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Sample records for suzuki coupling reactions

  1. Nanocatalysts for Suzuki cross-coupling reactions.

    Science.gov (United States)

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

    2011-10-01

    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). This journal is © The Royal Society of Chemistry 2011

  2. Nanocatalysts for Suzuki cross-coupling reactions

    KAUST Repository

    Fihri, Aziz

    2011-01-01

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

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

    Indian Academy of Sciences (India)

    ... deposited on nafion-graphene. They showed excellent catalytic activity towards Sonogashira and Suzuki-Miyaura cross-coupling reaction. Benzenediazonium salts were used as alternative to aromatic halide. The developed protocol offers recyclability, easy workups with short reaction time and good-to-excellent product ...

  4. Plasmonic harvesting of light energy for Suzuki coupling reactions.

    Science.gov (United States)

    Wang, Feng; Li, Chuanhao; Chen, Huanjun; Jiang, Ruibin; Sun, Ling-Dong; Li, Quan; Wang, Jianfang; Yu, Jimmy C; Yan, Chun-Hua

    2013-04-17

    The efficient use of solar energy has received wide interest due to increasing energy and environmental concerns. A potential means in chemistry is sunlight-driven catalytic reactions. We report here on the direct harvesting of visible-to-near-infrared light for chemical reactions by use of plasmonic Au-Pd nanostructures. The intimate integration of plasmonic Au nanorods with catalytic Pd nanoparticles through seeded growth enabled efficient light harvesting for catalytic reactions on the nanostructures. Upon plasmon excitation, catalytic reactions were induced and accelerated through both plasmonic photocatalysis and photothermal conversion. Under the illumination of an 809 nm laser at 1.68 W, the yield of the Suzuki coupling reaction was ~2 times that obtained when the reaction was thermally heated to the same temperature. Moreover, the yield was also ~2 times that obtained from Au-TiOx-Pd nanostructures under the same laser illumination, where a 25-nm-thick TiOx shell was introduced to prevent the photocatalysis process. This is a more direct comparison between the effect of joint plasmonic photocatalysis and photothermal conversion with that of sole photothermal conversion. The contribution of plasmonic photocatalysis became larger when the laser illumination was at the plasmon resonance wavelength. It increased when the power of the incident laser at the plasmon resonance was raised. Differently sized Au-Pd nanostructures were further designed and mixed together to make the mixture light-responsive over the visible to near-infrared region. In the presence of the mixture, the reactions were completed within 2 h under sunlight, while almost no reactions occurred in the dark.

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

    KAUST Repository

    Hassine, Ayoub

    2013-01-01

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

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

    KAUST Repository

    Polshettiwar, Vivek

    2010-02-28

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

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

    Science.gov (United States)

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

    2012-01-01

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

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

    KAUST Repository

    Fihri, Aziz

    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.

  9. Recent Advances in Noble Metal Nanocatalysts for Suzuki and Heck Cross-Coupling Reactions

    Directory of Open Access Journals (Sweden)

    Radha Narayanan

    2010-03-01

    Full Text Available Since metal nanoparticles have a high surface-to-volume ratio and very active surface atoms, they are very attractive catalysts for a wide variety of organic and inorganic reactions, compared to bulk catalysts. Metal nanoparticles suspended in colloidal solutions and those adsorbed onto bulk supports have been used as catalysts for a wide variety of carbon-carbon bond formation reactions such as the Suzuki and Heck cross-coupling reactions. This review article highlights some of the latest advances in the application of noble metal nanoparticles as catalysts for these two industrially important classes of cross-coupling reactions. We will discuss several important advances in using metal nanocatalysts in Suzuki and Heck cross-coupling reactions such as investigations on the nanoparticle shape dependence on the catalytic activity, novel types of supported metal nanoparticles as nanocatalysts, and the use of bi-metallic, tri-metallic and multi-metallic nanoparticles as catalysts for the Suzuki and Heck cross-coupling reactions.

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

    Indian Academy of Sciences (India)

    tions in various fields such as fuel cell, nanocomposite materials and electronic ... nium tetrafluroborate salts in methanol as solvent. The reactions were carried out at .... aReaction conditions: arenediazonium tetrafluoroborate salt (0.3 mmol), phenyl boronic acid (0.36 mmol), methanol (2 mL),. Catalyst Pd/Nf-G (0.2 mmol).

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

    KAUST Repository

    Fihri, Aziz

    2011-11-15

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

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

    NARCIS (Netherlands)

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

    2009-01-01

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

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

    Science.gov (United States)

    Zhang, Lilan; Guo, Yali; Iqbal, Anam; Li, Bo; Deng, Min; Gong, Deyan; Liu, Weisheng; Qin, Wenwu

    2017-04-01

    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-1 for the reduction of Cr(VI). Moreover, the electrocatalyst shows that Pd icosahedron possesses a bigger surface area of 8.56 m2/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).

  14. 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).

  15. Mesoporous palladium–copper ferrites as highly efficient and magnetically separable catalysts for Suzuki coupling reaction

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Jinhui, E-mail: jinhuitong@126.com [Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education (China); Key Laboratory of Gansu Polymer Materials, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Su, Lingdi [Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education (China); Key Laboratory of Gansu Polymer Materials, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Bo, Lili [College of Science, Gansu Agricultural University, Lanzhou 730070 (China); Cai, Xiaodong; Zhang, Qianping; Wang, Qizhao [Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education (China); Key Laboratory of Gansu Polymer Materials, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2016-01-15

    Highlights: • Mesoporous Cu–Pd ferrites were prepared by a facile, mild and environment-friendly route. • The catalysts have shown great efficiencies in Suzuki coupling reaction and up to 36.9 × 10{sup 3} h{sup −1} TOF can be obtained. • The catalyst can be magnetically separated easily and have shown prominent recyclability. - Abstract: Mesoporous Cu–Pd ferrites were prepared by using MCM-41 and SBA-15 mesoporous molecular sieves as hard templates and well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ICP-atomic emission spectroscopy, N{sub 2} adsorption–desorption and X-ray photoelectric spectroscopy (XPS). Compared with samples prepared by the sol–gel auto-combustion methods, the as-prepared mesoporous ferrites have shown uniform pore size and much higher specific surface areas. The samples showed a remarkably high activity in connection with the Suzuki coupling reaction, especially Cu{sub 0.99}Pd{sub 0.01}Fe{sub 2}O{sub 4} prepared by using MCM-41 as template obtained an excellent TOF as high as 36.9 × 10{sup 3} h{sup −1} and no obvious decrease in the activity was observed after ten consecutive runs.

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

    KAUST Repository

    Dehury, Niranjan

    2016-07-18

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

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

    Science.gov (United States)

    Baran, Talat

    2017-06-15

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

  18. Fast Suzuki-Miyaura cross-coupling reaction with hexacationic triarylphosphine Bn-Dendriphos as ligand

    NARCIS (Netherlands)

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

    2008-01-01

    The application of hexa[(dimethylamino)methyl]-functionalized triphenylphosphine (1) and its benzylammonium salt, Bn-Dendriphos (2), in the Suzuki-Miyaura cross-coupling of aryl bromides with arylboronic acids is described. The 3,5-bis[(benzyldimethylammonio)methyl] substitution pattern in 2 leads

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

    Directory of Open Access Journals (Sweden)

    Mujeeb Khan

    2017-05-01

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

  20. Suzuki Coupling Reactions Catalyzed by PdO Dispersed on Dealuminated Y Zeolite in Air under Ambient Conditions.

    Science.gov (United States)

    Okumura, Kazu; Mushiake, Takumi; Matsui, Yu; Ishii, Akira

    2015-06-08

    Suzuki coupling reactions are performed using PdO loaded on dealuminated Y (USY) zeolite. The reaction between bromobenzene and phenylboronic acid is complete in 15 min at room temperature in air, with a turnover number of 1300. The reaction can be repeated at least five times by using 1 wt % Pd. Inductively coupled plasma analysis does not reveal the dissolution of Pd from products, even if the reaction is repeated up to four times. Pd K-edge extended X-ray absorption fine structure analysis reveals the presence of molecular-like PdO and a mixture of Pd(0) -PdO before and after the reaction, respectively. This is probably because Pd stabilized by Al sites is present at the II sites of the Y-type zeolite, as estimated using first-principles calculations. Conversely, Pd species change to PdO clusters after repeated reactions in air using the thermally treated sample. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    KAUST Repository

    Batool, Farhat

    2016-11-18

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

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

    Directory of Open Access Journals (Sweden)

    Kin Hong Liew

    2014-01-01

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

  3. Construction of new biopolymer (chitosan)-based pincer-type Pd(II) complex and its catalytic application in Suzuki cross coupling reactions

    Science.gov (United States)

    Baran, Talat; Menteş, Ayfer

    2017-04-01

    In this paper we described the fabrication, characterization and application of a new biopolymer (chitosan)-based pincer-type Pd(II) catalyst in Suzuki cross coupling reactions using a non-toxic, cheap, eco-friendly and practical method. The catalytic activity tests showed remarkable product yields as well as TON (19800) and TOF (330000) values with a small catalyst loading. In addition, the catalyst indicated good recyclability in the Suzuki C-C reaction. This biopolymer supported catalyst can be used with various catalyst systems due to its unique properties, such as being inert, green in nature, low cost and chemically durable.

  4. Melamine and melamine-formaldehyde polymers as ligands for palladium and application to Suzuki-Miyaura cross-coupling reactions in sustainable solvents.

    Science.gov (United States)

    Edwards, Grant A; Trafford, Mitchell A; Hamilton, Alaina E; Buxton, Audrey M; Bardeaux, Matthew C; Chalker, Justin M

    2014-03-07

    The Suzuki-Miyaura cross-coupling reaction is a foundation stone of modern organic synthesis, as evidenced by its widespread use in the preparation of pharmaceuticals, agrochemicals, polymers, and other functional materials. With the prevalence of this venerable reaction in industrial synthesis, it is prudent to ensure its application adheres to the tenets of green chemistry. The introduction of cross-coupling catalysts that are active in sustainable solvents is therefore an important endeavor. In this report, a melamine-palladium complex is introduced as a versatile catalyst for the Suzuki-Miyaura cross-coupling reaction. This catalyst is soluble and active in both water and the renewable organic solvent ethyl lactate. The melamine-palladium catalyst can also be cross-linked by reaction with formaldehyde to generate an insoluble polymeric catalyst that can be recovered after the cross-coupling. The melamine-palladium system is inexpensive, easy to handle, bench-stable, and effective in catalysis in the presence of a variety of impurities (high cross-coupling yields were obtained in reactions run in unfiltered river water to illustrate this final point). Additionally, investigations reported herein revealed an intriguing relationship between catalytic efficiency and the base employed in the cross-coupling reaction. Implications for the mechanism of transmetalation in aqueous Suzuki-Miyaura cross-coupling reaction are discussed.

  5. A mesoporous "shell-in-shell" structured nanocatalyst with large surface area, enhanced synergy, and improved catalytic performance for Suzuki-Miyaura coupling reaction.

    Science.gov (United States)

    Liu, Baocang; Niu, Yuefang; Li, Yan; Yang, Fan; Guo, Jiamin; Wang, Qin; Jing, Peng; Zhang, Jun; Yun, Guohong

    2014-10-21

    A novel mesoporous "shell-in-shell" structured nanocatalyst (@Pd/meso-TiO2/Pd@meso-SiO2) with large surface area, enhanced synergy, and improved catalytic performance is created for catalyzing Suzuki-Miyaura coupling and 4-nitrophenol reduction reactions.

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

    Directory of Open Access Journals (Sweden)

    Tomohiro Hattori

    2015-01-01

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

  7. 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

  8. Selective C-Arylation of 2,5-Dibromo-3-hexylthiophene via Suzuki Cross Coupling Reaction and Their Pharmacological Aspects

    Directory of Open Access Journals (Sweden)

    Hafiz Mansoor Ikram

    2015-03-01

    Full Text Available The present study reports the synthesis of various new derivatives based on 5-aryl-2-bromo-3-hexylthiophene with moderate-to-good yields via a palladium-catalyzed Suzuki cross-coupling reaction. This coupling method involved the reaction of 2,5-dibromo-3-hexylthiophene with several arylboronic acids in order to synthesize corresponding thiophene derivatives under controlled and optimal reaction conditions. The different substituents (CH3, OCH3, Cl, F etc. present on arylboronic acids are found to have significant electronic effects on the overall properties of new products. The synthesized thiophene molecules were studied for their haemolytic, biofilm inhibition and anti-thrombolytic activities, and almost all products showed potentially good properties. The compound 2-bromo-5-(3-chloro-4-fluorophenyl-3-hexylthiophenein particular exhibited the highest values for haemolytic and bio-film inhibition activities among all newly synthesized derivatives. In addition, the compound 2-bromo-3-hexyl-5-(4-iodophenylthiophene also showed high anti-thrombolytic activity, suggesting the potential medicinal applications of these newly synthesized compounds.

  9. Suzuki reactions of extended scope: the '9-MeO-9-BBN variant' as a complementary format for cross-coupling.

    Science.gov (United States)

    Seidel, Günter; Fürstner, Alois

    2012-02-18

    While the Suzuki coupling has gained paramount importance, the basic set-up of the reaction has remained essentially unchanged for decades. It consists of the palladium-catalyzed coupling of organoboron reagents with aryl- or alkenyl halides, -sulfonates or related electrophiles in the presence of a base. One of the few alternative formats for this transformation is the '9-MeO-9-BBN variant', which is distinguished by not requiring an added base as a promoter. Rather, polar organometallic reagents R-M (R = Me, alkyl, aryl, heteroaryl, alkenyl, alkynyl etc.) are first intercepted with 9-MeO-9-BBN to give the corresponding borinate complexes, which then pass the R-group onto an organopalladium complex generated in situ as the electrophilic partner. This procedure allowed the structural reach of the Suzuki coupling to be extended, and served in a host of advanced applications, most notably for elaborate sp-sp(2) and sp(3)-sp(2) coupling processes. This journal is © The Royal Society of Chemistry 2012

  10. A Zinc Catalyzed C(sp(3) )-C(sp(2) ) Suzuki-Miyaura Cross-Coupling Reaction Mediated by Aryl-Zincates.

    Science.gov (United States)

    Procter, Richard J; Dunsford, Jay J; Rushworth, Philip J; Hulcoop, David G; Layfield, Richard A; Ingleson, Michael J

    2017-09-27

    The Suzuki-Miyaura (SM) reaction is one of the most important methods for C-C bond formation in chemical synthesis. In this communication, we show for the first time that the low toxicity, inexpensive element zinc is able to catalyze SM reactions. The cross-coupling of benzyl bromides with aryl borates is catalyzed by ZnBr2 , in a process that is free from added ligand, and is compatible with a range of functionalized benzyl bromides and arylboronic acid pinacol esters. Initial mechanistic investigations indicate that the selective in situ formation of triaryl zincates is crucial to promote selective cross-coupling reactivity, which is facilitated by employing an arylborate of optimal nucleophilicity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Suzuki-Miyaura Cross-Coupling Reactions of Highly Fluorinated Arylboronic Esters: Catalytic Studies and Stoichiometric Model Reactions on the Transmetallation Step.

    Science.gov (United States)

    Kohlmann, Johannes; Braun, Thomas; Laubenstein, Reik; Herrmann, Roy

    2017-09-07

    Fluorinated 4-aryl phenylalanine amino acid derivatives (aryl=2-C5 NF4 , 4-C6 H4 SF5 , 2-C6 H4 SCF3 , C6 F5 ) were obtained in Suzuki-Miyaura cross-coupling reactions of phenylalanine precursors with highly fluorinated aryl boronic acid and esters in the presence of CsF. Pd(II) complexes that possessed phenyl alanine derived ligands, such as trans-[PdBr{4-C6 H4 CH2 CH{NHC(O)CH3 }CO2 Et}(PiPr3 )2 ], were used as catalysts. Stoichiometric model reactions indicate the intermediate generation of the boronate Cs[BF(2-C5 NF4 )(pin)] (pin=pinacolato=O2 C2 Me4 ). The transmetallation step with Cs[BF(4-C6 H4 SF5 )(pin)], [NMe4 ][BF(2-C5 NF4 )(pin)] and/or the fluorido complex trans-[PdF{4-C6 H4 CH2 C{NHC(O)CH3 }(CO2 Et)2 }(PiPr3 )2 ] was investigated. A comparison of the reactions of trans-[PdX{4-C6 H4 CH2 C{NHC(O)CH3 }(CO2 Et)2 }(PiPr3 )2 ] (X=Br, F) with 2-Bpin-C5 NF4 or [NMe4 ][BF(2-C5 NF4 )(pin)] revealed the remarkable high reactivity of the fluorido complex towards 2-BpinC5 NF4 . Low-temperature NMR studies indicated the ionic species trans-[Pd{4-C6 H4 CH2 C{NHC(O)CH3 }(CO2 Et)2 }(PiPr3 )2 ][BF(2-C5 NF4 )(pin)] to be a highly reactive intermediate. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Directory of Open Access Journals (Sweden)

    Bo Zhou

    2011-01-01

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

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

    Science.gov (United States)

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

    2017-10-01

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

  14. Synthesis, Characterization and Microwave-Promoted Catalytic Activity of Novel N-phenylbenzimidazolium Salts in Heck-Mizoroki and Suzuki-Miyaura Cross-Coupling Reactions under Mild Conditions

    Directory of Open Access Journals (Sweden)

    Ülkü Yılmaz

    2013-02-01

    Full Text Available A number of novel benzimidazolium salts having aryl substituents such as N-phenyl, 4-chlorophenyl and various alkyl substituents were synthesized. Their microwave-assisted catalytic activities were evaluated in Heck-Mizoroki and Suzuki-Miyaura cross-coupling reactions using a catalytic system consisting of Pd(OAc2/K2CO3 in DMF/H2O under mild reaction conditions with consistent high yields, except those of 2-bromopyridine.

  15. Soluble Porous Coordination Frameworks Constructed from Inorganic Nanoparticles as Homogenized Heterogeneous Photocatalysts for Suzuki Coupling Reactions under Near-Infrared Light.

    Science.gov (United States)

    Luo, Yuting; Peng, Yong; Liu, Weisheng; Chen, Fengjuan; Wang, Baodui

    2017-07-03

    Self-assembly has emerged as a promising method to control the structure and properties of ensembles of inorganic nanoparticles (NPs) for exploiting their collective effects. However, the rational assembly of inorganic NPs into soluble porous architectures for use as homogenized heterogeneous catalysts has been less studied. Herein, it is shown that inorganic NPs can be used for the assembly of soluble porous coordination frameworks (PCFs) by atom-scale interfacial coordination-driven assembly. Owing to their large pore size, high dispersity in solution, strong absorption in the near-infrared (NIR) range, and long-lived electron-hole pair, the obtained soluble frameworks could serve as a platform for homogenized heterogeneous photocatalysts, which exhibited excellent activity, high apparent quantum efficiency, and recyclability in the catalysis of the noble-metal-free Suzuki coupling reactions under NIR light at room temperature. Moreover, PCF catalysts can be reused more than five times without significant loss of activity, which indicates long-term stability. The present strategy to fabricate soluble porous nanostructures opens a new chemical toolbox for homogenized heterogeneous catalysts and may bring new inspiration to photocatalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Palladium(ii-Acetylacetonato Complexes with Mesoionic Carbenes: Synthesis, Structures and Their Application in the Suzuki-Miyaura Cross Coupling Reaction

    Directory of Open Access Journals (Sweden)

    Lara Hettmanczyk

    2016-11-01

    Full Text Available A series of novel palladium(ii acetylacetonato complexes bearing mesoionic carbenes (MICs have been synthesized and characterized. The synthesis of the complexes of type (MICPd(acacI (MIC = 1-mesityl-3-methyl-4-phenyl-1,2,3-triazol-5-ylidene (1, 1,4-(2,4,6-methyl-phenyl-3-methyl-1,2,3-triazol-5-ylidene (2, 1,4-(2,6-diisopropyl-phenyl-3-methyl-1,2,3-triazol-5-ylidene (3; acac = acetylacetonato via direct metalation starting from the corresponding triazolium iodides and palladium(ii acetylacetonate is described herein. All complexes were characterized by 1H- and 13C-NMR spectroscopy and high resolution mass spectrometry. Additionally, two of the complexes were characterized by single crystal X-ray crystallography confirming a square-planar coordination geometry of the palladium(ii center. A delocalized bonding situation was observed within the triazolylidene rings as well as for the acac ligand respectively. Complex 2 was found to be an efficient pre-catalyst for the Suzuki-Miyaura cross coupling reaction between aryl-bromides or -chlorides with phenylboronic acid.

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

    Czech Academy of Sciences Publication Activity Database

    Pomeisl, Karel; Holý, Antonín; Pohl, Radek

    2007-01-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

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

    NARCIS (Netherlands)

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

    2008-01-01

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

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

    KAUST Repository

    Hassine, Ayoub

    2015-01-19

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

  1. Site-selective Suzuki-Miyaura coupling of heteroaryl halides - understanding the trends for pharmaceutically important classes.

    Science.gov (United States)

    Almond-Thynne, Joshua; Blakemore, David C; Pryde, David C; Spivey, Alan C

    2017-01-01

    Suzuki-Miyaura cross-coupling reactions of heteroaryl polyhalides with aryl boronates are surveyed. Drawing on data from literature sources as well as bespoke searches of Pfizer's global chemistry RKB and CAS Scifinder® databases, the factors that determine the site-selectivity of these reactions are discussed with a view to rationalising the trends found.

  2. Asymmetric Suzuki-Miyaura coupling of heterocycles via Rhodium-catalysed allylic arylation of racemates

    Science.gov (United States)

    Schäfer, Philipp; Palacin, Thomas; Sidera, Mireia; Fletcher, Stephen P.

    2017-06-01

    Using asymmetric catalysis to simultaneously form carbon-carbon bonds and generate single isomer products is strategically important. Suzuki-Miyaura cross-coupling is widely used in the academic and industrial sectors to synthesize drugs, agrochemicals and biologically active and advanced materials. However, widely applicable enantioselective Suzuki-Miyaura variations to provide 3D molecules remain elusive. Here we report a rhodium-catalysed asymmetric Suzuki-Miyaura reaction with important partners including aryls, vinyls, heteroaromatics and heterocycles. The method can be used to couple two heterocyclic species so the highly enantioenriched products have a wide array of cores. We show that pyridine boronic acids are unsuitable, but they can be halogen-modified at the 2-position to undergo reaction, and this halogen can then be removed or used to facilitate further reactions. The method is used to synthesize isoanabasine, preclamol, and niraparib--an anticancer agent in several clinical trials. We anticipate this method will be a useful tool in drug synthesis and discovery.

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

    Czech Academy of Sciences Publication Activity Database

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

    2016-01-01

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

  4. Diversity-oriented approach to macrocyclic cyclophane derivatives by Suzuki-Miyaura cross-coupling and olefin metathesis as key steps.

    Science.gov (United States)

    Kotha, Sambasivarao; Chavan, Arjun S; Shaikh, Mobin

    2012-01-06

    Palladium-catalyzed Suzuki-Miyaura (SM) cross-coupling reaction with allylboronic acid pinacol ester and titanium assisted cross-metathesis (CM)/ring-closing metathesis (RCM) cascade has been used to synthesize macrocyclic cyclophane derivatives.

  5. Palladium nanoparticle-graphene hybrids as active catalysts for the Suzuki reaction

    National Research Council Canada - National Science Library

    Li, Yang; Fan, Xiaobin; Qi, Junjie; Ji, Junyi; Wang, Shulan; Zhang, Guoliang; Zhang, Fengbao

    2010-01-01

    .... We demonstrate that the Pd-graphene hybrids can act as an efficient catalyst for the Suzuki reaction under aqueous and aerobic conditions, with the reaction reaching completion in as little as 5 min...

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

    KAUST Repository

    Marziale, Alexander N.

    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.

  7. Transforming Suzuki-Miyaura cross-couplings of MIDA boronates into a green technology: no organic solvents.

    Science.gov (United States)

    Isley, Nicholas A; Gallou, Fabrice; Lipshutz, Bruce H

    2013-11-27

    New technology has been developed that enables Suzuki-Miyaura couplings involving widely utilized MIDA boronates to be run in water as the only medium, mainly at room temperature. The protocol is such that no organic solvent is involved at any stage; from the reaction through to product isolation. Hence, using the E factor scale as a measure of greenness, the values for these cross-couplings approach zero.

  8. Synthesis of polychlorinated biphenyls and their metabolites with a modified Suzuki-coupling.

    Science.gov (United States)

    Kania-Korwel, Izabela; Parkin, Sean; Robertson, Larry W; Lehmler, Hans-Joachim

    2004-08-01

    A modified procedure for the synthesis of polychlorinated biphenyls (PCBs) utilizing the Suzuki-coupling, a palladium-catalyzed cross-coupling reaction, is described. The coupling of (chlorinated) benzene boronic acids with bromochlorobenzenes, using Pd(dppf)(2)Cl(2) (dppf = 1,1'-bis(diphenylphosphino)ferrocene) as the catalyst and aqueous sodium carbonate as the base, gave the desired PCB congeners in moderate to good yields. Eleven PCB congeners, including environmentally important PCB congeners and metabolites, were synthesized using this modified procedure. This new catalyst Pd(dppf)(2)Cl(2) offers the advantage of being less air-sensitive and has a longer shelf life compared to Pd(PPh(4))(4). Three new (di-)methoxylated PCB congeners were synthesized using the same procedure by either coupling a chlorinated benzene boronic acid with a bromo (di-)methoxybenzene or by coupling a (di-)methoxy benzene boronic acid with a chlorinated bromobenzene. The dimethoxylated PCB congeners were readily converted into the respective dihydroxylated PCB derivatives using boron tribromide in dichloromethane. This approach offers the advantage of high selectivity and moderate to good yields compared to conventional methods such as the Cadogan reaction and allows the use of less toxic starting materials.

  9. A novel polymer containing phosphorus-nitrogen ligands for stabilization of palladium nanoparticles: an efficient and recyclable catalyst for Suzuki and Sonogashira reactions in neat water.

    Science.gov (United States)

    Gholinejad, M; Hamed, F; Biji, P

    2015-08-28

    A new polymer containing phosphorus and nitrogen ligands was successfully synthesized, characterized and used for the stabilization of highly monodispersed palladium nanoparticles having an average diameter of 2-3 nm. The thermally stable heterogeneous catalyst was successfully applied in Suzuki-Miyaura and copper-free Sonogashira-Hagihara coupling reactions of aryl halides under low palladium loading conditions. Reactions were proceeded in neat water without using any organic co-solvents. The catalyst was successfully recycled for the sample Suzuki-Miyaura reaction nine consecutive times with small drop in catalytic activity.

  10. Linear scaling relationships and volcano plots in homogeneous catalysis - revisiting the Suzuki reaction.

    Science.gov (United States)

    Busch, Michael; Wodrich, Matthew D; Corminboeuf, Clémence

    2015-12-01

    Linear free energy scaling relationships and volcano plots are common tools used to identify potential heterogeneous catalysts for myriad applications. Despite the striking simplicity and predictive power of volcano plots, they remain unknown in homogeneous catalysis. Here, we construct volcano plots to analyze a prototypical reaction from homogeneous catalysis, the Suzuki cross-coupling of olefins. Volcano plots succeed both in discriminating amongst different catalysts and reproducing experimentally known trends, which serves as validation of the model for this proof-of-principle example. These findings indicate that the combination of linear scaling relationships and volcano plots could serve as a valuable methodology for identifying homogeneous catalysts possessing a desired activity through a priori computational screening.

  11. Application of the Suzuki-Miyaura Reaction in the Synthesis of Flavonoids

    Directory of Open Access Journals (Sweden)

    Fanie R. Van Heerden

    2013-04-01

    Full Text Available The application of the Suzuki-Miyaura reaction in the synthesis of flavonoids, an important class of natural products, is reviewed. This reaction has not only been employed to provide access to flavonoid nuclei, but has also been applied to the synthesis of dimeric flavonoids and in the synthesis of libraries of flavonoid derivatives for biological activity studies. The classes of flavonoids that are discussed are the chalcones, flavones, isoflavones, neoflavones, biflavones and derivatives of flavonoids obtained by C-C bond formation via the Suzuki-Miyaura reaction.

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Rukiye Fırıncı

    2016-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Hamza Boufroura

    2017-01-01

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

  15. PdCl2 Immobilized in Polyacrylamide: a Low Cost and Eco-Friendly Catalyst for Suzuki-Miyaura Reactions

    OpenAIRE

    Alvarenga,Glademir; Ruas,Caroline P.; JULIANO R.M. VICENTI; Duarte,Fábio A.; Gelesky,Marcos A.; Rosa,Gilber R.

    2016-01-01

    PdCl2 immobilized in polyacrylamide (PAM), named Pd/PAM, produced at an extremely low cost, was found to be an efficient catalyst for Suzuki-Miyaura cross-coupling reactions. Iodo- and bromoarenes may couple with phenylboronic acid under eco-friendly conditions (i.e., phosphine-free and with ethanol as the solvent) to give excellent product yields. Aryl chlorides, in contrast, were found to be unsuitable reagents in this context, yielding modest results. The recyclability of Pd/PAM is limited...

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

    KAUST Repository

    Marziale, Alexander N.

    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.

