of ∏-conjugated polymers through C-H activation.
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International Nuclear Information System (INIS)
Zhang, G.W.; Wang, L.; Xie, L.H.; Hou, X.Y.; Liu, Z.D.; Huang, W.; Huang, W.
2013-01-01
We describe bottom-up fluorenol approach to create soluble covalent organic nano molecular architectures (ONAs) as potential multicomponent organic semiconductors (MOSs). BPyFBFFA as a typical model of ONAs and MOSs exhibits a persistent chair-shaped geometric structure that consists of hole-transporting tri phenylamine (TPA), high-efficiency ter fluorene, and high-mobility pyrenes. BPyFBFFA was synthesized via the intermediates PyFA and BPyFA with iterative Friedel-Crafts reactions and Suzuki cross-coupling reactions. BPyFBFFA behaves as an efficient blue light-emitter without the low-energy green emission band. Complex diaryl fluorenes (CDAFs) are promising candidates for nano scale covalent organic frameworks and MOSs. Friedel-Crafts protocols offer versatile toolboxes for molecular architects to frame chemistry and materials, nano science, and molecular nano technology as well as molecular manufactures
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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...
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Phase Equilibria of the Sn-Ni-Si Ternary System and Interfacial Reactions in Sn-(Cu)/Ni-Si Couples
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.
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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
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Watermelon rind-mediated green synthesis of noble palladium nanoparticles: catalytic application
Lakshmipathy, R.; Palakshi Reddy, B.; Sarada, N. C.; Chidambaram, K.; Khadeer Pasha, Sk.
2015-02-01
The present study reports the feasibility of synthesis of palladium nanoparticles (Pd NPs) by watermelon rind. The aqueous extract prepared from watermelon rind, an agro waste, was evaluated as capping and reducing agent for biosynthesis of palladium nanoparticles. The formation of Pd NPs was visually monitored with change in color from pale yellow to dark brown and later monitored with UV-Vis spectroscopy. The synthesized Pd NPs were further characterized by XRD, FTIR, DLS, AFM and TEM techniques. The synthesized Pd NPs were employed in Suzuki coupling reaction as catalyst. The results reveal that watermelon rind, an agro waste, is capable of synthesizing spherical-shaped Pd NPs with catalytic activity.
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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
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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.
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Direct catalytic cross-coupling of organolithium compounds
Giannerini, Massimo; Fananas Mastral, Martin; Feringa, Ben L.
Catalytic carbon-carbon bond formation based on cross-coupling reactions plays a central role in the production of natural products, pharmaceuticals, agrochemicals and organic materials. Coupling reactions of a variety of organometallic reagents and organic halides have changed the face of modern
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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.
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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
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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.
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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.)
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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
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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)
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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.
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Palladiové nanočástice v katalýze spojovacích reakcí
Czech Academy of Sciences Publication Activity Database
Demel, Jan; Čejka, Jiří; Štěpnička, P.
2009-01-01
Roč. 103, č. 2 (2009), s. 145-153 ISSN 0009-2770 Institutional research plan: CEZ:AV0Z40400503 Keywords : palladium * palladium nanoparticles * Heck reaction * Suzuki reaction Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.717, year: 2009
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A Green Multicomponent Reaction for the Organic Chemistry Laboratory: The Aqueous Passerini Reaction
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…
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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.
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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.
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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.
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Living GenoChemetics by hyphenating synthetic biology and synthetic chemistry in vivo.
Sharma, Sunil V; Tong, Xiaoxue; Pubill-Ulldemolins, Cristina; Cartmell, Christopher; Bogosyan, Emma J A; Rackham, Emma J; Marelli, Enrico; Hamed, Refaat B; Goss, Rebecca J M
2017-08-09
Marrying synthetic biology with synthetic chemistry provides a powerful approach toward natural product diversification, combining the best of both worlds: expediency and synthetic capability of biogenic pathways and chemical diversity enabled by organic synthesis. Biosynthetic pathway engineering can be employed to insert a chemically orthogonal tag into a complex natural scaffold affording the possibility of site-selective modification without employing protecting group strategies. Here we show that, by installing a sufficiently reactive handle (e.g., a C-Br bond) and developing compatible mild aqueous chemistries, synchronous biosynthesis of the tagged metabolite and its subsequent chemical modification in living culture can be achieved. This approach can potentially enable many new applications: for example, assay of directed evolution of enzymes catalyzing halo-metabolite biosynthesis in living cells or generating and following the fate of tagged metabolites and biomolecules in living systems. We report synthetic biological access to new-to-nature bromo-metabolites and the concomitant biorthogonal cross-coupling of halo-metabolites in living cultures.Coupling synthetic biology and chemical reactions in cells is a challenging task. The authors engineer bacteria capable of generating bromo-metabolites, develop a mild Suzuki-Miyaura cross-coupling reaction compatible with cell growth and carry out the cross-coupling chemistry in live cell cultures.
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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.
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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.
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Direct catalytic asymmetric aldol-Tishchenko reaction.
Gnanadesikan, Vijay; Horiuchi, Yoshihiro; Ohshima, Takashi; Shibasaki, Masakatsu
2004-06-30
A direct catalytic asymmetric aldol reaction of propionate equivalent was achieved via the aldol-Tishchenko reaction. Coupling an irreversible Tishchenko reaction to a reversible aldol reaction overcame the retro-aldol reaction problem and thereby afforded the products in high enantio and diastereoselectivity using 10 mol % of the asymmetric catalyst. A variety of ketones and aldehydes, including propyl and butyl ketones, were coupled efficiently, yielding the corresponding aldol-Tishchenko products in up to 96% yield and 95% ee. Diastereoselectivity was generally below the detection limit of 1H NMR (>98:2). Preliminary studies performed to clarify the mechanism revealed that the aldol products were racemic with no diastereoselectivity. On the other hand, the Tishchenko products were obtained in a highly enantiocontrolled manner.
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Jevric, Martyn; Broman, Søren Lindbæk; Nielsen, Mogens Brøndsted
2013-05-03
The dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch has attracted interest as a molecular switch for advanced materials and molecular electronics. We report here two synthetic approaches using palladium catalysis for synthesizing dihydroazulene (DHA) photoswitches with thioacetate anchoring groups intended for molecular electronics applications. The first methodology involves a Suzuki coupling using tert-butyl thioether protecting groups. Conversion to the thioacetate using boron tribromide/acetyl chloride results in the formation of the product as a mixture of regioisomers mediated by a ring-opening reaction. The second approach circumvents isomerization by the synthesis of stannanes as intermediates and their use in a Stille coupling. Although fully unsaturated azulenes are formed as byproducts during the synthesis of the DHA stannanes, this approach allowed the regioselective incorporation of the thioacetate anchoring group in either one of the two ends (positions 2 or 7) or at both.
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Peroxidase-Catalyzed Oxidative Coupling of Phenols in the Presence of Geosorbents
Energy Technology Data Exchange (ETDEWEB)
Huang, Qingguo; Weber, Walter J., Jr.
2003-03-26
This study focuses on elucidation of the reaction behaviors of peroxidase-mediated phenol coupling in the presence of soil/sediment materials. Our goal is a mechanistic understanding of the influences of geosorbent materials on enzymatic coupling reactions in general and the development of methods for predicting such influences. Extensive experimental investigations of coupling reactions were performed under strategically selected conditions in systems containing model geosorbents having different properties and chemical characteristics. The geosorbents tested were found to influence peroxidase-mediated phenol coupling through one or both of two principal mechanisms; i.e., (1) mitigation of enzyme inactivation and/or (2) participation in cross-coupling reactions. Such influences were found to correlate with the chemical characteristics of the sorbent materials and to be simulated well by a modeling approach designed in this paper. The results of the study have important implications for potential engineering implementation and enhancement of enzymatic coupling reactions in soil/subsurface remediation practice.
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Insights into Sonogashira cross-coupling by high-throughput kinetics and descriptor modeling
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.
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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.
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Frei, Reto; Breitbach, Anthony S; Blackwell, Helen E
2012-05-01
We report the highly efficient syntheses of a series of focused libraries in the small molecule macroarray format using Suzuki-Miyaura and copper-catalyzed azide-alkyne cycloaddition (or "click") reactions. The libraries were based on stilbene and triazole scaffolds, which are known to have a broad range of biological activities, including quorum-sensing (QS) modulation in bacteria. The library products were generated in parallel on the macroarray in extremely short reaction times (~10-20 min) and isolated in excellent purities. Biological testing of one macroarray library post-cleavage (ex situ) revealed several potent agonists of the QS receptor, LuxR, in Vibrio fischeri. These synthetic agonists, in contrast to others that we have reported, were only active in the presence of the native QS signal in V. fischeri, which is suggestive of a different mode of activity. Notably, the results presented herein showcase the ready compatibility of the macroarray platform with chemical reactions that are commonly utilized in small molecule probe and drug discovery today. As such, this work serves to expand the utility of the small molecule macroarray as a rapid and operationally straightforward approach toward the synthesis and screening of bioactive agents.
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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.
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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
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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.
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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
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Mechanism of the Suzuki–Miyaura Cross-Coupling Reaction Mediated by [Pd(NHC)(allyl)Cl] Precatalysts
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.
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A coupled model of transport-reaction-mechanics with trapping. Part I - Small strain analysis
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.
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Reactions to framing of cessation messages: insights from dual-smoker couples.
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.
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/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.
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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.
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Neuron-glia metabolic coupling: Role in plasticity and neuroprotection
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).
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Kinetic Studies of Oxidative Coupling of Methane Reaction on Model Catalysts
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
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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...
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Gorgun, Kamuran; Caglar, Yasemin
2018-04-01
Carbazole compounds in particular represent one of the most intensely used and studied class of semiconducting materials. In this study, considering the information given in the literature the Ullman and Suzuki-Miyaura coupling reaction were carried out using carbazole, 1,4-dibromobenzene and pyrene-1-boronic acid. The synthesized carbazole derivatives are characterized by 1H NMR and elemental analysis. The spectroscopic and thermal properties of the synthesized novel carbazole derivative 9-(4-(pyren-4-yl)phenyl)-9H-carbazole (Cz-py) were investigated. And also, the n-Si/p-Cz:py heterojunction diode was fabricated. The electrical properties of this diode were characterized by current-voltage (I-V) and capacitance-voltage (C-V) measurements.
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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.
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Metabolite coupling in genome-scale metabolic networks
Directory of Open Access Journals (Sweden)
Palsson Bernhard Ø
2006-03-01
Full Text Available Abstract Background Biochemically detailed stoichiometric matrices have now been reconstructed for various bacteria, yeast, and for the human cardiac mitochondrion based on genomic and proteomic data. These networks have been manually curated based on legacy data and elementally and charge balanced. Comparative analysis of these well curated networks is now possible. Pairs of metabolites often appear together in several network reactions, linking them topologically. This co-occurrence of pairs of metabolites in metabolic reactions is termed herein "metabolite coupling." These metabolite pairs can be directly computed from the stoichiometric matrix, S. Metabolite coupling is derived from the matrix ŜŜT, whose off-diagonal elements indicate the number of reactions in which any two metabolites participate together, where Ŝ is the binary form of S. Results Metabolite coupling in the studied networks was found to be dominated by a relatively small group of highly interacting pairs of metabolites. As would be expected, metabolites with high individual metabolite connectivity also tended to be those with the highest metabolite coupling, as the most connected metabolites couple more often. For metabolite pairs that are not highly coupled, we show that the number of reactions a pair of metabolites shares across a metabolic network closely approximates a line on a log-log scale. We also show that the preferential coupling of two metabolites with each other is spread across the spectrum of metabolites and is not unique to the most connected metabolites. We provide a measure for determining which metabolite pairs couple more often than would be expected based on their individual connectivity in the network and show that these metabolites often derive their principal biological functions from existing in pairs. Thus, analysis of metabolite coupling provides information beyond that which is found from studying the individual connectivity of individual
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Extent of reaction in open systems with multiple heterogeneous reactions
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.
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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
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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).
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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.
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Arthuis, Martin; Pontikis, Renée; Florent, Jean-Claude
2009-03-06
An efficient synthetic route toward the synthesis of highly substituted arylethylidene-isoquinolinones/isochromanones is reported. The tandem carbopalladation/Suzuki-Miyaura coupling sequence stereoselectively provided various functionalized polycyclic compounds in moderate to excellent yields.
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Transition metal complexes bearing NHC ligands substituted with secondary polyfluoroalkyl groups
Czech Academy of Sciences Publication Activity Database
Kolaříková, V.; Šimůnek, O.; Rybáčková, M.; Cvačka, Josef; Březinová, Anna; Kvíčala, J.
2015-01-01
Roč. 44, č. 45 (2015), s. 19663-19673 ISSN 1477-9226 Institutional support: RVO:61388963 Keywords : complexes * catalysis * Suzuki-Miyaura coupling Subject RIV: CA - Inorganic Chemistry Impact factor: 4.177, year: 2015
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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.
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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.
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Propagating fronts in reaction-transport systems with memory
Energy Technology Data Exchange (ETDEWEB)
Yadav, A. [Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314 (United States)], E-mail: ayadav1@lsu.edu; Fedotov, Sergei [School of Mathematics, University of Manchester, Manchester M60 1DQ (United Kingdom)], E-mail: sergei.fedotov@manchester.ac.uk; Mendez, Vicenc [Grup de Fisica Estadistica, Departament de Fisica, Universitat Autonoma de Barcelona, E-08193 Bellaterra (Spain)], E-mail: vicenc.mendez@uab.es; Horsthemke, Werner [Department of Chemistry, Southern Methodist University, Dallas, TX 75275-0314 (United States)], E-mail: whorsthe@smu.edu
2007-11-26
In reaction-transport systems with non-standard diffusion, the memory of the transport causes a coupling of reactions and transport. We investigate the effect of this coupling for systems with Fisher-type kinetics and obtain a general analytical expression for the front speed. We apply our results to the specific case of subdiffusion.
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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.
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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.
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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.
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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.
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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.
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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.
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Channel coupling in A(e,e N)B reactions
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...
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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.
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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
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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.
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Spatial coupling in heterogeneous catalysis
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.
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Astruc, Didier; Ornelas, Cátia; Diallo, Abdou K; Ruiz, Jaime
2010-07-20
This article is an account of the work carried out in the authors' laboratory illustrating the usefulness of dendrimer design for nanoparticle palladium catalysis. The "click" synthesis of dendrimers constructed generation by generation by 1-->3 C connectivity, introduces 1,2,3-triazolyl ligands insides the dendrimers at each generation. Complexation of the ligands by Pd(II) followed by reduction to Pd(0) forms dendrimer-stabilized Pd nanoparticles (PdNPs) that are extremely reactive in the catalysis of olefin hydrogenation and C-C bond coupling reactions. The stabilization can be outer-dendritic for the small zeroth-generation dendrimer or intra-dendritic for the larger first- and second-generation dendrimers. The example of the Miyaura-Suzuki reaction that can be catalyzed by down to 1 ppm of PdNPs with a "homeopathic" mechanism (the less, the better) is illustrated here, including catalysis in aqueous solvents.
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Zheng, Guangchao; Kaefer, Katharina; Mourdikoudis, Stefanos; Polavarapu, Lakshminarayana; Vaz, Belén; Cartmell, Samantha E; Bouleghlimat, Azzedine; Buurma, Niklaas J; Yate, Luis; de Lera, Ángel R; Liz-Marzán, Luis M; Pastoriza-Santos, Isabel; Pérez-Juste, Jorge
2015-01-15
We present a novel strategy based on the immobilization of palladium nanoparticles (Pd NPs) on filter paper for development of a catalytic system with high efficiency and recyclability. Oleylamine-capped Pd nanoparticles, dispersed in an organic solvent, strongly adsorb on cellulose filter paper, which shows a great ability to wick fluids due to its microfiber structure. Strong van der Waals forces and hydrophobic interactions between the particles and the substrate lead to nanoparticle immobilization, with no desorption upon further immersion in any solvent. The prepared Pd NP-loaded paper substrates were tested for several model reactions such as the oxidative homocoupling of arylboronic acids, the Suzuki cross-coupling reaction, and nitro-to-amine reduction, and they display efficient catalytic activity and excellent recyclability and reusability. This approach of using NP-loaded paper substrates as reusable catalysts is expected to open doors for new types of catalytic support for practical applications.
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Journal of Chemical Sciences | Indian Academy of Sciences
Indian Academy of Sciences (India)
Supported Pd nanoparticles on acetyl acetone modified silica gel was prepared and its catalytic application in the Suzuki-Miyaura reaction of various aryl halides with phenylboronic acid was investigated. The reaction was carried out in water as solvent under green conditions in the presence of NaHCO3 as the base.
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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.
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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.
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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.
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The Stille Reaction (Vittorio Farina, Venkat Krishnamurthy, and William J. Scott)
Cochran, John C.
1999-10-01
In 1997, Volume 50 of Organic Reactions was published in a handsome and appropriate gold hard-cover edition. This was only the third volume in this prestigious series that consisted of a single chapter. The treatise, The Stille Reaction, describes a palladium-catalyzed cross-coupling between a carbon ligand on tin and a carbon with electrophilic character. This reaction has been around only since 1977, and the literature is covered here through 1994 with a few references in 1995. It is truly astounding that, in the space of about 17 years, a new reaction could generate enough literature for not only a chapter in Organic Reactions, but a complete volume of 652 pages, 864 literature citations, and more than 4300 specific reaction examples. The editorial board of Organic Reactions has graciously decided to make this extensive review available to a broader audience by authorizing a paperback edition of The Stille Reaction. While the mechanistic details of the Stille reaction are generally understood, there are many fine points that must be tuned to each case. For instance, about 15 different solvents have been used, ranging in polarity from benzene to water; at least ten different ligands for the palladium atom are available and they range from hard to soft; CuI, Ag2CO3, and LiCl are sometimes useful cocatalysts but sometimes have no effect, and in some cases LiCl is inhibitory; vinyl triflates couple with alkenyl-, alkynyl- and allylstannanes but not with arylstannanes; reaction temperatures vary from room temperature to refluxing DMF. An important consideration is that most stannanes are reasonably air and moisture stable and do not react with most common functional groups. Thus, it is not necessary to build protection-deprotection sequences into the synthetic scheme. The extensive reaction examples are arranged in 33 tables that show, for each reaction, the structures of the electrophile, the stannane, and the product and specify the catalyst, cocatalyst, solvent
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Nickel(II) complexes containing ONS donor ligands: Synthesis ...
Indian Academy of Sciences (India)
MS received 23 July 2014; revised 28 November 2014; accepted 28 November 2014 ... Nickel(II) complexes; X-ray structure; Kumada-Corriu reaction; Suzuki reaction; ...... 29 75. 37. Kovala-Demertzi D, Demertzis M A, Miller J R,. Papadopoulou C ... Biochem. 86 555. 38. Bellamy L J 1985 In The Infrared Spectra of Complex.
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Femtosecond laser control of chemical reactions
CSIR Research Space (South Africa)
Du Plessis, A
2010-08-31
Full Text Available Femtosecond laser control of chemical reactions is made possible through the use of pulse-shaping techniques coupled to a learning algorithm feedback loop – teaching the laser pulse to control the chemical reaction. This can result in controllable...
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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}.
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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.
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Modeling non-adiabatic photoexcited reaction dynamics in condensed phases
International Nuclear Information System (INIS)
Coker, D.F.
2003-01-01
Reactions of photoexcited molecules, ions, and radicals in condensed phase environments involve non-adiabatic dynamics over coupled electronic surfaces. We focus on how local environmental symmetries can effect non-adiabatic coupling between excited electronic states and thus influence, in a possibly controllable way, the outcome of photo-excited reactions. Semi-classical and mixed quantum-classical non-adiabatic molecular dynamics methods, together with semi-empirical excited state potentials are used to probe the dynamical mixing of electronic states in different environments from molecular clusters, to simple liquids and solids, and photo-excited reactions in complex reaction environments such as zeolites
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Sn-In-Ag phase equilibria and Sn-In-(Ag)/Ag interfacial reactions
International Nuclear Information System (INIS)
Chen Sinnwen; Lee Wanyu; Hsu Chiaming; Yang Chingfeng; Hsu Hsinyun; Wu Hsinjay
2011-01-01
Research highlights: → Thermodynamic models of Sn-In and Sn-In-Ag are developed using the CALPHAD approach. → Reaction layer in the Sn-In-(Ag)/Ag couples at 100 deg. C is thinner than those at 25 deg. C, 50 deg. C, and 75 deg. C. → Reactions in the Sn-20 wt%In-2.8 wt%Ag/Ag couples are faster than those in the Sn-20 wt%In/Ag couples. - Abstract: Experimental verifications of the Sn-In and Sn-In-Ag phase equilibria have been conducted. The experimental measurements of phase equilibria and thermodynamic properties are used for thermodynamic modeling by the CALPHAD approach. The calculated results are in good agreement with experimental results. Interfacial reactions in the Sn-In-(Ag)/Ag couples have been examined. Both Ag 2 In and AgIn 2 phases are formed in the Sn-51.0 wt%In/Ag couples reacted at 100 and 150 deg. C, and only the Ag 2 In phase is formed when reacted at 25, 50 and 75 deg. C. Due to the different growth rates of different reaction phases, the reaction layer at 100 deg. C is thinner than those at 25 deg. C, 50 deg. C, and 75 deg. C. In the Sn-20.0 wt%In/Ag couples, the ζ phase is formed at 250 deg. C and ζ/AgIn 2 phases are formed at 125 deg. C. Compared with the Sn-20 wt%In/Ag couples, faster interfacial reactions are observed in the Sn-20.0 wt%In-2.8 wt%Ag/Ag couples, and minor Ag addition to Sn-20 wt%In solder increases the growth rates of the reaction phases.
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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.
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Iwanaga, Tetsuo; Ogawa, Marina; Yamauchi, Tomokazu; Toyota, Shinji
2016-05-20
We designed anthracene bisimide (ABI) derivatives having two triphenylamine (TPA) groups as donor units at the 9,10-positions to form a novel π-conjugated donor-acceptor system. These compounds and their analogues with ethynylene linkers were synthesized by Suzuki-Miyaura and Sonogashira coupling reactions, respectively. In UV-vis spectra, the linker-free derivatives showed broad absorption bands arising from intramolecular charge-transfer interactions. Introducing ethynylene linkers resulted in a considerable red shift of the absorption bands. In fluorescence spectra, the ethynylene derivatives showed intense emission bands at 600-650 nm. Their photophysical and electrochemical properties were compared with those of the corresponding mono TPA derivatives on the basis of theoretical calculations and cyclic voltammetry to evaluate the intramolecular electronic interactions between the donor and acceptor units.
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Solid-Phase Synthesis of Smac Peptidomimetics Incorporating Triazoloprolines and Biarylalanines
DEFF Research Database (Denmark)
Le Quement, Sebastian T.; Ishoey, Mette; Petersen, Mette T.
2011-01-01
by deactivating proteolytic caspases. The Smac protein has an antagonistic effect on IAPs, thus providing structural clues for the synthesis of new pro-apoptotic compounds. Herein, we report a solid-phase approach for the synthesis of Smac-derived tetrapeptide libraries. On the basis of a common (N......-Me)AVPF sequence, peptides incorporating triazoloprolines and biarylalanines were synthesized by means of Cu(I)-catalyzed azide–alkyne cycloaddition and Pd-catalyzed Suzuki cross-coupling reactions. Solid-phase procedures were optimized to high efficiency, thus accessing all products in excellent crude purities...... and yields (both typically above 90%). The peptides were subjected to biological evaluation in a live/dead cellular assay which revealed that structural decorations on the AVPF sequence indeed are highly important for cytotoxicity toward HeLa cells....
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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.
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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.
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Synthetic approach of norbadione A: new preparation of alcohols from sulfones and boron compounds
International Nuclear Information System (INIS)
Billaud, C.