  17. The Suzuki Reaction in Aqueous Media Promoted by P, N Ligands

    Directory of Open Access Journals (Sweden)

    Phillip W. Gingrich

    2011-07-01

    Full Text Available The synthesis and structure of palladium complexes of trisubstituted PTA derivatives, PTAR3, are described. Water-soluble phosphine ligands 1,3,5-triaza-7-phosphaadmantane (PTA, tris(aminomethylphosphine trihydrobromide, tri(aminomethyl phosphine, 3,7-dimethyl-1,5,7-triaza-3-phosphabicyclo[3,3,1]nonane (RO-PTA, 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA, lithium 1,3,5-triaza-7-phosphaadamantane-6-carboxylate (PTA-CO2Li, 2,4,6-triphenyl-1,3,5-triaza-7-phosphatricyclo [3.3.1.1]decane, and 2,4,6-triphenyl-1,3,5-triaza-7-phosphatricyclo[3.3.1.1]decane were used as ligands for palladium catalyzed Suzuki reactions in aqueous media. RO-PTA in combination with palladium acetate or palladium chloride was the most active catalyst for Suzuki cross coupling of aryl bromides and phenylboronic acid at 80 °C in 1:1 water:acetonitrile. The activity of Pd(II complexes of RO-PTA is comparable to PPh2(m-C6H4SO3Na (TPPMS and P(m-C6H4SO3Na3 (TPPTS and less active than tri(4,6-dimethyl-3-sulfonatophenylphosphine trisodium salt (TXPTS. Activated, deactivated, and sterically hindered aryl bromides were examined, with yields ranging from 50% to 90% in 6 h with 5% palladium precatalyst loading. X-ray crystal structures of (RO-PTAPdCl2, (PTAR32PdCl2 (R = Ph, p-tert-butylC6H5, and PTAR3 (R = p-tert-butylC6H5 are reported.

  18. Efficient synthesis of PtPd/Fe3O4 nanoparticles and its magnetic recoverability and stable recyclability for the Heck and Suzuki reactions

    Science.gov (United States)

    Sun, Yuanxu; Zhu, Xiaoqing; Guo, Dandan; Chen, Xiao; Dai, Jingtao

    2017-07-01

    Platinum and palladium bimetal nanoparticles on ferroferric oxide (PtPd/Fe3O4 NPs) nanocomposite catalysts were successfully synthesized with polyvinyl pyrrolidone as a stabilizing agent. The resultant samples were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, inductively coupled plasma, and magnetic studies. The catalytic performance of the PtPd/Fe3O4 NPs in the Heck and Suzuki coupling reactions was evaluated. Results showed that the cubic phase of Pt and Pd bimetal nanoparticles coexists with that of Fe3O4. The PtPd/Fe3O4 NP catalysts, which were approximately 22 nm in size, showed excellent catalytic activity in the Heck and Suzuki reactions. Moreover, the catalyst can be recovered with a magnet and reused several times without the significant loss of catalytic activity.

  19. 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.

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

    KAUST Repository

    Nolan, Steven Patrick

    2017-09-06

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

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

    Directory of Open Access Journals (Sweden)

    Suresh B. Waghmode

    2011-03-01

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

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

    KAUST Repository

    Decottignies, Audrey

    2013-02-01

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

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

    Directory of Open Access Journals (Sweden)

    Mujeeb Khan

    2017-01-01

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

  4. Solvent-free, microwave-assisted synthesis of thiophene oligomers via Suzuki coupling.

    Science.gov (United States)

    Melucci, Manuela; Barbarella, Giovanna; Sotgiu, Giovanna

    2002-12-13

    The purpose of this study was to obtain a rapid, efficient, and environmentally friendly methodology for the synthesis of highly pure thiophene oligomers. The solvent-free, microwave-assisted coupling of thienyl boronic acids and esters with thienyl bromides, using aluminum oxide as the solid support, allowed us to rapidly check the reaction trends on changing times, temperature, catalyst, and base and easily optimize the experimental conditions to obtain the targeted product in fair amounts. This procedure offers a novel, general, and very rapid route to the preparation of soluble thiophene oligomers. Thus, for example, quaterthiophene was obtained in 6 min by reaction of 2-bromo-2,2'-bithiophene with bis(pinacolato)diboron (isolated yield 65%), whereas quinquethiophene was obtained in 11 min by reaction of dibromoterthiophene with thienylboronic acid (isolated yield 74%). The synthesis of new chiral 2,2'-bithiophenes is reported. The detailed analysis of the byproducts of some reactions allowed us to elucidate a few aspects of reaction mechanisms. While the use of microwaves proved to be very convenient for the coupling between conventional thienyl moieties, the same was not true for the coupling of thienyl rings to thienyl-S,S-dioxide moieties. Indeed, in this case, the targeted product was obtained in low yields because of the competitive, accelerated, Diels-Alder reaction that affords a variety of condensation products.

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

    Science.gov (United States)

    Meng, Guangrong; Szostak, Michal

    2016-06-15

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

  6. Ultrasonic assisted synthesis of palladium-nickel/iron oxide core-shell nanoalloys as effective catalyst for Suzuki-Miyaura and p-nitrophenol reduction reactions.

    Science.gov (United States)

    Ghanbari, Najmeh; Hoseini, S Jafar; Bahrami, Mehrangiz

    2017-11-01

    In this study, ultrasonic assisted synthesis of Pd-Ni/Fe3O4 core-shell nanoalloys is reported. Unique reaction condition was prepared by ultrasonic irradiation, releasing the stored energy in the collapsed bubbles and heats the bubble contents that leads to Pd(II) and Ni(II) reduction. Co-precipitation method was applied for the synthesis of Fe3O4 nanoparticles (NPs). Immobilized solution was produced by sonicating the aqueous mixture of Fe3O4 and mercaptosuccinic acid to obtain Pd-Ni alloys on Fe3O4 magnetic NP cores. The catalytic activity of the synthesized Pd-Ni/Fe3O4 core-shells was investigated in the Suzuki-Miyaura CC coupling reaction and 4-nitrophenol reduction, which exhibited a high catalytic activity in both reactions. These magnetic NPs can be separated from the reaction mixture by external magnetic field. This strategy is simple, economical and promising for industrial applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Palladium(0 Deposited on PAMAM Dendrimers as a Catalyst for C–C Cross Coupling Reactions

    Directory of Open Access Journals (Sweden)

    Tomasz Borkowski

    2011-01-01

    Full Text Available PAMAM dendrimers of generations G2–G3 as well as a partially substituted derivative of generation G4 and a low-molecular-weight tricyclic ligand 4 were used to bind Pd(0 nanoparticles. The obtained adducts were tested as catalysts for C–C cross-coupling reactions, such as the Suzuki-Miyaura, Hiyama, Heck and Sonogashira reaction. The highest yields of the coupling product, diphenylacetylene, were obtained with all the catalysts studied in the Sonogashira coupling performed in ethanol with K2CO3 as base. Very good results, 85–100%, were also found in the Suzuki-Miyaura cross-coupling, while the efficiency of the Hiyama coupling appeared lower, with 38–52% of 2-Methylbiphenyl formed. In all reactions, the G2–Pd(0 catalyst, containing an unmodified dendrimer, afforded the highest yields of the cross-coupling products.

  8. Advances in Metal-Catalyzed Cross-Coupling Reactions of Halogenated Quinazolinones and Their Quinazoline Derivatives

    Directory of Open Access Journals (Sweden)

    Malose Jack Mphahlele

    2014-10-01

    Full Text Available Halogenated quinazolinones and quinazolines are versatile synthetic intermediates for the metal-catalyzed carbon–carbon bond formation reactions such as the Kumada, Stille, Negishi, Sonogashira, Suzuki-Miyaura and Heck cross-coupling reactions or carbon-heteroatom bond formation via the Buchwald-Hartwig cross-coupling to yield novel polysubstituted derivatives. This review presents an overview of the application of these methods on halogenated quinazolin-4-ones and their quinazolines to generate novel polysubstituted derivatives.

  9. Theoretical study on the mechanism of Ni-catalyzed alkyl-alkyl Suzuki cross-coupling.

    Science.gov (United States)

    Li, Zhe; Jiang, Yuan-Ye; Fu, Yao

    2012-04-02

    Ni-catalyzed cross-coupling of unactivated secondary alkyl halides with alkylboranes provides an efficient way to construct alkyl-alkyl bonds. The mechanism of this reaction with the Ni/L1 (L1=trans-N,N'-dimethyl-1,2-cyclohexanediamine) system was examined for the first time by using theoretical calculations. The feasible mechanism was found to involve a Ni(I)-Ni(III) catalytic cycle with three main steps: transmetalation of [Ni(I)(L1)X] (X=Cl, Br) with 9-borabicyclo[3.3.1]nonane (9-BBN)R(1) to produce [Ni(I)(L1)(R(1))], oxidative addition of R(2) X with [Ni(I)(L1)(R(1))] to produce [Ni(III)(L1)(R(1))(R(2))X] through a radical pathway, and C-C reductive elimination to generate the product and [Ni(I)(L1)X]. The transmetalation step is rate-determining for both primary and secondary alkyl bromides. KOiBu decreases the activation barrier of the transmetalation step by forming a potassium alkyl boronate salt with alkyl borane. Tertiary alkyl halides are not reactive because the activation barrier of reductive elimination is too high (+34.7 kcal mol(-1)). On the other hand, the cross-coupling of alkyl chlorides can be catalyzed by Ni/L2 (L2=trans-N,N'-dimethyl-1,2-diphenylethane-1,2-diamine) because the activation barrier of transmetalation with L2 is lower than that with L1. Importantly, the Ni(0)-Ni(II) catalytic cycle is not favored in the present systems because reductive elimination from both singlet and triplet [Ni(II)(L1)(R(1))(R(2))] is very difficult. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Assembling formation of highly dispersed Pd nanoparticles supported 1D carbon fiber electrospun with excellent catalytic active and recyclable performance for Suzuki reaction

    Science.gov (United States)

    Yu, Dongdong; Bai, Jie; Wang, Junzhong; Liang, Haiou; Li, Chunping

    2017-03-01

    In this work, the preparation of the palladium nanoparticles with carbon nanofibers (Pd NPs/CNFs) catalyst for the Suzuki reaction was described. In the process, palladium nanoparticles were formed in the reaction of palladium chloride and glucose. The Pd NPs/CNFs complex catalyst was prepared in subsequent calcination processes, a series of characterization revealed that the Pd NPs were well-dispersed on the surfaces of the carbon nanofibers or embedded in the carbon nanofibers. This catalyst showed high catalytic activity for the Suzuki reaction of aryl halide and aryl boronic acid in the ethanol/water (v/v = 4/3) solution, and the catalyst still had good stability after 10 cycles.

  11. Kinetic data for the transmetalation/reductive elimination in palladium-catalyzed Suzuki-Miyaura reactions: unexpected triple role of hydroxide ions used as base.

    Science.gov (United States)

    Amatore, Christian; Jutand, Anny; Le Duc, Gaëtan

    2011-02-18

    The mechanism of the reaction of trans-[ArPdX(PPh(3))(2)] (Ar=p-Z-C(6)H(4); Z=CN, F, H; X=I, Br, Cl) with Ar'B(OH)(2) (Ar'=p-Z'-C(6)H(4); Z'=CN, H, OMe) has been established in DMF in the presence of the base OH(-) in the context of real palladium-catalyzed Suzuki-Miyaura reactions. The formation of the cross-coupling product ArAr' and [Pd(0)(PPh(3))(3)] has been followed through the application of electrochemical techniques. Kinetic data have been obtained for the first time, with determination of the observed rate constant, k(obs), of the overall reaction. trans-[ArPdX(PPh(3))(2)] is not reactive in the absence of the base. The base OH(-) plays three roles. It favors the reaction: 1) by formation of trans-[ArPd(OH)(PPh(3))(2)], a key complex which, in contrast to trans-[ArPdX(PPh(3))(2)], reacts with Ar'B(OH)(2) (rate-determining transmetalation), and 2) by unexpected promotion of the reductive elimination from the intermediate trans-[ArPdAr'(PPh(3))(2)], which generates ArAr' and a Pd(0) species. Conversely, the base OH(-) disfavors the reaction by formation of the unreactive anionic Ar'B(OH)(3)(-). As a consequence of these antagonistic effects of OH(-), the overall reactivity is controlled by the concentration of OH(-) and passes through a maximum as the concentration of OH(-) is increased. Therefore, the base favors the rate-determining transmetalation and unexpectedly also the reductive elimination. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Carbon-Carbon Cross Coupling Reactions in Ionic Liquids Catalysed by Palladium Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    Martin H. G. Prechtl

    2010-05-01

    Full Text Available A brief summary of selected pioneering and mechanistic contributions in the field of carbon-carbon cross-coupling reactions with palladium nanoparticles (Pd-NPs in ionic liquids (ILs is presented. Five exemplary model systems using the Pd-NPs/ILs approach are presented: Heck, Suzuki, Stille, Sonogashira and Ullmann reactions which all have in common the use of ionic liquids as reaction media and the use of palladium nanoparticles as reservoir for the catalytically active palladium species.

  13. Nano Pd(0) supported on cellulose: a highly efficient and recyclable heterogeneous catalyst for the Suzuki coupling and aerobic oxidation of benzyl alcohols under liquid phase catalysis.

    Science.gov (United States)

    Jamwal, Navjot; Sodhi, Ravinderpal Kour; Gupta, Princy; Paul, Satya

    2011-12-01

    Nano palladium(0) supported on cellulose was found to be highly efficient recyclable heterogeneous catalyst for the Suzuki coupling between aryl bromides and phenyl boronic acid in water and aerobic oxidation of benzyl alcohols using air as the source of molecular oxygen in acetonitrile. The Cell-Pd(0) was prepared by stirring commercially available cellulose with Pd(OAc)(2) in ethanol at 25°C followed by reduction with hydrazine hydrate, leading finally to nano Pd(0) particles uniformly distributed on surface of cellulose. This catalytic system provides biaryls and polyaryls in excellent yields with very high turn over numbers via Suzuki coupling; and benzaldehyde derivatives in high yields and selectivity by oxidation in air. Cell-Pd(0) was characterized by X-ray diffraction techniques (XRD), thermal analysis (TGA), scanning electron microscope (SEM) and transmission electron microscope (TEM). Copyright © 2011 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Takuya Nagamine

    2011-03-01

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

  16. A Suzuki Coupling Based Route to 2,2'-Bis(2-indenyl)biphenyl Derivatives

    NARCIS (Netherlands)

    IJpeij, Edwin G.; Beijer, Felix H.; Arts, Henricus J.; Newton, Claire; Vries, Johannes G. de; Gruter, Gert-Jan M.

    2002-01-01

    Because of the promising performance in olefin polymerization of 2,2'-bis(2-indenyldiyl)biphenyl zirconium dichloride, we developed a new and broadly applicable route to 2,2'-bis(2-indenyl)biphenyl derivatives. Reaction of the known 2,2'-diiodobiphenyl with the new 2-indenyl boronic acid did not

  17. Palladium-catalyzed cross-coupling reactions of aryl boronic acids with aryl halides in water.

    Science.gov (United States)

    Wang, Shaoyan; Zhang, Zhiqiang; Hu, Zhizhi; Wang, Yue; Lei, Peng; Chi, Haijun

    2009-01-01

    An efficient Suzuki cross-coupling reaction using a variety of aryl halides in neat water was developed. The Pd-catalyzed reaction between aryl bromides or chlorides and phenyl boronic acids was compatible with various functional groups and affords biphenyls in good to excellent yields without requirement of organic cosolvents. The air stability and solubility in water of the palladium-phosphinous acid complexes were considered to facilitate operation of the coupling reaction and product isolation. The reaction conditions including Pd catalyst selection, temperature, base and catalyst recoverability were also investigated.

  18. Synthesis and Characterization of Triphenylphosphine Adducts of Ferrocene-Based Palladacycles and Their Performance in the Suzuki and Sonogashira Reactions with Bromo- and Chloroarenes

    Directory of Open Access Journals (Sweden)

    Wei-Jun Fu

    2012-05-01

    Full Text Available A new triphenylphosphine adduct of cyclopalladated ferrocenylpyridazine containing a chloride anion, 2a, has been synthesized from the reaction of the chloride-bridged palladacyclic dimer 1a with triphenylphosphine. The corresponding adducts 3a,b containing iodide anion have been readily prepared through anion exchange reactions of 2a,b with NaI in acetone. These complexes were characterized by elemental analysis, IR and 1H-NMR. Additionally, their crystal structures have been determined by X-ray diffraction and intermolecular C–H···X (Cl, Br, I bonds were found in the crystals. The use of these palladacycles as catalysts for the Suzuki and Sonogashira reactions was examined. The complexes 2a,b exhibited higher catalytic activity than the corresponding 3a,b in the Suzuki reaction. However, the order of activity of adducts with varying halogen anions is 3a~3b > 2a~2b in the Sonogashira reaction.

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

    KAUST Repository

    Chartoire, Anthony

    2012-03-13

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

  20. High-quality conjugated polymers via one-pot Suzuki-Miyaura homopolymerization

    NARCIS (Netherlands)

    Zhou, Difei; Doumon, Nutifafa Y.; Abdu-Aguye, Mustapha; Bartesaghi, Davide; Loi, Maria A.; Koster, L. Jan Anton; Chiechi, Ryan C.; Hummelen, Jan C.

    2017-01-01

    This paper describes a one-pot Suzuki-Miyaura homopolymerization that involves in situ borylation/cross coupling of dibrominated donor-acceptor conjugated macromonomers, in contrast to the standard Stille copolymerization of thienosilole and isoindigo monomers. Reaction kinetics investigation

  1. Suzuki-Miyaura coupling of halophenols and phenol boronic acids: systematic investigation of positional isomer effects and conclusions for the synthesis of phytoalexins from pyrinae.

    Science.gov (United States)

    Schmidt, Bernd; Riemer, Martin

    2014-05-02

    The Suzuki-Miyaura couplings of o-, m-, and p-halophenols with o-, m-, and p-phenol boronic acids were investigated for all combinations under standardized conditions, using Pd/C as a heterogeneous catalyst and water as a solvent. In the case of iodophenols, conventional heating was used, while for bromophenols significantly better results could be obtained using microwave irradiation. This systematic study revealed that 2,4'-biphenol is particularly difficult to access, irrespective of the starting materials used, but that these difficulties can be overcome by using different additives. The conclusions drawn from this investigation allowed us to identify conditions for the protecting group-free or minimized total synthesis of biaryl-type phytoalexins. These compounds possess antibacterial activity and are produced by fruit trees as a response to microbial infection.

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

    KAUST Repository

    Song, Hyon Min

    2012-01-01

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

  3. Palladium-catalyzed coupling reactions

    CERN Document Server

    Molnár, Árpád

    2013-01-01

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

  4. Natural DNA-modified graphene/Pd nanoparticles as highly active catalyst for formic acid electro-oxidation and for the Suzuki reaction.

    Science.gov (United States)

    Qu, Konggang; Wu, Li; Ren, Jinsong; Qu, Xiaogang

    2012-09-26

    Natural DNA has been considered as a building block for developing novel functional materials. It is abundant, renewable, and biodegradable and has a well-defined structure and conformation with many unique features, which are difficult to find in other polymers. Herein, calf thymus DNA modified graphene/Pd nanoparticle (DNA-G-Pd) hybrid materials are constructed for the first time using DNA as a mediator, and the prepared DNA-G-Pd hybrid shows high catalytic activity for fuel cell formic acid electro-oxidation and for organic Suzuki reaction. The main advantages of using DNA are not only because the aromatic nucleobases in DNA can interact through π-π stacking with graphene basal surface but also because they can chelate Pd via dative bonding in such defined sites along the DNA lattice. Our results indicate that isolated, homogeneous, and ultrafine spherical Pd nanoparticles are densely in situ decorated on DNA-modified graphene surfaces with high stability and dispersibility. The prepared DNA-G-Pd hybrid has much greater activity and durability for formic acid electro-oxidation than the commercial Pd/C catalyst and polyvinylpyrrolidone-mediated graphene/Pd nanoparticle (PVP-G-Pd) hybrid used for direct formic acid fuel cells (DFAFCs). Besides, the DNA-G-Pd hybrid can also be an efficient and recyclable catalyst for the organic Suzuki reaction in aqueous solution under aerobic conditions without any preactivation. Since DNA can chelate various transition metal cations, this proof-of-concept protocol provides the possibility for the tailored design of other novel catalytic materials based on graphene with full exploitation of their properties.

  5. Palladium-Catalysed Coupling Reactions

    NARCIS (Netherlands)

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

    2012-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Atsushi Ohtaka

    2015-02-01

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

  7. Tutvustatakse Suzuki meetodit

    Index Scriptorium Estoniae

    2001-01-01

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

  8. Rapid Synthesis of D-A'-π-A Dyes through a One-Pot Three-Component Suzuki-Miyaura Coupling and an Evaluation of their Photovoltaic Properties for Use in Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Irie, Shunsuke; Fuse, Shinichiro; Maitani, Masato M; Wada, Yuji; Ogomi, Yuhei; Hayase, Shuzi; Kaiho, Tatsuo; Masui, Hisashi; Tanaka, Hiroshi; Takahashi, Takashi

    2016-02-12

    Twenty-four D-A'-π-A dyes were rapidly synthesized through a one-pot three-component Suzuki-Miyaura coupling reaction, which was assisted by microwave irradiation. We measured the absorption spectra, electrochemical properties, and solar-cell performance of all the synthesized dyes. The D5 πA4 dye contained our originally designed rigid and nonplanar donor and exerted the highest efficiency at 5.4 %. The short-circuit current (Jsc ) was the most important parameter for the conversion efficiency (η) in the case of the organic D-A'-π-A dyes. Optimal ranges for the D-A'-π-A dyes were observed for high values of Jsc /λmax at λ=560-620 nm, an optical-absorption edge of λ=690-790 nm, and EHOMO and ELUMO values of <1.14 and -0.56 to -0.76 V, respectively. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Directory of Open Access Journals (Sweden)

    Kamal M. Dawood

    2017-05-01

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

  10. Direct One-Pot Synthesis of Primary 4-Amino-2,3-diaryl-quinolines via Suzuki-Miyaura Cross-Coupling of 2-Aryl-4-azido-3-iodoquinolines with Arylboronic Acids

    Directory of Open Access Journals (Sweden)

    Mamasegare Mabel Mphahlele

    2011-10-01

    Full Text Available Palladium-catalyzed Suzuki-Miyaura cross-coupling of 2-aryl-4-azido-3-iodo-quinolines with arylboronic acids afforded the corresponding primary 4-amino-2,3-diarylquinolines in a single-pot operation along with symmetrical biaryls and traces of the 2,3-diaryl-4-azidoquinolines. A plausible mechanism, which implicates palladium hydride species in the reduction of the incipient 2,3-diaryl-4-azidoquinolines to afford the 4-amino-2,3-diarylquinolines is proposed.

  11. Calix[4]arenes with one and two N-linked imidazolium units as precursors of N-heterocyclic carbene complexes. Coordination chemistry and use in Suzuki-Miyaura cross-coupling.

    Science.gov (United States)

    Brenner, Eric; Matt, Dominique; Henrion, Mickaël; Teci, Matthieu; Toupet, Loïc

    2011-10-14

    The calix[4]arene-imidazolium salts 5-(3-butyl-1-imidazolylium)-25,26,27,28-tetrabenzyloxy-calix[4]arene bromide (cone) (2), and 5,11-bis(3-alkyl-1-imidazolylium)-25,26,27,28-tetrabenzyloxycalix[4]arene diiodide (cone) (R = methyl, 3a; R = n-butyl, 3b) have been synthesised. Reaction of 2 in dioxane with PdCl(2) in the presence of CsCO(3) and KBr (80 °C, 24 h) gives the carbene complex trans-[PdBr(2)(calix-monocarbene)(2)] (14), containing two N-heterocyclic carbene ligands derived from 2 (yield: 63%). Repeating the reaction in pyridine instead of dioxane gives the mixed pyridine-carbene complex trans-[PdBr(2)(calix-carbene)(pyridine)] (15) in 75% yield. Treatment of the bis-imidazolium salt 3a with [Pd(OAc)(2)] affords a chelate complex, trans-[PdI(2){calix-bis(carbene)}] (16), in which a metallo-(bis-carbene) fragment caps the upper rim of the calixarene basket. Complex 16, as well as its analogue 17, obtained from 3b, display apparent C(s)-symmetry in solution. This is not the case in the solid state, a single X-ray diffraction study carried out for 16 revealing a pinced cone structure for the calixarene skeleton, which reduces the symmetry to C(1). The chelate complex 17 shows poor activity in Suzuki-Miyaura cross-coupling of phenyl boronic acid and p-tolyl halides, an observation that suggests the presence of a strained metallocyclic unit preventing easy stereochemical rearrangement to an active species. Unlike 17, complexes 14 and 15 show good activities in cross-coupling. A comparative study using the carbene precursor 1-butyl-3-(2,6-diisopropylphenyl)imidazolium bromide (18), which is devoid of the receptor fragment, strongly suggests that the carbene ligands of 14 and 15 operate typically as bulky NHC-ligands.

  12. Fractional diffusion equations coupled by reaction terms

    Science.gov (United States)

    Lenzi, E. K.; Menechini Neto, R.; Tateishi, A. A.; Lenzi, M. K.; Ribeiro, H. V.

    2016-09-01

    We investigate the behavior for a set of fractional reaction-diffusion equations that extend the usual ones by the presence of spatial fractional derivatives of distributed order in the diffusive term. These equations are coupled via the reaction terms which may represent reversible or irreversible processes. For these equations, we find exact solutions and show that the spreading of the distributions is asymptotically governed by the same the long-tailed distribution. Furthermore, we observe that the coupling introduced by reaction terms creates an interplay between different diffusive regimes leading us to a rich class of behaviors related to anomalous diffusion.

  13. Mild Negishi cross-coupling reactions catalyzed by acenaphthoimidazolylidene palladium complexes at low catalyst loadings.

    Science.gov (United States)

    Liu, Zelong; Dong, Ningning; Xu, Mizhi; Sun, Zheming; Tu, Tao

    2013-08-02

    Considering that the strong σ-donor property of ylidenes derived from π-extended imidazolium salts is conducive to increasing the catalytic activity of the resulting palladium N-heterocyclic carbene complexes, robust acenaphthoimidazol-ylidene palladium complexes 3a-c with varying bulky substituted groups were prepared from the corresponding acenaphthoimidazolium chlorides by heating with PdCl2 and K2CO3 in neat 3-chloropyridine in satisfactory yields. Even at a catalyst loading as low as 0.25 mol %, complex 3a exhibited extremely high catalytic activity toward Negishi cross-coupling of alkylzinc reagents with a wide range of (hetero)aryl halides under mild reaction conditions within 30 min. Besides a great number of bromoarenes, various less expensive and inactive (hetero)aryl chlorides were coupled successfully with the alkyl- and arylzinc reagents, in which active functional groups (such as -NH2) were well tolerated even in one-pot dicoupling transformations without protection. In addition, in the case of coupling with secondary alkylzinc reagents, undesired β-hydride elimination leading to isomerized linear products was efficaciously suppressed. The catalyst system also displayed superiority in the construction of heterobiaryls through the coupling of heteroarylzinc reagents and heterocylic chloroarenes which were hardly accessible from the corresponding organoboron reagents by Suzuki-coupling reactions. Therefore, the protocol described in this paper represents a mild, general, and scalable approach to access various structurally intriguing and functionalized (hetero)aryls.

  14. Autobiography: Kinuko Suzuki, MD.

    Science.gov (United States)

    Healy, Eileen

    2014-02-01

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

  15. Semiconductor Photocatalysis for Chemoselective Radical Coupling Reactions.

    Science.gov (United States)

    Kisch, Horst

    2017-04-18

    Photocatalysis at semiconductor surfaces is a growing field of general photocatalysis because of its importance for the chemical utilization of solar energy. By analogy with photoelectrochemistry the basic mechanism of semiconductor photocatalysis can be broken down into three steps: photogenerated formation of surface redox centers (electron-hole pairs), interfacial electron transfer from and to substrates (often coupled with proton-transfer), and conversion of primary redox intermediates into the products. Sun driven water cleavage and carbon dioxide fixation are still in the state of basic research whereas aerial degradation reactions of pollutants have reached practical application for the cleaning of air. In addition, a great variety of organic transformations (not syntheses) have been reported. They include cis-trans isomerizations, valence isomerizations, cycloaddition reactions, intramolecular or intermolecular C-N and C-C couplings, partial oxidations, and reductions. In all cases, well-known products were formed but very rarely also isolated. As compared to conventional homogeneous organic synthesis, the photocatalytic reaction mode is of no advantage, although the opposite is quite often claimed in the literature. It is also noted that a high quantum yield does not implicate a high product yield, since it is measured at very low substrate conversion in order to minimize secondary photoreactions. That is especially important in semiconductor photocatalysis since photocorrosion of the photocatalyst often prevents long-time irradiation, as is the case for colloidal metal sulfide semiconductors, which in general are photochemically too unstable to be used in synthesis. In this Account, we first classify the numerous organic photoreactions catalyzed by semiconductor powders. The classification is based on easily obtainable experimental facts, namely the nature of the light absorbing reaction component and the reaction stoichiometry. Next we discuss the

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-15

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

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

    KAUST Repository

    Benhamou, Laure

    2014-01-13

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

  18. Metal-catalysed and Electrolytic Aryl Coupling Reactions of 2 ...

    African Journals Online (AJOL)

    chemlab

    acetate-catalysed aryl coupling of furfural in acetonitrile in the presence of dioxygen under pressure. Various reaction conditions have been exploited, and mechanistic aspects of the reaction are discussed. Keywords: Furfural; heteroaromatic coupling; difurans; palladium catalysis; reoxidation. 1. Introduction. Furfural ...