2005-12-01
The synthetic approach of norbadione A, a pigment from mushrooms related to pulvinic acids, was studied. This compound has the property to complex caesium and has shown an antioxidant activity. The first strategy, based on a double Suzuki-Miyaura coupling between a naphtho-lactone with two boron functions and two pulvinic moieties with a triflate was unsuccessful and has shown a deactivating effect of the lactone. Modifications aimed to inhibit the electro-attracting character of the lactone permitted to obtain a bis(coupled) product with a poor yield. A second approach based on a the cyclization of enol aryl-acetates was studied in order to build the pulvinic moiety in several steps. The important reaction of introduction of an alkyl-acetate from a triflate was realised by a palladium-mediated coupling. The cyclization attempts carried out using a naphthalenic compound allowed us to isolate a monocyclised product. A parallel study was to first build a tetronic moiety and then to construct the exocyclic double bond by a method developed in the laboratory for the preparation of an iodated pulvinic compound. Finally, a new preparation of alcohols from sulfones and boron compounds was developed. Two known reactions in the chemistry of boron were combined. The first one is the reaction between anions of sulfones and tri-alkyl-boranes, the second one is a thermal isomerization which places the boron atom in a terminal position. A new preparation of primary alcohols was thus carried out. (author)
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Palladium-Catalyzed Suzuki–Miyaura Cross-Coupling in Continuous Flow
Directory of Open Access Journals (Sweden)
Christophe Len
2017-05-01
Full Text Available Carbon–carbon cross-coupling reactions are among the most important processes in organic chemistry and Suzuki–Miyaura reactions are the most widely used protocols. For a decade, green chemistry and particularly catalysis and continuous flow, have shown immense potential in achieving the goals of “greener synthesis”. To date, it seems difficult to conceive the chemistry of the 21st century without the industrialization of continuous flow process in the area of pharmaceuticals, drugs, agrochemicals, polymers, etc. A large variety of palladium Suzuki–Miyaura cross-coupling reactions have been developed using a continuous flow sequence for preparing the desired biaryl derivatives. Our objective is to focus this review on the continuous flow Suzuki–Miyaura cross-coupling using homogeneous and heterogeneous catalysts.
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Indian Academy of Sciences (India)
Konstantin Novoselov, University of Manchester, Manchester, United Kingdom. Chemistry. “for palladium-catalyzed cross couplings in organic synthesis” to. Richard F Heck, University of Delaware, USA;. Ei-ichi Negishi, Purdue University, West Lafayette, IN, USA;. Akira Suzuki, Hokkaido University, Sapporo, Japan.
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Synthesis of azaphenanthridines via anionic ring closure
DEFF Research Database (Denmark)
Hansen, Henriette Møller; Lysén, M.; Begtrup, M.
2005-01-01
A new and convergent synthesis of azaphenanthridines via an anionic ring closure is reported. Ortho-lithiation/in situ borylation of cyanopyridines produces the corresponding cyanopyridylboronic esters, which undergo a Suzuki-Miyaura cross-coupling to give the key intermediates. Addition of lithium...
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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.
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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.
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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
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Fusion barrier distributions in 28,30Si + 124Sn reactions
International Nuclear Information System (INIS)
Danu, L.S.; Nayak, B.K.; Biswas, D.C.; Saxena, A.; Thomas, R.G.; Mirgule, E.T.; Choudhury, R.K.
2009-01-01
The coupling of various degrees of freedom such as static deformation, inelastic excitation and nucleon transfer with the relative motion gives rise to a distribution of barrier in heavy ion induced fusion reactions. The barrier distribution is a fingerprint of the reaction characterizing the important channel couplings. The relative importance of various couplings in fusion reaction is of topical interest. In an earlier study with deformed projectiles 28,30 Si on 115 In target, it was observed that the barrier distributions get affected due to coulomb reorientation of the deformed projectile nuclei in the field of target nucleus thus giving rise to fusion hindrance at sub-barrier energies. In that study, we considered deformed projectile rotational and positive Q-value transfer channel couplings to relative motion in fusion for investigation of Coulomb reorientation and no inelastic coupling of the 115 In target was considered. In the present work, we have extended the measurements with 124 Sn target and inelastic coupling of target has been considered in the coupled channel calculations. The fusion barrier distributions for 28,30 Si + 124 Sn systems have been obtained by quasi-elastic scattering measurements at backward angles and the results compared with the predictions of coupled channel calculations
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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.
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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
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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...
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Mamane, Victor; Aubert, Emmanuel; Peluso, Paola; Cossu, Sergio
2013-08-02
Lithiation of the achiral tetrahalogenated 4,4'-bipyridine 1 with alkyllithiums was investigated. n-BuLi was found to induce either the chlorine-directed deprotolithiation reaction alone or with a concomitant halogen-lithium exchange furnishing after iodine trapping chiral 4,4'-bipyridines 2 and 6, respectively. The role of n-BuLi in the deprotolithiation process of 1 was elucidated on the basis of isolated secondary derivatives. After deprotolithiation, the lithiated species could be trapped by different electrophiles such as MeI, TMSCl, MeSSMe, R3SnCl (R = Me or n-Bu), and PPh2Cl. Moreover, 4,4'-bipyridine 2 was submitted to cross-coupling reactions (Suzuki and Sonogashira) which occurred selectively at the carbon-iodine bond. All compounds of this new family of atropisomeric 4,4'-bipyridines were separated by chiral HPLC (high-performance liquid chromatography), and the absolute configurations of obtained enantiomers were mainly assigned by XRD (X-ray diffraction) using anomalous dispersion.
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Synthesis of Arylthiopyrimidines by Copper-catalyzed Aerobic Oxidative C-S Cross-coupling
Energy Technology Data Exchange (ETDEWEB)
Lee, Ok Suk; Kim, Hyeji; Sohn, Jeong-Hun [Chungnam National University, Daejeon (Korea, Republic of); Lee, Hee-Seung [KAIST, Daejeon (Korea, Republic of); Shin, Hyunik [Yonsung Fine Chemicals R and D Center, Suwon (Korea, Republic of)
2016-02-15
Copper-catalyzed C–S cross-coupling reactions have been considered as powerful tools in synthetic chemistry and utilized for diverse heterocycle syntheses. In the reactions, the aspects of no need of ligands has been particular advantage over other metal catalysis. We have developed a Cu-catalyzed cascade reaction for the synthesis of fully substituted 2-arylthiopyrimidines from 3,4-dihydropyrimidine-2(1H)-thiones (DHPMs) under aerobic conditions. This cascade reaction of DHPM with aryl iodide proceeds presumably via sequential tautomerization, C–S cross-coupling, and oxidative dehydrogenation (oxidation followed by elimination). Considering that DHPM substrates were easily synthesized by Biginelli three component coupling reaction of aryl aldehyde, β-ketoester, and thiourea, the present method provides a direct access toward diverse 2-arylthiopyrimidines which have been used as a prominent substructure of drug molecules.
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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.
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Investigations of chemical reactions between U-Zr alloy and FBR cladding materials
International Nuclear Information System (INIS)
Ishii, Tetsuya; Ukai, Shigeharu
2005-07-01
U-Pu-Zr alloys are candidate materials for commercial FBR fuel. However, informations about chemical reactions with cladding materials developed by JNC for commercial FBR have not been well obtained. In this work, the reaction zones formed in four diffusion couples U-10wt.%Zr/PNC-FMS, U-10wt.%Zr/9Cr-ODS, U-10wt.%Zr/12Cr-ODS, and U-10wt.%Zr/Fe at about 1013K have been examined and following results were obtained. 1) At about 1013K, in the U-10wt.%Zr/Fe couple, the liquid phase zones were obtained. In the other couples U-10wt.%Zr/PNC-FMS, U-10wt.%Zr/9Cr-ODS and U-10wt.%Zr/12Cr-ODS, no liquid phase zones were obtained. The obtained chemical reaction zones in the later 3 couples were similar to the reported ones obtained in U-Zr/Fe couples without liquid phase formation. In comparison with the reaction zones obtained in the U-10wt.%Zr/Fe couple, the reaction zones inside cladding materials obtained in the PNC-FMS, 9Cr-ODS, and 12Cr-ODS couples were thin. 2) From the investigations of relationship between the obtained depths of the chemical reaction zones inside cladding materials and composition of the cladding materials, it was considered that the depth of chemical reaction zone would depend on the Cr content of the cladding materials and the depth would decrease with increasing Cr content, resulting in prevention of liquid phase formation. 3) From the investigations of the mechanisms of chemical reactions between U-Pu-Zr/cladding materials, it was considered that the same effect of Cr obtained in the U-Zr/cladding materials would be expected in U-Pu-Zr/cladding materials. Those seemed to indicate that the threshold temperatures of liquid phase formation for U-Pu-Zr/PNC-FMS, U-Pu-Zr/9Cr-ODS, and U-Pu-Zr/12Cr-ODS might be higher than that for U-Pu-Zr/Fe. (author)
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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
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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
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Directory of Open Access Journals (Sweden)
Azzedine Bouleghlimat
2017-09-01
Full Text Available In this communication, we present studies of the oxidative homocoupling of arylboronic acids catalyzed by immobilised palladium nanoparticles in aqueous solution. This reaction is of significant interest because it shares a key transmetallation step with the well-known Suzuki-Miyaura cross-coupling reaction. Additives can have significant effects on catalysis, both in terms of reaction mechanism and recovery of catalytic species, and our aim was to study the effect of added halides on catalytic efficiency and catalyst recovery. Using kinetic studies, we have shown that added halides (added as NaCl and NaBr can increase the catalytic activity of the palladium nanoparticles more than 10-fold, allowing reactions to be completed in less than half a day at 30 °C. However, this increased activity comes at the expense of catalyst recovery. The results are in agreement with a reaction mechanism in which, under conditions involving high concentrations of chloride or bromide, palladium leaching plays an important role. Considering the evidence for analogous reactions occurring on the surface of palladium nanoparticles under different reaction conditions, we conclude that additives can exert a significant effect on the mechanism of reactions catalyzed by nanoparticles, including switching from a surface reaction to a solution reaction. The possibility of this switch in mechanism may also be the cause for the disagreement on this topic in the literature.
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Su, Gaoxing; Jiang, Huaqiao; Zhu, Hongyan; Lv, Jing-Jing; Yang, Guohai; Yan, Bing; Zhu, Jun-Jie
2017-08-31
Plasmonic Au-Pd nanostructures have drawn significant attention for use in heterogeneous catalysis. In this study, palladium nanodendrite-tipped gold nanorods (PdND-T-AuNRs) were subjected to a facile fabrication under mild reaction conditions. The palladium amounts on the two tips were tunable. In the preparation of PdND-T-AuNRs, dense capped AuNRs, a low reaction temperature, and suitable stabilizing agents were identified as critical reaction parameters for controlling palladium nanodendrites deposited on both ends of AuNRs. After overgrowth with palladium nanodendrites, the longitudinal surface plasmonic resonance peaks of PdND-T-AuNRs were red-shifted from 810 nm to 980 nm. The electrocatalytic activity of PdND-T-AuNRs for ethanol oxidation was examined, which was a bit weaker than that of cuboid core-shell Au-Pd nanodendrites; however, PdND-T-AuNRs were more stable in ethanol electrooxidation. Moreover, the photocatalytic activity of PdND-T-AuNRs for Suzuki cross-coupling reactions was investigated. At room temperature, nearly 100% yield was obtained under laser irradiation. The results can further enhance our capability of fine-tuning the optical, electronic, and catalytic properties of the bimetallic Au-Pd nanostructures.
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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.
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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.)
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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.
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Ruthenium(ii)-catalyzed olefination via carbonyl reductive cross-coupling.
Wei, Wei; Dai, Xi-Jie; Wang, Haining; Li, Chenchen; Yang, Xiaobo; Li, Chao-Jun
2017-12-01
Natural availability of carbonyl groups offers reductive carbonyl coupling tremendous synthetic potential for efficient olefin synthesis, yet the catalytic carbonyl cross-coupling remains largely elusive. We report herein such a reaction, mediated by hydrazine under ruthenium(ii) catalysis. This method enables facile and selective cross-couplings of two unsymmetrical carbonyl compounds in either an intermolecular or intramolecular fashion. Moreover, this chemistry accommodates a variety of substrates, proceeds under mild reaction conditions with good functional group tolerance, and generates stoichiometric benign byproducts. Importantly, the coexistence of KO t Bu and bidentate phosphine dmpe is vital to this transformation.
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Coupled geochemical and solute transport code development
International Nuclear Information System (INIS)
Morrey, J.R.; Hostetler, C.J.
1985-01-01
A number of coupled geochemical hydrologic codes have been reported in the literature. Some of these codes have directly coupled the source-sink term to the solute transport equation. The current consensus seems to be that directly coupling hydrologic transport and chemical models through a series of interdependent differential equations is not feasible for multicomponent problems with complex geochemical processes (e.g., precipitation/dissolution reactions). A two-step process appears to be the required method of coupling codes for problems where a large suite of chemical reactions must be monitored. Two-step structure requires that the source-sink term in the transport equation is supplied by a geochemical code rather than by an analytical expression. We have developed a one-dimensional two-step coupled model designed to calculate relatively complex geochemical equilibria (CTM1D). Our geochemical module implements a Newton-Raphson algorithm to solve heterogeneous geochemical equilibria, involving up to 40 chemical components and 400 aqueous species. The geochemical module was designed to be efficient and compact. A revised version of the MINTEQ Code is used as a parent geochemical code
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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.
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Achieving Synchronization in Arrays of Coupled Differential Systems with Time-Varying Couplings
Directory of Open Access Journals (Sweden)
Xinlei Yi
2013-01-01
Full Text Available We study complete synchronization of the complex dynamical networks described by linearly coupled ordinary differential equation systems (LCODEs. Here, the coupling is timevarying in both network structure and reaction dynamics. Inspired by our previous paper (Lu et al. (2007-2008, the extended Hajnal diameter is introduced and used to measure the synchronization in a general differential system. Then we find that the Hajnal diameter of the linear system induced by the time-varying coupling matrix and the largest Lyapunov exponent of the synchronized system play the key roles in synchronization analysis of LCODEs with identity inner coupling matrix. As an application, we obtain a general sufficient condition guaranteeing directed time-varying graph to reach consensus. Example with numerical simulation is provided to show the effectiveness of the theoretical results.
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Catalytic Organometallic Reactions of Ammonia
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
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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
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Concise Synthesis of Macrocycles by Multicomponent Reactions
Abdelraheem, Eman M. M.; Khaksar, Samad; Dömling, Alexander
2018-01-01
A short reaction pathway was devised to synthesize a library of artificial 18-27-membered macrocycles. The five-step reaction sequence involves ring opening of a cyclic anhydride with a diamine, esterification, coupling with an amino acid isocyanide, saponification, and, finally, macro-ring closure
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Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling
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
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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.
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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.
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Bray–Liebhafsky oscillatory reaction in the radiofrequency electromagnetic field
Energy Technology Data Exchange (ETDEWEB)
Stanisavljev, Dragomir R., E-mail: dragisa@ffh.bg.ac.rs [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, P.O. Box 473, 11001 Belgrade (Serbia); Velikić, Zoran [Institute of Physics, University of Belgrade, Pregrevica 118, Zemun (Serbia); Veselinović, Dragan S.; Jacić, Nevena V.; Milenković, Maja C. [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, P.O. Box 473, 11001 Belgrade (Serbia)
2014-09-30
Highlights: • Oscillatory Bray–Liebhafsky reaction is coupled with the radiofrequency radiation. • The effects of radiofrequency field on oscillatory parameters are investigated. • Radiofrequency power of up to the 0.2 W did not produced observable changes. • The explanation related with dissipative and capacitive effects is given. • Open the possibility of investigations of reactive effects on biological systems. - Abstract: Oscillatory Bray–Liebhafsky (BL) reaction is capacitively coupled with the electromagnetic radiation in the frequency range 60–110 MHz. Because of the specific reaction dynamics characterized by several characteristic parameters (induction period, period between chemical oscillations and their amplitude) it served as a good model system for the investigation of the effects of radiofrequent (RF) radiation. RF power of up to 0.2 W did not produce observable changes of the BL reaction parameters in the limit of the experiment reproductivity. Results indicate that, under the given experimental conditions, both dissipative and reactive properties of the solution are not considerably coupled with the RF electrical field.
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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)
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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
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Investigation of coupling scheme for neutronic and thermal-hydraulic codes
International Nuclear Information System (INIS)
Wang Guoli; Yu Jianfeng; Pen Muzhang; Zhang Yuman.
1988-01-01
Recently, a number of coupled neutronics/thermal-hydraulics codes have been used in reaction design and safty analysis, which have been obtained by coupling previous neutronic and thermal-hydraulic codes. The different coupling schemes affect computer time and accuracy of calculation results. Numberical experiments of several different coupling schemes and some heuristic results are described
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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.)
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Organic Reactions in Aqueous Media (by Chao-Jun Li and Tak-Hang Chan)
Rosan, Reviewed Alan M.
2000-06-01
the index. The text does not explicitly include a discussion of what has come to be broadly termed biphasic reaction conditions. Understandably, enzymatic reactions are beyond the scope of the presentation. This book has a decidedly applied character with an understated environmental theme, and the authors succinctly present the extraordinary effects of water on the kinetics, efficiency, and stereoselectivity of a large number of diverse reactions. In addition to their emphasis on the historically significant aqueous Diels-Alder reaction, discovered in 1980, and the literature regarding reactions of various nucleophilic organometals, the authors are to be commended for gathering together a wide and diverse body of information: it is clear that many of the examples shown are gems buried among larger bodies of work. Thus the book does an excellent job of culling and surveying a vast amount of data. There is, however, less emphasis on organizing the mechanistic bases underlying these often dramatic effects. For example, the apparent lack of generality of the effect of water on rate and selectivity in pericyclic reactions calls for some theoretical foundation. The singularly effective use of aqueous TlOH in the Suzuki reaction is cited without comment. On the other hand, the authors' concept of a mechanistic triad that incorporates to various degrees anion, radical, or covalent character in the carbon-carbon bond-forming step between various organometals and carbonyl substrates is appealing and suggests the need for future sophisticated experimental design. The most interesting sections are those dealing with synthesis and industrial applications. Unfortunately the latter is also the shortest chapter. The synthetic examples are timely and well chosen and include water-promoted Heck, Stille, Suzuki, and aldol reactions. There is an extensive, highly informative listing and survey of the use of water-soluble phosphines (both achiral and chiral) and an excellent discussion
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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)
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Modification of aniline containing proteins using an oxidative coupling strategy.
Hooker, Jacob M; Esser-Kahn, Aaron P; Francis, Matthew B
2006-12-13
A new bioconjugation reaction has been developed based on the chemoselective modification of anilines through an oxidative coupling pathway. Aryl amines were installed on the surface of protein substrates through lysine acylation reactions or through the use of native chemical ligation techniques. Upon exposure to NaIO4 in aqueous buffer, the anilines coupled rapidly to the aromatic rings of N,N-dialkyl-N'-acyl-p-phenylenediamines. The identities of the reaction products were confirmed using ESI-MS and through comparison to small molecule analogs. Control experiments indicated that none of the native amino acids participated in the reaction. The resulting bioconjugates were found to be stable toward hydrolysis from pH 4 to pH 11 and in the presence of many commonly used oxidants, reductants, and nucleophiles. A fluorescent phenylenediamine reagent was synthesized for the selective detection of aniline labeled proteins in mixtures, and the reaction was used to append the C-terminus of the green fluorescent protein with a single PEG chain. When combined with techniques for the incorporation of unnatural amino acids into proteins, this bioorthogonal coupling method should prove useful for a number of applications requiring a high degree of labeling specificity.
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Scalable BDDC Algorithms for Cardiac Electromechanical Coupling
Pavarino, L. F.
2017-03-17
The spread of electrical excitation in the cardiac muscle and the subsequent contraction-relaxation process is quantitatively described by the cardiac electromechanical coupling model. The electrical model consists of the Bidomain system, which is a degenerate parabolic system of two nonlinear partial differential equations (PDEs) of reaction-diffusion type, describing the evolution in space and time of the intra- and extracellular electric potentials. The PDEs are coupled through the reaction term with a stiff system of ordinary differential equations (ODEs), the membrane model, which describes the flow of the ionic currents through the cellular membrane and the dynamics of the associated gating variables. The mechanical model consists of the quasi-static finite elasticity system, modeling the cardiac tissue as a nearly-incompressible transversely isotropic hyperelastic material, and coupled with a system of ODEs accounting for the development of biochemically generated active force.
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Scalable BDDC Algorithms for Cardiac Electromechanical Coupling
Pavarino, L. F.; Scacchi, S.; Verdi, C.; Zampieri, E.; Zampini, Stefano
2017-01-01
The spread of electrical excitation in the cardiac muscle and the subsequent contraction-relaxation process is quantitatively described by the cardiac electromechanical coupling model. The electrical model consists of the Bidomain system, which is a degenerate parabolic system of two nonlinear partial differential equations (PDEs) of reaction-diffusion type, describing the evolution in space and time of the intra- and extracellular electric potentials. The PDEs are coupled through the reaction term with a stiff system of ordinary differential equations (ODEs), the membrane model, which describes the flow of the ionic currents through the cellular membrane and the dynamics of the associated gating variables. The mechanical model consists of the quasi-static finite elasticity system, modeling the cardiac tissue as a nearly-incompressible transversely isotropic hyperelastic material, and coupled with a system of ODEs accounting for the development of biochemically generated active force.
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Reaction mechanisms in heavy ion fusion
Directory of Open Access Journals (Sweden)
Lubian J.
2011-10-01
Full Text Available We discuss the reaction mechanisms involved in heavy ion fusion. We begin with collisions of tightly bound systems, considering three energy regimes: energies above the Coulomb barrier, energies just below the barrier and deep sub-barrier energies. We show that channel coupling effects may influence the fusion process at above-barrier energies, increasing or reducing the cross section predicted by single barrier penetration model. Below the Coulomb barrier, it enhances the cross section, and this effect increases with the system’s size. It is argued that this behavior can be traced back to the increasing importance of Coulomb coupling with the charge of the collision partners. The sharp drop of the fusion cross section observed at deep sub-barrier energies is addressed and the theoretical approaches to this phenomenon are discussed. We then consider the reaction mechanisms involved in fusion reactions of weakly bound systems, paying particular attention to the calculations of complete and incomplete fusion available in the literature.
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Controlling site selectivity in Pd-catalyzed oxidative cross-coupling reactions.
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.
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Cryochemistry: freezing effect on peptide coupling in different organic solutions.
Vajda, T; Szókán, G; Hollósi, M
1998-06-01
The freezing effect on peptide coupling in organic solutions of different polarity has been investigated and compared with the results obtained in liquid phase. The model reaction of DCC-activated coupling of Boc-Ala-Phe-OH with H-Ala-OBu(t) has been carried out in dioxane, dimethylsulfoxide and formamide, as well as in mixtures (90%/10%, v/v) of dioxane with acetonitrile, dimethylformamide, dimethylsulfoxide and formamide. The reactions have been traced and evaluated by RP-HPLC analysis. Freezing the reaction mixture resulted in all cases in a significant suppression of the N-dipeptidylurea side-product formation together with a slight decrease of tripeptide epimerization. The coupling yields and the side effects depended on the solvent, with the dioxane and dioxane/acetonitrile mixture produced the best results. The role of freezing and solvent in the improved results is discussed.
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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...
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Preparation and Reaction Chemistry of Novel Silicon-Substituted 1,3-Dienes
Directory of Open Access Journals (Sweden)
Partha P. Choudhury
2015-09-01
Full Text Available 2-Silicon-substituted 1,3-dienes containing non transferrable groups known to promote transmetallation were prepared by Grignard chemistry and enyne metathesis. These dienes participated in one pot metathesis/Diels-Alder reactions in regio- and diastereoselective fashions. Electron-rich alkenes showed the fastest rates in metathesis reactions, and ethylene, a commonly used metathesis promoter slowed enyne metathesis. 2-Pyridyldimethylsilyl and 2-thienyldimethylsilyl substituted Diels-Alder cycloadducts participated in cross-coupling chemistry and the 2-thienyldimethylsilyl substituted cycloadducts underwent cross-coupling under very mild reaction conditions.
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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.
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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.
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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.
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Synthesis and biological evaluation of vinylogous combretastatin A-4 derivatives.
Kaffy, Julia; Pontikis, Renée; Florent, Jean-Claude; Monneret, Claude
2005-07-21
Stereospecific syntheses of the Z-E and E-Z vinylogues of combretastatin A-4, and two B-ring related analogues, were achieved through a Suzuki-Miyaura coupling. As compared to CA4, the derivative with a phenyl moiety has shown increased potency in its ability to inhibit tubulin polymerisation.
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Journal of Chemical Sciences | Indian Academy of Sciences
Indian Academy of Sciences (India)
Emerging trends at the interface of chemistry and biology: Applications to the ... Suzuki-Miyaura, Mizoroki-Heck carbon-carbon coupling and hydrogenation .... The change in colour can easily be distinguished from other metal complexes by the naked eye. .... Influence of magnetic field on the electrodeposition of Ni-Co alloy.
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O'Rourke, Natasha F; Micalizio, Glenn C
2016-03-18
Stereodivergent metallacycle-mediated cross-coupling reactions are described for the synthesis of densely functionalized vinylcyclopropanes from the union of alkynes with cyclopropenes. Strategies explored include hydroxyl-directed and nondirected processes, with the latter of these delivering vinylcyclopropanes with exquisite levels of regio- and stereoselectivity. Challenges inherent to these coupling reactions include diastereoselectivity (with respect to the cyclopropene) and regioselectivity (with respect to both coupling partners).