  19. 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.

  20. Iodination of carbohydrate-derived 1,2-oxazines to enantiopure 5-iodo-3,6-dihydro-2H-1,2-oxazines and subsequent palladium-catalyzed cross-coupling reactions

    Directory of Open Access Journals (Sweden)

    Michal Medvecký

    2016-12-01

    Full Text Available Iodination of carbohydrate-derived 3,6-dihydro-2H-1,2-oxazines of type 3 using iodine and pyridine in DMF furnished 5-iodo-substituted 1,2-oxazine derivatives 4 with high efficacy. The alkenyl iodide moiety of 1,2-oxazine derivatives syn-4 and anti-4 was subsequently exploited for the introduction of new functionalities at the C-5 position by applying palladium-catalyzed carbon–carbon bond-forming reactions such as Sonogashira, Heck, or Suzuki coupling reactions as well as a cyanation reaction. These cross-coupling reactions led to a series of 5-alkynyl-, 5-alkenyl-, 5-aryl- and 5-cyano-substituted 1,2-oxazine derivatives being of considerable interest for further synthetic elaborations. This was exemplarily demonstrated by the hydrogenation of syn-21 and anti-24 and by a click reaction of a 5-alkynyl-substituted precursor.

  1. Recent advances in copper-catalyzed asymmetric coupling reactions

    Directory of Open Access Journals (Sweden)

    Fengtao Zhou

    2015-12-01

    Full Text Available Copper-catalyzed (or -mediated asymmetric coupling reactions have received significant attention over the past few years. Especially the coupling reactions of aryl or alkyl halides with nucleophiles became a very powerful tool for the formation of C–C, C–N, C–O and other carbon–heteroatom bonds as well as for the construction of heteroatom-containing ring systems. This review summarizes the recent progress in copper-catalyzed asymmetric coupling reactions for the formation of C–C and carbon–heteroatom bonds.

  2. Recyclable nickel catalysed Suzuki–Miyaura reaction in the ...

    Indian Academy of Sciences (India)

    In this report, Suzuki-Miyaura coupling reaction was performed in the presence of polyethyleneimine (PEI) as ligand, NiCl2·6H2O and K2CO3 in ethylene glycol at 80-100°C under phosphinefree conditions. By this method, structurally different aryl bromides and iodides were reacted with phenylboronic acid and potassium ...

  3. Efficient one-step Suzuki arylation of unprotected halonucleosides, using water-soluble palladium catalysts.

    Science.gov (United States)

    Western, Elizabeth C; Daft, Jonathan R; Johnson, Edward M; Gannett, Peter M; Shaughnessy, Kevin H

    2003-08-22

    Modification of nucleosides to give pharmaceutically active compounds, mutagenesis models, and oligonucleotide structural probes continues to be of great interest. The aqueous-phase modification of unprotected halonucleosides is reported herein. Using a catalyst derived from tris(3-sulfonatophenyl)phosphine (TPPTS) and palladium acetate, 8-bromo-2'-deoxyguanosine (8-BrdG) is coupled with arylboronic acids to give 8-aryl-2'-deoxyguanosine adducts (8-ArdG) in excellent yield in a 2:1 water:acetonitrile solvent mixture. The TPPTS ligand was found to be superior to water-soluble alkylphosphines for this coupling reaction. The coupling chemistry has been extended to 8-bromo-2'-deoxyadenosine (8-BrdA) and 5-iodo-2'-deoxyuridine (5-IdU), as well as the ribonucleosides 8-bromoguanosine and 8-bromoadenosine. Good to excellent yields of arylated adducts are obtained in all cases. With use of tri(4,6-dimethyl-3-sulfonatophenyl)phosphine (TXPTS), the Suzuki coupling of 8-BrdA and 5-IdU can be accomplished in less than 1 h at room temperature. This methodology represents an efficient and general method for halonucleoside arylation that does not require prior protection of the nucleoside.

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

    Index Scriptorium Estoniae

    Mets, Lembi

    2000-01-01

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

  5. Coupled effects of dehydration reaction, dilatant strengthening and shear heating on dynamic fault slip

    Science.gov (United States)

    Yamashita, T.

    2012-12-01

    It is believed that dynamic fault slip is affected by thermal pressurization. However, dilatant strengthening and dehydration reaction may significantly affect the degree of thermal pressurization. In addition, it is not clear how such effects influence the fault slip as a whole. We theoretically study how dilatant strengthening, frictional heating and dehydration reaction are coupled and how they affect dynamic slip assuming a fault in a thermoporoelastic medium saturated with fluid. After mathematical analysis is carried out for 1D model, the behavior of 2D fault model is studied numerically. The porosity is assumed to increase with increasing fault slip following Suzuki and Yamashita (2008). Our mathematical formulation of dehydration reaction is based on Brantut et al.(2010); the dehydration reaction is assumed to be endothermic. In addition, starting from the temperature Ts, all the frictional energy is assumed to be absorbed by the dehydration reaction rather than converted into heat. Although Brantut et al.(2010) assumed a constant slip velocity, we consider the temporal evolution of slip assuming the Coulomb law of friction on the fault. We first make the analysis assuming adiabatic and undrained conditions for the 1D model. We find that three nondimensional parameters Su, P0 and G0 determine the system behavior if the initial temperature T0 and dehydration starting temperature Ts are given, where Su (>0) is a parameter proportional to the pore creation rate, P0 (>0) is the initial nondimensional frictional stress and G0 (>0) is a parameter proportional to the mass fraction of fluid released per unit of total rock mass divided by the energy change per unit volume of the slip zone. The nondimensional frictional stress P is defined by the Coulomb frictional stress divided by the initial shear stress, which suggests the relation 0Ts, where Te is the temperature. We find for Te>Ts that the evolution of P is described by the equation dP/dT=(1-P)(Su-G0*P), where

  6. Silicon-based C–N Cross-coupling Reaction

    National Research Council Canada - National Science Library

    Shimizu, Kenta; Minami, Yasunori; Goto, Osamu; Ikehira, Hideyuki; Hiyama, Tamejiro

    2014-01-01

    Palladium-catalyzed C–N bond-forming cross-coupling reaction of N-trimethylsilylamines with aryl bromides and chlorides is found to proceed in the presence of a fluoride activator in 1,3-dimethyl-2-imidazolidinone (DMI...

  7. Suzuki and the Teaching of Writing: A Surprising Connection.

    Science.gov (United States)

    Resch, Paula C.

    Process writing and Suzuki's Mother Tongue Method of music instruction are similar in many ways. Like Suzuki teachers, teachers of writing who use the process method are humanizing children in a technological age. Both Suzuki and leaders of the writing renaissance believe that every child can be a musician or a writer. Both methods tell learners…

  8. Observation and Analysis of Suzuki String Teaching.

    Science.gov (United States)

    Colprit, Elaine J.

    2000-01-01

    Examines teacher and student behaviors in 48 violin and cello lessons taught by 12 expert Suzuki string teachers. Reveals that approximately 45% of the mean percentage of time was devoted to teacher verbalizations, 20% to teacher modeling, and 41% to student performance. (CMK)

  9. Powerful Learning Experiences and Suzuki Music Teachers

    Science.gov (United States)

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

    2016-01-01

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

  10. Single-pot template transformations of cyanopyridines on a Pd(II) centre: syntheses of ketoimine and 2,4-dipyridyl-1,3,5-triazapentadiene palladium(II) complexes and their catalytic activity for microwave-assisted Suzuki-Miyaura and Heck reactions.

    Science.gov (United States)

    Kopylovich, Maximilian N; Lasri, Jamal; Guedes da Silva, M Fátima C; Pombeiro, Armando J L

    2009-04-28

    [2 + 3] cycloaddition of the pyrrolin N-oxide (-)O[upper bond 1 start](+)N[double bond, length as m-dash]CHCH(2)CH(2)C[upper bond 1 end]Me(2) with 2-cyanopyridine NC(5)H(4)(2-CN) in the presence of PdCl(2) at room temperature in acetone gives the ketoimine palladium(II) complex cis-[PdCl(2){N(=[upper bond 1 start]CCH(2)CH(2)C(Me)(2)N[upper bond 1 end]H)C(=O)C(5)H(4)N}] containing the (E)-N-(5,5-dimethylpyrrolidin-2-ylidene)picolinamide ligand, in good yield (85%). The reaction of with 3-cyanopyridine NC(5)H(4)(3-CN) or 4-cyanopyridine NC(5)H(4)(4-CN) under the same experimental conditions gives the simple adducts of cyanopyridines trans-[PdCl(2){NC(5)H(4)(3-CN)}(2)] or trans-[PdCl(2){NC(5)H(4)(4-CN)}(2)] , respectively. When the cyanopyridines NC(5)H(3)R(1)R(2) (R(1) = 2-CN, R(2) = H ; R(1) = 3-CN, R(2) = H ; R(1) = 4-CN, R(2) = H ; R(1) = 4-CN, R(2) = 2-Cl ; R(1) = 3-CN, R(2) = 5-Me ) are heated at 100 degrees C for 12 h with 2-butanone oxime (used as a reagent and solvent) in the presence of PdCl(2), the 2,4-dipyridyl-1,3,5-triazapentadienate (or bis-imidoylamidinate) palladium(II) complexes [Pd{HN[double bond, length as m-dash]C(NC(5)H(3)R(2))NC(NC(5)H(3)R(2))[double bond, length as m-dash]NH}(2)] (2-NC(5)H(3), R(2) = H ; 3-NC(5)H(3), R(2) = H ; 4-NC(5)H(3), R(2) = H ; 4-NC(5)H(3), R(2) = 2-Cl ; 3-NC(5)H(3), R(2) = 5-Me ) are synthesized by one-pot template transformations followed by deprotonation by a base (n-PrNH(2)). The compounds were characterized by IR, (1)H and (13)C NMR spectroscopies, FAB(+)-MS, elemental analyses and, in the cases of , , and , also by X-ray diffraction analyses. The catalytic activity of complexes and was studied under microwave irradiation for C-C coupling reactions, in the solid phase on a silica gel support, and it was found that complex is the most active one with the maximum TON of 2.0.10(5) and TOF of 1.3.10(4) min(-1) for Suzuki-Miyaura, and TON of 800 and TOF of 27 min(-1) for Heck reactions.

  11. Catalytic bismetallative multicomponent coupling reactions: scope, applications, and mechanisms

    Science.gov (United States)

    Cho, Hee Yeon

    2014-01-01

    Catalytic reactions have played an indispensable role in organic chemistry for the last several decades. In particular, catalytic multicomponent reactions have attracted a lot of attention due to their efficiency and expediency towards complex molecule synthesis. The presence of bismetallic reagents (e.g. B–B, Si–Si, B–Si, Si–Sn, etc.) in this process renders the products enriched with various functional groups and multiple stereocenters. For this reason, catalytic bismetallative coupling is considered an effective method to generate the functional and stereochemical complexity of simple hydrocarbon substrates. This review highlights key developments of transition-metal catalyzed bismetallative reactions involving multiple π components. Specifically, it will highlight the scope, synthetic applications, and proposed mechanistic pathways of this process. PMID:24736839

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

    Czech Academy of Sciences Publication Activity Database

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

    2000-01-01

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

  13. Synthesis of Dichlorophosphinenickel(II) Compounds and Their Catalytic Activity in Suzuki Cross-Coupling Reactions: A Simple Air-Free Experiment for Inorganic Chemistry Laboratory

    Science.gov (United States)

    Thananatthanachon, Todsapon; Lecklider, Michelle R.

    2017-01-01

    In this experiment, students perform an air-free synthesis of three dichlorophosphinenickel(II) compounds, NiCl[subscript 2](PPh[subscript 3])[subscript 2], NiCl[subscript 2](PCy[subscript 3])[subscript 2], and NiCl[subscript 2](DPPE), using NiCl[subscript 2]·6H[subscript 2]O and the appropriate phosphine as the precursors. These colorful nickel…

  14. Synthesis of zwitterionic palladium complexes and their application as catalysts in cross-coupling reactions of aryl, heteroaryl and benzyl bromides with organoboron reagents in neat water.

    Science.gov (United States)

    Ramakrishna, V; Dastagiri Reddy, N

    2017-07-04

    N-(3-Chloro-2-quinoxalinyl)-N'-arylimidazolium salts (aryl = 2,6-diisopropylphenyl [HL1Cl]Cl, aryl = mesityl [HL2Cl]Cl) have been synthesized by treating 2,3-dichloroquinoxaline with the corresponding N'-arylimidazole in neat water. Facile reactions of these imidazolium salts with Pd(PPh 3 ) 4 and Pd 2 (dba) 3 /PPh 3 (dba = dibenzyledene acetone) at 50 °C have afforded zwitterionic palladium(ii) complexes [Pd(HL1)(PPh 3 )Cl 2 ] (I) and [Pd(HL2)(PPh 3 )Cl 2 ] (II) in excellent yields. I and II have been tested for their ability to catalyze Suzuki-Miyaura cross coupling (SMC) reactions in neat water/K 2 CO 3 and are found to be highly active for carrying out these reactions between aryl bromides and organoboron reagents. Furthermore, the scope of the catalyst I was also examined by employing (hetero)aryl bromides, hydrophilic aryl bromides, benzyl bromides and various organoboron reagents. More than 80 aryl/benzyl bromide-arylboronic acid combinations were screened in neat water/K 2 CO 3 and it was found that I was a versatile catalyst, which produced biaryls/diarylmethanes in excellent yields. A TON of 82 000 was achieved by using I. Studies on the mechanism have also been carried out to investigate the involvement of carbene complexes in the catalytic path. Poison tests and a two-phase test were also conducted and the results are reported.

  15. The Philosophy of Shinichi Suzuki: "Music Education as Love Education"

    Science.gov (United States)

    Hendricks, Karin S.

    2011-01-01

    This article attempts to bridge the philosophical gap between Western music education philosophers and practicing Suzuki music teachers. Specifically addressed is Estelle Jorgensen's critique of Suzuki-trained educators who may rely too heavily on rote pedagogical methods without careful reflection of the philosophical principles underlying their…

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

    DEFF Research Database (Denmark)

    Abu, Rohana; Woodley, John M.

    2015-01-01

    In recent years, much interest has been shown in the use of multi-enzyme cascades as a tool in organic synthesis. Such enzymatic cascades can provide added value to a synthetic scheme by starting from cheaper raw materials or making more valuable products. Additionally, they can be used to help s...... parameters such as the equilibrium constant on the multienzyme cascades and the conventional methods of equilibrium shifting are also discussed in addition to methods used to estimate such values....... 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...

  17. A novel reverse flow reactor coupling endothermic and exothermic reactions. Part II: sequential reactor configuration for reversible endothermic reactions

    NARCIS (Netherlands)

    van Sint Annaland, M.; Scholts, H.A.R.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    2002-01-01

    The new reactor concept for highly endothermic reactions at elevated temperatures with possible rapid catalyst deactivation based on the indirect coupling of endothermic and exothermic reactions in reverse flow, developed for irreversible reactions in Part I, has been extended to reversible

  18. Gold(III)-catalyzed three-component coupling reaction (TCC) selective toward furans.

    Science.gov (United States)

    Li, Jian; Liu, Li; Ding, Dong; Sun, Jiangtao; Ji, Yangxuan; Dong, Jialing

    2013-06-07

    An efficient three-component coupling reaction toward a variety of furan derivatives has been developed. This cascade transformation proceeds via the gold-catalyzed coupling reaction of phenylglyoxal derivatives, secondary amines, and terminal alkynes, under the reaction conditions, that undergoes cyclization into the furan core.

  19. Multi-reaction-channel fitting calculations in a coupled-channel ...

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... 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 reactions ...

  20. 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.

  1. Copper-mediated fluoroalkylation reactions with iododifluoroacetamides: controlling the selectivity among cross-coupling, intramolecular cyclization, and homocoupling reactions.

    Science.gov (United States)

    Zhu, Jieming; Zhang, Wei; Zhang, Laijun; Liu, Jun; Zheng, Ji; Hu, Jinbo

    2010-08-20

    Cu-mediated fluoroalkylation reactions with iododifluoroacetamides 1 have been systematically investigated. It was found that three types of reactions may coexist in Cu-mediated reactions between iododifluoroacetamides and aryl/alkenyl iodides: cross-coupling, intramolecular cyclization, and homocoupling reactions. The selectivity among these three types of reactions could be controlled by tuning the substituents on the nitrogen atom of iododifluoroacetamides, and/or by removing the cross-coupling reaction partner (aryl/alkenyl halides). The general rule is as follows: (a) in the presence of proper aryl/alkenyl iodides, the cross-coupling products 2 (or 6) are generally formed as the major products; (b) in the absence of aryl/alkenyl iodides, and when R(1) = alkyl and R(2) = aryl groups, or when R(1) = R(2) = aryl groups, the intramolecular cyclization products 3 can be formed predominantly; and (c) in the absence of aryl/alkenyl iodides, and when R(1) = R(2) = alkyl groups, or when R(1) = H and R(2) = alkyl, aryl groups, the homocoupling products 4 can be formed dominantly. Our experimental results also indicate that in many cases when cross-coupling, homocoupling, and intramolecular cyclization reactions coexist in the Cu-mediated reaction system, the reactivity decreases in the following order: cross-coupling > intramolecular cyclization > homocoupling.

  2. Regiocontrolled Microwave Assisted Bifunctionalization of 7,8-Dihalogenated Imidazo[1,2-a]pyridines: A One Pot Double-Coupling Approach

    Directory of Open Access Journals (Sweden)

    Alain Gueiffier

    2012-09-01

    Full Text Available The reactivity of the 7-chloro-8-iodo- and 8-chloro-7-iodoimidazo[1,2-a]pyridines 1ae diversely substituted on the 2 position, towards Suzuki-Miyaura, Sonogashira, and Buchwald-Hartwig cross-coupling reactions as well as cyanation was evaluated. Various methodologies are proposed to introduce aryl, heteroaryl, alkyne, amine or cyano groups in the two positions depending on the nature of the substituent present in position 2. In both series, the substitution of the iodine atom was totally regioselective and the difficulty was to substitute the chlorine atom in a second step. Until now, only hetero(aryl groups could be introduced though Suzuki-Miyaura cross-coupling. We overcame this problem evaluating both regioisomers in parallel. The double coupling approach was also studied allowing the one pot Suzuki/Suzuki, cyanation/Sonogashira and cyanation/Buchwald reactions leading to polyfunctionnalized imidazo[1,2-a]pyridines.

  3. A novel reverse flow reactor coupling endothermic and exothermic reactions. Part I: comparison of reactor configurations for irreversible endothermic reactions

    NARCIS (Netherlands)

    van Sint Annaland, M.; Scholts, H.A.R.; Kuipers, J.A.M.; van Swaaij, Willibrordus Petrus Maria

    2002-01-01

    A new reactor concept is studied for highly endothermic heterogeneously catalysed gas phase reactions at high temperatures with rapid but reversible catalyst deactivation. The reactor concept aims to achieve an indirect coupling of energy necessary for endothermic reactions and energy released by

  4. Acute Stress Reactions in Couples after a Burn Event to Their Young Child

    NARCIS (Netherlands)

    Bakker, A.; Van Loey, N.E.; Van der Heijden, P.G.M.|info:eu-repo/dai/nl/073087998; Van Son, M.J.M.|info:eu-repo/dai/nl/068440340

    2012-01-01

    Objective This multicenter study examines acute stress reactions in couples following a burn event to their preschool child. Methods Participants were 182 mothers and 154 fathers, including 143 couples, of 193 children (0–4 years) with acute burns. Parents’ self-reported acute stress reactions and

  5. Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions.

    Science.gov (United States)

    Sahin, Ziya; Akkoς, Senem; İlhan, İlhan Özer; Kayser, Veysel

    2017-07-30

    Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. Detailed and generalized protocols are also presented for testing the catalytic activity of such complexes in arylation and Suzuki-Miyaura cross-coupling reactions. Representative results are shown for the catalytic activity of the four complexes in arylation and Suzuki-Miyaura type reactions. For each of the reactions investigated, at least one of the four complexes successfully catalyzed the reaction, qualifying them as promising candidates for catalysis of many carbon-carbon bond-forming reactions. The protocols presented are general enough to be adapted for the synthesis, purification and catalytic activity testing of new palladium N-heterocyclic carbene complexes.

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

    Indian Academy of Sciences (India)

    reaction equations have been constructed using the auxiliary equation method. These equations arise in a variety of contexts not only in biological, chemical and physical sciences but also in ecological and social sciences.

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

    NARCIS (Netherlands)

    Gümrükçü, Y.

    2014-01-01

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

  8. 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.

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

    Indian Academy of Sciences (India)

    Nonlinear diffusion equation; auxiliary equation method; solitary wave solution. PACS Nos 05.45.Yv; 02.30. ... tions not only of nonlinear partial differential equations but also of their coupled versions. These methods .... Case 1d: If A = 1, C = 2 − m2 and D = 1 − m2, then [18] z(ξ) = cn(ξ)/sn(ξ), and, from (7), we have u(ξ) = D1.

  10. Separable coupled-channels momentum space potentials for nuclear reactions

    Science.gov (United States)

    Hlophe, Linda; Eremenko, Vasily; Elster, Charlotte; Nunes, Filomena; Deltuva, Arbanas; Escher, Jutta; Thompson, Ian; Torus Collaboration

    2015-10-01

    Many nuclei are deformed and their properties may be described using a rotational model. This involves defining a deformed surface of the nucleus and constructing the nuclear interaction as a function of distance to the surface. The resulting potential has non-zero matrix elements between different rotational states which are characterized by the nuclear spin-parity Iπ, leading to channel couplings. Our goal is to utilize these coupled-channels potentials in momentum space Faddeev calculations which take into account core excitations. For this purpose their separable representation in momentum space is necessary. We accomplish this by employing the separable representation scheme developed by Ernst, Shakin, and Thaler (EST). Since the potentials are complex, the multichannel EST scheme is generalized to non-Hermitian potentials. In the case of proton-nucleus interactions the EST scheme is further extended to include charged particles. The multichannel EST scheme is applied to scattering off 10Be and 12C. For 10Be only couplings to the first excited state (Iπ =2+) were included while for 12C the first two excited states (Iπ =2+ ,4+) were taken into account. Research for this project was supported in part by the US Department of Energy, Office of Science of Nuclear Physics contact.

  11. 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.

  12. 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.

  13. Reductive coupling reaction of benzyl, allyl and alkyl halides in aqueous medium promoted by zinc

    Directory of Open Access Journals (Sweden)

    Sá Ana C. P. F. de

    2003-01-01

    Full Text Available Organic halides undergo reductive dimerization (Wurtz-type coupling promoted by zinc at room temperature in aqueous medium. The reaction yields are strongly enhanced by copper catalysis. This coupling procedure provides an efficient and simple method for the homocoupling of benzylic and allylic bromides and primary alkyl iodides.

  14. Cultural Translation in Two Directions: The Suzuki Method in Japan and Germany

    Science.gov (United States)

    Mehl, Margaret

    2009-01-01

    The Suzuki Method represents a significant contribution by a Japanese, Suzuki Shin'ichi (1898-1998), to the teaching of musical instruments worldwide. Western observers often represent the method as "Japanese," although it could be called "Western" with equal justification. Suzuki left no detailed description of his method.…

  15. Visible-Light Photoredox-Catalyzed Coupling Reaction of Azoles with α-Carbamoyl Sulfides.

    Science.gov (United States)

    Jarrige, Lucie; Levitre, Guillaume; Masson, Géraldine

    2016-08-19

    A simple, straightforward strategy for the synthesis of N-substituted azoles is reported that involves a visible-light photoredox-catalyzed coupling reaction of azoles with α-carbamoyl sulfides. A variety of heterocyclic units, including pyrazoles, benzopyrazoles, benzoimidazoles, and purines, can be efficiently incorporated under mild reaction conditions in respectable yields.

  16. A novel reverse flow reactor coupling endothermic and exothermic reactions: an experimental study

    NARCIS (Netherlands)

    van Sint Annaland, M.; Nijssen, R.C.

    2002-01-01

    A new reactor concept is studied for highly endothermic heterogeneously catalysed gas phase reactions at high temperatures with rapid but reversible catalyst deactivation. The reactor concept aims to achieve an indirect coupling of energy necessary for endothermic reactions and energy released by

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

    African Journals Online (AJOL)

    Kinetics of the Coupled Gas-Iron Reactions Involving Silicon and Carbon. ... proceeds as written for high initial carbon contents but proceeds in the reverse direction for high initial silicon contents. The rate-limiting factors seem to be the surface chemical reactions, with rate of supply of silicon monoxide probably contributing.

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

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... The rate-limiting factors seem to be the surface chemical reactions, with rate of supply of silicon monoxide probably contributing. 1. INTRODUCTION. In order to gain an insight into the nature of the coupled reactions existing between carbon and silicon when a gas phase containing carbon dioxide, carbon.

  19. Catalytic coupling reaction mechanism of 4-nitrobenzenethiol on silver clusters: a density functional theoretical study.

    Science.gov (United States)

    Chen, Xiao; Wei, Wei; Li, Laicai; Liu, Liuxie; Pan, Rui; Tian, Anmin

    2017-10-23

    The catalytic coupling reaction mechanism of the transformation from 4-nitrobenzenethiol (4-NBT) to 4,4'-dimercaptoazobenzene (4,4'-DMAB) on a silver cluster was studied by density functional theory. Reactants, intermediates, transition states and products were optimized with the B3LYP method using the 6-311 + G(d,p) basis set (Ag using the pseudo potential basis set of LanL2DZ). Transition states and intermediates were confirmed by the corresponding vibration analysis and intrinsic reaction coordinates (IRC). Consistent with literature reports, the key point of the transformation from 4-NBT absorbed on the surface of Ag 5 clusters to 4,4'-DMAB is the elimination of two O atoms on the amino group. Meanwhile, the catalytic coupling reaction of 4-nitrobenzenethiol on a silver cluster is easy to carry out under irradiation. The possibility of "inter system channeling" (ISC) between different potential energy surfaces in the coupling reaction of 4-NBT is further discussed. The irradiation has an auxiliary catalytic effect on the coupling reaction. Our research results can explain the observed experimental phenomena. Graphical abstract Catalytic coupling reaction mechanism of the transformation from 4-nitrothiophenol (4-NBT) to 4,4'-dimercaptoazobenzene (4,4'-DMAB) on silver clusters studied by density functional theory.

  20. 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

    radical as an intermediate leading to the proposal of an SRN1 pathway for the coupling. The mechanistic information gave rise to suspicion about two previously published cross-coupling reactions catalyzed by manganese(II) salts. As a result, the coupling between aryl halides and organostannanes as well......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...... as between aryl halides and amines were revisited. Both reactions were found impossible to reproduce without the addition of small amounts of palladium or copper and are therefore not believed to be catalyzed by manganese....

  1. Synthesis of diverse dihydropyrimidine-related scaffolds by fluorous benzaldehyde-based Biginelli reaction and post-condensation modifications

    Directory of Open Access Journals (Sweden)

    Bruno Piqani

    2011-09-01

    Full Text Available Dihydropyrimidinones and dihydropyrimidinethiones generated from the Biginelli reactions of perfluorooctanesulfonyl-attached benzaldehydes are used as common intermediates for post-condensation modifications such as cycloaddition, Liebeskind–Srogl reaction and Suzuki coupling to form biaryl-substituted dihydropyrimidinone, dihydropyrimidine, and thiazolopyrimidine compounds. The high efficiency of the diversity-oriented synthesis is achieved by conducting a multicomponent reaction for improved atom economy, under microwave heating for fast reaction, and with fluorous solid-phase extractions (F-SPE for ease of purification.

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

    Directory of Open Access Journals (Sweden)

    Mnaza Noreen

    2017-01-01

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

  3. Kodaly, Dalcroze, Orff, and Suzuki: Application in the Secondary Schools.

    Science.gov (United States)

    Turpin, Douglas

    1986-01-01

    Suggestions to help music teachers adapt the following teaching methods are provided: the Dalcroze method for dance class; the Kodaly method for instrumentalists; the Orff method for string players; the Suzuki method for instrumentalists; and the Kodaly method for chorus. (RM)

  4. EFFECTS OF SOLVENT, BASE, AND TEMPERATURE IN THE OPTIMISATION OF A NEW CATALYTIC SYSTEM FOR SONOGASHIRA CROSS-COUPLING USING NCP PINCER PALLADACYCLE

    Directory of Open Access Journals (Sweden)

    Diego S. Rosa

    2015-05-01

    Full Text Available The optimisation of a new catalyst system using NCP pincer palladacycle 1 was investigated using the experimental design technique. NCP pincer palladacycle 1 was previously investigated in Suzuki-Miyaura and Heck-Mizoroki cross-couplings and found to be a highly efficient catalyst precursor. In this study, the effects of the type of base (K3PO4 or DABCO, solvent (DMF or dioxane and reaction temperature (130 or 150 ºC in the second step on the reactional yield in Sonogashira cross-coupling were assessed using the two-factor design. The results showed that temperature is statistically significant in relation to the reaction yield.

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

    Directory of Open Access Journals (Sweden)

    Tunde V. Ojumu

    2012-10-01

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

  6. Coupled Serpentinsation and Carbonation Reaction in Ultrabasic Minerals

    Science.gov (United States)

    Dufaud, F.; Martinez, I.; Shilobreeva, S.; Fiquet, G.

    2006-12-01

    Because of its significant atmospheric abundance compared with the other greenhouse gases, CO2 is by far the most important. One of the options to reduce the anthropogenic CO2 emission into the atmosphere is the mineral storage: the process that converts gaseous CO2 into a geologically stable phase, such as a carbonate. Such reactions, however, are characterized by slow kinetics, which have to be measured since it could be the most limiting factor of geochemical storage of CO2. We have carried out carbonation experiments on olivine, serpentine and orthopyroxene under various conditions in an hydraulic press (1-1.7kbar and 400-500°C). Powders (100-200μm grain size) of these minerals were kept in contact with oxalic acid used as a source of CO2 in platinum capsules and reacted at high pressure and temperature. Experiments conducted under such conditions provide large carbonation rates. The amounts of carbonate formed were measured by decarbonation of the reacted material. Chemical and carbon isotopic mass balance calculations were also done in order to provide precise monitoring of carbonation rates. Mineralogical study of the reacted samples using both SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy) allowed the identification of the dissolution/precipitation carbonation mechanisms and the observation of nanometer sized magnesite crystals, systematically associated to protoserpentine phases. Strong differences in carbonate textures and carbonation rates were measured as a function of the initial mineral, water fugacity and NaCl concentrations. Similarities and differences of these results with experiments carried out under usual CO2 storage conditions in basic and ultrabasic rock will be discussed.

  7. Reactions of nitroxides 15. Cinnamates bearing a nitroxyl moiety synthesized using a Mizoroki–Heck cross-coupling reaction

    Directory of Open Access Journals (Sweden)

    Jerzy Zakrzewski

    2015-07-01

    Full Text Available Cinnamic acid derivatives bearing a nitroxyl moiety (2,2,6,6-tetramethyl-1-oxyl-4-piperidyl 3-E-aryl acrylates were synthesized in 30–100% yield using a Mizoroki–Heck cross-coupling reaction between 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl and iodobenzene derivatives in the presence of palladium(II acetate coordinated with a tri(o-tolylphosphine ligand immobilized in a polyurea matrix.

  8. Applications of Palladium-Catalyzed C–N Cross-Coupling Reactions

    Science.gov (United States)

    2016-01-01

    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. PMID:27689804

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

    NARCIS (Netherlands)

    Aalbers, Friso S; Fraaije, Marco W

    2017-01-01

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

  10. Reductive coupling reaction of benzyl, allyl and alkyl halides in aqueous medium promoted by zinc

    OpenAIRE

    Sá Ana C. P. F. de; Pontes Giovanna M. A.; Anjos José A. L. dos; Santana Sidney R.; Bieber Lothar W.; Malvestiti Ivani

    2003-01-01

    Organic halides undergo reductive dimerization (Wurtz-type coupling) promoted by zinc at room temperature in aqueous medium. The reaction yields are strongly enhanced by copper catalysis. This coupling procedure provides an efficient and simple method for the homocoupling of benzylic and allylic bromides and primary alkyl iodides. Haletos orgânicos sofrem dimerização redutiva (acoplamento tipo Wurtz) promovida por zinco a temperatura ambiente em meio aquoso. Essas reações são catalisadas p...

  11. Dynamical Coupled-Channel Model of Meson Production Reactions in the Nucleon Resonance Region

    Energy Technology Data Exchange (ETDEWEB)

    T.-S. H. Lee; A. Matsuyama; T. Sato

    2006-11-15

    A dynamical coupled-channel model is presented for investigating the nucleon resonances (N*) in the meson production reactions induced by pions and photons. Our objective is to extract the N* parameters and to investigate the meson production reaction mechanisms for mapping out the quark-gluon substructure of N* from the data. The model is based on an energy-independent Hamiltonian which is derived from a set of Lagrangians by using a unitary transformation method.

  12. Coupling reaction between electron-rich pyrimidinones and α-amino acids promoted by phosphonium salts.

    Science.gov (United States)

    ElMarrouni, Abdelatif; Fabrellas, Josep M; Heras, Montserrat

    2011-09-07

    Coupling reaction between electron-rich 2-morpholino-4(3H)-pyrimidinone and nucleophilic side chains of several natural α-amino acids promoted by phosphonium salt has been developed to prepare new optically active pyrimidin-4-yl amino acids. The best results were obtained using a two-step method through the easily available benzotriazolyl-1-oxy intermediate. A detailed optimization study of this reaction is discussed.

  13. Reaction engineering simulations of oxidative coupling of methane in a circulating fluidized-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Pannek, U.; Mleczko, L. [Bochum Univ. (Germany). Lehrstuhl fuer Technische Chemie

    1998-10-01

    Oxidative coupling of methane in a circulating fluidized-bed reactor was investigated by means of reaction engineering modeling and simulations. A model of the reactor that combines comprehensive kinetics of the OCM and a model for the description of the bed hydrodynamics was developed and applied to predict the reactor performance. The important goal of the simulations was a better understanding of the effect of the hydrodynamic conditions in the riser reactor on the reaction pathway and the product distribution. (orig.)

  14. 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)

  15. 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.

  16. A gradient descent algorithm for minimizing amino acid coupling reactions when synthesizing cyclic-peptide libraries.

    Science.gov (United States)

    Darwen, Paul J; Tran, Tran T; Bourne, Gregory T; Nielson, Jonathon L; Smythe, Mark L

    2006-08-01

    Combinatorial chemistry has become an invaluable tool in medicinal chemistry for the identification of new drug leads. For example, libraries of predetermined sequences and head-to-tail cyclized peptides are routinely synthesized in our laboratory using the IRORI approach. Such libraries are used as molecular toolkits that enable the development of pharmacophores that define activity and specificity at receptor targets. These libraries can be quite large and difficult to handle, due to physical and chemical constraints imposed by their size. Therefore, smaller sub-libraries are often targeted for synthesis. The number of coupling reactions required can be greatly reduced if the peptides having common amino acids are grouped into the same sub-library (batching). This paper describes a schedule optimizer to minimize the number of coupling reactions by rotating and aligning sequences while simultaneously batching. The gradient descent method thereby reduces the number of coupling reactions required for synthesizing cyclic peptide libraries. We show that the algorithm results in a 75% reduction in the number of coupling reactions for a typical cyclic peptide library.

  17. Ni- or Cu-catalyzed cross-coupling reaction of alkyl fluorides with Grignard reagents.

    Science.gov (United States)

    Terao, Jun; Ikumi, Aki; Kuniyasu, Hitoshi; Kambe, Nobuaki

    2003-05-14

    n-Octyl fluoride underwent a cross-coupling reaction with n-propylmagnesium bromide in the presence of 1,3-butadiene using NiCl2 as a catalyst at room temperature to give undecane in moderate yields. This alkyl-alkyl cross-coupling proceeded more efficiently when CuCl2 was employed instead of NiCl2. Addition of 1,3-butadiene dramatically improved the yields of the coupling products from primary alkyl Grignard reagents in both Ni- and Cu-catalyzed reactions. Alkyl fluorides efficiently reacted with tertiary alkyl and phenyl Grignard reagents using CuCl2 in the absence of 1,3-butadiene to afford the coupling products in high yields. The competitive reaction of a mixture of alkyl halides (R-X; X = F, Cl, Br) with nC5H11MgBr showed that the reactivities of the halides increase in the order R-Cl R-F R-Br. In contrast, in the Cu-catalyzed reaction with PhMgBr, the reactivities increase in the order R-Cl R-Br R-F.

  18. Practical Aspects of Carbon-Carbon Cross-Coupling Reactions Using Heteroarenes

    NARCIS (Netherlands)

    Slagt, Vincent F.; Vries, André H.M. de; Vries, Johannes G. de; Kellogg, Richard M.

    2010-01-01

    The use of cross-coupling reactions for the preparation of alkylated and arylated heteroaromatic compounds has increased tremendously over the past two decades. This has been driven on the one hand by the increasingly complex structures of new drugs, most of which contain one or more heterocyclic

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

    NARCIS (Netherlands)

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

    2006-01-01

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

  20. C (sp2)–C (sp2) cross coupling reaction catalyzed by a palladacycle ...

    Indian Academy of Sciences (India)

    =C(O)(C10H7)] PdCl2} as efficient catalyst has been investigated. The mononuclear palladacycle complex showed excellent activity in aqueous phase including the C(sp2)–C(sp2) cross coupling reactions. The advantages of the protocol are ...

  1. Phosphoric Acid-Mediated Synthesis of Vinyl Sulfones through Decarboxylative Coupling Reactions of Sodium Sulfinates with Phenylpropiolic Acids.

    Science.gov (United States)

    Rong, Guangwei; Mao, Jincheng; Yan, Hong; Zheng, Yang; Zhang, Guoqi

    2015-08-07

    A novel phosphoric acid -mediated synthesis of vinyl sulfones through decarboxylative coupling reactions of sodium sulfinates with phenylpropiolic acids is described. This transformation is efficient and environmentally friendly.

  2. Employing Arynes in Diels-Alder Reactions and Transition-Metal-Free Multicomponent Coupling and Arylation Reactions.

    Science.gov (United States)

    Bhojgude, Sachin Suresh; Bhunia, Anup; Biju, Akkattu T

    2016-09-20

    Arynes are highly reactive intermediates having several applications in organic synthesis for the construction of various ortho-disubstituted arenes. Traditionally, arynes are generated in solution from haloarenes under strongly basic conditions. However, the scopes of many of the aryne reactions are limited because of the harsh conditions used for their generation. The renaissance of interest in aryne chemistry is mainly due to the mild conditions for their generation by the fluoride-induced 1,2-elimination of 2-(trimethylsilyl)aryl triflates. This Account is focused on the Diels-Alder reaction of arynes and their transition-metal-free application in multicomponent couplings as well as arylation reactions. The Diels-Alder reaction of arynes is a powerful tool for constructing benzo-fused carbocycles and heterocycles. In 2012, we developed an efficient, broad-scope, and scalable Diels-Alder reaction of pentafulvenes with arynes affording benzonorbornadiene derivatives. Subsequently, we accomplished the Diels-Alder reaction of arynes with dienes such as 1,2-benzoquinones and tropones. Moreover, we uncovered a transition-metal-free protocol for the synthesis of 9,10-dihydrophenanthrenes by the reaction of arynes with styrenes that proceeds via a Diels-Alder/ene-reaction cascade. In addition, we demonstrated the reaction of arynes with indene/benzofurans, which proceeds via a tandem [4 + 2]/[2 + 2] sequence. Multicomponent coupling (MCC) involving arynes mainly comprises the initial addition of a nucleophile to the aryne followed by interception of the aryl anion intermediate with an electrophile (provided the nucleophilic and electrophilic moieties do not belong to the same molecule). We have disclosed aryne MCCs initiated by N-heterocycles such as (iso)quinoline, pyridine, and aziridines. When (iso)quinoline is used as the nucleophilic trigger and N-substituted isatin as the third component, the reaction affords spirooxazino(iso)quinolines via 1,4-dipolar

  3. Slow slip generated by dehydration reaction coupled with slip-induced dilatancy and thermal pressurization

    Science.gov (United States)

    Yamashita, Teruo; Schubnel, Alexandre

    2016-10-01

    Sustained slow slip, which is a distinctive feature of slow slip events (SSEs), is investigated theoretically, assuming a fault embedded within a fluid-saturated 1D thermo-poro-elastic medium. The object of study is specifically SSEs occurring at the down-dip edge of seismogenic zone in hot subduction zones, where mineral dehydrations (antigorite, lawsonite, chlorite, and glaucophane) are expected to occur near locations where deep slow slip events are observed. In the modeling, we introduce dehydration reactions, coupled with slip-induced dilatancy and thermal pressurization, and slip evolution is assumed to interact with fluid pressure change through Coulomb's frictional stress. Our calculations show that sustained slow slip events occur when the dehydration reaction is coupled with slip-induced dilatancy. Specifically, slow slip is favored by a low initial stress drop, an initial temperature of the medium close to that of the dehydration reaction equilibrium temperature, a low permeability, and overall negative volume change associated with the reaction (i.e., void space created by the reaction larger than the space occupied by the fluid released). Importantly, if we do not assume slip-induced dilatancy, slip is accelerated with time soon after the slip onset even if the dehydration reaction is assumed. This suggests that slow slip is sustained for a long time at hot subduction zones because dehydration reaction is coupled with slip-induced dilatancy. Such slip-induced dilatancy may occur at the down-dip edge of seismogenic zone at hot subduction zones because of repetitive occurrence of dehydration reaction there.

  4. Direct simulation of proton-coupled electron transfer reaction dynamics and mechanisms

    Science.gov (United States)

    Kretchmer, Joshua S.; Miller, Thomas F., III

    2014-03-01

    Proton-coupled electron transfer (PCET) reactions, in which both an electron and an associated proton undergo reactive transfer, play an important role in many chemical and biological systems. Due to the complexity of this class of reactions, a variety of different mechanisms fall under the umbrella of PCET. However, the physical driving forces that determine the preferred mechanism in a given system still remain poorly understood. Towards this end, we extend ring polymer molecular dynamics (RPMD), a path-integral quantum dynamics method, to enable the direct simulation and characterization of PCET reaction dynamics in both fully atomistic and system-bath models of organometallic catalysts. In addition to providing validation for the simulation method via extensive comparison with existing PCET rate theories, we analyze the RPMD trajectories to investigate the competition between the concerted and sequential reaction mechanisms for PCET, elucidating the large role of the solvent in controlling the preferred mechanism. We further employ RPMD to determine the kinetics and mechanistic features of concerted PCET reactions across different regimes of electronic and vibrational coupling, providing evidence for a new and distinct PCET reaction mechanism.

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

    Directory of Open Access Journals (Sweden)

    Mohamed Abboud

    2012-02-01

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

  6. Windsor and Perry: reactions of siblings in same-sex and heterosexual couples.

    Science.gov (United States)

    Clark, Jennifer B; Riggle, Ellen D B; Rostosky, Sharon S; Rothblum, Esther D; Balsam, Kimberly F

    2015-01-01

    The U.S. Supreme Court decisions in U.S. v. Windsor (570 U.S. 307) and Hollingsworth v. Perry (570 U.S. 399) created a focal point for public discussion of marriage equality for same-sex couples. This article reports the results of an exploratory study of the reactions of individuals currently or previously in same-sex couple relationships and a heterosexual sibling who is currently or previously married (N = 371) to the Supreme Court decisions. Thematic content analysis was used to explore participants' responses to an open-ended question on a survey. Reactions of individuals from same-sex couples revealed the following themes: (1) longitudinal perspectives on the advancement of rights for same-sex couples; (2) emotional responses celebrating the decisions or expressing relief; (3) affirmation of their relationship or rights; (4) practical consequences of the extension of rights; and (5) minority stress related to anticipation of future prejudice or discrimination. Themes in the heterosexual siblings' responses were (1) ally support; (2) flat support without emotion or elaboration; (3) indifference to or ignorance about the decisions; and (4) disapproval of the decisions. These themes are compared and discussed in light of prior research on reactions to marriage restriction debates and marriage (in)equality and family relationships.

  7. Terminal Alkyne Coupling on a Corrugated Noble Metal Surface: From Controlled Precursor Alignment to Selective Reactions.

    Science.gov (United States)

    Lin, Tao; Zhang, Liding; Björk, Jonas; Chen, Zhi; Ruben, Mario; Barth, Johannes V; Klappenberger, Florian

    2017-11-07

    Surface-templated covalent coupling of organic precursors currently emerges as a promising route to the atom-precise fabrication of low-dimensional carbon materials. Here, we investigate the adsorption and the coupling reactions of 4,4''-diethynyl-1,1':4',1''-terphenyl on Au(110) under ultra-high vacuum conditions by using scanning tunneling microscopy combined with density functional theory and kinetic Monte Carlo calculations. Temperature treatment induces both 1,2,4-asymmetric cyclotrimerization and homocoupling, resulting in various reaction products, including a previously unreported, surface-templated H-shaped pentamer. Our analysis of the temperature-dependent relative product abundances unravels that 1,2,4-trimerization and homocoupling proceed via identical intermediate species with the final products depending on the competition of coupling to a third monomer versus dehydrogenation. Our study sheds light on the control of coupling reactions by corrugated surfaces and annealing protocols. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Cross-Coupling Reactions as Valuable Tool for the Preparation of PET Radiotracers

    Directory of Open Access Journals (Sweden)

    Marc Pretze

    2011-01-01

    Full Text Available The increasing application of positron emission tomography (PET in nuclear medicine has stimulated the extensive development of a multitude of new radiotracers and novel radiolabeling procedures with the most prominent short-lived positron emitters carbon-11 and fluorine-18. Radiolabeling with these radionuclides represents a remarkable challenge. Special attention has to be paid to synthesis time and specific labeling techniques due to the short physical half life of the respective radionuclides 11C (t1/2 = 20.4 min and 18F (t1/2 = 109.8 min. In the past, numerous transition metal-catalyzed reactions were employed in organic chemistry, even though only a handful of these coupling reactions were adopted in radiochemical practice. Thus, the implementation of modern synthesis methods like cross-coupling reactions offers the possibility to develop a wide variety of novel radiotracers. The introduction of catalysts based on transition metal complexes bears a high potential for rapid, efficient, highly selective and functional group-tolerating incorporation of carbon-11 and fluorine-18 into target molecules. This review deals with design, application and improvement of transition metal-mediated carbon-carbon as well as carbon-heteroatom cross-coupling reactions as a labeling feature with the focus on the preparation of radiolabeled compounds for molecular imaging.

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

    Energy Technology Data Exchange (ETDEWEB)

    Fedorowski, Jennifer [Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States); LaCourse, William R., E-mail: lacourse@umbc.edu [Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States)

    2010-01-04

    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.

  10. C-C Coupling Reactions between Benzofurazan Derivatives and 1,3-Diaminobenzenes

    Directory of Open Access Journals (Sweden)

    Gabriele Micheletti

    2017-04-01

    Full Text Available Aromatic substitution reactions between 1,3-diaminobenzene and chloronitrobenzofurazan derivatives have never been reported so far. The aim of the current study was to synthesize novel electron-donor and -acceptor architectures of interest in applied fields and to provide new insights on the nucleophilic behavior of 1,3-diaminobenzenes. The reaction of 1,3-dipiperidinyl-, 1,3-dimorpholinyl-, 1,3-dipyrrolidinyl-, or 1,3-dimethylamino-benzene with 7-chloro-4,6-dinitrobenzofuroxan or with a series of chloro-nitrobenzofurazans has been carried out in mild conditions. The partners reactivity has been investigated by monitoring the reaction course through 1H-NMR spectroscopy. The reaction occurred in a regioselective way, providing in good yields the novel C-C coupling compounds. Indications on the reactivity behavior for the studied nucleophiles have been relieved.

  11. Present status of coupled-channels calculations for heavy-ion subbarrier fusion reactions

    Directory of Open Access Journals (Sweden)

    Hagino K.

    2016-01-01

    Full Text Available The coupled-channels method has been a standard tool in analyzing heavy-ion fusion reactions at energies around the Coulomb barrier. We investigate three simplifications usually adopted in the coupledchannels calculations. These are i the exclusion of non-collective excitations, ii the assumption of coordinate independent coupling strengths, and iii the harmonic oscillator approximation for multiphonon excitations. In connection to the last point, we propose a novel microscopic method based on the beyond-mean-field approach in order to take into account the anharmonic effects of collective vibrations.

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

    Science.gov (United States)

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

    2012-04-15

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

  13. Coupling Reactions of α-Bromocarboxylate with Non-Aromatic N-Heterocycles

    Directory of Open Access Journals (Sweden)

    Jozef Csollei

    2009-08-01

    Full Text Available The conditions for the C-N bond forming reaction (C-N coupling reaction between α-bromocarboxylate and nitrogen-containing non-aromatic heterocyclic rings under heterogeneous copper(I oxide catalysis are investigated in this paper. All the generated compounds were fully characterized by IR, NMR and MS spectroscopy. Ab initio/DFT calculations of partial charges on nitrogen atoms in all the discussed heterocycles and on C(2 of carboxylate under applied conditions were predicted. These in silico results correlate relatively with the experimental observations.

  14. Palladium-catalyzed cross coupling reactions of 4-bromo-6H-1,2-oxazines

    Directory of Open Access Journals (Sweden)

    Reinhold Zimmer

    2009-09-01

    Full Text Available A number of 4-aryl- and 4-alkynyl-substituted 6H-1,2-oxazines 8 and 9 have been prepared in good yields via cross coupling reactions of halogenated precursors 2, which in turn are easily accessible by bromination of 6H-1,2-oxazines 1. Lewis-acid promoted reaction of 1,2-oxazine 9c with 1-hexyne provided alkynyl-substituted pyridine derivative 12 thus demonstrating the potential of this approach for the synthesis of pyridines.

  15. pincer complex in Suzuki–Miyaura cross-coupling reaction under ...

    Indian Academy of Sciences (India)

    Chromatograph 6890 Series, Hewlett Packard equipped with an HP5-MS capillary column (30 m × 0.25 mm ×. 0.25 μm) and an FID detector. All GCMS analyses were done by Agilent 7890A GC system connected with. 5975C inert XL EI/CI MSD (with triple axis detector). 2.1 General procedure for the coupling reaction.

  16. Oxidation of butane to butanol coupled to electrochemical redox reaction of NAD+/NADH.

    Science.gov (United States)

    Kang, Hye Sun; Na, Byung Kwan; Park, Doo Hyun

    2007-08-01

    A crude cell extract from a butane-utilizing bacterium, Alcaligenes sp., catalyzed the oxidation of butane to butanol coupled to NADH. A graphite electrode modified with Neutral Red (NR-electrode) catalyzed the reduction of NAD(+) to NADH. About 4.9 mM butanol was produced from 50% n-butane/O(2) mixture through the combined reactions of the crude enzyme and the NR-electrode in 250 ml reactor for 3 h.

  17. Rhodium-catalyzed cross-coupling reaction of arylboronates and diazoesters and tandem alkylation reaction for the synthesis of quaternary α,α-heterodiaryl carboxylic esters.

    Science.gov (United States)

    Tsoi, Yuk-Tai; Zhou, Zhongyuan; Yu, Wing-Yiu

    2011-10-07

    A rhodium-catalyzed one-pot three-component coupling reaction was developed for the synthesis of quaternary α,α-heterodiaryl carboxylic esters. This reaction involves cross-coupling of the arylrhodium(I) complexes with α-aryldiazoacetates to form oxa-π-allylrhodium complexes. With KOtBu and alkyl halides, tandem alkylation of the allyl complex occurs to form a quaternary stereocenter at the carbenic carbon. © 2011 American Chemical Society

  18. Density Functional Reactivity Theory Characterizes Charge Separation Propensity in Proton-Coupled Electron Transfer Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shubin [Univ. of North Carolina, Chapel Hill, NC (United States); Ess, Daniel H. [Brigham Young Univ., Provo, UT (United States); Univ. of North Carolina, Chapel Hill, NC (United States); Schauer, Cynthia [Univ. of North Carolina, Chapel Hill, NC (United States)

    2011-04-20

    Proton-coupled electron transfer (PCET) reactions occur in many biological and artificial solar energy conversion processes. In these reactions the electron is often transferred to a site distant to the proton acceptor site. In this work, we employ the dual descriptor and the electrophilic Fukui function from density functional reactivity theory (DFRT) to characterize the propensity for an electron to be transferred to a site other than the proton acceptor site. The electrophilic regions of hydrogen bond or van der Waal reactant complexes were examined using these DFRT descriptors to determine the region of space to which the electron is most likely to be transferred. This analysis shows that in PCET reactions the electrophilic region of the reactant complex does not include the proton acceptor site.

  19. The Language of Teaching Coordination: Suzuki Training Meets the Alexander Technique.

    Science.gov (United States)

    Madden, Catherine

    2002-01-01

    Details an investigation of the language of Suzuki instruction and the students' interpretation of that language. Describes the Alexander Technique and Suzuki training and provides specific examples illustrating the interaction of language and coordination in this context. Proposes that teachers of movement, voice and acting can benefit from these…

  20. A Conjugated Microporous Polymer for Palladium-Free, Visible Light-Promoted Photocatalytic Stille-Type Coupling Reactions.

    Science.gov (United States)

    Ghasimi, Saman; Bretschneider, Simon A; Huang, Wei; Landfester, Katharina; Zhang, Kai A I

    2017-08-01

    The Stille coupling reaction is a versatile method to mainly form aromatic C-C bonds. However, up to now, the use of palladium catalysts is necessary. Here, a palladium-free and photocatalytic Stille-type coupling reaction of aryl iodides and aryl stannanes catalyzing a conjugated microporous polymer-based phototcatalyst under visible light irradiation at room temperature is reported. The novel coupling reaction mechanism occurs between the photogenerated aryl radical under oxidative destannylation of the aryl stannane, and the electron-activated aryl iodide, resulting into the aromatic C-C bond formation reaction. The visible light-promoted Stille-type coupling reaction using the polymer-based pure organic photocatalyst offers a simple, sustainable, and more economic synthetic pathway toward palladium-free aromatic C-C bond formation.

  1. A general strategy for nanohybrids synthesis via coupled competitive reactions controlled in a hybrid process.

    Science.gov (United States)

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

    2015-03-30

    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 synthesis can be realized by the hybrid process, which enables us to investigate nanohybrid formation at each stage through their solution color changes and TEM images. By adjusting the bi-channel solvents and kinetic parameters of each stage, the primary components of alloyed cores and the second components of transition metal doping ZnO or Al2O3 as surface coatings can be successively formed. The core alloying and shell gradient-doping strategy can efficiently eliminate the crystal lattice mismatch in different components. Consequently, varieties of gradient core-shell nanohybrids can be synthesized using CoM, FeM, AuM, AgM (M = Zn or Al) alloys as cores and transition metal gradient-doping ZnO or Al2O3 as shells, endowing these nanohybrids with unique magnetic and optical properties (e.g., high temperature ferromagnetic property and enhanced blue emission).

  2. Palladium-catalyzed cross-coupling reactions of potassium alkenyltrifluoroborates with organic halides in aqueous media.

    Science.gov (United States)

    Alacid, Emilio; Nájera, Carmen

    2009-03-20

    Potassium vinyl and alkenyltrifluoroborates are cross-coupled with aryl and heteroaryl bromides using 1 mol % Pd loading of 4-hydroxyacetophenone oxime derived palladacycle or Pd(OAc)2 as precatalysts, K2CO3 as base, and TBAB as additive and water reflux under conventional or microwave heating to afford styrenes, stilbenoids, and alkenylbenzenes. These borates can be cross-coupled diastereoselectively with allyl and benzyl chlorides using KOH as base in acetone-water (3:2) at 50 degrees C and 0.1 mol % Pd loading, giving the corresponding 1,4-dienes and allylarenes, respectively. These simple phosphine-free reaction conditions allow the palladium recycling from the aqueous phase during up to five runs by extractive separation of the products, which contain 58-105 ppm of Pd.

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qingxiang, E-mail: axiang236@126.com [Department of Chemistry and Environment Science, Zhangzhou Normal University, Zhangzhou 363000 (China); Ding, Yingtao; Gao, Feng [Department of Chemistry and Environment Science, Zhangzhou Normal University, Zhangzhou 363000 (China); Jiang, Shulian [Zhangzhou Product Quality Supervision and Inspection Institute, Zhangzhou 363000 (China); Zhang, Bin; Ni, Jiancong; Gao, Fei [Department of Chemistry and Environment Science, Zhangzhou Normal University, Zhangzhou 363000 (China)

    2013-07-25

    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{sup 13} strands cm{sup −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{sub 3}{sup −}) was electrodeposited on the surface of a glassy carbon electrode (GCE) to form a steady and ordered AN-SO{sub 3}{sup −} layer. Then the amino-terminated capture probe was covalently grafted to the surface of SO{sub 3}{sup −}-AN deposited GCE through the sulfamide coupling reaction between the amino groups in the probe DNA and the sulfonic groups in the AN-SO{sub 3}{sup −}. The step-by-step modification process was characterized by electrochemistry and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. Using Ru(NH{sub 3}){sub 6}{sup 3+} as probe, the probe density and the hybridization efficiency of the biosensor were determined to be 3.18 × 10{sup 13} strands cm{sup −2} and 86.5%, respectively. The hybridization performance of the biosensor was examined by differential pulse voltammetry using Co(phen){sub 3}{sup 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){sub 3}{sup 3+/2+} increased linearly with the logarithm values of the concentration

  4. Coupled transport and reaction kinetics control the nitrate source-sink function of hyporheic zones

    Science.gov (United States)

    Zarnetske, Jay P.; Haggerty, Roy; Wondzell, Steven M.; Bokil, Vrushali A.; GonzáLez-Pinzón, Ricardo

    2012-11-01

    The fate of biologically available nitrogen (N) and carbon (C) in stream ecosystems is controlled by the coupling of physical transport and biogeochemical reaction kinetics. However, determining the relative role of physical and biogeochemical controls at different temporal and spatial scales is difficult. The hyporheic zone (HZ), where groundwater-stream water mix, can be an important location controlling N and C transformations because it creates strong gradients in both the physical and biogeochemical conditions that control redox biogeochemistry. We evaluated the coupling of physical transport and biogeochemical redox reactions by linking an advection, dispersion, and residence time model with a multiple Monod kinetics model simulating the concentrations of oxygen (O2), ammonium (NH4), nitrate (NO3), and dissolved organic carbon (DOC). We used global Monte Carlo sensitivity analyses with a nondimensional form of the model to examine coupled nitrification-denitrification dynamics across many scales of transport and reaction conditions. Results demonstrated that the residence time of water in the HZ and the uptake rate of O2 from either respiration and/or nitrification determined whether the HZ was a source or a sink of NO3 to the stream. We further show that whether the HZ is a net NO3 source or net NO3 sink is determined by the ratio of the characteristic transport time to the characteristic reaction time of O2 (i.e., the Damköhler number, DaO2), where HZs with DaO2 < 1 will be net nitrification environments and HZs with DaO2 ≪ 1 will be net denitrification environments. Our coupling of the hydrologic and biogeochemical limitations of N transformations across different temporal and spatial scales within the HZ allows us to explain the widely contrasting results of previous investigations of HZ N dynamics which variously identify the HZ as either a net source or sink of NO3. Our model results suggest that only estimates of residence times and O2uptake rates

  5. Partitioned coupling of advection-diffusion-reaction systems and Brinkman flows

    Science.gov (United States)

    Lenarda, Pietro; Paggi, Marco; Ruiz Baier, Ricardo

    2017-09-01

    We present a partitioned algorithm aimed at extending the capabilities of existing solvers for the simulation of coupled advection-diffusion-reaction systems and incompressible, viscous flow. The space discretisation of the governing equations is based on mixed finite element methods defined on unstructured meshes, whereas the time integration hinges on an operator splitting strategy that exploits the differences in scales between the reaction, advection, and diffusion processes, considering the global system as a number of sequentially linked sets of partial differential, and algebraic equations. The flow solver presents the advantage that all unknowns in the system (here vorticity, velocity, and pressure) can be fully decoupled and thus turn the overall scheme very attractive from the computational perspective. The robustness of the proposed method is illustrated with a series of numerical tests in 2D and 3D, relevant in the modelling of bacterial bioconvection and Boussinesq systems.