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Criticality calculations in reactor accelerator coupling experiment (Race)
International Nuclear Information System (INIS)
Reda, M.A.; Spaulding, R.; Hunt, A.; Harmon, J.F.; Beller, D.E.
2005-01-01
A Reactor Accelerator Coupling Experiment (RACE) is to be performed at the Idaho State University Idaho Accelerator Center (IAC). The electron accelerator is used to generate neutrons by inducing Bremsstrahlung photon-neutron reactions in a Tungsten- Copper target. This accelerator/target system produces a source of ∼1012 n/s, which can initiate fission reactions in the subcritical system. This coupling experiment between a 40-MeV electron accelerator and a subcritical system will allow us to predict and measure coupling efficiency, reactivity, and multiplication. In this paper, the results of the criticality and multiplication calculations, which were carried out using the Monte Carlo radiation transport code MCNPX, for different coupling design options are presented. The fuel plate arrangements and the surrounding tank dimensions have been optimized. Criticality using graphite instead of water for reflector/moderator outside of the core region has been studied. The RACE configuration at the IAC will have a criticality (k-effective) of about 0,92 and a multiplication of about 10. (authors)
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Morphological patterns of lip prints in Mangaloreans based on Suzuki and Tsuchihashi classification
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
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Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling
Takanabe, Kazuhiro
2012-01-01
Natural gas conversion remains one of the essential technologies for current energy needs. This review focuses on the mechanistic aspects of the development of efficient and durable catalysts for two reactions, carbon dioxide reforming 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 support the design of industrial catalysts. CO 2 reforming of methane utilizes CO 2, which is often stored in large quantities, to convert as a reactant. Strategies to eliminate carbon deposition, which is the major problem associated with this reaction, are discussed. The oxidative coupling of methane directly produces ethylene in one reactor through a slightly exothermic reaction, potentially minimizing the capital cost of the natural gas conversion process. The focus of discussion in this review will be on the attainable yield of C 2 products by rigorous kinetic analyses.
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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
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Coupled microwave/photoassisted methods for environmental remediation.
Horikoshi, Satoshi; Serpone, Nick
2014-11-05
The microwave-induced acceleration of photocatalytic reactions was discovered serendipitously in the late 1990s. The activity of photocatalysts is enhanced significantly by both microwave radiation and UV light. Particularly relevant, other than as a heat source, was the enigmatic phenomenon of the non-thermal effect(s) of the microwave radiation that facilitated photocatalyzed reactions, as evidenced when examining various model contaminants in aqueous media. Results led to an examination of the possible mechanism(s) of the microwave effect(s). In the present article we contend that the microwaves' non-thermal effect(s) is an important factor in the enhancement of TiO2-photoassisted reactions involving the decomposition of organic pollutants in model wastewaters by an integrated (coupled) microwave-/UV-illumination method (UV/MW). Moreover, such coupling of no less than two irradiation methods led to the fabrication and ultimate investigation of microwave discharged electrodeless lamps (MDELs) as optimal light sources; their use is also described. The review focuses on the enhanced activity of photocatalytic reactions when subjected to microwave radiation and concentrates on the authors' research of the past few years.
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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.
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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
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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…
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Supercritical CO{sub 2} mediated synthesis and catalytic activity of graphene/Pd nanocomposites
Energy Technology Data Exchange (ETDEWEB)
Tang, Lulu [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of); Nguyen, Van Hoa [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of); Department of Chemistry, Nha Trang University, 2 Nguyen Dinh Chieu, Nha Trang (Viet Nam); Shim, Jae-Jin, E-mail: jjshim@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of)
2015-11-15
Highlights: • RGO/Pd composite was efficiently prepared via a facile method in supercritical CO{sub 2}. • Graphene sheets were coated uniformly with Pd nanoparticles with a size of ∼8 nm. • Composites exhibited excellent catalytic activity in the Suzuki reaction even after 10 cycles. - Abstract: Graphene sheets were decorated with palladium nanoparticles using a facile and efficient method in supercritical CO{sub 2}. The nanoparticles were formed on the graphene sheets by the simple hydrogen reduction of palladium(II) hexafluoroacetylacetonate precursor in supercritical CO{sub 2}. The product was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Highly dispersed nanoparticles with various sizes and shapes adhered well to the graphene sheets. The composites showed high catalytic activities for the Suzuki reaction under aqueous and aerobic conditions within 5 min. The effects of the different Pd precursor loadings on the catalytic activities of the composites were also examined.
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Selamat, Norhidayah; Heng, Lee Yook; Hassan, Nurul Izzaty; Karim, Nurul Huda Abd
2015-09-01
The tetradentate ligand with four donor atoms OONN was synthesized. Bis(phenoxy)bipyridine ligand was prepared by Suzuki coupling reaction between 6,6'-dibromo-2,2'-bipyridyl and 2-hydroxyphenylboronic acid with presence of palladium (II) acetate. Bis(phenoxy)bipyridine ligand was also synthesized by demethylating of 6,6'-bis(2-methoxyphenyl)-2,2'-bipyridyl ligand through solvent free reaction using pyridine hydrocloride. The formation of both phenoxy and methoxy ligands was confirmed by 1H, 2D cosy and 13C NMR spectroscopy, ESI-MS spectrometry, FTIR spectroscopy. The purity of the ligand was confirmed by melting point. Binding studies of small molecules with DNA are useful to understand the reaction mechanism and to provide guidance for the application and design of new and more efficient drugs targeted to DNA. In this study, the binding interaction between the synthesized ligand with calf thymus-DNA (ct-DNA) has been investigated by UV/Vis DNA titration study. From the UV/Vis DNA study, it shows that bis(phenoxy)bipyridine ligand bind with ct-DNA via outside binding with binding contant Kb = 1.19 × 103 ± 0.08 M-1.
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International Nuclear Information System (INIS)
Selamat, Norhidayah; Heng, Lee Yook; Hassan, Nurul Izzaty; Karim, Nurul Huda Abd
2015-01-01
The tetradentate ligand with four donor atoms OONN was synthesized. Bis(phenoxy)bipyridine ligand was prepared by Suzuki coupling reaction between 6,6’-dibromo-2,2’-bipyridyl and 2-hydroxyphenylboronic acid with presence of palladium (II) acetate. Bis(phenoxy)bipyridine ligand was also synthesized by demethylating of 6,6’-bis(2-methoxyphenyl)-2,2’-bipyridyl ligand through solvent free reaction using pyridine hydrocloride. The formation of both phenoxy and methoxy ligands was confirmed by 1 H, 2D cosy and 13 C NMR spectroscopy, ESI-MS spectrometry, FTIR spectroscopy. The purity of the ligand was confirmed by melting point. Binding studies of small molecules with DNA are useful to understand the reaction mechanism and to provide guidance for the application and design of new and more efficient drugs targeted to DNA. In this study, the binding interaction between the synthesized ligand with calf thymus-DNA (ct-DNA) has been investigated by UV/Vis DNA titration study. From the UV/Vis DNA study, it shows that bis(phenoxy)bipyridine ligand bind with ct-DNA via outside binding with binding contant K b = 1.19 × 10 3 ± 0.08 M −1
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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
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Sonogashira–Hagihara reactions of halogenated glycals
Directory of Open Access Journals (Sweden)
Dennis C. Koester
2012-05-01
Full Text Available Herein, we report on our findings of the Sonogashira–Hagihara reaction with 1-iodinated and 2-brominated glycals using several aromatic and aliphatic alkynes. This Pd-catalyzed cross-coupling reaction presents a facile access to alkynyl C-glycosides and sets the stage for a reductive/oxidative refunctionalization of the enyne moiety to regenerate either C-glycosidic structures or pyran derivatives with a substituent in position 2.
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Model-independent determination of hadronic neutral-current couplings
International Nuclear Information System (INIS)
Claudson, M.; Paschos, E.A.; Strait, J.; Sulak, L.R.
1979-01-01
Completion of a second generation of experiments on neutrino-induced neutral-current reactions allows a more discriminating study of neutral-current couplings to hadrons. To minimize the sensitivity to model-dependent analyses of inclusive and exclusive pion data, we base our work on measurements of deep-inelastic and elastic reactions alone. Within the regions allowed by the deep-inelastic data for scattering on isoscalar targets, the coupling constants are fit to the q 2 dependence of the neutrino-proton elastic scattering data. This procedure initially yields two solutions for the couplings. One of these, at theta/sub L/ = 55 0 and theta/sub R/ = 205 0 , is predominantly isoscalar and therefore is ruled out by only qualitative consideration of exclusive pion data. The other solution at theta/sub D/ = 140 0 and and theta/sub R/ = 330 0 , is thus a unique determination of the hadronic neutral-current couplings. It coincides with solution A obtained in earlier work, and is insensitive to variations of M/sub A/ within 2 standard deviations of the world average. When constrained to the coupling constants required by the Weinberg-Salam model, the fit agrees with the data to within 1 standard deviation
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Zong, Shan; Wang, Xin; Lin, Wenhai; Liu, Shi; Zhang, Wei
2018-06-20
Design and synthesis of biocompatible and multi-functional photothermal agents is crucial for effective cancer phototherapy. In order to achieve this ambition, simple D-A-D structural bisbithiophenyl diketopyrrolopyrrole (TDPP) was fabricated. In this molecule, the donor, 2-thiophenylboric acid, was conjugated via Suzuki coupling reaction, which could expand the emission wavelength to the red region of the spectrum. TDPP could self-assemble into stable and uniform nanoparticles (TDPP NPs) in the assistant of amphiphilic Pluronic F-127 polymer. Exposing the TDPP NPs (100 µg/mL) aqueous dispersion to 638 nm (0.61 W/cm2) laser irradiation resulted in a temperature elevation of approximately 30 oC within 5 min, which is high enough for inducing the cytotoxicity and tumor inhibition. Because of the bathochromic shift absorption of TDPP NPs in water, TDPP NPs could also act as a contrast agent for near-infrared fluorescence imaging (NIRF) to visualize the drug distribution in vivo. Coupled with the infrared thermal imaging properties of the photothermal agent, TDPP NPs were proved to be a multifunctional theranostic agent for dual-modal imaging-guided phototherapy.
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An Efficient and Versatile Synthesis of Isoflavones from 2-Methoxybenzoic Acids
Energy Technology Data Exchange (ETDEWEB)
Lee, Jae In [Duksung Women' s University, Seoul (Korea, Republic of)
2016-07-15
Isoflavones (3-aryl-4H-1-benzopyran-4-ones) are found naturally in soybeans and many plants of the Leguminosae family. They have attracted much attention due to their biological activities, such as their anti-cancer, anti-inflammatory, and antifungal properties. Isoflavones intake through foods is important to human health, because they potentially regulate fatty acid metabolism and methoxy-substituted isoflavones in particular increase cell permeability. Isoflavones have also been synthesized by the coupling of 3-iodochromones with arylboronic acids. The condensation of 2'-hydroxyacetophenones with DMF dimethyl acetal formed 3-(dimethylamino)-2'-hydroxyphenylpropenones, which were cyclized using iodine to form 3-iodochromones. This process was followed by Suzuki coupling with arylboronic acids or aryl boronates to obtain isoflavones. The synthesis of isoflavones (6) from 5 was based on the formylation of the methylene group of 5 using DMF-POCl{sub 3}. Previously, the reaction of the DMF-POCl{sub 3} complex on benzyl 2-hydroxyphenyl ketones led to isoflavones, for which DMF was used as the reagent and solvent for 18 h at gentle reflux.