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

    Directory of Open Access Journals (Sweden)

    Maria Crespo

    2017-08-01

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

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

    Directory of Open Access Journals (Sweden)

    İsmail Özdemir

    2010-01-01

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

  8. The Use of Palladium on Magnetic Support as Catalyst for Suzuki–Miyaura Cross-Coupling Reactions

    Directory of Open Access Journals (Sweden)

    Magne O. Sydnes

    2017-01-01

    Full Text Available The development of new solid supports for palladium has received a lot of interest lately. These catalysts have been tested in a range of cross-coupling reactions, such as Suzuki–Miyaura, Mizoroki-Heck, and Sonogashira cross-coupling reactions, with good outcomes. Attaching the catalyst to a solid support simplifies the operations required in order to isolate and recycle the catalyst after a reaction has completed. Palladium on solid supports made of magnetic materials is particularly interesting since such catalysts can be removed very simply by utilizing an external magnet, which withholds the catalyst in the reaction vessel. This review will showcase some of the latest magnetic solid supports for palladium and highlight these catalysts’ performance in Suzuki–Miyaura cross-coupling reactions.

  9. Aqueous sodium hydroxide promoted cross-coupling reactions of alkenyltrialkoxysilanes under ligand-free conditions.

    Science.gov (United States)

    Alacid, Emilio; Najera, Carmen

    2008-03-21

    Fluoride-free cross-coupling reactions of alkenyltrialkoxysilanes with aryl iodides, bromides, and chlorides are performed on water using sodium hydroxide as activator at 120 degrees C under normal or microwave heating. This process occurs in the presence of Pd(OAc)(2) or 4-hydroxyacetophenone oxime-derived palladacycle 1 as precatalysts under ligand-free conditions with low Pd loadings (0.01-1 mol %) and using tetra-n-butylammonium bromide as additive. Different commercially available vinylalkoxylsilanes can be cross-coupled under these reaction conditions to the corresponding styrenes, the best substrates being vinyltrimethoxy- or vinyltriethoxysilane. Alkenyltriethoxysilanes, prepared by Wilkinson-catalyzed hydrosilylation of alkynes with triethoxysilane, are stereospecifically arylated with aryl and vinyl halides under microwave irradiation in moderate to high beta/alpha regioselectivity affording unsymmetrical stilbenes, alkenylbenzenes, and conjugate dienes, respectively. This simple procedure allows the palladium recycling from the aqueous phase during three runs by extractive separation of the products, which contain very low levels of Pd (21-27.5 ppm for an aryl iodide and up to 76 ppm for a bromide).

  10. REDUCTION OF CARBON DIOXIDE COUPLED WITH THE OXYHYDROGEN REACTION IN ALGAE.

    Science.gov (United States)

    Gaffron, H

    1942-11-20

    1. Unicellular algae possessing a hydrogenase system (Scenedesmus and other species), and having been adapted by anaerobic incubation to the hydrogen metabolism, reduce oxygen to water according to the equation O(2) + 2H(2) --> 2H(2)O. 2. The oxyhydrogen reaction proceeds undisturbed only in the presence of carbon dioxide, which simultaneously is reduced according to the equation CO(2) + 2H(2) --> H(2)O + (CH(2)O) = (carbohydrate). 3. The maximum yield of the induced reduction is one-half molecule of carbon dioxide reduced for each molecule of oxygen absorbed. 4. Partial reactions are recognizable in the course of the formation of water and it is with the absorption of the second equivalent of hydrogen that the carbon dioxide reduction appears to be coupled. 5. The velocity of the reaction increases in proportion to the partial pressure of oxygen, but only up to a certain point where any excess of oxygen causes the inactivation of the hydrogenase system. The reaction then ends prematurely. 6. During the oxyhydrogen reaction little or no oxygen is consumed for normal respiratory processes. 7. Small concentrations of cyanide, affecting neither photosynthesis nor photoreduction in the same cells, first inhibit the induced reduction of carbon dioxide and then lead to a complete inactivation of the hydrogenase system. 8. Hydroxylamine, added after adaptation, has either no inhibitory effect at all, or prevents solely the induced reduction of carbon dioxide without inactivating the hydrogenase system. 9. Dinitrophenol prevents the dark reduction of carbon dioxide while the reduction of oxygen continues to the formation of water. 10. Glucose diminishes the absorption of hydrogen, probably in its capacity as a competing hydrogen donor. 11. The induced reduction of carbon dioxide can be described as an oxido-reduction similar to that produced photochemically in the same cells.

  11. Reactions of exotic nuclei with the quark-meson coupling model

    Science.gov (United States)

    McRae, E.; Simenel, C.; Simpson, E. C.; Thomas, A. W.

    2017-11-01

    The nucleon-nucleon interaction is an important requirement for investigations of nuclear structure and reactions, as well as for astrophysical models such as r-process nucleosynthesis and neutron stars. The traditional approach to low-energy nuclear physics is to treat nucleons as immutable objects interacting via phenomenological forces. The use of phenomenological interactions, rather than one derived from a microscopic theory, raises questions as to the reliability of predictions for exotic regions of the nuclear chart. The quark-meson coupling (QMC) model uses a relativistic mean-field approach to provide a microscopically derived nucleon-nucleon interaction, which takes into account the quark structure of the nucleon. The Skyrme energy density functional is a popular phenomenological tool in studies of nuclear structure and reactions. In this work, the QMC density functional was used to produce a set of Skyrme parameterisations, in the hopes that they will give more reliable predictions for exotic nuclei. In conjunction with Hartree-Fock-Bogoliubov (HFB) calculations, the Skyrme-QMC (SQMC) parameterisations have been used to model the ground-state properties of individual nuclei and nucleus-nucleus potentials for Ca + Sn reactions. The SQMC parameterisation performs with an accuracy comparable to modern phenomenological functionals. From this, one can investigate the importance of the isovector terms of the nucleon-nucleon interaction, which are particularly significant for exotic, neutron-rich regions of the nuclear chart. One of the notable successes of the QMC model is its derivation of nuclear spin-orbit coupling. The isovector dependence of the spin-orbit equation of state is remarkably similar to that of the modern UNEDF1 phenomenological density functional. HFB calculations along the Sn isotopic chain reveal that the isovector properties of the spin-orbit term impact binding energies to a level that will be significant for astrophysical r

  12. C–C Cross-Coupling Reactions of O6-Alkyl-2-Haloinosine Derivatives and a One-Pot Cross-Coupling/O6-Deprotection Procedure

    Science.gov (United States)

    Gurram, Venkateshwarlu; Pottabathini, Narender; Garlapati, Ramesh; Chaudhary, Avinash B.; Patro, Balaram; Lakshman, Mahesh K.

    2012-01-01

    Reaction conditions for the C–C cross-coupling of O6-alkyl-2-bromo- and 2-chloroinosine derivatives with aryl-, hetaryl-, and alkylboronic acids were studied. Optimization experiments with silyl-protected 2-bromo-O6-methylinosine led to the identification of [PdCl2(dcpf)]/K3PO4 in 1,4-dioxane as the best condition for these reactions (dcpf = 1,1’-bis(dicyclohexylphosphino)ferrocene). Attempted O6-demethylation, as well as the replacement of the C-6 methoxy group by amines, was unsuccessful, which led to the consideration of Pd-cleavable groups such that C–C cross-coupling and O6-deprotection could be accomplished in a single step. Thus, inosine 2-chloro-O6-allylinosine was chosen as the substrate and, after re-evaluation of the cross-coupling conditions with 2-chloro-O6-methylinosine as a model substrate, one-step C–C cross-coupling/deprotection reactions were performed with the O6-allyl analogue. These reactions are the first such examples of a one-pot procedure for the modification and deprotection of purine nucleosides under C–C cross-coupling conditions. PMID:22570232

  13. C-C cross-coupling reactions of O6-alkyl-2-haloinosine derivatives and a one-pot cross-coupling/O6-deprotection procedure.

    Science.gov (United States)

    Gurram, Venkateshwarlu; Pottabathini, Narender; Garlapati, Ramesh; Chaudhary, Avinash B; Patro, Balaram; Lakshman, Mahesh K

    2012-08-01

    Reaction conditions for the CC cross-coupling of O(6)-alkyl-2-bromo- and 2-chloroinosine derivatives with aryl-, hetaryl-, and alkylboronic acids were studied. Optimization experiments with silyl-protected 2-bromo-O(6)-methylinosine led to the identification of [PdCl(2)(dcpf)]/K(3)PO(4) in 1,4-dioxane as the best conditions for these reactions (dcpf=1,1'-bis(dicyclohexylphosphino)ferrocene). Attempted O(6)-demethylation, as well as the replacement of the C-6 methoxy group by amines, was unsuccessful, which led to the consideration of Pd-cleavable groups such that C-C cross-coupling and O(6)-deprotection could be accomplished in a single step. Thus, inosine 2-chloro-O(6)-allylinosine was chosen as the substrate and, after re-evaluation of the cross-coupling conditions with 2-chloro-O(6)-methylinosine as a model substrate, one-step C-C cross-coupling/deprotection reactions were performed with the O(6)-allyl analogue. These reactions are the first such examples of a one-pot procedure for the modification and deprotection of purine nucleosides under C-C cross-coupling conditions. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Coupling of Carbon Dioxide Fixation to the Oxyhydrogen Reaction in the Isolated Chloroplast of Chlamydomonas reinhardtii.

    Science.gov (United States)

    Chen, C; Gibbs, M

    1992-11-01

    The oxyhydrogen reaction (the reduction of O(2) to water by H(2)) in the presence of CO(2) was studied in the isolated Chlamydomonas reinhardtii chloroplast by monitoring the rate of (14)CO(2) incorporation into acid-stable products in the dark. The endogenous rate of CO(2) uptake (50-125 nmol/mg chlorophyll per h) was increased about 3- to 4-fold by ATP and additionally when combined with glucose, ribose-5-phosphate, and glycerate-3-phosphate. The rate was diminished 50 to 75%, respectively, when H(2) was replaced by N(2) or by air. Decrease in CO(2) uptake by dl-glyceraldehyde was taken to indicate that the regenerative phase and complete Calvin cycle turnover were involved. Diminution of CO(2) incorporation by rotenone, antimycin A, and 2,5-dibromo-3-methyl-6-isopropanol-p-benzoquinone was attributed to an inhibition of the oxyhydrogen reaction, resulting in an elevated NADPH/NADP ratio. If so, then the diminished CO(2) uptake could have been by "product inhibition" of the carbon metabolic network. Our data are consistent with the proposal (H. Gaffron [1942] J Gen Physiol 26: 241-267) that CO(2) fixation coupled to the oxyhydrogen reaction is dependent to some extent on exchloroplastic metabolism. This support is primarily ATP provided by mitochondrial respiration.

  15. Coupled Enzyme Reactions Performed in Heterogeneous Reaction Media: Experiments and Modeling for Glucose Oxidase and Horseradish Peroxidase in a PEG/Citrate Aqueous Two-Phase System

    Science.gov (United States)

    2015-01-01

    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. PMID:24517887

  16. A novel 4-aminoantipyrine-Pd(II complex catalyzes Suzuki–Miyaura cross-coupling reactions of aryl halides

    Directory of Open Access Journals (Sweden)

    Claudia A. Contreras-Celedón

    2014-12-01

    Full Text Available A simple and efficient catalytic system based on a Pd complex of 4-aminoantipyrine, 4-AAP–Pd(II, was found to be highly active for Suzuki–Miyaura cross-coupling of aryl iodides and bromides with phenylboronic acids under mild reaction conditions. Good to excellent product yields from the cross-coupling reaction can be achieved when the reaction is carried out in ethanol, in the open air, using low loading of 4-AAP–Pd(II as a precatalyst, and in the presence of aqueous K2CO3 as the base. A variety of functional groups are tolerated.

  17. New Spectrophotometric Method for the Assay of Sulfadiazine Drug Based on Diazotization Coupling Reaction

    Directory of Open Access Journals (Sweden)

    Al-Rufaie Mohauman Mohammad

    2016-12-01

    Full Text Available A sensitive, simple and rapid spectrophotometric procedure for the assay of trace quantities of sulfadiazine (SDZ drug as bulk and in diluted solution is characterized. The procedure depends on the diazotization reaction which is produced by coupling SDZ with (4-amino-2-hydroxy acetophenon (AHA to produce an intense colored complex spectrophotometrically determined at 410 nm. Beer’s law was applied in the range of concentration 0.5 - 15 ppm; the molar absorptivity and Sandell’s sensitivity were 2.8484 × 104 L mol-1 cm-1 and 0.008 μg cm-2 respectively. The method limit of detection (LOD was 0.443 μg mL-1 and LOQ (the method limit of quantitation was 0.249 μg mL-1. The procedure is not based on solvent extraction and the additives and excipients do not significantly influence the developed procedure.

  18. Three-Component Coupling Reactions of Arynes for the Synthesis of Benzofurans and Coumarins

    Directory of Open Access Journals (Sweden)

    Eito Yoshioka

    2014-01-01

    Full Text Available The domino three-component coupling reaction of arynes with DMF and active methylenes or methines was studied as a highly efficient method for preparing heterocycles. Coumarin derivative 5 was formed when diethyl malonate (2 or α-bromomalonate (3 were used as a C2-unit. In contrast, dihydrobenzofurans 7a and 7b were obtained by using α-chloroenolates generated from α-chloromalonates 4a and 4b and Et2Zn. The benzofuran 15a could be obtained by using ethyl iodoacetate (14 as a C1-unit. The one-pot conversion of dihydrobenzofurans 7a, 7b and 8a into benzofurans 15a and 15b was also studied. The direct synthesis of benzofuran 15b was achieved by using the active methine 18 having ketone and ester groups.

  19. Mechanism of coupling drug transport reactions located in two different membranes

    Directory of Open Access Journals (Sweden)

    Helen I. Zgurskaya

    2015-02-01

    Full Text Available Gram- negative bacteria utilize a diverse array of multidrug transporters to pump toxic compounds out of cells. Some transporters together with periplasmic membrane fusion proteins (MFPs and outer membrane channels assemble trans-envelope complexes that expel multiple antibiotics across outer membranes of Gram-negative bacteria and into the external medium. Others further potentiate this efflux by pumping drugs across the inner membrane into the periplasm. Together these transporters create a powerful network of efflux that protect bacteria against a broad range of antimicrobial agents. This review is focused on the mechanism of coupling transport reactions located in two different membranes of Gram-negative bacteria. Using a combination of biochemical, genetic and biophysical approaches we have reconstructed the sequence of events leading to the assembly of trans-envelope drug efflux complexes and characterized the roles of periplasmic and outer membrane proteins in this process. Our recent data suggest a critical step in the activation of intermembrane efflux pumps, which is controlled by MFPs. We propose that the reaction cycles of transporters are tightly coupled to the assembly of the trans-envelope complexes. Transporters and MFPs exist in the inner membrane as dormant complexes. The activation of complexes is triggered by MFP binding to the outer membrane channel, which leads to a conformational change in the membrane proximal domain of MFP needed for stimulation of transporters. The activated MFP-transporter complex engages the outer membrane channel to expel substrates across the outer membrane. The recruitment of the channel is likely triggered by binding of effectors (substrates to MFP or MFP-transporter complexes. This model together with recent structural and functional advances in the field of drug efflux provides a fairly detailed understanding of the mechanism of drug efflux across the two membranes.

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

    Energy Technology Data Exchange (ETDEWEB)

    Berlowitz, D.R.

    1996-11-01

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

  1. The effect of the Coriolis coupling on H+ND reaction: A time dependent wave packet study

    Science.gov (United States)

    Akpinar, Sinan; Hekim, Seda Surucu

    2013-07-01

    We present a quantum scattering calculation of initial-state-resolved reaction probabilities, integral cross section, initial state selected reaction rate constants and thermal rate constant for exchange and depletion channels of the H+ND reaction. The calculations are carried out using Coriolis coupling (CC) method on the modified NH2AA1 potential energy surface(PES). The initial state selected reaction probabilities are calculated for 0.0-0.5 eV of collision energy range. The reaction probabilities for depletion channel shows some sharp and large resonances associated with long-lived collision complexes, as compared to exchange channel. Integral cross sections for both reactions depend strongly on initial rotational states. The calculated thermal reaction rate constant for the depletion channel is in a good agreement with the values previously obtained by the centrifugal sudden approximation, experimental and semiclassical results.

  2. Peroxynitrite Chemistry Derived from Nitric Oxide Reaction with a Cu(II)-OOH Species and a new Copper Mediated NO Reductive Coupling Reaction

    Science.gov (United States)

    Kim, Sunghee; Siegler, Maxime A.; Karlin, Kenneth D.

    2014-01-01

    New peroxynitrite-copper chemistry ensues via addition of nitric oxide (•NO(g)) to a CuII-hydroperoxo species. In characterizing the system, the ligand-Cu(I) complex was shown to effect •NO(g) reductive coupling, a new reaction type. Biological implications are discussed. PMID:24322625

  3. Peroxynitrite chemistry derived from nitric oxide reaction with a Cu(II)-OOH species and a copper mediated NO reductive coupling reaction.

    Science.gov (United States)

    Kim, Sunghee; Siegler, Maxime A; Karlin, Kenneth D

    2014-03-18

    New peroxynitrite-copper chemistry ensues via addition of nitric oxide (˙NO(g)) to a Cu(II)-hydroperoxo species. In characterizing the system, the ligand-Cu(i) complex was shown to effect a seldom observed ˙NO(g) reductive coupling reaction. Biological implications are discussed.

  4. An effective Pd nanocatalyst in aqueous media: stilbene synthesis by Mizoroki–Heck coupling reaction under microwave irradiation

    Directory of Open Access Journals (Sweden)

    Carolina S. García

    2017-08-01

    Full Text Available Aqueous Mizoroki–Heck coupling reactions under microwave irradiation (MW were carried out with a colloidal Pd nanocatalyst stabilized with poly(N-vinylpyrrolidone (PVP. Many stilbenes and novel heterostilbenes were achieved in good to excellent yields starting from aryl bromides and different olefins. The reaction was carried out in a short reaction time and with low catalyst loading, leading to high turnover frequency (TOFs of the order of 100 h−1. The advantages like operational simplicity, high robustness, efficiency and turnover frequency, the utilization of aqueous media and simple product work-up make this protocol a great option for stilbene syntheses by Mizoroki–Heck reaction.

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

    Science.gov (United States)

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

    2017-06-01

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

  6. Role of solvent dynamics in ultrafast photoinduced proton-coupled electron transfer reactions in solution.

    Science.gov (United States)

    Hazra, Anirban; Soudackov, Alexander V; Hammes-Schiffer, Sharon

    2010-09-30

    A theoretical formulation for modeling photoinduced nonequilibrium proton-coupled electron transfer (PCET) reactions in solution is presented. In this formulation, the PCET system is described by donor and acceptor electron-proton vibronic free energy surfaces that depend on a single collective solvent coordinate. Dielectric continuum theory is used to obtain a generalized Langevin equation of motion for this collective solvent coordinate. The terms in this equation depend on the solvent properties, such as the dielectric constants, relaxation time, and molecular moment of inertia, as well as the solute properties characterizing the vibronic surfaces. The ultrafast dynamics following photoexcitation is simulated using a surface hopping method in conjunction with the Langevin equation of motion. This methodology is used to examine a series of model photoinduced PCET systems, where the initial nonequilibrium state is prepared by vertical photoexcitation from the ground electronic state to the donor electronic state. Analysis of the dynamical trajectories provides insight into the interplay between the solvent dynamics and the electron-proton transfer for these types of processes. In addition, these model studies illustrate how the coupling between the electron-proton transfer and the solvent dynamics can be tuned by altering the solute and solvent properties.

  7. Application of dimeric and monomeric ortho-palladated complexes as an efficient catalysts for Heck cross-coupling reaction

    Directory of Open Access Journals (Sweden)

    Ali Naghipour

    2013-10-01

    Full Text Available The catalytic acvtivity of dimeric and monomeric ortho-palladated complexes [Pd{C6H2(CH2NH2-(OMe2,3,4}(µ-Cl]22 and [Pd{C6H2(CH2NH2-(OMe2,3,4}Cl(PPh3](3, were investigated in Heck cross-coupling reaction. These complexes are more active and efficient catalysts for Heck cross-coupling reaction. The palladium complexes 2 and 3 are employed in the Heck cross-coupling reaction between styrene and acrylate with several aryl halides. High yields of corresponding C–C products, low catalyst loadings, mild reaction conditions and short reaction times are important features of these homogeneous reactions. The cross-coupled prod-ucts were produced in high yields using catalytic amounts of [Pd{C6H2(CH2NH2-(OMe2,3,4}(µ-Cl]2 or [Pd{C6H2(CH2NH2-(OMe2,3,4}Cl(PPh3] as a thermally stable and oxygen insensitive complexes in NMP at 130 ºC.

  8. A Multiscale, Mortar-Coupled Advection-Diffusion-Reaction Model for Biofilm Growth in Porous Media

    Science.gov (United States)

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

    2016-12-01

    Multiscale models of reactive transport and biofilm growth in porous media are capable of capturing complex pore-scale processes while leveraging the efficiency of continuum-scale models. In particular, porosity and permeability changes caused by biofilm development result in complex feedbacks between transport and reaction that are difficult to quantify at the continuum scale. Pore-scale models are needed to accurately resolve these dynamics but are often impractical for applications due to their high computational cost. To address this challenge, we develop a multiscale model of biofilm growth in which non-overlapping regions at pore and continuum spatial scales are coupled with a mortar method that ensures continuity of flux across the interface. Thus, regions of high reactivity are resolved at the pore scale for accuracy while regions of low reactivity are resolved at the continuum scale for efficiency. By benchmarking the multiscale model against a fully pore-scale model, we find the multiscale model has a reduced run time while producing a consistent result in terms of biofilm growth, distribution, and solute utilization. We effectively extend a previous model by incorporating a multiscale flow solver and parallelizing solution of the computationally-intensive pore-scale component for increased scalability. We find that mortar coupling is a flexible and effective technique able to join differing computational grids and differing physics in adjacent regions for both fluid flow and solute transport. These results demonstrate the practicality of multiscale mortar-coupled models in studying the complexity of subsurface systems while considering computational limitations in their numerical solution. While recent work has demonstrated growing interest in the development of general multiscale models, more work is needed for their use in real-world applications. Our contribution is a step on the path toward accurate, efficient, and practical reactive transport

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

    Directory of Open Access Journals (Sweden)

    M. Vamsi Krishna

    2007-01-01

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

  10. Diffusive coupling can discriminate between similar reaction mechanisms in an allosteric enzyme system

    Directory of Open Access Journals (Sweden)

    Nicola Ernesto M

    2010-11-01

    Full Text Available Abstract Background A central question for the understanding of biological reaction networks is how a particular dynamic behavior, such as bistability or oscillations, is realized at the molecular level. So far this question has been mainly addressed in well-mixed reaction systems which are conveniently described by ordinary differential equations. However, much less is known about how molecular details of a reaction mechanism can affect the dynamics in diffusively coupled systems because the resulting partial differential equations are much more difficult to analyze. Results Motivated by recent experiments we compare two closely related mechanisms for the product activation of allosteric enzymes with respect to their ability to induce different types of reaction-diffusion waves and stationary Turing patterns. The analysis is facilitated by mapping each model to an associated complex Ginzburg-Landau equation. We show that a sequential activation mechanism, as implemented in the model of Monod, Wyman and Changeux (MWC, can generate inward rotating spiral waves which were recently observed as glycolytic activity waves in yeast extracts. In contrast, in the limiting case of a simple Hill activation, the formation of inward propagating waves is suppressed by a Turing instability. The occurrence of this unusual wave dynamics is not related to the magnitude of the enzyme cooperativity (as it is true for the occurrence of oscillations, but to the sensitivity with respect to changes of the activator concentration. Also, the MWC mechanism generates wave patterns that are more stable against long wave length perturbations. Conclusions This analysis demonstrates that amplitude equations, which describe the spatio-temporal dynamics near an instability, represent a valuable tool to investigate the molecular effects of reaction mechanisms on pattern formation in spatially extended systems. Using this approach we have shown that the occurrence of inward

  11. Four-body continuum-discretized coupled-channels calculations applied to {sup 6}He reactions

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Gallardo, M. [Consejo Superior de Investigaciones Cientificas (CSIC), Madrid (Spain). Inst. de Estructura de la Materia; Arias, J.M.; Gomez-Camacho, J.M.; Moro, A.M. [Universidad de Sevilla (Spain). Dept. de Fisica Atomica, Molecular y Nuclear; Thompson, I.J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Physical Science Directorate; Tostevin, J.A. [University of Surrey, Guildford (United Kingdom). Dept. of Physics

    2010-07-01

    Full text. The scattering of a weakly bound three-body system by a target is discussed. The continuum-discretized coupled-channels (CDCC) framework, recently extended to four-body reactions (three-body projectile plus target), is used for the scattering calculations. Two different methods are used to discretized the three-body continuum of the projectile. In the first case, we make use of a Pseudo-State (PS) method in which the states of the projectile are represented by the eigenstates of its internal Hamiltonian in a truncated basis of square-integrable functions. In particular, we use the transformed harmonic oscillator (THO) method, in which the PS basis is obtained by applying a local scale transformation to the Harmonic Oscillator basis. In the second case, we applied the binning procedure that has just been extended to three-body projectiles. This discretization method requires to calculate first the true continuum of the projectile and then this continuum is discretized making bins or packages of energy. This has been the method used for many years in standard three-body (two-body projectile plus target) CDCC calculations. Its extension to three-body projectiles uses the eigenchannel expansion of the three-body S-matrix. We applied this formalism to several reactions induced by the Borromean nucleus {sup 6}He at different energies, namely {sup 6}He+{sup 9}Be at 16.2 MeV, {sup 6}He+{sup 64}Zn at 13.6 MeV, {sup 6}He+{sup 120}Sn at 17.4 MeV, and {sup 6}He+{sup 208}Pb at 22 MeV. Four-body CDCC calculations for elastic and breakup observables are presented for these reactions comparing both discretization methods, THO and binning. The effect of the mass of the target, which is clearly related to the influence of Coulomb couplings, is investigated. The elastic cross sections are also compared to existing experimental data. (author)

  12. Soret and dufour effects on free convection flow of a couple stress fluid in a vertical channel with chemical reaction

    Directory of Open Access Journals (Sweden)

    Srinivasacharya D.

    2013-01-01

    Full Text Available The Soret and Dufour effects in the presence of chemical reaction on natural convection heat and mass transfer of a couple stress fluid in a vertical channel formed by two vertical parallel plates is presented. The governing non-linear partial differential equations are transformed into a system of ordinary differential equations using similarity transformations. The resulting equations are then solved using Homotopy Analysis Method (HAM. Profiles of dimensionless velocity, temperature and concentration are shown graphically for various values of Dufour number, Soret number, Couple stress parameter and chemical reaction parameter.

  13. Polymer and Membrane Design for Low Temperature Catalytic Reactions

    KAUST Repository

    Villalobos, Luis Francisco

    2016-02-29

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

  14. Using Anilines as Masked Cross-Coupling Partners: Design of a Telescoped Three-Step Flow Diazotization, Iododediazotization, Cross-Coupling Process.

    Science.gov (United States)

    Teci, Matthieu; Tilley, Michael; McGuire, Michael A; Organ, Michael G

    2016-11-21

    The conversion of commercially available anilines into biaryl and biarylacetylene products was realized by using a telescoped, three-reactor flow diazotization/iododediazotization/cross-coupling process. The segmented flow stream created by off-gassing during the Sandmeyer sequence was restored to a continuous column of reaction solution by using a specially designed continuous-flow unit controlled by custom software created in-house. The resultant aryl iodide was then combined with a stream of cross-coupling solution that fed into the final reactor. The system proved versatile as modifications to the diazotization/iododediazotization sequence could be made rapidly to account for any substrate specificity (e.g., solubility problems), leading to a wide substrate scope of Suzuki-Miyaura and Sonogashira cross-coupled products. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Kinetic reactions in thin polyaniline films revisited through Raman-impedance dynamic coupling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, X.; Bernard, M.C. [CNRS, UPR 015, LISE, F-75005 Paris (France); UPMC Univ Paris 06, UPR 015, LISE, F-75005 Paris (France); Deslouis, C., E-mail: claude.deslouis@upmc.f [CNRS, UPR 015, LISE, F-75005 Paris (France); UPMC Univ Paris 06, UPR 015, LISE, F-75005 Paris (France); Joiret, S.; Rousseau, P. [CNRS, UPR 015, LISE, F-75005 Paris (France); UPMC Univ Paris 06, UPR 015, LISE, F-75005 Paris (France)

    2011-04-01

    Recently introduced as a new technique in electrochemistry, the Raman-impedance dynamic coupling allows one characterizing transfer functions so far not accessible to experiment such as instantaneous concentrations of adsorbed species in response to potential modulations. These were assessed from the measurement of the time-dependent Raman band intensities of different moieties of reduced and oxidized polyaniline. The local concentrations were assumed to be proportional to these instantaneous band intensities. This technique was used to analyze the kinetics of thin polyaniline films at high pH in the limit of electronic conductivity of the film (pH {<=} 3.7). A model was developed for the different available transfer functions such as Raman (viz. concentrations)/potential, Raman/charge or classical EIS, from a mechanism based on two electron transfer between leucoemeraldine and emeraldine salt and base and a protonation reaction between the last two ones. Among the main results, the band ascribable to leucoemeraldine was found to be proportional to the total charge in the pH and potential ranges investigated which confirms the fact that it is the only reduced species involved in the redox process. A frequency-dependent relaxation was found for emeraldine base vs. charge, with an increase in intensity and a decrease of the characteristic frequency when both the pH and potential increased. Emeraldine salt (polaronic) showed practically no relaxation vs. charge at variance with the bipolaronic one but the response of the latter remained weak and noisy. An improvement in the accuracy of the coupled techniques would bring information that could not be resolved by any of the other alternative techniques alone.

  16. 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.

  17. Linear scaling relationships and volcano plots in homogeneous catalysis – revisiting the Suzuki reaction† †Electronic supplementary information (ESI) available: Detailed derivation of the linear scaling relationships and construction of the volcano plots as well as comparisons of computed values using PBE0-dDsC and M06 functionals is included. See DOI: 10.1039/c5sc02910d Click here for additional data file.

    Science.gov (United States)

    Busch, Michael; Wodrich, Matthew D.

    2015-01-01

    Linear free energy scaling relationships and volcano plots are common tools used to identify potential heterogeneous catalysts for myriad applications. Despite the striking simplicity and predictive power of volcano plots, they remain unknown in homogeneous catalysis. Here, we construct volcano plots to analyze a prototypical reaction from homogeneous catalysis, the Suzuki cross-coupling of olefins. Volcano plots succeed both in discriminating amongst different catalysts and reproducing experimentally known trends, which serves as validation of the model for this proof-of-principle example. These findings indicate that the combination of linear scaling relationships and volcano plots could serve as a valuable methodology for identifying homogeneous catalysts possessing a desired activity through a priori computational screening. PMID:28757966

  18. Deactivation and Regeneration of NaTaO3 Photocatalyst in Co-operating Dehydrogenation Coupling of Isopropanol and Hydrogenation Coupling of Acetone Reaction System.

    Science.gov (United States)

    Cao, Baoyue; Yu, Yan; Xu, Shan; Wang, Xiangting; Zhang, Li; Wang, Zhijian; Wang, Shumin; Zhang, Guochun

    2017-11-07

    Photocatalyst activity is influenced by many factors, such as adsorption of by-products, runoff of surface hydroxyl groups, and carriers. In this study, a simple and efficient photocatalyst regeneration method was developed. Results indicated that NaTaO3 photocatalyst lost its photo-activity after three cycles of reaction that involves coupling of isopropanol and hydrogenation coupling of acetone reaction system. Runoff of Na on the surface was the main reason for the deactivation of NaTaO3 photocatalyst. After hydrothermal treatment of the deactivated NaTaO3 with 10 M NaOH at 180 °C for 12 h, its photocatalytic activity was restored to the original level. The photocatalytic activity remained stable even after 10 cycles This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

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

    KAUST Repository

    Khan, Abdulaziz M.

    2016-04-26

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

  20. Phenylenevinylene oligomers by Mizoroki-Heck cross coupling reaction. Structural and optoelectronic characterization

    Science.gov (United States)

    Estrada, Sandra E.; Ochoa-Puentes, Cristian; Sierra, Cesar A.

    2017-04-01

    In order to study the effect of the molecular structure on the optical properties of totally trans-trans phenylenevinylene oligomers (OPVs), sixteen 1,4-distyrylbenzene derivatives (1a-i and 2a-g) functionalized with different electron-donating (ED) and electron-withdrawing (EW) groups were synthesized by the Mizoroki-Heck cross coupling reaction in moderate to good yields (40-95%). The implemented methodology, with a small modification previously reported by our group, allows obtaining the desired vinyl configuration as well as one novel OPV compound (1h). After structural characterization by several techniques (e.g. FTIR, 1H, 13C and Solid-State NMR), particular emphasis was placed upon the investigation of their optical properties by UV-vis and fluorescence spectroscopies. The results showed that, with only one exception, the ED and EW groups at the ends of OPV systems lead to a bathochromic shift. This effect is intensified with the introduction of methoxy groups on the central ring. Consistent with these, the HOMO-LUMO gaps (ΔE) decreases as the strength of ED and EW substituents increases. The ED and EW substituents also lead to a decrease in the Φf values. This contribution in the area of organic electronics can be used as a reference to better select the most appropriate technological application for each OPV and this can be extrapolated to their respective structurally analogous segmented polymer.

  1. Traveling waves in a coupled reaction-diffusion and difference model of hematopoiesis

    Science.gov (United States)

    Adimy, M.; Chekroun, A.; Kazmierczak, B.

    2017-04-01

    The formation and development of blood cells is a very complex process, called hematopoiesis. This process involves a small population of cells called hematopoietic stem cells (HSCs). The HSCs are undifferentiated cells, located in the bone marrow before they become mature blood cells and enter the blood stream. They have a unique ability to produce either similar cells (self-renewal), or cells engaged in one of different lineages of blood cells: red blood cells, white cells and platelets (differentiation). The HSCs can be either in a proliferating or in a quiescent phase. In this paper, we distinguish between dividing cells that enter directly to the quiescent phase and dividing cells that return to the proliferating phase to divide again. We propose a mathematical model describing the dynamics of HSC population, taking into account their spatial distribution. The resulting model is a coupled reaction-diffusion equation and difference equation with delay. We study the existence of monotone traveling wave fronts and the asymptotic speed of spread.

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

    KAUST Repository

    Hong, Jongsup

    2015-08-01

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

  3. Palladium-Catalyzed Cross-Coupling of Silyl Electrophiles with Alkylzinc Halides: A Silyl-Negishi Reaction.

    Science.gov (United States)

    Cinderella, Andrew P; Vulovic, Bojan; Watson, Donald A

    2017-06-14

    We report the first example of a silyl-Negishi reaction between secondary zinc organometallics and silicon electrophiles. This palladium-catalyzed process provides direct access to alkyl silanes. The delicate balance of steric and electronic parameters of the employed DrewPhos ligand is paramount to suppressing isomerization and promoting efficient and selective cross-coupling.

  4. Preparation and Diels–Alder/cross coupling reactions of a 2-diethanolaminoboron-substituted 1,3-diene

    Directory of Open Access Journals (Sweden)

    Liqiong Wang

    2009-09-01

    Full Text Available A 2-diethanolamine boronyl substituted 1,3-diene has been synthesized in high yield and characterized spectroscopically as well as by X-ray crystallography. This diene has then subsequently been used in a number of fast, high yielding Diels–Alder/cross coupling reactions.

  5. 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.

  6. Coupling Reaction of Oligo p-Phenylene Ethynylene and Peptide Antagonist RM26 Labeling with 131

    Directory of Open Access Journals (Sweden)

    JIAN Yuan1,2;ZHOU Zhi-jun2;ZHUO Lian-gang2;ZHAO Peng2;LIAO Wei2;WANG Guan-quan2;LIU Ning1

    2016-08-01

    Full Text Available Investigations reveale that oligo p-phenylene ethynylene (OPE molecule can insert into cell membrane, which leads to its cellular internization capacility. Antagonists have high cancer cell affinity, high uptake in cancer cells and fast clearance in normal tissue, these capabilities have attracted much research interest in radiopharmaceutical development. Combining the strong cell-penetrating ability and high affinity of Gastrin-releasing peptide which is overexpressed in the PC-3 cells, the thesis designed and synthesized unsymmetric OPE(NH2 molecule. Then the OPE(NH2 molecule was followed by the coupling reaction with RM26 peptide to obtain the OPE-RM26, and (Tyr3-RM26 was also got for controling study. After that, the (Tyr3-RM26 and OPE-RM26 were radiolabeled with I-131 to give high radiolabeling yields that could up to 95%. The radiolabeling compound was stable after 24 h storage at room temperature. These labeled compounds are ready for animal in-vivo experiment. It is expected that OPE-RM26-131I has multi-properties with targeting membrane crossing fire of radioactive elements. The molecule may fast travel to the target tissue and bind to GRP receptor and internalized into cancer cells. The casade process will give rise to its cancer cell toxicity due to longer retention and more killing effect of ray’s irradiation to cancer cells. In this way, OPE-RM26-131I can achieve better anti-cancer ability.

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

    Science.gov (United States)

    Scott, Laurie

    1992-01-01

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

  8. Nonsymmetrical 3,4-dithienylmaleimides by cross-coupling reactions with indium organometallics: synthesis and photochemical studies.

    Science.gov (United States)

    Mosquera, Angeles; Férnandez, M Isabel; Canle Lopez, Moisés; Pérez Sestelo, José; Sarandeses, Luis A

    2014-10-27

    The synthesis and photochemical study of novel nonsymmetrical 1,2-dithienylethenes (DTEs) with a maleimide bridge have been carried out. The synthetic approach to the DTEs was based on successive selective palladium-catalyzed cross-coupling reactions of 5-susbtituted-2-methyl-3-thiophenyl indium reagents with 3,4-dichloromaleimides. The required organoindium reagents were prepared from 2-methyl-3,5-dibromothiophene by a selective (C-5) coupling reaction with triorganoindium compounds (R3 In) and subsequent metal-halogen exchange. The coupling reactions usually gave good yields and have a high atom economy with substoichiometric amounts of R3 In. The results of photochemical studies show that these novel dithienylmaleimides undergo a photocyclization reaction upon irradiation in the UV region and a photocycloreversion after excitation in the visible region, thus they can be used as photochemical switches. ON-OFF operations can be repeated in successive cycles without appreciable loss of effectiveness in the process. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-07-01

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

  10. Music and movement: A comparative study between the BAPNE and Suzuki Methods

    Directory of Open Access Journals (Sweden)

    De Munari Elisa

    2016-01-01

    Full Text Available The aim of this article is to compare the Suzuki and BAPNE methods based on bibliography published for both approaches. In the field of musical and instrumental education and especially for the childhood stage, the correct use of the body and voice are of fundamental importance. These two methods differ from one another; one principally musical and instrumental, which is the Suzuki method, and one non-musical, the BAPNE method, which aims at stimulating attention, concentration, memory and the executing function of the pupil through music and body percussion. Comparing different approaches may provide teachers with a useful insight for facing different issues related to their discipline.

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

    Directory of Open Access Journals (Sweden)

    Takashi Nishikata

    2016-05-01

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

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

    Directory of Open Access Journals (Sweden)

    Thepchai, R.

    2007-05-01

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

  13. Wave packet motions coupled to electron transfer in reaction centers of Chloroflexus aurantiacus.

    Science.gov (United States)

    Yakovlev, Andrei G; Shkuropatova, Tatiana A; Vasilieva, Lyudmila G; Shkuropatov, Anatoli Ya; Shuvalov, Vladimir A

    2008-08-01

    Transient absorption difference spectroscopy with approximately 20 femtosecond (fs) resolution was applied to study the time and spectral evolution of low-temperature (90 K) absorbance changes in isolated reaction centers (RCs) of Chloroflexus (C.) aurantiacus. In RCs, the composition of the B-branch chromophores is different with respect to that of purple bacterial RCs by occupying the B(B) binding site of accessory bacteriochlorophyll by bacteriopheophytin molecule (Phi(B)). It was found that the nuclear wave packet motion induced on the potential energy surface of the excited state of the primary electron donor P* by approximately 20 fs excitation leads to a coherent formation of the states P+Phi(B)(-) and P+B(A)(-) (B(A) is a bacteriochlorophyll monomer in the A-branch of cofactors). The processes were studied by measuring coherent oscillations in kinetics of the absorbance changes at 900 nm and 940 nm (P* stimulated emission), at 750 nm and 785 nm (Phi(B) absorption bands), and at 1,020-1028 nm (B(A)(-) absorption band). In RCs, the immediate bleaching of the P band at 880 nm and the appearance of the stimulated wave packet emission at 900 nm were accompanied (with a small delay of 10-20 fs) by electron transfer from P* to the B-branch with bleaching of the Phi(B) absorption band at 785 nm due to Phi(B)(-) formation. These data are consistent with recent measurements for the mutant HM182L Rb. sphaeroides RCs (Yakovlev et al., Biochim Biophys Acta 1757:369-379, 2006). Only at a delay of 120 fs was the electron transfer from P* to the A-branch observed with a development of the B(A)(-) absorption band at 1028 nm. This development was in phase with the appearance of the P* stimulated emission at 940 nm. The data on the A-branch electron transfer in C. aurantiacus RCs are consistent with those observed in native RCs of Rb. sphaeroides. The mechanism of charge separation in RCs with the modified B-branch pigment composition is discussed in terms of coupling between

  14. Soret and dufour effects on free convection flow of a couple stress fluid in a vertical channel with chemical reaction

    OpenAIRE

    Srinivasacharya D.; Kaladhar K.

    2013-01-01

    The Soret and Dufour effects in the presence of chemical reaction on natural convection heat and mass transfer of a couple stress fluid in a vertical channel formed by two vertical parallel plates is presented. The governing non-linear partial differential equations are transformed into a system of ordinary differential equations using similarity transformations. The resulting equations are then solved using Homotopy Analysis Method (HAM). Profiles of dimensionless velocity, temperature...

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

    DEFF Research Database (Denmark)

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

    2015-01-01

    amine product. Using 2-propylamine as the amine donor of the ω-transaminase reaction, gives acetone as a by-product, which in turn allows the coupling of the ω-transaminase reaction with the Oppenauer oxidation. The Oppenauer reaction converts secondary alcohols into ketones, and these can subsequently...

  16. Non-steady state mass action dynamics without rate constants: dynamics of coupled reactions using chemical potentials

    Science.gov (United States)

    Cannon, William R.; Baker, Scott E.

    2017-10-01

    Comprehensive and predictive simulation of coupled reaction networks has long been a goal of biology and other fields. Currently, metabolic network models that utilize enzyme mass action kinetics have predictive power but are limited in scope and application by the fact that the determination of enzyme rate constants is laborious and low throughput. We present a statistical thermodynamic formulation of the law of mass action for coupled reactions at both steady states and non-stationary states. The formulation uses chemical potentials instead of rate constants. When used to model deterministic systems, the method corresponds to a rescaling of the time dependent reactions in such a way that steady states can be reached on the same time scale but with significantly fewer computational steps. The relationships between reaction affinities, free energy changes and generalized detailed balance are central to the discussion. The significance for applications in systems biology are discussed as is the concept and assumption of maximum entropy production rate as a biological principle that links thermodynamics to natural selection.

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

    Science.gov (United States)

    Nelson, David J.

    1984-01-01

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

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

    Science.gov (United States)

    Bugeja, Clare

    2009-01-01

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

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

    KAUST Repository

    Liang, Yin

    2014-03-24

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

  20. Investigation of thermochemistry associated with the carbon-carbon coupling reactions of furan and furfural using ab initio methods.

    Science.gov (United States)

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

    2014-06-26

    Upgrading 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 low 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-06-26

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

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

    Science.gov (United States)

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

  3. Coupling of Carbon Dioxide Fixation to the Oxyhydrogen Reaction in the Isolated Chloroplast of Chlamydomonas reinhardtii

    National Research Council Canada - National Science Library

    Changguo Chen; Martin Gibbs

    1992-01-01

    The oxyhydrogen reaction (the reduction of O to water by H ) in the presence of CO was studied in the isolated Chlamydomonas reinhardtii chloroplast by monitoring the rate of CO incorporation into acid-stable products in the dark...

  4. Dendrimer-Encapsulated Palladium Nanoparticles for Continuous-Flow Suzuki–Miyaura Cross-Coupling Reactions

    NARCIS (Netherlands)

    Ricciardi, R.; Huskens, Jurriaan; Holtkamp, M.; Karst, U.; Verboom, Willem

    2015-01-01

    Generation three, four, and five (G3, G4, and G5) poly(amidoamine) dendrimers were used for the encapsulation of palladium nanoparticles (Pd NPs) and their covalent anchoring within glass microreactors. G3-encapsulated Pd NPs showed the highest activity for a model Suzuki–Miyaura cross-coupling

  5. Pd nanoclusters in C-C coupling reaction: proof of leaching

    NARCIS (Netherlands)

    Thathagar, Mehul B.; ten Elshof, Johan E.; Rothenberg, Gadi

    2006-01-01

    A simple experiment based on exclusion of Pd nanoclusters was used to identify the true catalytic species in cluster-catalyzed Heck cross-couplings. A special reactor was used in which two compartments are separated by a nanoporous membrane that allows the passage of Pd atoms and ions but not of Pd

  6. Cross-coupling reactions of nucleoside triphosphates followed by polymerase incorporation. Construction and applications of base-functionalized nucleic acids.

    Science.gov (United States)

    Hocek, Michal; Fojta, Miroslav

    2008-07-07

    Construction of functionalized nucleic acids (DNA or RNA) via polymerase incorporation of modified nucleoside triphosphates is reviewed and selected applications of the modified nucleic acids are highlighted. The classical multistep approach for the synthesis of modified NTPs by triphosphorylation of modified nucleosides is compared to the novel approach consisting of direct aqueous cross-coupling reactions of unprotected halogenated nucleoside triphosphates. The combination of cross-coupling of NTPs with polymerase incorporation gives an efficient and straightforward two-step synthesis of modified nucleic acids. Primer extension using biotinylated templates followed by separation using streptavidine-coated magnetic beads and DNA duplex denaturation is used for preparation of modified single stranded oligonucleotides. Examples of using this approach for electrochemical DNA labelling and bioanalytical applications are given.

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

    DEFF Research Database (Denmark)

    Muniruzzaman, Muhammad; Rolle, Massimo

    2016-01-01

    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...... 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......, conservative and reactive transport examples are presented to demonstrate the capability of the proposed model to simulate transport of charged species in heterogeneous porous media with spatially variable physical and chemical properties. The results reveal that the Coulombic cross-coupling between dispersive...

  8. Cross-coupling reactions of nucleoside triphosphates followed by polymerase incorporation. Construction and applications of base-functionalized nucleic acids

    Czech Academy of Sciences Publication Activity Database

    Hocek, Michal; Fojta, Miroslav

    2008-01-01

    Roč. 6, č. 13 (2008), s. 2233-2241 ISSN 1477-0520 R&D Projects: GA ČR GA203/05/0043; GA ČR GA203/07/1195; GA MŠk LC512; GA MŠk(CZ) LC06035 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50040507 Keywords : DNA * nucleotides * cross-coupling reactions Subject RIV: CC - Organic Chemistry Impact factor: 3.550, year: 2008

  9. Iridium-catalyzed C–H coupling reaction of heteroaromatic compounds with bis(pinacolato)diboron: regioselective synthesis of heteroarylboronates

    OpenAIRE

    Takagi, Jun; Sato, Kazuaki; Hartwig, John F; Ishiyama, Tatsuo; Miyaura, Norio

    2002-01-01

    The C–H coupling of aromatic heterocycles with bis(pinacolato)diboron was carried out in octane at 80–100°C in the presence of a 1/2[IrCl(COD)]2-(4,4 -di-tert-butyl-2,2 -bipyridine) catalyst (3 mol%). The reactions of five-membered substrates such as thiophene, furan, pyrrole, and their benzo-fused derivatives exclusively produced 2-borylated products, whereas those of six-membered heterocycles including pyridine and quinoline selectively occurred at the 3-position. Regioselective sy...

  10. Coupling Hyporheic Nitrification-Denitrification: Evaluating Net Nitrate Source-Sink Dynamics as a Function of Transport and Reaction Kinetics

    Science.gov (United States)

    Zarnetske, J. P.; Haggerty, R.; Wondzell, S. M.; Bokil, V. A.; Gonzalez Pinzon, R. A.

    2011-12-01

    The fate of biologically-available nitrogen (N) and carbon (C) in stream ecosystems is controlled by the coupling of physical transport and biogeochemical reaction kinetics. However, determining the relative role of physical and biogeochemical controls at different temporal and spatial scales is difficult. Hyporheic and riparian zones, where ground waters and stream waters mix, can be important locations controlling N and C transformations because they create strong gradients in both the physical and biogeochemical conditions that control redox biogeochemistry. We evaluated the coupling of physical transport and biogeochemical redox reactions by linking an advection, dispersion, and residence time model with a multiple Monod kinetics model simulating the concentrations of oxygen (O2), ammonium (NH4), nitrate (NO3), and dissolved organic carbon (DOC). The model successfully simulated the O2, NH4, NO3 and DOC concentration profiles observed in the hyporheic zone at our study site. We then used global Monte Carlo sensitivity analyses with a nondimensional form of the model to examine coupled nitrification-denitrification dynamics across many scales of transport and reaction conditions. Results demonstrated that the residence time of water in hyporheic systems and the uptake rate of O2 from either respiration and/or nitrification determined whether a hyporheic system was a source or a sink of NO3 to the stream. We further show that the net NO3 source or sink function of a hyporheic system is determined by the ratio of characteristic transport time to the characteristic reaction time of O2 (i.e., the Damköhler number, DaO2), where hyporheic systems with DaO2 > 1 will be net denitrification environments. Our coupling of the hydrologic and biogeochemical limitations of N transformations across different temporal and spatial scales within hyporheic zones allows us to explain the widely contrasting results of previous investigations of hyporheic N dynamics which variously

  11. Crawling and turning in a minimal reaction-diffusion cell motility model: Coupling cell shape and biochemistry

    Science.gov (United States)

    Camley, Brian A.; Zhao, Yanxiang; Li, Bo; Levine, Herbert; Rappel, Wouter-Jan

    2017-01-01

    We study a minimal model of a crawling eukaryotic cell with a chemical polarity controlled by a reaction-diffusion mechanism describing Rho GTPase dynamics. The size, shape, and speed of the cell emerge from the combination of the chemical polarity, which controls the locations where actin polymerization occurs, and the physical properties of the cell, including its membrane tension. We find in our model both highly persistent trajectories, in which the cell crawls in a straight line, and turning trajectories, where the cell transitions from crawling in a line to crawling in a circle. We discuss the controlling variables for this turning instability and argue that turning arises from a coupling between the reaction-diffusion mechanism and the shape of the cell. This emphasizes the surprising features that can arise from simple links between cell mechanics and biochemistry. Our results suggest that similar instabilities may be present in a broad class of biochemical descriptions of cell polarity.

  12. Coupling Key Transport and Reaction Kinetics to Evaluate the Nitrate Source-Sink Function of Groundwater-Surface Water Environments

    Science.gov (United States)

    Zarnetske, J. P.

    2012-12-01

    Groundwater-surface water exchange environments, including groundwater discharge to coastal ecosystems, are characterized by strong hydrological and biogeochemical gradients. These gradients control the fate and transport of important ecosystem solutes, such as biologically-available nitrogen (N) and carbon. However, it is difficult to quantify the spatiotemporal coupling of these physical and biogeochemical gradients. Our recent investigations of N in groundwater-surface water environments (GSEs) help determine the relative role of these physical and biogeochemical controls across a range of temporal and spatial scales. For example, we used an advection, dispersion, and residence time model coupled with multiple Monod kinetic models to simulate the GSE concentrations of oxygen (O2), ammonium (NH4), nitrate (NO3), and dissolved organic carbon (DOC). This modeling showed how physical transport and biogeochemical reaction kinetics couple in GSEs to control the fate of NO3. Further, we examined coupled nitrification-denitrification (N source-sink) dynamics across many scales of transport and reaction conditions with global Monte Carlo sensitivity analyses and a nondimensional form of the models. Results demonstrated that the residence time of water in the GSE and the uptake rate of O2 from either respiration and/or nitrification determined whether the GSE was a source or a sink of NO3 to the surface waters. We further show that whether the GSE is a net NO3 source or net NO3 sink is determined by the ratio of the characteristic transport time to the characteristic reaction time of O2 (i.e., the Damköhler number, DaO2), where GSEs with DaO2 > 1 will be net denitrification environments. Previous investigations of N dynamics variously identified stream GSEs as either a net source or sink of NO3. Our coupling of the hydrological and biogeochemical limitations of N transformations across different temporal and spatial scales within the GSE of streams allows us to explain

  13. Hydrogen- Bond- Assisted Activation of Allylic Alcohols for Palladium- Catalyzed Coupling Reactions

    NARCIS (Netherlands)

    Gumrukcu, Y.; de Bruin, B.; Reek, J.

    2014-01-01

    We report direct activation of allylic alcohols using a hydrogen-bond-assisted palladium catalyst and use this for alkylation and amination reactions. The novel catalyst comprises a palladium complex based on a functionalized monodentate phosphoramidite ligand in combination with urea additives and

  14. In Vivo and in Vitro Evidence for Biochemical Coupling of Reactions Catalyzed by Lysophosphatidylcholine Acyltransferase and Diacylglycerol Acyltransferase*

    Science.gov (United States)

    Pan, Xue; Chen, Guanqun; Kazachkov, Michael; Greer, Michael S.; Caldo, Kristian Mark P.; Zou, Jitao; Weselake, Randall J.

    2015-01-01

    Seed oils of flax (Linum usitatissimum L.) and many other plant species contain substantial amounts of polyunsaturated fatty acids (PUFAs). Phosphatidylcholine (PC) is the major site for PUFA synthesis. The exact mechanisms of how these PUFAs are channeled from PC into triacylglycerol (TAG) needs to be further explored. By using in vivo and in vitro approaches, we demonstrated that the PC deacylation reaction catalyzed by the reverse action of acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT) can transfer PUFAs on PC directly into the acyl-CoA pool, making these PUFAs available for the diacylglycerol acyltransferase (DGAT)-catalyzed reaction for TAG production. Two types of yeast mutants were generated for in vivo and in vitro experiments, respectively. Both mutants provide a null background with no endogenous TAG forming capacity and an extremely low LPCAT activity. In vivo experiments showed that co-expressing flax DGAT1-1 and LPCAT1 in the yeast quintuple mutant significantly increased 18-carbon PUFAs in TAG with a concomitant decrease of 18-carbon PUFAs in phospholipid. We further showed that after incubation of sn-2-[14C]acyl-PC, formation of [14C]TAG was only possible with yeast microsomes containing both LPCAT1 and DGAT1-1. Moreover, the specific activity of overall LPCAT1 and DGAT1-1 coupling process exhibited a preference for transferring 14C-labeled linoleoyl or linolenoyl than oleoyl moieties from the sn-2 position of PC to TAG. Together, our data support the hypothesis of biochemical coupling of the LPCAT1-catalyzed reverse reaction with the DGAT1-1-catalyzed reaction for incorporating PUFAs into TAG. This process represents a potential route for enriching TAG in PUFA content during seed development in flax. PMID:26055703

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

    Index Scriptorium Estoniae

    Liiv, Valdur

    2000-01-01

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

  16. 76 FR 30425 - Receipt of Petition for Decision That Nonconforming 2007-2011 Suzuki GSX1300R Motorcycles Are...

    Science.gov (United States)

    2011-05-25

    ... [Docket No. NHTSA-2011-0055; Notice 1] Receipt of Petition for Decision That Nonconforming 2007-2011... Administration, DOT. ACTION: Notice of receipt of petition for decision that nonconforming 2007-2011 Suzuki...

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

    Science.gov (United States)

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

    2018-01-01

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

  18. QM/MM study of the C-C coupling reaction mechanism of CYP121, an essential Cytochrome p450 of Mycobacterium tuberculosis

    OpenAIRE

    Dumas, Victoria Gisel; Defelipe, Lucas Alfredo; Petruk, Ariel Alcides; Turjanski, Adrian; Marti, Marcelo Adrian

    2016-01-01

    Among 20 p450s of Mycobacterium tuberculosis (Mt), CYP121 has received an outstanding interest, not only due to its essentiality for bacterial viability but also because it catalyzes an unusual carbon-carbon coupling reaction. Based on the structure of the substrate bound enzyme, several reaction mechanisms were proposed involving first Tyr radical formation, second Tyr radical formation, and C?C coupling. Key and unknown features, being the nature of the species that generate the first and s...