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Bandari, Rajendar; Höche, Thomas; Prager, Andrea; Dirnberger, Klaus; Buchmeiser, Michael R
2010-04-19
Monolithic polymeric supports have been prepared by electron-beam-triggered free-radical polymerization using a mixture of glycidyl methacrylate and trimethylolpropane triacrylate in 2-propanol, 1-dodecanol, and toluene. Under appropriate conditions, phase separation occurred, which resulted in the formation of a porous monolithic matrix that was characterized by large (convective) pores in the 30 μm range as well as pores of 7 nm were hydrolyzed by using poly(styrenesulfonic acid) (Mw = 69,400 g mol(-1), PDI=2.4). The remaining epoxy groups inside pores of nanoparticles 2 nm in diameter were formed. The palladium-nanoparticle-loaded monoliths were used in both Heck- and Suzuki-type coupling reactions achieving turnover numbers of up to 167,000 and 63,000, respectively. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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Spirobifluorene Core-Based Novel Hole Transporting Materials for Red Phosphorescence OLEDs
Directory of Open Access Journals (Sweden)
Ramanaskanda Braveenth
2017-03-01
Full Text Available Two new hole transporting materials, named HTM 1A and HTM 1B, were designed and synthesized in significant yields using the well-known Buchwald Hartwig and Suzuki cross- coupling reactions. Both materials showed higher decomposition temperatures (over 450 °C at 5% weight reduction and HTM 1B exhibited a higher glass transition temperature of 180 °C. Red phosphorescence-based OLED devices were fabricated to analyze the device performances compared to Spiro-NPB and NPB as reference hole transporting materials. Devices consist of hole transporting material as HTM 1B showed better maximum current and power efficiencies of 16.16 cd/A and 11.17 lm/W, at the same time it revealed an improved external quantum efficiency of 13.64%. This efficiency is considerably higher than that of Spiro-NPB and NPB-based reference devices.
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Directory of Open Access Journals (Sweden)
Paul Hommes
2016-06-01
Full Text Available The scope of a flexible route to unsymmetrically functionalized bipyridines is described. Starting from 1,3-diketones 1a–e, the corresponding β-ketoenamines 2a–e were converted into different β-ketoenamides 3a–g by N-acylation with 2-pyridinecarboxylic acid derivatives. These β-ketoenamides were treated with a mixture of TMSOTf and Hünig’s base to promote the cyclocondensation to 4-hydroxypyridine derivatives. Their immediate O-nonaflation employing nonafluorobutanesulfonyl fluoride provided the expected 4-nonafloxy-substituted bipyridine derivatives 5a–g in moderate to good overall yields. The bipyridyl nonaflates are excellent precursors for palladium-catalyzed reactions as demonstrated by representative Suzuki and Sonogashira couplings. Thus, a library of specifically substituted bipyridine derivatives was generated, showing the versatility of the simple 1,3-diketone-based approach to this important class of ligands.
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Versatile synthesis and biological evaluation of novel 3’-fluorinated purine nucleosides
Directory of Open Access Journals (Sweden)
Hang Ren
2015-12-01
Full Text Available A unified synthetic strategy accessing novel 3'-fluorinated purine nucleoside derivatives and their biological evaluation were achieved. Novel 3’-fluorinated analogues were constructed from a common 3’-deoxy-3’-fluororibofuranose intermediate. Employing Suzuki and Stille cross-coupling reactions, fifteen 3’-fluororibose purine nucleosides 1–15 and eight 3’-fluororibose 2-chloro/2-aminopurine nucleosides 16–23 with various substituents at position 6 of the purine ring were efficiently synthesized. Furthermore, 3’-fluorine analogs of natural products nebularine and 6-methylpurine riboside were constructed via our convergent synthetic strategy. Synthesized nucleosides were tested against HT116 (colon cancer and 143B (osteosarcoma cancer tumor cell lines. We have demonstrated 3’-fluorine purine nucleoside analogues display potent tumor cell growth inhibition activity at sub- or low micromolar concentration.
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A finite range coupled channel Born approximation code
International Nuclear Information System (INIS)
Nagel, P.; Koshel, R.D.
1978-01-01
The computer code OUKID calculates differential cross sections for direct transfer nuclear reactions in which multistep processes, arising from strongly coupled inelastic states in both the target and residual nuclei, are possible. The code is designed for heavy ion reactions where full finite range and recoil effects are important. Distorted wave functions for the elastic and inelastic scattering are calculated by solving sets of coupled differential equations using a Matrix Numerov integration procedure. These wave functions are then expanded into bases of spherical Bessel functions by the plane-wave expansion method. This approach allows the six-dimensional integrals for the transition amplitude to be reduced to products of two one-dimensional integrals. Thus, the inelastic scattering is treated in a coupled channel formalism while the transfer process is treated in a finite range born approximation formalism. (Auth.)
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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.)
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Analysis of transfer reactions: determination of spectroscopic factors
Energy Technology Data Exchange (ETDEWEB)
Keeley, N. [CEA Saclay, Dept. d' Astrophysique, de Physique des Particules de Physique Nucleaire et de l' Instrumentation Associee (DSM/DAPNIA/SPhN), 91- Gif sur Yvette (France); The Andrzej So an Institute for Nuclear Studies, Dept. of Nuclear Reactions, Warsaw (Poland)
2007-07-01
An overview of the most popular models used for the analysis of direct reaction data is given, concentrating on practical aspects. The 4 following models (in order of increasing sophistication): the distorted wave born approximation (DWBA), the adiabatic model, the coupled channels born approximation, and the coupled reaction channels are briefly described. As a concrete example, the C{sup 12}(d,p)C{sup 13} reaction at an incident deuteron energy of 30 MeV is analysed with progressively more physically sophisticated models. The effect of the choice of the reaction model on the spectroscopic information extracted from the data is investigated and other sources of uncertainty in the derived spectroscopic factors are discussed. We have showed that the choice of the reaction model can significantly influence the nuclear structure information, particularly the spectroscopic factors or amplitudes but occasionally also the spin-parity, that we wish to extract from direct reaction data. We have also demonstrated that the DWBA can fail to give a satisfactory description of transfer data but when the tenets of the theory are fulfilled DWBA can work very well and will yield the same results as most sophisticated models. The use of global rather than fitted optical potentials can also lead to important differences in the extracted spectroscopic factors.
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Wang, Guangwei; Mohan, Swathi; Negishi, Ei-ichi
2011-01-01
All four stereoisomers (7–10) of ethyl undeca-2,4-dienoate were prepared in ≥98% isomeric purity by Pd-catalyzed alkenylation (Negishi coupling) using ethyl (E)- and (Z)-β-bromoacrylates. Although the stereoisomeric purity of the 2Z,4E-isomer (8) prepared by Suzuki coupling using conventional alkoxide and carbonate bases was ≤ 95%, as reported earlier, the use of CsF or nBu4NF as a promoter base has now been found to give all of 7–10 in ≥98% selectivity. Other widely known methods reveal considerable limitations. Heck alkenylation was satisfactory for the syntheses of the 2E,4E and 2E,4Z isomers of ≥98% purity, but the purity of the 2Z,4E isomer was ≤ 95%. Mutually complementary Horner–Wadsworth–Emmons and Still–Gennari (SG) olefinations are also of considerably limited scopes. Neither 2E,4Z nor 2Z,4Z isomer is readily prepared in ≥90% selectivity. In addition to (2Z,4E)-dienoic esters, some (2Z,4E,6E)- and (2Z,4E,6Z)-trienoic esters have been prepared in ≥98% selectivity by a newly devised Pd-catalyzed alkenylation–SG olefination tandem process. As models for conjugated higher oligoenoic esters, all eight stereoisomers for ethyl trideca-2,4,6-trienoate (23–30) have been prepared in ≥98% overall selectivity. PMID:21709262
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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
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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.
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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.
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International Nuclear Information System (INIS)
Duffy, Paul; Reynolds, Lyndsey A.; Sanders, Stephanie E.; Metz, Kevin M.; Colavita, Paula E.
2013-01-01
Composite materials are of interest because they can potentially combine the properties of their respective components in a manner that is useful for specific applications. Here, we report on the use of coffee as a low-cost, green reductant for the room temperature formation of catalytically active, supported metal nanoparticles. Specifically, we have leveraged the reduction potential of coffee in order to grow Pd and Ag nanoparticles at the surface of porous carbon microspheres synthesized via ultraspray pyrolysis. The metal nanoparticle-on-carbon microsphere composites were characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA). To demonstrate the catalytic activity of Pd/C and Ag/C materials, Suzuki coupling reactions and nitroaromatic reduction reactions were employed, respectively. - Highlights: • Natural reductants were used as green electroless deposition reagents. • Room temperature synthesis of supported Ag and Pd nanoparticles was achieved. • Carbon porous microspheres were used as supports. • Synthesis via natural reductants yielded catalytically active nanoparticles.
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Hazarika, Munmi; Borah, Debajit; Bora, Popymita; Silva, Ana R; Das, Pankaj
2017-01-01
This paper describes a simple in-situ process of synthesizing highly dispersed palladium nanoparticles (PdNPs) using aqueous leaf extract of GarciniapedunculataRoxb as bio-reductant and starch (0.3%) as bio-stabilizer. The PdNPs are characterized by techniques like FTIR, TEM, SEM-EDX, XRD and XPS analysis. It is worthnoting thatwhen the synthesis of nanoparticles was carried out in absence of starch, agglomeration of particles has been noticed.The starch-assisted PdNPs showed excellent aqueous-phase catalytic activities for three important reactions: the Suzuki-Miyaura cross-coupling reactions of aryl halides (aryl bromides and iodides) with arylboronic acids; selective oxidations of alcohols to corresponding carbonyl compounds; and reduction of toxic Cr(VI) to nontoxic Cr(III). Our catalyst could be reused up to four cycles without much compromising with its activity. Furthermore, the material also demonstrated excellent antimicrobial and anti-biofilm activities against a novel multidrug resistant clinical bacterial isolate Cronobactersakazakii strain AMD04. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of PdNPswere found to be 0.06 and 0.12 mM respectively.
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Exact analytical solutions for nonlinear reaction-diffusion equations
International Nuclear Information System (INIS)
Liu Chunping
2003-01-01
By using a direct method via the computer algebraic system of Mathematica, some exact analytical solutions to a class of nonlinear reaction-diffusion equations are presented in closed form. Subsequently, the hyperbolic function solutions and the triangular function solutions of the coupled nonlinear reaction-diffusion equations are obtained in a unified way
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A novel tandem Betti/Ullmann oxidation reaction as an efficient route ...
Indian Academy of Sciences (India)
Betti reaction; cross-coupling reaction; oxidation; heterogeneous catalysis. Abstract. A novel tandem Betti/Ullmann/oxidation reaction was used for synthesis of new oxazepine derivatives containing kojic acid. This protocol ... This method provides a new and useful strategy for the construction of heterocycles. Also novel Betti ...
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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.
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DEFF Research Database (Denmark)
Larsen, M.; Krebs, Frederik C; Harrit, N.
1999-01-01
Four 5,17-bis-aryl-25,26,27,28-tetrapropoxycalix[4]arenes were prepared via Negishi, Suzuki and Ullman type couplings [aryl = phenyl (1), 3-bromophenyl (2), 1-naphthyl (3) and carbazol-9-yl (4)]. The influence of the aryl groups on the structure was studied by X-ray crystallography, NMR, electron...
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Czech Academy of Sciences Publication Activity Database
Tichý, Michal; Pohl, Radek; Tloušťová, Eva; Weber, Jan; Bahador, G.; Lee, Y. J.; Hocek, Michal
2013-01-01
Roč. 21, č. 17 (2013), s. 5362-5372 ISSN 0968-0896 R&D Projects: GA ČR GAP207/11/0344 Institutional support: RVO:61388963 Keywords : nucleosides * pyrimido[4,5-b]indoles * Suzuki and Stille cross - coupling * anti-dengue virus activity Subject RIV: CC - Organic Chemistry Impact factor: 2.951, year: 2013
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Electron transfer reactions to probe the electrode/solution interface
Energy Technology Data Exchange (ETDEWEB)
Capitanio, F.; Guerrini, E.; Colombo, A.; Trasatti, S. [Milan Univ., Milan (Italy). Dept. of Physical Chemistry and Electrochemistry
2008-07-01
The reactions that occur at the interface between an electrode and an electrolyte were examined with particular reference to the interaction of different electrode surfaces with redox couples. A semi-integration or convolution technique was used to study the kinetics of electron transfer on different electrode materials with different hydrophilic behaviour, such as Boron-Doped-Diamond (BDD), Au and Pt. Standard reversible redox couples were also investigated, including (Fe3+/2+, Fe(CN)63-/4-, Ru(NH3)63+/2+, Co(NH3)63+/2+, Ir4+/3+, V4+/5+ and V3+/2+). The proposed method proved to be simple, straightforward and reliable since the obtained kinetic information was in good agreement with data in the literature. It was concluded that the kinetics of the electrode transfer reactions depend on the chemical nature of the redox couple and electrode material. The method should be further extended to irreversible couples and other electrode materials such as mixed oxide electrodes. 3 refs., 2 figs.
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A Stefan model for mass transfer in a rotating disk reaction vessel
BOHUN, C. S.