  19. Grief reactions of couples to perinatal loss: A one-year prospective follow-up.

    Science.gov (United States)

    Tseng, Ying-Fen; Cheng, Hsiu-Rong; Chen, Yu-Ping; Yang, Shu-Fei; Cheng, Pi-Tzu

    2017-12-01

    To explore couples' perceptions of the effects of perinatal loss on their marital relationship, social support and grief 1 year postloss, and analyse what factors changed the severity of their grief. Perinatal losses are traumatic events in the lives of families and can have serious long-term consequences for the psychological health of parents and any subsequent children. A prospective follow-up study. We recruited, at a teaching hospital in southern Taiwan, a convenience sample of 30 couples whose babies either miscarried or were stillborn. At 1 month (T1), 3 months (T2), 6 months (T3) and 1 year (T4) after the pregnancy loss, all participants completed four questionnaires. To analyse the changing status of their grief and its related factors, we used a generalised estimating equation (GEE) to account for correlations between repeated observations. Postbereavement grief levels fell over the four time-points. Mothers reported feeling more grief than did the fathers. Couples with a history of infertility, no religious beliefs or no living children before the loss felt more grief from a perinatal miscarriage or stillbirth. Furthermore, couples reported more grief if their marital satisfaction level was low, if their socioemotional support from husband's parents was low or if they had never participated in a ritual for their deceased baby. Six months postloss is the crucial period for bereaved parents after a perinatal loss. Being a mother, having no previous living children and low-level socioemotional support from the husband's parents are significant high-risk factors for a high level of grief 1 year after perinatal death. We recommend that health professionals increase their ability to identify the factors that psychologically affect postloss grief. Active postloss follow-up programmes should focus on these factors to offer specific support and counselling. © 2017 John Wiley & Sons Ltd.

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

    Science.gov (United States)

    Piquemal, M.

    2013-04-01

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

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

    Science.gov (United States)

    Bedford, Robin B

    2015-05-19

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

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

    Science.gov (United States)

    Keeley, N.; Mackintosh, R. S.

    2018-01-01

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

  3. Coupling Reactions of Carbon Dioxide with Epoxides Catalyzed by Vanadium Aminophenolate Complexes.

    Science.gov (United States)

    Elkurtehi, Ali I; Kerton, Francesca M

    2017-03-22

    A series of vanadium compounds supported by tetradentate aminobis(phenolate) ligands were screened for catalytic reactivity in the reaction of propylene oxide (PO) with CO2 : [VO(OMe)(O2 NOBuMeMeth )], [VO(OMe)(ON2 OBuMe )], [VO(OMe)(O2 NNBuBuPy )], and [VO(OMe)(O2 NOBuBuFurf )]. They showed similar reactivities, but reaction rates were higher for [VO(OMe)(ON2 OBuMe )], which was studied in more detail. Turnover frequencies for conversion of PO over 500 h-1 were observed. Activation energies were determined experimentally through in situ IR spectroscopy for propylene carbonate (48.2 kJ mol-1 ), styrene carbonate (45.6 kJ mol-1 ), and cyclohexene carbonate (54.7 kJ mol-1 ) formation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Removal of acetaldehyde gas using wet scrubber coupled with photo-Fenton reaction

    Directory of Open Access Journals (Sweden)

    Masahiro Tokumura

    2016-03-01

    Full Text Available The feasibility of the combined air-cleaning method, which consisted of a wet scrubber and the photo-Fenton reaction, in the removal of gaseous acetaldehyde was evaluated. An acetaldehyde-gas removal efficiency of 99% was achieved in the one-pass test (residence time of 17 s using an inlet acetaldehyde-gas concentration of 1000 ppb at an initial total-iron-ion concentration of 50 mg L−1 and initial hydrogen peroxide concentration of 630 mg L−1. Even at the low initial total-iron-ion concentration of 4 mg L−1, a removal efficiency of 92% was achieved. The acetaldehyde removal efficiency was relatively independent of the initial hydrogen peroxide concentration. UV irradiation further augmented the rate of the photo-Fenton reaction leading to enhanced acetaldehyde-gas removal.

  5. Stochastic focusing coupled with negative feedback enables robust regulation in biochemical reaction networks.

    Science.gov (United States)

    Milias-Argeitis, Andreas; Engblom, Stefan; Bauer, Pavol; Khammash, Mustafa

    2015-12-06

    Nature presents multiple intriguing examples of processes that proceed with high precision and regularity. This remarkable stability is frequently counter to modellers' experience with the inherent stochasticity of chemical reactions in the regime of low-copy numbers. Moreover, the effects of noise and nonlinearities can lead to 'counterintuitive' behaviour, as demonstrated for a basic enzymatic reaction scheme that can display stochastic focusing (SF). Under the assumption of rapid signal fluctuations, SF has been shown to convert a graded response into a threshold mechanism, thus attenuating the detrimental effects of signal noise. However, when the rapid fluctuation assumption is violated, this gain in sensitivity is generally obtained at the cost of very large product variance, and this unpredictable behaviour may be one possible explanation of why, more than a decade after its introduction, SF has still not been observed in real biochemical systems. In this work, we explore the noise properties of a simple enzymatic reaction mechanism with a small and fluctuating number of active enzymes that behaves as a high-gain, noisy amplifier due to SF caused by slow enzyme fluctuations. We then show that the inclusion of a plausible negative feedback mechanism turns the system from a noisy signal detector to a strong homeostatic mechanism by exchanging high gain with strong attenuation in output noise and robustness to parameter variations. Moreover, we observe that the discrepancy between deterministic and stochastic descriptions of stochastically focused systems in the evolution of the means almost completely disappears, despite very low molecule counts and the additional nonlinearity due to feedback. The reaction mechanism considered here can provide a possible resolution to the apparent conflict between intrinsic noise and high precision in critical intracellular processes. © 2015 The Author(s).

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    (thiophen-2-yl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (DT-TPD), and 2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)pyridine (EDOT-Pyr) are generated. Polymers are characterized by 1H NMR, cyclic voltammetry, UV-Vis, GIXRD, SCLC hole mobilities, and are implemented into polymer solar cells fabricated in air......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...... quantities of defects can dramatically influence the solar cell, performance of DArP polymers offers critical insight alongside other structural and optoelectronic comparisons. Even via traditional methods, carbazole-based donors are frequently prone to homocoupling defects, which has been shown to - along...

  7. Reaction Rates in Chemically Heterogeneous Rock: Coupled Impact of Structure and Flow Properties Studied by X-ray Microtomography.

    Science.gov (United States)

    Al-Khulaifi, Yousef; Lin, Qingyang; Blunt, Martin J; Bijeljic, Branko

    2017-04-04

    We study dissolution in a chemically heterogeneous medium consisting of two minerals with contrasting initial structure and transport properties. We perform a reactive transport experiment using CO 2 -saturated brine at reservoir conditions in a millimeter-scale composite core composed of Silurian dolomite and Ketton limestone (calcite) arranged in series. We repeatedly image the composite core using X-ray microtomography (XMT) and collect effluent to assess the individual mineral dissolution. The mineral dissolution from image analysis was comparable to that measured from effluent analysis using inductively coupled plasma mass spectrometry (ICP-MS). We find that the ratio of the effective reaction rate of calcite to that of dolomite decreases with time, indicating the influence of dynamic transport effects originating from changes in pore structure coupled with differences in intrinsic reaction rates. Moreover, evolving flow and transport heterogeneity in the initially heterogeneous dolomite is a key determinant in producing a two-stage dissolution in the calcite. The first stage is characterized by a uniform dissolution of the pore space, while the second stage follows a single-channel growth regime. This implies that spatial memory effects in the medium with a heterogeneous flow characteristic (dolomite) can change the dissolution patterns in the medium with a homogeneous flow characteristic (calcite).

  8. Comparison Analysis of Customer Perceived Values Between Honda Mobilio and Suzuki Ertiga in Manado City

    OpenAIRE

    Koagow, Rendy Rezza

    2015-01-01

    The rapid development of automotive industry in Indonesia has caused tight level of competition, especially in automobile industry, The number of products which have the same form, usability, and other features have made consumers it difficult to distinguish the products. The purpose of this research is to know the difference between the costumer perceived value of Honda Mobilio and Suzuki Ertiga. This research is comparative research that is aimed to describe the difference between Honda Mob...

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

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Oeyvind

    2011-02-15

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

  10. Cobalt-mediated cross-coupling reactions of primary and secondary alkyl halides with 1-(trimethylsilyl)ethenyl- and 2-trimethylsilylethynylmagnesium reagents.

    Science.gov (United States)

    Ohmiya, Hirohisa; Yorimitsu, Hideki; Oshima, Koichiro

    2006-07-06

    [reaction: see text] This paper describes cobalt-mediated cross-coupling reactions of alkyl halides with 1-(trimethylsilyl)ethenylmagnesium bromide and 2-(trimethylsilyl)ethynylmagnesium bromide, respectively. The cobalt system allows for employing secondary as well as primary alkyl halides as the substrates. The reactions offer facile formations of alkyl-alkenyl and alkyl-alkynyl bonds. The reaction mechanism would include single-electron transfer from a cobalt complex to alkyl halide to generate the corresponding alkyl radical. The cobalt system thus enables sequential radical cyclization/alkenylation and cyclization/alkynylation reactions of 6-halo-1-hexene derivatives.

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

    Science.gov (United States)

    Ioannou, Aristos; Daskalakis, Vangelis; Varotsis, Constantinos

    2017-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Zhimin Li

    2016-10-01

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

  13. Coupled Mineral Dissolution and Precipitation Reactions in Shale-Hydraulic Fracturing Fluid Systems

    Science.gov (United States)

    Joe-Wong, C. M.; Harrison, A. L.; Thomas, D.; Dustin, M. K.; Jew, A. D.; Brown, G. E.; Maher, K.; Bargar, J.

    2015-12-01

    Hydraulic fracturing of low-permeability, hydrocarbon-rich shales has recently become an important energy source in the United States. However, hydrocarbon recovery rates are low and drop rapidly after a few months. Hydraulic fracture fluids, which contain dissolved oxygen and numerous organic additives, induce dissolution and precipitation reactions that change the porosity and permeability of the shale. To investigate these reactions, we studied the interactions of four shales (Eagle Ford, Barnett, Marcellus, and Green River) with a simulated hydraulic fracture fluid in batch reactors at 80 °C. The shales were chosen for both economic viability and chemical variety, allowing us to explore the reactivities of different components. The Eagle Ford shale is carbonate rich, and the Green River shale contains significant siderite and kerogen. The Barnett shale also has a high organic content, while the Marcellus shale has the highest fractions of clay and pyrite. Our experiments show that hydrochloric acid in the fluid promotes carbonate mineral dissolution, rapidly raising the pH from acidic to circumneutral levels for the Eagle Ford and Green River shales. Dissolution textures in the Green River shale and large cavities in the Barnett shale indicate significant mineralogical and physical changes in the reacted rock. Morphological changes are not readily apparent in the Eagle Ford and Marcellus shales. For all shales, ongoing changes to the solution Al: Si ratio suggest incongruent aluminosilicate dissolution. Siderite or pyrite dissolution occurs within days and is followed by the formation of secondary Fe precipitates in suspension and coating the walls of the reactor. However, little evidence of any coatings on shale surfaces was found. The net effect of these reactions on porosity and permeability and their influence on the long-term efficacy of oil and gas recovery after hydraulic fracturing are critical to the energy landscape of the United States.

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

    DEFF Research Database (Denmark)

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

    .2 Metal complex of ligands possessing both H-donor and H-acceptor sites in the second coordination sphere should be interesting candidates for proton transfer reactions induced by photooxidation of the metal ion. We have prepared new oxime-containing ligands which coordinate to metal ions...... such that a pyridine group is sterically restricted so it does not coordinate. Instead it can act as proximal base for accepting the oxime proton. [1] M. H. V. Huynh, T. J. Meyer, Chem. Rev. 2007, 107, 5004-5064. [2] T. Irebo, O. Johansson, L. Hammarström, J. Am. Chem. Soc., 2008, 130, 9194-9195....

  15. Palladium Catalyst Supported on Zeolite for Cross-coupling Reactions: An Overview of Recent Advances.

    Science.gov (United States)

    Kumbhar, Arjun

    2017-02-01

    Over the last 30-40 years, Pd-catalyzed C-C bond-forming reactions have gained immense importance for their use in synthesis of biologically and pharmaceutically important organic fragments. Heterogeneous Pd catalysts supported on porous materials, especially zeolites, have many advantages as they have high surface area with tunable acidity and basicity, hydrophobic and hydrophilic character, shape and size selectivity, as well as chemical and thermal stability. They also offer very easy recovery and reusability. This review covers the literature published on the synthesis and characterization of Pd catalysts supported on zeolites and their applications in various organic transformations.

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

    Science.gov (United States)

    Lennox, J Christian; Dempsey, Jillian L

    2017-11-22

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

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

    Directory of Open Access Journals (Sweden)

    Zou Haiming

    2017-12-01

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

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

    Science.gov (United States)

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

    2015-01-14

    A three dimensional potential energy surface for the F + H2 → 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 + H2 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.

  19. Coupling of Carbon Dioxide Fixation to the Oxyhydrogen Reaction in the Isolated Chloroplast of Chlamydomonas reinhardtii1

    Science.gov (United States)

    Chen, Changguo; Gibbs, Martin

    1992-01-01

    The oxyhydrogen reaction (the reduction of O2 to water by H2) in the presence of CO2 was studied in the isolated Chlamydomonas reinhardtii chloroplast by monitoring the rate of 14CO2 incorporation into acid-stable products in the dark. The endogenous rate of CO2 uptake (50-125 nmol/mg chlorophyll per h) was increased about 3- to 4-fold by ATP and additionally when combined with glucose, ribose-5-phosphate, and glycerate-3-phosphate. The rate was diminished 50 to 75%, respectively, when H2 was replaced by N2 or by air. Decrease in CO2 uptake by dl-glyceraldehyde was taken to indicate that the regenerative phase and complete Calvin cycle turnover were involved. Diminution of CO2 incorporation by rotenone, antimycin A, and 2,5-dibromo-3-methyl-6-isopropanol-p-benzoquinone was attributed to an inhibition of the oxyhydrogen reaction, resulting in an elevated NADPH/NADP ratio. If so, then the diminished CO2 uptake could have been by “product inhibition” of the carbon metabolic network. Our data are consistent with the proposal (H. Gaffron [1942] J Gen Physiol 26: 241-267) that CO2 fixation coupled to the oxyhydrogen reaction is dependent to some extent on exchloroplastic metabolism. This support is primarily ATP provided by mitochondrial respiration. PMID:16653129

  20. Inductively coupled plasma mass spectrometer with axial field in a quadrupole reaction cell.

    Science.gov (United States)

    Bandura, Dmitry R; Baranov, Vladimir I; Tanner, Scott D

    2002-10-01

    A novel reaction cell for ICP-MS with an electric field provided inside the quadrupole along its axis is described. The field is implemented via a DC bias applied to additional auxiliary electrodes inserted between the rods of the quadrupole. The field reduces the settling time of the pressurized quadrupole when its mass bandpass is dynamically tuned. It also improves the transmission of analyte ions. It is shown that for the pressurized cell with the field activated, the recovery time for a change in quadrupole operating parameters is reduced to 610 times, respectively. The use of a retarding axial field for in-situ energy discrimination against cluster and polyatomic ions is shown. When the cell is pressurized with O2 for suppression of 129Xe+, the formation of 127IH2+ by reactions with gas impurities limits the detection of 129I to isotopic abundance of approximately 10(-6). In-cell energy discrimination against 127IH2+ utilizing a retarding axial field is shown to reduce the abundance of the background at m/z = 129 to ca. 3 x 10(-8) of the 127I+ signal. In-cell energy discrimination against 127IH2+ is shown to cause less I+ loss than a post-cell potential energy barrier for the same degree of 127IH2+ suppression.

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

    Science.gov (United States)

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

    2017-07-01

    Flame atmospheric pressure chemical ionization (FAPCI) combined with negative electrospray ionization (ESI) mass spectrometry was developed to detect the ion/molecule reactions (IMRs) products between nitric acid (HNO3) and negatively charged amino acid, angiotensin I (AI) and angiotensin II (AII), and insulin ions. Nitrate and HNO3-nitrate ions were detected in the oxyacetylene flame, suggesting that a large quantity of nitric acid (HNO3) was produced in the flame. The HNO3 and negatively charged analyte ions produced by a negative ESI source were delivered into each arm of a Y-shaped stainless steel tube where they merged and reacted. The products were subsequently characterized with an ion trap mass analyzer attached to the exit of the Y-tube. HNO3 showed the strongest affinity to histidine and formed (Mhistidine-H+HNO3)- complex ions, whereas some amino acids did not react with HNO3 at all. Reactions between HNO3 and histidine residues in AI and AII resulted in the formation of dominant [MAI-H+(HNO3)]- and [MAII-H+(HNO3)]- ions. Results from analyses of AAs and insulin indicated that HNO3 could not only react with basic amino acid residues, but also with disulfide bonds to form [M-3H+(HNO3)n]3- complex ions. This approach is useful for obtaining information about the number of basic amino acid residues and disulfide bonds in peptides and proteins.

  2. Reaction

    African Journals Online (AJOL)

    raoul

    12 janv. 2012 ... recours à la TEP-FDG couplée au scanner serait d'un grand apport, en différenciant masse splénique bénigne et maligne, et en identifiant d'autres sites métastatiques hypermétaboliques insoupçonnées sur l'imagerie conventionnelle. L'imagerie de la métastase splénique pourrait également bénéficier de ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-04-01

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

  4. Towards silicon speciation in light petroleum products using gas chromatography coupled to inductively coupled plasma mass spectrometry equipped with a dynamic reaction cell

    Energy Technology Data Exchange (ETDEWEB)

    Chainet, Fabien, E-mail: fabien.chainet@ifpen.fr [IFP Energies nouvelles, Rond-point de l' échangeur de Solaize, BP 3, 69360 Solaize (France); Lienemann, Charles-Philippe; Ponthus, Jeremie [IFP Energies nouvelles, Rond-point de l' échangeur de Solaize, BP 3, 69360 Solaize (France); Pécheyran, Christophe; Castro, Joaudimir; Tessier, Emmanuel; Donard, Olivier François Xavier [LCABIE-IPREM, UMR 5254, CNRS-UPPA, Helioparc, 2 av. Pr. Angot, 64053 Pau (France)

    2014-07-01

    Silicon speciation has recently gained interest in the oil and gas industry due to the significant poisoning problems caused by silicon on hydrotreatment catalysts. The poisoning effect clearly depends on the structure of the silicon species which must be determined and quantified. The hyphenation of gas chromatography (GC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) allows a specific detection to determine the retention times of all silicon species. The aim of this work is to determine the retention indices of unknown silicon species to allow their characterization by a multi-technical approach in order to access to their chemical structure. The optimization of the dynamic reaction cell (DRC) of the ICP-MS using hydrogen as reactant gas successfully demonstrated the resolution of the interferences ({sup 14}N{sup 14}N{sup +} and {sup 12}C{sup 16}O{sup +}) initially present on {sup 28}Si. The linearity was excellent for silicon compounds and instrumental detection limits ranged from 20 to 140 μg of Si/kg depending on the response of the silicon compounds. A continuous release of silicon in the torch was observed most likely due to the use of a torch and an injector which was made of quartz. A non-universal response for silicon was observed and it was clearly necessary to use response coefficients to quantify silicon compounds. Known silicon compounds such as cyclic siloxanes (D{sub 3}–D{sub 16}) coming from PDMS degradation were confirmed. Furthermore, more than 10 new silicon species never characterized before in petroleum products were highlighted in polydimethylsiloxane (PDMS) degradation samples produced under thermal cracking of hydrocarbons. These silicon species mainly consisted of linear and cyclic structures containing reactive functions such as ethoxy, peroxide and hydroxy groups which can be able to react with the alumina surface and hence, poison the catalyst. This characterization will further allow the development of innovative

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

    Directory of Open Access Journals (Sweden)

    Simon Bonte

    2016-03-01

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

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

    Directory of Open Access Journals (Sweden)

    Leah O. Nyangasi

    2017-01-01

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

  7. Monte Carlo Simulations of Coupled Diffusion and Surface Reactions during the Aqueous Corrosion of Borosilicate Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Kerisit, Sebastien N.; Pierce, Eric M.; Ryan, Joseph V.

    2015-01-01

    Borosilicate nuclear waste glasses develop complex altered layers as a result of coupled processes such as hydrolysis of network species, condensation of Si species, and diffusion. However, diffusion has often been overlooked in Monte Carlo models of the aqueous corrosion of borosilicate glasses. Therefore, three different models for dissolved Si diffusion in the altered layer were implemented in a Monte Carlo model and evaluated for glasses in the compositional range (75-x) mol% SiO2 (12.5+x/2) mol% B2O3 and (12.5+x/2) mol% Na2O, where 0 ≤ x ≤ 20%, and corroded in static conditions at a surface-to-volume ratio of 1000 m-1. The three models considered instantaneous homogenization (M1), linear concentration gradients (M2), and concentration profiles determined by solving Fick’s 2nd law using a finite difference method (M3). Model M3 revealed that concentration profiles in the altered layer are not linear and show changes in shape and magnitude as corrosion progresses, unlike those assumed in model M2. Furthermore, model M3 showed that, for borosilicate glasses with a high forward dissolution rate compared to the diffusion rate, the gradual polymerization and densification of the altered layer is significantly delayed compared to models M1 and M2. Models M1 and M2 were found to be appropriate models only for glasses with high release rates such as simple borosilicate glasses with low ZrO2 content.

  8. Toolbox approach to the search for effective ligands for catalytic asymmetric Cr-mediated coupling reactions.

    Science.gov (United States)

    Guo, Haibing; Dong, Cheng-Guo; Kim, Dae-Shik; Urabe, Daisuke; Wang, Jiashi; Kim, Joseph T; Liu, Xiang; Sasaki, Takeo; Kishi, Yoshito

    2009-10-28

    Chromium catalysts derived from chiral sulfonamides represented by A effect the couplings of aldehydes with vinyl, allyl, or alkyl halides. With three distinct sites for structural modification, A affords access to a structurally diverse pool of chiral sulfonamides. The Cr catalysts derived from these sulfonamides exhibit a broad range of catalyst-substrate matching profiles. A strategy is presented to search for a satisfactory chiral sulfonamide for a given substrate. In order to demonstrate the generality and effectiveness of this approach, five diverse C-C bond-forming cases have been selected from the halichondrin synthesis. For each of the cases, two ligands have been deliberately searched for, to induce the formation of (R)- and (S)-alcohols, respectively, at the arbitrarily chosen efficiency level of ">or=80% yield with >or=20:1 stereoselectivity in the presence of

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

    Science.gov (United States)

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

    2018-02-01

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

  10. A Local Integral Equation Formulation Based on Moving Kriging Interpolation for Solving Coupled Nonlinear Reaction-Diffusion Equations

    Directory of Open Access Journals (Sweden)

    Kanittha Yimnak

    2014-01-01

    Full Text Available The meshless local Pretrov-Galerkin method (MLPG with the test function in view of the Heaviside step function is introduced to solve the system of coupled nonlinear reaction-diffusion equations in two-dimensional spaces subjected to Dirichlet and Neumann boundary conditions on a square domain. Two-field velocities are approximated by moving Kriging (MK interpolation method for constructing nodal shape function which holds the Kronecker delta property, thereby enhancing the arrangement nodal shape construction accuracy, while the Crank-Nicolson method is chosen for temporal discretization. The nonlinear terms are treated iteratively within each time step. The developed formulation is verified in two numerical examples with investigating the convergence and the accuracy of numerical results. The numerical experiments revealing the solutions by the developed formulation are stable and more precise.

  11. Electrode Reactions Coupled with Chemical Reactions of Oxygen, Water and Acetaldehyde in an Ionic Liquid: New Approaches for Sensing Volatile Organic Compounds

    Science.gov (United States)

    Chi, Xiaowei; Tang, Yongan; Zeng, Xiangqun

    2017-01-01

    Water and oxygen are ubiquitous present in ambient conditions. This work studies the unique oxygen, trace water and a volatile organic compound (VOC) acetaldehyde redox chemistry in a hydrophobic and aprotic ionic liquid (IL), 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide ([Bmpy] [NTf2]) by cyclic voltammetry and potential step methods. One electron oxygen reduction leads to superoxide radical formation in the IL. Trace water in the IL acts as a protic species that reacts with the superoxide radical. Acetaldehyde is a stronger protic species than water for reacting with the superoxide radical. The presence of trace water in the IL was also demonstrated to facilitate the electro-oxidation of acetaldehyde, with similar mechanism to that in the aqueous solutions. A multiple-step coupling reaction mechanism between water, superoxide radical and acetaldehyde has been described. The unique characteristics of redox chemistry of acetaldehyde in [Bmpy][NTf2] in the presence of oxygen and trace water can be controlled by electrochemical potentials. By controlling the electrode potential windows, several methods including cyclic voltammetry, potential step methods (single-potential, double-potential and triple-potential step methods) were established for the quantification of acetaldehyde. Instead of treating water and oxygen as frustrating interferents to ILs, we found that oxygen and trace water chemistry in [Bmpy][NTf2] can be utilized to develop innovative electrochemical methods for electroanalysis of acetaldehyde. PMID:29142331

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-02-15

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

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

    KAUST Repository

    Meconi, Giulia Magi

    2017-05-24

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

  14. Cross-coupling reaction of alkyl halides with grignard reagents catalyzed by Ni, Pd, or Cu complexes with pi-carbon ligand(s).

    Science.gov (United States)

    Terao, Jun; Kambe, Nobuaki

    2008-11-18

    Transition metal-catalyzed cross-coupling reactions of organic halides and pseudo-halides containing a C-X bond (X = I, Br, Cl, OTf, OTs, etc.) with organometallic reagents are among the most important transformations for carbon-carbon bond formation between a variety of sp, sp(2), and sp(3)-hybridized carbon atoms. In particular, researchers have widely employed Ni- and Pd-catalyzed cross-coupling to synthesize complex organic structures from readily available components. The catalytic cycle of this process comprises oxidative addition, transmetalation, and reductive elimination steps. In these reactions, various organometallic reagents could bear a variety of R groups (alkyl, vinyl, aryl, or allyl), but the coupling partner has been primarily limited to sp and sp(2) carbon compounds: alkynes, alkenes, and arenes. With alkyl coupling partners, these reactions typically run into two problems within the catalytic cycle. First, oxidative addition of alkyl halides to a metal catalyst is generally less efficient than that of aryl or alkenyl compounds. Second, the alkylmetal intermediates formed tend to undergo intramolecular beta-hydrogen elimination. In this Account, we describe our efforts to overcome these problems for Ni and Pd chemistry. We have developed new catalytic systems that do not involve M(0) species but proceed via an anionic complex as the key intermediate. For example, we developed a unique cross-coupling reaction of alkyl halides with organomagnesium or organozinc reagents catalyzed by using a 1,3-butadiene as the additive. This reaction follows a new catalytic pathway: the Ni or Pd catalyst reacts first with R-MgX to form an anionic complex, which then reacts with alkyl halides. Bis-dienes were also effective additives for the Ni-catalyzed cross-coupling reaction of organozinc reagents with alkyl halides. This catalytic system tolerates a wide variety of functional groups, including nitriles, ketones, amides, and esters. In addition, we have extended

  15. Straightforward Synthesis of 2(5H-Furanones as Promising Cross-Coupling Partners: Direct Furanone Annulation Utilizing Ti-Mediated Aldol Addition

    Directory of Open Access Journals (Sweden)

    Yuki Ban

    2016-09-01

    Full Text Available Direct 2(5H-furanone annulation produces promising cross-coupling partners incorporating m- or p-bromo- and p-tosyloxyphenyl groups into the 5-position of a notable 2(5H-furanone pharmacore. The present one-pot annulation method involves two distinctive reactions: (i a powerful and crossed Ti-direct aldol addition and (ii an acid-induced characteristic cyclo-condensation, leading to 2(5H-furanones. Suzuki-Miyaura cross-coupling of 5-(4-bromophenyl-furan-2(5H-ones, 5-(4-tosyloxyphenyl-3,4-dimethylfuran-2(5H-ones and a furan derivative successfully afforded the corresponding products with the 2(5H-furanone skeleton.

  16. Combining the Petasis 3-component reaction with multiple modes of cyclization: a build/couple/pair strategy for the synthesis of densely functionalized small molecules.

    Science.gov (United States)

    Flagstad, Thomas; Hansen, Mette R; Le Quement, Sebastian T; Givskov, Michael; Nielsen, Thomas E

    2015-01-12

    A build/couple/pair strategy for the synthesis of complex and densely functionalized small molecules is presented. The strategy relies on synthetically tractable building blocks (build), that is, diversely substituted hydrazides, α-hydroxy aldehydes, and boronic acids, which undergo Petasis 3-component reactions (couple) to afford densely functionalized anti-hydrazido alcohols. The resulting scaffolds can subsequently be converted via chemoselective cyclization reactions (pair), including intramolecular Diels-Alder or Ru-alkylidene catalyzed ring-closing metathesis, into sets of structurally diverse heterocycles in good yields in only 3-4 steps.

  17. 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.

  18. Tetra- and mono-organotin reagents in palladium-mediated cross-coupling reactions for the labeling with carbon-11 of PET tracers

    Energy Technology Data Exchange (ETDEWEB)

    Bourdier, T.; Huiban, M.; Sobrio, F.; Perrio, C.; Barre, E. [Groupe de Dev Methodol en Tomographie par Emission de Positons, UMR CEA 2E, Universite deCaen, Centre Cyceron, F-14070 Caen Cedex (France); Fouquet, A.; Huet, A. [Laboratoire de Chimie Organique et Organometallique, UMR CNRS 3802, Univ Bordeaux I, F-33405 Talence Cedex (France)

    2008-07-01

    The palladium-catalyzed cross-coupling reactions between a (trimethylstannyl)arene and [{sup 11}C]methyl iodide (Stille reaction) or between an aryl halide and a [{sup 11}C]monomethyltin reagent issued from Lappert's stannylene, were developed for the synthesis of polyfunctional [{sup 11}C]methyl quinolines and quinoline-imides as potential tracers for positron emission tomography (PET). (authors)

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

    Science.gov (United States)

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

    2016-03-03

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

  20. Metal-tag labeling coupled with multiple reaction monitoring-mass spectrometry for absolute quantitation of proteins.