2015-01-01
chemical reactions occurring in the bulk. The wide range in the reaction rates of the underlying chemistry allows for a natural decoupling of the problem into a simplified set of weakly coupled convective-reaction-diffusion equations for the slowly reacting
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Statistical theory of precompound nuclear reactions
International Nuclear Information System (INIS)
Nishioka, H.
1986-01-01
The purpose of the paper is to show the application of the Grassmann-integration method (or the graded-symmetry method) to a pre-equilibrium process in nuclear reactions. The Grassmann-integration method for random systems was first introduced by Efetov and later largely extended and applied to nuclear physics by Verbaarschot, Weidenmuller and Zirnbauer (referred to as VWZ). They have applied it to the equilibrium nuclear reactions; namely; the compound-nucleus reactions. It will be shown in this paper that this method is also applicable to non-equilibrium nuclear reactions. Applying this method to precompound nuclear reactions, the authors have obtained the same expression of the cross-section as Agassi, Weidenmuller and Mantzouranis (referred to as AWM) in the weak-coupling limit. In the general case their results show an important modification to AWM
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Coupled Microwave/Photoassisted Methods for Environmental Remediation
Directory of Open Access Journals (Sweden)
Satoshi Horikoshi
2014-11-01
Full Text Available The microwave-induced acceleration of photocatalytic reactions was discovered serendipitously in the late 1990s. The activity of photocatalysts is enhanced significantly by both microwave radiation and UV light. Particularly relevant, other than as a heat source, was the enigmatic phenomenon of the non-thermal effect(s of the microwave radiation that facilitated photocatalyzed reactions, as evidenced when examining various model contaminants in aqueous media. Results led to an examination of the possible mechanism(s of the microwave effect(s. In the present article we contend that the microwaves’ non-thermal effect(s is an important factor in the enhancement of TiO2-photoassisted reactions involving the decomposition of organic pollutants in model wastewaters by an integrated (coupled microwave-/UV-illumination method (UV/MW. Moreover, such coupling of no less than two irradiation methods led to the fabrication and ultimate investigation of microwave discharged electrodeless lamps (MDELs as optimal light sources; their use is also described. The review focuses on the enhanced activity of photocatalytic reactions when subjected to microwave radiation and concentrates on the authors’ research of the past few years.
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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.
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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.
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Propargylamine-isothiocyanate reaction: efficient conjugation chemistry in aqueous media
DEFF Research Database (Denmark)
Viart, Helene Marie-France; Larsen, T. S.; Tassone, Chiara
2014-01-01
A coupling reaction between secondary propargyl amines and isothiocyanates in aqueous media is described. The reaction is high-yielding and affords cyclized products within 2-24 h. A functionalized ether lipid was synthesized in 8 steps, formulated as liposomes with POPC and conjugated to FITC un...
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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.
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Interfacial reactions in intermetallic matrix composites
International Nuclear Information System (INIS)
Cantrell, L.B.; Clevenger, E.M.; Perepezko, J.H.
1993-01-01
The thermal stability of advanced composites is dominated by the behavior of internal interfaces. Analysis of these internal interfaces often involves consideration of at least ternary order phase equilibria. Limited thermodynamic data exists for ternary and higher order systems. However, a combined approach based upon the use of binary data to estimate ternary phase equilibria and experimentally determined reaction pathways is effective in the analysis of interface reactions in composite systems. In blended powder samples, thermal analysis was used to find possible reaction temperatures, while X-ray analysis, EDS, and EPMA of diffusion couples were used to assess interdiffusion reaction pathways. The approach is illustrated by compatibility studies between TiAl and TiSi 2 at 1,100 C, and in-situ reactions between B 4 C and TiAl at 1300 C where multiple reaction sequences have been analyzed to provide guidance for the design of in-situ reaction processing of composites
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Isotopic studies on oxidative methane coupling over samarium oxide
International Nuclear Information System (INIS)
Otsuka, Kiyoshi; Inaida, Masakatsu; Wada, Yuji; Komatsu, Takayuki; Morikawa, Akira
1989-01-01
The evident kinetic isotope effect was observed for the formations of ethylene and ethane through the oxidative coupling of methane on Sm 2 O 3 , when CH 4 and CD 4 were used as the reactants. Ethanes formed in the reaction of a mixture of CH 4 , CD 4 , and O 2 were C 2 H 6 , C 2 H 3 D 3 , and C 2 D 6 as major products. These results indicate that the rate-determining step of the reaction is abstraction of hydrogen from methane and that ethane is formed through the coupling of methyl intermediate. (author)
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Meng, Guangrong; Lalancette, Roger; Szostak, Roman; Szostak, Michal
2017-09-01
Despite recent progress in catalytic cross-coupling technologies, the direct activation of N-alkyl-N-aryl amides has been a challenging transformation. Here, we report the first Suzuki cross-coupling of N-methylamino pyrimidyl amides (MAPA) enabled by the controlled n N → π Ar conjugation and the resulting remodeling of the partial double bond character of the amide bond. The new mode of amide activation is suitable for generating acyl-metal intermediates from unactivated primary and secondary amides.
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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
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Czech Academy of Sciences Publication Activity Database
Cimrová, Věra; Kmínek, Ivan; Výprachtický, Drahomír; Pokorná, Veronika
2015-01-01
Roč. 59, 24 February (2015), s. 298-304 ISSN 0032-3861 R&D Projects: GA ČR(CZ) GA13-26542S; GA ČR GAP106/12/0827 Institutional support: RVO:61389013 Keywords : low-bandgap thienothiadiazole copolymer * Suzuki coupling * photophysics and photovoltaics Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.586, year: 2015
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Synthesis, characterization and catalytic utilization of a ferrocene diamidodiphosphane
Czech Academy of Sciences Publication Activity Database
Štěpnička, P.; Schulz, J.; Císařová, I.; Fejfarová, Karla
2007-01-01
Roč. 72, č. 4 (2007), s. 453-467 ISSN 0010-0765 Grant - others:GAMŠk(CZ) LC06070 Program:LC Institutional research plan: CEZ:AV0Z10100521 Keywords : ferrocene * phosphines * amides * Suzuki-Miyaura cross-coupling, crystal structure determination * igands * x-ray diffraction Subject RIV: CA - Inorganic Chemistry Impact factor: 0.879, year: 2007
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The quantum dynamics of electronically nonadiabatic chemical reactions
Truhlar, Donald G.
1993-01-01
Considerable progress was achieved on the quantum mechanical treatment of electronically nonadiabatic collisions involving energy transfer and chemical reaction in the collision of an electronically excited atom with a molecule. In the first step, a new diabatic representation for the coupled potential energy surfaces was created. A two-state diabatic representation was developed which was designed to realistically reproduce the two lowest adiabatic states of the valence bond model and also to have the following three desirable features: (1) it is more economical to evaluate; (2) it is more portable; and (3) all spline fits are replaced by analytic functions. The new representation consists of a set of two coupled diabatic potential energy surfaces plus a coupling surface. It is suitable for dynamics calculations on both the electronic quenching and reaction processes in collisions of Na(3p2p) with H2. The new two-state representation was obtained by a three-step process from a modified eight-state diatomics-in-molecules (DIM) representation of Blais. The second step required the development of new dynamical methods. A formalism was developed for treating reactions with very general basis functions including electronically excited states. Our formalism is based on the generalized Newton, scattered wave, and outgoing wave variational principles that were used previously for reactive collisions on a single potential energy surface, and it incorporates three new features: (1) the basis functions include electronic degrees of freedom, as required to treat reactions involving electronic excitation and two or more coupled potential energy surfaces; (2) the primitive electronic basis is assumed to be diabatic, and it is not assumed that it diagonalizes the electronic Hamiltonian even asymptotically; and (3) contracted basis functions for vibrational-rotational-orbital degrees of freedom are included in a very general way, similar to previous prescriptions for locally
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Modeling of coupled geochemical and transport processes: An overview
International Nuclear Information System (INIS)
Carnahan, C.L.
1989-10-01
Early coupled models associated with fluid flow and solute transport have been limited by assumed conditions of constant temperature, fully saturated fluid flow, and constant pore fluid velocity. Developments including coupling of chemical reactions to variable fields of temperature and fluid flow have generated new requirements for experimental data. As the capabilities of coupled models expand, needs are created for experimental data to be used for both input and validation. 25 refs
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Reciprocity relation for multichannel coupling kernels
International Nuclear Information System (INIS)
Cotanch, S.R.; Satchler, G.R.
1981-01-01
Assuming time-reversal invariance of the many-body Hamiltonian, it is proven that the kernels in a general coupled-channels formulation are symmetric, to within a specified spin-dependent phase, under the interchange of channel labels and coordinates. The theorem is valid for both Hermitian and suitably chosen non-Hermitian Hamiltonians which contain complex effective interactions. While of direct practical consequence for nuclear rearrangement reactions, the reciprocity relation is also appropriate for other areas of physics which involve coupled-channels analysis
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Fu, Yue; Huang, Jingli; Liu, Wenbin; Fang, Xiangliang; Wang, Xinhua
2016-05-24
Thirteen holotypes of the orthoclad genus Rheocricotopus from Sino-Indian Region: R. (Psilocricotopus) hidakadeeus Sasa & Suzuki, R. (P.) isigadeeus Sasa & Suzuki, R. (P.) kurocedeus Sasa, R. (P.) tokarakeleus Sasa & Suzuki, R. (P.) tobatervicesimus Kikuchi & Sasa, R. (Rheocricotopus) inaquereus Sasa, Kitami & Suzuki, R. (R.) inaxeyeus Sasa, Kitami & Suzuki, R. (R.) shoufukusecundus Sasa, R. (R.) tamahumeralis Sasa, R. (R.) tatequintus Sasa, R. (R.) tedorisecundus Sasa, R. (R.) togapeniculus Sasa & Okazawa and R. (R.) yakulemeus Sasa & Suzuki are re-examined and illustrated, Some additional descriptions, corrections and a key of these thirteen holotypes are given.
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A computational glance at organometallic cyclizations and coupling reactions
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....
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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...
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Decay to Equilibrium for Energy-Reaction-Diffusion Systems
Haskovec, Jan
2018-02-06
We derive thermodynamically consistent models of reaction-diffusion equations coupled to a heat equation. While the total energy is conserved, the total entropy serves as a driving functional such that the full coupled system is a gradient flow. The novelty of the approach is the Onsager structure, which is the dual form of a gradient system, and the formulation in terms of the densities and the internal energy. In these variables it is possible to assume that the entropy density is strictly concave such that there is a unique maximizer (thermodynamical equilibrium) given linear constraints on the total energy and suitable density constraints. We consider two particular systems of this type, namely, a diffusion-reaction bipolar energy transport system, and a drift-diffusion-reaction energy transport system with confining potential. We prove corresponding entropy-entropy production inequalities with explicitly calculable constants and establish the convergence to thermodynamical equilibrium, first in entropy and later in L norm using Cziszár–Kullback–Pinsker type inequalities.
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Decay to Equilibrium for Energy-Reaction-Diffusion Systems
Haskovec, Jan; Hittmeir, Sabine; Markowich, Peter A.; Mielke, Alexander
2018-01-01
We derive thermodynamically consistent models of reaction-diffusion equations coupled to a heat equation. While the total energy is conserved, the total entropy serves as a driving functional such that the full coupled system is a gradient flow. The novelty of the approach is the Onsager structure, which is the dual form of a gradient system, and the formulation in terms of the densities and the internal energy. In these variables it is possible to assume that the entropy density is strictly concave such that there is a unique maximizer (thermodynamical equilibrium) given linear constraints on the total energy and suitable density constraints. We consider two particular systems of this type, namely, a diffusion-reaction bipolar energy transport system, and a drift-diffusion-reaction energy transport system with confining potential. We prove corresponding entropy-entropy production inequalities with explicitly calculable constants and establish the convergence to thermodynamical equilibrium, first in entropy and later in L norm using Cziszár–Kullback–Pinsker type inequalities.
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Czech Academy of Sciences Publication Activity Database
Dzhabarov, Vagif; Výprachtický, Drahomír; Cimrová, Věra
2018-01-01
Roč. 98, January (2018), s. 420-429 ISSN 0014-3057 R&D Projects: GA ČR(CZ) GA13-26542S Institutional support: RVO:61389013 Keywords : dialkylfluorene-bithiophene copolymers * microwave-assisted heating * Suzuki coupling Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 3.531, year: 2016
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Direct Formation of Silane Coupling Agents on Glass for Improved Composite Performance
National Research Council Canada - National Science Library
Boyles, David
2003-01-01
...; and 3) reaction of aminoalkenes with the reduced surface via a hydrosilylation reaction which formed the coupling agent directly on the surface of the glass fiber for glass surfaces incorporated into epoxy systems...
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Electrochemical reaction rates in a dye-sensitised solar cell - the iodide/tri-iodide redox system
DEFF Research Database (Denmark)
Bay, L.; West, K.; Winther-Jensen, B.
2006-01-01
The electrochemical reaction rate of the redox couple iodide/tri-iodide in acetonitrile is characterised by impedance spectroscopy. Different electrode materials relevant for the function of dye-sensitised solar cells (DSSC) are investigated. Preferably, the reaction with the iodide....../tri-iodide couple should be fast at the counter electrode, i.e. this electrode must have a high catalytic activity towards the redox couple, and the same reaction must be slow on the photo electrode. The catalytic activity is investigated for platinum, poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy......), and polyaniline (PANI)-all deposited onto fluorine-doped tin oxide (FTO) glass. Both Pt and PEDOT are found to have sufficiently high catalytic activities for practical use as counter electrodes in DSSC. The reaction resistance on FTO and anatase confirmed the beneficial effect of a compact anatase layer on top...
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Electrochemical reaction rates in a dye sentisised solar cell - the iodide/tri-iodide redox system
DEFF Research Database (Denmark)
Bay, Lasse; West, Keld; Winter-Jensen, Bjørn
2006-01-01
The electrochemical reaction rate of the redox couple iodide / tri-iodide in acetonitrile is characterised by impedance spectroscopy. Different electrode materials relevant for the function of dye-sensitised solar cells (DSSC) are investigated. Preferably, the reaction with the iodide / tri......-iodide couple should be fast at the counter electrode, i.e. this electrode must have a high catalytic activity towards the redox couple, and the same reaction must be slow on the photo electrode. The catalytic activity is investigated for platinum, poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPy......), and polyaniline (PANI) - all deposited onto fluorine doped tin oxide (FTO) glass. Both Pt and PEDOT are found to have sufficiently high catalytic activities for practical use as counter electrode in DSSC. The reaction resistance on FTO and anatase confirmed the beneficial effect of a compact anatase layer on top...
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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
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Nuclear excitations and reaction mechanisms. Progress report, 1 November 1979-30 September 1980
International Nuclear Information System (INIS)
1980-01-01
Among the topics investigated were the following: photon scattering and consistency condition between seagull quadrupole terms and the absorption sum rule; Raman scattering to negative-parity states; nonlocal terms due to exchange and retardation effects in charge-transfer reactions; consistency and meaning of various approximate channel coupling array equations; derivation of equations used in empirical nuclear reaction analyses; multicluster, n-particle scattering theory; converged molecular bound state calculations; consistency of approximate channel coupling array equations; derivations of equations used in empirical nuclear reaction analyses; and WKB-type approximation in angular momenta for central potentials. References to publications are given
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Femtosecond laser control of chemical reaction of carbon monoxide and hydrogen
CSIR Research Space (South Africa)
Du Plessis, A
2010-09-01
Full Text Available Femtosecond laser control of chemical reactions is made possible through the use of pulse-shaping techniques coupled to a learning algorithm feedback loop – teaching the laser pulse to control the chemical reaction. This can result in controllable...
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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→∞.
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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.
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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
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Energy Technology Data Exchange (ETDEWEB)
Kim, Minji; Lee, Chilwon; Gong, Myoungseon [Dankook Univ., Yongin (Korea, Republic of)
2014-06-15
A series of novel fused-ring spiro compounds, spiro[benzo[ij]tetraphene-7,9'-fluorene] derivatives containing an end-capping aryl substituent at both the C3 and C10-positions has been designed and synthesized via multi-step Suzuki coupling reactions. 3-(1-Naphthyl)-10-phenyl, 3-(2-naphthyl)-10-phenyl and 3-[4-(1-naphthyl)phenyl]-10-phenyl showed improved glass transition temperatures (T{sub g}) with good thermal stability. Their photophysical, electrochemical, and electroluminescent properties were investigated and were used to construct blue organic light emission diodes (OLEDs). The typical OLED devices showed excellent performance; the based device exhibited highly efficient deep blue-light emission with a maximum efficiency of 5.27 cd/A (EQE, 4.63%) with CIE (x = 0.133, y = 0.144). According to these characteristics, these deep-blue light emitting materials have sufficient potential for fluorescent OLED applications.
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Nondoped deep blue OLEDs based on Bis-(4-benzenesulfonyl-phenyl)-9-phenyl-9H-carbazoles
International Nuclear Information System (INIS)
Huang, Bin; Yin, Zhihui; Ban, Xinxin; Ma, Zhongming; Jiang, Wei; Tian, Wenwen; Yang, Min; Ye, Shanghui; Lin, Baoping; Sun, Yueming
2016-01-01
Two bipolar materials based on 9-phenylcarbazole and diphenyl sulfone for nondoped deep blue OLEDs, namely bis-(4-benzenesulfonyl-phenyl)-9-phenyl-9H-carbazoles, have been designed and synthesized by Suzuki coupling reactions. Their thermal, photophysical, and electrochemical properties have been systematically investigated. The nondoped devices using 3,6–bis–(4-benzenesulfonyl-phenyl)-9-phenyl-9H-carbazoles and 2,7-bis-(4-benzenesulfonyl-phenyl)-9-phenyl-9H-carbazoles as the emitters show deep blue emission color with peaks at 424 and 444 nm, and the Commission Internationale de l'Eclairage (CIE) coordinates of (0.177, 0.117) and (0.160, 0.117), respectively. Furthermore, these materials based devices have high color-purity with small width at half-maximum (FWHM) of 65 and 73 nm, respectively. The results provide a novel approach for the design of deep blue emitter for nondoped OLEDs.
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OXIDATIVE COUPLING OF METHANE USING INORGANIC MEMBRANE REACTORS
Energy Technology Data Exchange (ETDEWEB)
Dr. Y.H. Ma; Dr. W.R. Moser; Dr. A.G. Dixon; Dr. A.M. Ramachandra; Dr. Y. Lu; C. Binkerd
1998-04-01
The objective of this research is to study the oxidative coupling of methane in catalytic inorganic membrane reactors. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and higher yields than in conventional non-porous, co-feed, fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gas phase reactions, which are believed to be a main route for the formation of CO{sub x} products. Such gas phase reactions are a cause of decreased selectivity in the oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Membrane reactor technology also offers the potential for modifying the membranes both to improve catalytic properties as well as to regulate the rate of the permeation/diffusion of reactants through the membrane to minimize by-product generation. Other benefits also exist with membrane reactors, such as the mitigation of thermal hot-spots for highly exothermic reactions such as the oxidative coupling of methane. The application of catalytically active inorganic membranes has potential for drastically increasing the yield of reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity.
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Reaction of nickel with uranium mononitride; Reaction du nickel avec le nitrure d'uranium
Energy Technology Data Exchange (ETDEWEB)
Anselin, F; Calais, D; Lorenzelli, N; Passefort, J C [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires
1965-07-01
UN-Ni system has been investigated in solid phase by diffusion couples UN-Ni or by mixed powders pressed and sintered. Studies have been carried out by micrography, X-rays and microanalysis with a CASTAING microprobe. UN-Ni compatibility is quite good up to 600 C; beyond this temperature diffusion zones corresponding to UNi{sub 5} and U{sub 2}N{sub 3} appear in the couples either reaction : 3 U N + 5 Ni {yields} U{sub 2}N{sub 3} + UNi{sub 5}; UN + 5 Ni {yields} UNi{sub 5}+ 1/2 N{sub 2} takes place from 700 C according to nitrogen pressure involved. For temperatures between 800 and 1000 C nickel solubility in uranium nitride is 1500 {+-} 500 wt ppm. (authors) [French] Le systeme UN-Ni a ete etudie par diffusion en phase solide a partir de couples (UN-Ni) ou de melanges pulverulents presses et frittes. Les techniques utilisees sont la micrographie, les rayons X et l'analyse ponctuelle a la microsonde de CASTAING. La compatibilite UN-Ni est bonne jusqu'a 600 C; au-dela il apparait dans les couples de diffusion des zones correspondant a UNi{sub 5} et U{sub 2}N{sub 3}. L'une ou l'autre des deux reactions: 3UN + 5 Ni {yields} U{sub 2}N{sub 3} + UNi{sub 5}; UN + 5 Ni {yields} UNi{sub 5} + 1/2 N{sub 2} se produisant des 700 C suivant la pression d'azote exercee. La solubilite du nickel dans le nitrure d'uranium pour des temperatures comprises entre 800 et 1000 C est de 1500 {+-} 500 ppm en poids. (auteurs)
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Göppel, Tobias; Palyulin, Vladimir V; Gerland, Ulrich
2016-07-27
An out-of-equilibrium physical environment can drive chemical reactions into thermodynamically unfavorable regimes. Under prebiotic conditions such a coupling between physical and chemical non-equilibria may have enabled the spontaneous emergence of primitive evolutionary processes. Here, we study the coupling efficiency within a theoretical model that is inspired by recent laboratory experiments, but focuses on generic effects arising whenever reactant and product molecules have different transport coefficients in a flow-through system. In our model, the physical non-equilibrium is represented by a drift-diffusion process, which is a valid coarse-grained description for the interplay between thermophoresis and convection, as well as for many other molecular transport processes. As a simple chemical reaction, we consider a reversible dimerization process, which is coupled to the transport process by different drift velocities for monomers and dimers. Within this minimal model, the coupling efficiency between the non-equilibrium transport process and the chemical reaction can be analyzed in all parameter regimes. The analysis shows that the efficiency depends strongly on the Damköhler number, a parameter that measures the relative timescales associated with the transport and reaction kinetics. Our model and results will be useful for a better understanding of the conditions for which non-equilibrium environments can provide a significant driving force for chemical reactions in a prebiotic setting.
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Direct activation of allylic alcohols in palladium catalyzed coupling reactions
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
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NMR reaction monitoring in flow synthesis.
Gomez, M Victoria; de la Hoz, Antonio
2017-01-01
Recent advances in the use of flow chemistry with in-line and on-line analysis by NMR are presented. The use of macro- and microreactors, coupled with standard and custom made NMR probes involving microcoils, incorporated into high resolution and benchtop NMR instruments is reviewed. Some recent selected applications have been collected, including synthetic applications, the determination of the kinetic and thermodynamic parameters and reaction optimization, even in single experiments and on the μL scale. Finally, software that allows automatic reaction monitoring and optimization is discussed.
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Techniques for heavy-ion coupled-channels calculations. I. Long-range Coulomb coupling
International Nuclear Information System (INIS)
Rhoades-Brown, M.; Macfarlane, M.H.; Pieper, S.C.
1980-01-01
Direct-reaction calculations for heavy ions require special computational techniques that take advantage of the physical peculiarities of heavy-ion systems. This paper is the first of a series on quantum-mechanical coupled-channels calculations for heavy ions. It deals with the problems posed by the long range of the Coulomb coupling interaction. Our approach is to use the Alder-Pauli factorization whereby the channel wave functions are expressed as products of Coulomb functions and modulating amplitudes. The equations for the modulating amplitudes are used to integrate inwards from infinity to a nuclear matching radius ( approx. = 20 fm). To adequate accuracy, the equations for the amplitudes can be reduced to first order and solved in first Born approximation. The use of the Born approximation leads to rapid recursion relations for the solutions of the Alder-Pauli equations and hence to a great reduction in computational labor. The resulting coupled-channels Coulomb functions can then be matched in the usual way to solutions of the coupled radial equations in the interior region of r space. Numerical studies demonstrate the reliability of the various techniques introduced
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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
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Bonin, Hélène; Delbrayelle, Dominique; Demonchaux, Patrice; Gras, Emmanuel
2010-04-21
Boronic esters have long been considered as poor partners in cross-coupling reactions with arene diazoniums. Here is reported an unprecedented application of self-activated boronic esters in a base-free cross-coupling reaction with diazonium salts under mild and user friendly conditions.
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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
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Heijnen, Dorus; Tosi, Filippo; Vila, Carlos; Stuart, Marc C. A.; Elsinga, Philip H.; Szymanski, Wiktor; Feringa, Ben L.
2017-01-01
The discovery of an ultrafast cross-coupling of alkyland aryllithium reagents with a range of aryl bromides is presented. The essential role of molecular oxygen to form the active palladium catalyst was established; palladium nanoparticles that are highly active in cross-coupling reactions with
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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