    Science.gov (United States)

    Wang, Xueying; Wang, Xin; Qin, Weijie; Lin, Hongjun; Wang, Jifeng; Wei, Junying; Zhang, Yangjun; Qian, Xiaohong

    2013-09-21

    Mass spectrometry-based quantitative proteomics, consisting of relative and absolute parts, has been used to discover and validate proteins with key functions related to physiological and pathological processes. Currently, stable isotope dilution-multiple reaction monitoring-mass spectrometry (SID-MRM-MS) is the most commonly used method for the absolute determination of proteins in a biological sample. A prerequisite for this method is obtaining internal standards with isotope labels. Although many approaches have been developed for the labeling and preparation of internal peptides, expensive stable isotope labeling coupled with SID-MRM-MS has limited the application and development of an absolute quantitative method. Recently, a low-cost strategy using metal-tag labeling and MS has been developed for relative quantification of peptides or proteins. The introduction of labeling using metal tags has the merits of allowing multiple labeling and enlarging the mass shift to overcome the overlap of adjacent isotope clusters. However, most papers described MRM-MS for protein absolute quantification based on the metal in its peptides labelled with metal by inductively coupled plasma mass spectrometry (ICP MS) but not on its peptides labelled with metal. In this work, a novel approach based on metal-tag labeling coupled with MRM-MS was established for the absolute quantification of peptides or proteins. The principle of the method is that a bifunctional chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid bearing an N-hydroxysuccinimide ester (DOTA-NHS ester), is used to modify the N-termini of signature peptides from a target protein, and the modified peptides then chelate a certain metal, such as thulium, to form metal-tagged peptides (Tm-DOTA-P). Internal peptides are chemically synthesized and labeled with another metal, such as terbium (Tb-DOTA-P), as the internal standard. Both the Tb-DOTA- and Tm-DOTA-labeled peptides in samples can be analysed via

  1. Expanding the substrate scope of Ugi five-center, four-component reaction U-5C-4CR): ketones as coupling partners for secondary amino acids.

    Science.gov (United States)

    Dawidowski, Maciej; Sobczak, Sławomir; Wilczek, Marcin; Kulesza, Artur; Turło, Jadwiga

    2014-02-01

    Various symmetrical and unsymmetrical ketones were successfully coupled with secondary amino acids in the course of Ugi five-center, four-component reaction (U-5C-4CR), thus expanding the molecular diversity possible to be achieved by the reaction. The chemical yields depended on the degree of hindrance of the components employed and were satisfactory in view of possible steric interactions in the U-5C-4CR zwitterionic intermediate. The sense of diastereoinduction for reactions employing unsymmetrical ketones was examined by converting the resulting Ugi adducts into the corresponding rigid 2,6-diketopiperazine derivatives.

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

    Science.gov (United States)

    Mann, Jay; And Others

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

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

    DEFF Research Database (Denmark)

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

    2010-01-01

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

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

    NARCIS (Netherlands)

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

    1989-01-01

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

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    A “build/couple/pair” pathway for the systematic synthesis of structurally diverse small molecules is presented. The Petasis 3-component reaction was used to synthesize anti-amino alcohols displaying pairwise reactive combinations of alkene moieties. Upon treatment with a ruthenium alkylidene-cat......-catalyst, these dienes selectively underwent ring-closing metathesis reactions to form 5- and 7-membered heterocycles and cyclic aminals via a tandem isomerization/N-alkyliminium cyclization sequence.......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...

  6. Sanger DNA-sequencing reactions performed in a solid-phase nanoreactor directly coupled to capillary gel electrophoresis.

    Science.gov (United States)

    Soper, S A; Williams, D C; Xu, Y; Lassiter, S J; Zhang, Y; Ford, S M; Bruch, R C

    1998-10-01

    A miniaturized, solid-phase nanoreactor was developed to prepare Sanger DNA-sequencing ladders which was directly interfaced to a capillary gel electrophoresis system. A biotinylated fragment of the rat brain actin gene (1 kbp) was amplified by PCR and attached to the interior wall of an (aminoalkyl)silane-derivatized fused-silica capillary tube via a biotin/streptavidin/biotin linkage. Coverage of the capillary wall with the biotinylated DNA averaged 77 +/- 10%. Stability of the anchored template under pressure (33 nL/s) and electroosmotic flows (11.3 nL/s) were favorable, requiring rinsing for > 150 h to reduce the surface coverage by only 50%. In addition, the immobilized template was stable toward temperatures required for preparing sequencing ladders, even under cycling conditions. Standard Sanger dideoxynucleotide termination performed in a large-volume (approximately 8 microL) solid-phase reactor using the thermally stable polymerase enzymes Taq and Vent and the polymerases T7 and Bst with off-line slab gel electrophoresis and autoradiographic detection indicated that acceptable fragment generation was achieved only in the case of the thermally stable polymerases. Banding was not apparent for T7 and Bst since all reagents were inserted into the column in a single plug at the beginning of the reaction. A small volume reactor (volume approximately 62 nL) was then used to perform DNA polymerase reactions and was coupled directly to a capillary gel column for separation. The capillary reactor was placed inside a thermocycler to control the temperature during chain extension and was directly connected to the gel column via zero dead volume fused-silica connectors. The complementary DNA fragments generated (C-track only) in the reactor were denatured using heat and directly injected onto the gel-filled capillary for size separation with detection accomplished using near-IR laser-induced fluorescence. Extension and single-base separation resolution of the C

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

    Science.gov (United States)

    Tsai, Song-Ling; Liu, Yi-Kai; Pan, Heng; Liu, Chien-Hung; Lee, Ming-Tsang

    2016-01-08

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

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

    Directory of Open Access Journals (Sweden)

    Song-Ling Tsai

    2016-01-01

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

  9. Global description of the 7Li+p reaction at 5.44 MeV/u in a continuum-discretized coupled-channels approach

    Science.gov (United States)

    Pakou, A.; Cappuzzello, F.; Keeley, N.; Acosta, L.; Agodi, C.; Aslanoglou, X.; Calabrese, S.; Carbone, D.; Cavallaro, M.; Foti, A.; Marquínez-Durán, G.; Martel, I.; Mazzocco, M.; Parascandolo, C.; Pierroutsakou, D.; Rusek, K.; Sgouros, O.; Soukeras, V.; Strano, E.; Zagatto, V. A. B.; Zerva, K.

    2017-09-01

    The complete set of open channels for the 7Li+p system, namely elastic scattering, inelastic scattering, breakup, the 7Li+p →7Be+n charge exchange reaction, and the 7Li+p →4He+4He reaction, was measured in the same experiment in inverse kinematics at an energy of 5.44 MeV/u. Data were also obtained for the charge exchange reaction at energies of 5.0 and 3.57 MeV/u. The elastic and inelastic scattering and breakup data were reported previously and are reviewed here and, together with the new data for the other two reactions, are discussed coherently within the same continuum-discretized coupled-channels model framework.

  10. Decay of iron(V) nitride complexes by a N-N bond-coupling reaction in solution: a combined spectroscopic and theoretical analysis.

    Science.gov (United States)

    Krahe, Oliver; Bill, Eckhard; Neese, Frank

    2014-08-11

    Cryogenically trapped Fe(V) nitride complexes with cyclam-based ligands were found to decay by bimolecular reactions, forming exclusively Fe(II) compounds. Characterization of educts and products by Mössbauer spectroscopy, mass spectrometry, and spectroscopy-oriented DFT calculations showed that the reaction mechanism is reductive nitride coupling and release of dinitrogen (2 Fe(V)≡N→Fe(II)-N=N-Fe(II)→2 Fe(II)+N2). The reaction pathways, representing an "inverse" of the Haber-Bosch reaction, were computationally explored in detail, also to judge the feasibility of yielding catalytically competent Fe(V)(N). Implications for the photolytic cleavage of Fe(III) azides used to generate high-valent Fe nitrides are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Study of NaCl:Mn{sup 2+} nanostructures in the Suzuki phase by optical spectroscopy and atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mejía-Uriarte, E.V., E-mail: elsi.mejia@ccadet.unam.mx [Laboratorio de Fotónica de Microondas, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, AP 70-186, C.P. 04510, D.F. México (Mexico); Kolokoltsev, O. [Laboratorio de Fotónica de Microondas, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, AP 70-186, C.P. 04510, D.F. México (Mexico); Navarrete Montesinos, M. [Instituto de Ingeniería, Universidad Nacional Autónoma de México, D.F. México (Mexico); Camarillo, E.; Hernández A, J.; Murrieta S, H. [Instituto de Física, Universidad Nacional Autónoma de México, AP 20-364, C.P. 01000, D.F. México (Mexico)

    2015-04-15

    NaCl:Mn{sup 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{sup 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{sup 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.

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

    CERN Multimedia

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

  13. Titanium-mediated reductive cross-coupling reactions of imines with terminal alkynes: An efficient route for the synthesis of stereodefined allylic amines

    Directory of Open Access Journals (Sweden)

    Kebin Mao

    2013-03-01

    Full Text Available Low-valency titanium species, generated in situ by using Ti(OiPr4/2 c-C5H9MgCl reagent, react with imines to give a titanium-imine complex that can couple with terminal alkynes to provide azatitanacyclopentenes with excellent regioselectivity. Stereodefined allylic amines are obtained in good yields after hydrolysis or iodonolysis of the corresponding azatitanacyclopentenes. When ethynylcyclopropane is used as the coupling partner to react with imines in this reaction, the initially generated allylic amine undergoes an unexpected 1,3-amino migration on silica gel during the column chromatography.

  14. Total synthesis of the cyclopeptide alkaloid abyssenine A. Application of inter- and intramolecular copper-mediated coupling reactions in organic synthesis.

    Science.gov (United States)

    Toumi, Mathieu; Couty, François; Evano, Gwilherm

    2007-11-23

    The first total synthesis of the 15-membered ring cyclopeptide alkaloid abyssenine A 1 has been achieved with a longest linear sequence of 15 steps. Central to the synthetic approach was an efficient copper-mediated Ullmann coupling/Claisen rearrangement sequence allowing for both ipso and ortho functionalization of aromatic iodide 4. This sequence was used for the synthesis of the aromatic core. The synthetic utility of copper-catalyzed coupling reactions was further demonstrated to install the enamide with a concomitant straightforward macrocyclization starting from acyclic alpha-amido-omega-vinyl iodide 13.

  15. Low-Valent Ate Complexes Formed in Cobalt-Catalyzed Cross-Coupling Reactions with 1,3-Dienes as Additives.

    Science.gov (United States)

    Kreyenschmidt, Friedrich; Koszinowski, Konrad

    2018-01-24

    The combination of CoCl2 and 1,3-dienes is known to catalyze challenging alkyl-alkyl cross-coupling reactions between Grignard reagents and alkyl halides, but the mechanism of these valuable transformations remains speculative. Herein, electrospray-ionization mass spectrometry is used to identify and characterize the elusive intermediates of these and related reactions. The vast majority of detected species contain low-valent cobalt(I) centers and diene molecules. Charge tagging, deuterium labeling, and gas-phase fragmentation experiments elucidate the likely origin of these species and show that the diene not only binds to Co as a π ligand, but also undergoes migratory insertion reactions into Co-H and Co-R bonds. The resulting species have a strong tendency to form anionic cobalt(I) ate complexes, the superior nucleophilicity of which should render them highly reactive toward electrophilic substrates and, thus, presumably is the key to the high catalytic efficiency of the system under investigation. Upon the reaction of the in situ formed cobalt(I) ate complexes with organyl halides, only the final cross-coupling product could be detected, but no cobalt(III) species. This finding implies that this reaction step proceeds in a direct manner without any intermediate or, alternatively, that it involves an intermediate with a very short lifetime. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. 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.

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

    Directory of Open Access Journals (Sweden)

    Wei Long

    2015-11-01

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

  18. A Sequential Indium-Mediated Aldehyde Allylation/Palladium-Catalyzed Cross-Coupling Reaction in the Synthesis of 2-Deoxy-β-C-Aryl Glycosides

    Science.gov (United States)

    Moral, John Alec; Moon, Seong-Jin; Rodriguez-Torres, Samuel; Minehan, Thomas G.

    2009-01-01

    Indium-mediated allylation of aldehydes with 2-chloro-3-iodopropene, followed by a palladium-catalyzed cross-coupling reaction with triarylindium reagents or arylboronic acids, leads to aryl-substituted homoallylic alcohols in good to excellent yields and diastereoselectivities. The products obtained from reactions conducted with D-glyceraldehyde acetonide can be transformed into 2-deoxy-β-C-aryl ribofuranosides in high overall yields. Similarly, 2-deoxy-β-C-aryl allopyranosides may be prepared efficiently from 2,4-O-benzylidene erythrose. PMID:19630430

  19. Functionalization of Azacalixaromatics by Cu(II)-Catalyzed Oxidative Cross-Coupling Reaction between the Arene C-H Bond and Boronic Acids.

    Science.gov (United States)

    Liu, Yang; Long, Chao; Zhao, Liang; Wang, Mei-Xiang

    2016-10-07

    Catalyzed by Cu(ClO4)2·6H2O under mild aerobic conditions using air as the oxidant, azacalix[1]arene[3]pyridines underwent a highly efficient oxidative cross-coupling reaction with a large number of aryl-, alkenyl-, and alkylboronic acids to afford diverse functionalized macrocycles. Stoichiometric reactions of an arylboronic acid with isolated and structurally well-defined high valent organocopper compounds indicated the involvement of arylcopper(II) rather than arylcopper(III) species as an organometallic intermediate in catalysis.

  20. Isothermal Reactor for Continuous Flow Microwave-Assisted Chemical Reaction

    Science.gov (United States)

    Matsuzawa, Mitsuhiro; Togashi, Shigenori; Hasebe, Shinji

    An isothermal reactor in which reaction solutions can be controlled at constant temperature under constant microwave irradiation was developed. This is useful for investigating microwave effects on chemical reactions that are not observed under conventional heating conditions. We devised a structure in which a heat-transfer medium with a low dielectric loss factor, which hardly absorbs any microwaves, flowed outside a spiral reaction tube and designed the basic structure of the reactor using electromagnetic simulation to optimize the energy absorption rate. The conditions for increasing the temperature controlling ability of the reactor were also investigated theoretically and experimentally by taking into consideration the influences of three elements: the velocity of the internal fluid, the material for the tube, and the velocity of the external fluid. The velocity of the external fluid had the greatest influence on temperature controlling ability and the material for the tube had the least influence under the experimental conditions. The overall heat transfer coefficient was about 3.9×102 W/(m2·K) when water flowed through the quartz reaction tube at 7.1 mm/s and the external fluid flowed outside the tube at 44 mm/s. We also tested and confirmed that the temperature of water used as internal fluid could be controlled to within ±1.5 K at 309.3 K when microwaves at 26 W were irradiated into the reactor, whereas the temperature of water was over 373 K and boiled without the heat-transfer medium flowing outside the reaction tube using a conventional method of microwave heating. In addition, we investigated microwave effects on Suzuki-Miyaura coupling reaction using the developed isothermal reactor and we confirmed that the temperatures were controlled well in the reactor. The yields obtained by microwave heating were almost the same as that obtained by oil-bath heating.

  1. Improving the throughput of batch photochemical reactions using flow: Dual photoredox and nickel catalysis in flow for C(sp2)C(sp3) cross-coupling.

    Science.gov (United States)

    Abdiaj, Irini; Alcázar, Jesús

    2017-12-01

    We report herein the transfer of dual photoredox and nickel catalysis for C(sp 2 )C(sp 3 ) cross coupling form batch to flow. This new procedure clearly improves the scalability of the previous batch reaction by the reactor's size and operating time reduction, and allows the preparation of interesting compounds for drug discovery in multigram amounts. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Use of stable isotope dimethyl labeling coupled to selected reaction monitoring to enhance throughput by multiplexing relative quantitation of targeted proteins

    OpenAIRE

    Aye, Thin Thin; Low, Teck Yew; Bjørlykke, Yngvild; Barsnes, Harald; Heck, Albert J. R.; Berven, Frode

    2012-01-01

    In this manuscript, we present a proof-of-concept study for targeted relative protein quantitation workflow using chemical labeling in the form of dimethylation, coupled with selected reaction monitoring (dimethyl-SRM). We first demonstrate close to complete isotope incorporation for all peptides tested. The accuracy, reproducibility, and linear dynamic range of quantitation are further assessed based on known ratios of nonhuman standard proteins spiked into human cerebrospinal fluid (CSF) as...

  3. Coriolis coupling effects in the calculation of state-to-state integral and differential cross sections for the H+D2 reaction.

    Science.gov (United States)

    Chu, Tian-Shu; Han, Ke-Li; Hankel, Marlies; Balint-Kurti, Gabriel G

    2007-06-07

    The quantum wavepacket parallel computational code DIFFREALWAVE is used to calculate state-to-state integral and differential cross sections for the title reaction on the BKMP2 surface in the total energy range of 0.4-1.2 eV with D2 initially in its ground vibrational-rotational state. The role of Coriolis couplings in the state-to-state quantum calculations is examined in detail. Comparison of the results from calculations including the full Coriolis coupling and those using the centrifugal sudden approximation demonstrates that both the energy dependence and the angular dependence of the calculated cross sections are extremely sensitive to the Coriolis coupling, thus emphasizing the importance of including it correctly in an accurate state-to-state calculation.

  4. Synthesis of di-, tri-, and tetrasulfides through multifold carbon-sulfur cross-coupling reactions with indium tri(organothiolates) in a one-pot procedure.

    Science.gov (United States)

    Lee, Phil Ho; Park, Youngchul; Park, Sangkyun; Lee, Euijae; Kim, Sunggak

    2011-02-04

    Pd-catalyzed multifold (2-, 3-, and 4-fold) carbon-sulfur cross-coupling reaction of indium tri(organothiolates) with polybromonated aromatic and heteroaromatic compounds was developed in a one-pot procedure. Both 2,5-dibromopyridine and 2,6-dibromopyridine reacted with indium tri(organothiolates) (0.68 equiv) in the presence of 4 mol % of Pd(OAc)(2), 4.2 mol % of Xantphos, and 1 equiv of diisopropylethylamine (DIPEA), producing disulfides in good to excellent yields. These results indicate that indium tri(organothiolates) transfer all three alkyl- or arylthio groups attached to indium metal to electrophilic coupling partners. Indium tri(organothiolates) derived from alkyl thiol having a low boiling point, such as n-propyl, isopropyl, and tert-butyl thiol, acted as good nucleophilic coupling partners. In addition, indium tri(arylthiolates) derived from aryl thiols possessing an electron-withdrawing or -donating group on the aromatic ring participated well in the Pd-catalyzed multifold carbon-sulfur cross-coupling reaction. 4,4'-Dibromo-1,1'-biphenyl, 9,10-dibromoanthracene, 2,4-dibromoanisole, 2,7-dibromo-9,9-dimethylfluorene, 3,4-dibromothiophene, 2,3-dibromothiophene, 2,2'-bithiophene, 1,3,5-tribromobenzene, and 1,2,4,5-tetrabromobenzene were converted smoothly to the corresponding di-, tri-, and tetrasulfides.

  5. A Quantum-Chemical DFT Approach to Elucidation of the Chirality Transfer Mechanism of the Enantioselective Suzuki–Miyaura Cross-Coupling Reaction

    Directory of Open Access Journals (Sweden)

    Radomir Jasiński

    2017-01-01

    Full Text Available The DFT calculations of the simplified model of the asymmetric Suzuki–Miyaura coupling reaction were performed at the M062x/LANL2DZ theory level at first. It was found that enantioselective reactions mediated by the palladium complexes of chiral C,P-ligands follow a four-stage mechanism similar to that proposed previously as one of the most credible mechanisms. It should be underlined that the presence of substituents in the substrates and the chiral ligand at ortho positions determines the energies of possible diastereoisomeric transition states and intermediates in initial reaction steps. This suggests that, in practice, a sharp selection of theoretically possible paths of chirality transfer from the catalyst to the product should have a place and, therefore, the absolute configuration of the formed atropisomeric product is defined and can be predicted.

  6. An ab initio investigation of the significance of the HOOF intermediate in coupling reactions involving FOO(x) and HO(x) species

    Science.gov (United States)

    Francisco, J. S.

    1993-02-01

    Ab initio calculations are used to investigate the stability and role of HOOF in the reaction of FO with HO radicals. The heat of formation for HOOF is estimated as 0.4 +/- 2 kcal/mol using an isodesmic reaction scheme. Spectroscopic properties of the HOOF intermediate is also provided in order to facilitate its identification. Decomposition pathways of the intermediate are examined. The lowest energy pathway is the formation of F atoms and HO2 radicals and requires 27.2 kcal/mol to proceed. Reactions leading to the formation of the HOOF intermediate are examined in regard to their importance in understanding stratospheric chemistry involving the coupling of fluorine and fluorine oxide with HO(x) species in catalytic cycles.

  7. Mutations to R. sphaeroides Reaction Center Perturb Energy Levels and Vibronic Coupling but Not Observed Energy Transfer Rates.

    Science.gov (United States)

    Flanagan, Moira L; Long, Phillip D; Dahlberg, Peter D; Rolczynski, Brian S; Massey, Sara C; Engel, Gregory S

    2016-03-10

    The bacterial reaction center is capable of both efficiently collecting and quickly transferring energy within the complex; therefore, the reaction center serves as a convenient model for both energy transfer and charge separation. To spectroscopically probe the interactions between the electronic excited states on the chromophores and their intricate relationship with vibrational motions in their environment, we examine coherences between the excited states. Here, we investigate this question by introducing a series of point mutations within 12 Å of the special pair of bacteriochlorophylls in the Rhodobacter sphaeroides reaction center. Using two-dimensional spectroscopy, we find that the time scales of energy transfer dynamics remain unperturbed by these mutations. However, within these spectra, we detect changes in the mixed vibrational-electronic coherences in these reaction centers. Our results indicate that resonance between bacteriochlorophyll vibrational modes and excitonic energy gaps promote electronic coherences and support current vibronic models of photosynthetic energy transfer.

  8. Palladium nanoparticles immobilized on multifunctional ‎hyperbranched polyglycerol-grafted magnetic nanoparticles as a ‎sustainable and efficient catalyst for C-C coupling reactions

    Directory of Open Access Journals (Sweden)

    Mina Amini

    2016-07-01

    Full Text Available This study offers an exclusive class of magnetic nanoparticles supported hyperbranched polyglycerol (MNP/HPG that was functionalized with citric acid (MNP/HPG-CA as a host immobilization of palladium nanoparticles. The MNP/HPG-CA/Pd catalyst was fully characterized using some different techniques such as thermogravimetric analysis (TGA, x-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, energy-dispersive x-ray spectroscopy (EDX, inductively coupled plasma (ICP and x-ray photoelectron spectroscopy (XPS. The new catalytic system showed high activity for the Suzuki–Miyaura cross-coupling and Heck reaction under mild and green conditions. Besides, the MNP/HPG-CA/Pd was found to be a convenient catalyst for copper-free Sonogashira coupling reaction in water as a green solvent at room temperature. Moreover, the catalyst could be recovered easily and reused several times without significant loss of reactivity. Ease of preparation, oxygen insensitive, phosphine-free, air- and moisture-stable, and high reusability of this immobilized palladium catalyst are the noteworthy advantages of this catalytic system.

  9. Palladium Nanoparticles Immobilized on Individual Calcium Carbonate Plates Derived from Mussel Shell Waste: An Ecofriendly Catalyst for the Copper-Free Sonogashira Coupling Reaction.

    Science.gov (United States)

    Saetan, Trin; Lertvachirapaiboon, Chutiparn; Ekgasit, Sanong; Sukwattanasinitt, Mongkol; Wacharasindhu, Sumrit

    2017-09-05

    The conversion of waste into high-value materials is considered an important sustainability strategy in modern chemical industries. A large volume of shell waste is generated globally from mussel cultivation. In this work, mussel shell waste (Perna viridis) is transformed into individual calcium carbonate plates (ICCPs) and is applied as a support for a heterogeneous catalyst. Palladium nanoparticles (3-6 nm) are deposited with an even dispersion on the ICCP surface, as demonstrated by X-ray diffraction and scanning electron microscopy. Using this system, Sonogashira cross-coupling reactions between aryl iodides and terminal acetylenes were accomplished in high yields with the use of 1 % Pd/ICCP in the presence of potassium carbonate without the use of any copper metal or external ligand. The Pd/ICCP catalyst could also be reused up to three times and activity over 90 % was maintained with negligible Pd-metal leaching. This work demonstrates that mussel shell waste can be used as an inexpensive and effective support for metal catalysts in coupling reactions, as demonstrated by the successful performance of the Pd-catalyzed, copper-free Sonogashira cross-coupling process. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. A New Versatile Route to Unstable Diazo Compounds via Oxadiazolines and Use In Aryl-Alkyl Cross-Coupling Reactions.

    Science.gov (United States)

    Greb, Andreas; Poh, Jian-Siang; Greed, Stephanie; Battilocchio, Claudio; Pasau, Patrick; Blakemore, David C; Ley, Steven Victor

    2017-10-31

    Coupling of readily available boronic acids and diazo compounds has emerged recently as a powerful metal-free carbon-carbon bond forming method. However, the difficulty in forming the unstable diazo compound partner in a mild fashion has hitherto limited their general use and scope of the transformation. Here, we report the application of oxadiazolines as precursors for the generation of an unstable family of diazo compounds using flow UV photolysis and their first use in divergent protodeboronative and oxidative C(sp2)-C(sp3) cross-coupling processes, with excellent functional group tolerance. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Chemical resolution of Pu+ from U+ and Am+ using a band-pass reaction cell inductively coupled plasma mass spectrometer.

    Science.gov (United States)

    Tanner, Scott D; Li, Chunsheng; Vais, Vladimir; Baranov, Vladimir I; Bandura, Dmitry R

    2004-06-01

    Determination of the concentration and distribution of the Pu and Am isotopes is hindered by the isobaric overlaps between the elements themselves and U, generally requiring time-consuming chemical separation of the elements. A method is described in which chemical resolution of the elemental ions is obtained through ion-molecule reactions in a reaction cell of an ICPMS instrument. The reactions of "natural" U(+), (242)Pu(+), and (243)Am(+) with ethylene, carbon dioxide, and nitric oxide are reported. Since the net sensitivities to the isotopes of an element are similar, chemical resolution is inferred when one isobaric element reacts rapidly with a given gas and the isobar (or in this instance surrogate isotope) is unreactive or slowly reactive. Chemical resolution of the m/z 238 isotopes of U and Pu can be obtained using ethylene as a reaction gas, but little improvement in the resolution of the m/z 239 isobars is obtained. However, high efficiency of reaction of U(+) and UH(+) with CO(2), and nonreaction of Pu(+), allows the sub-ppt determination of (239)Pu, (240)Pu, and (242)Pu (single ppt for (238)Pu) in the presence of 7 orders of magnitude excess U matrix without prior chemical separation. Similarly, oxidation of Pu(+) by NO, and nonreaction of Am(+), permit chemical resolution of the isobars of Pu and Am over 2-3 orders of magnitude relative concentration. The method provides the potential for analysis of the actinides with reduced sample matrix separation.

  12. A fully coupled diffusion-reaction scheme for moisture sorption-desorption in an anhydride-cured epoxy resin

    KAUST Repository

    El Yagoubi, Jalal

    2012-11-01

    Thermoset materials frequently display non-classical moisture sorption behaviors. In this paper, we investigated this issue from an experimental point of view as well as in terms of modeling the water transport. We used the gravimetric technique to monitor water uptake by epoxy samples, with several thicknesses exposed to different levels of humidity during absorption and desorption tests. Our results revealed that the polymer displays a two-stage behavior with a residual amount of water that is desorbed progressively. We proposed a phenomenological reaction-diffusion scheme to describe this behavior. The model describes water transport as a competition between diffusion and the reaction, during which the local diffusivity and solubility depend on the local advancement of the reaction. We then implemented our model using COMSOL Multiphysics and identified it using a MATLAB-COMSOL optimization tool and the experimental data. We discussed the relation between the hydrophilicity of the product of the reaction and the diffusion behavior. We examined the reaction-induced modification of the water concentration field. It is worth noting that part of the phenomenology can be explained by the presence of hydrolyzable groups. © 2012 Elsevier Ltd. All rights reserved.

  13. Palladium-catalyzed Kumada coupling reaction of bromoporphyrins with silylmethyl Grignard reagents: preparation of silylmethyl-substituted porphyrins as a multipurpose synthon for fabrication of porphyrin systems.

    Science.gov (United States)

    Sugita, Noriaki; Hayashi, Satoshi; Hino, Fumio; Takanami, Toshikatsu

    2012-12-07

    We have developed an efficient method for preparing silylmethyl-substituted porphyrins via the palladium-catalyzed Kumada cross-coupling reaction of bromoporphyrins with silylmethyl Grignard reagents. We demonstrated the synthetic utility of these silylmethylporphyrins as a multipurpose synthon for fabricating porphyrin derivatives through a variety of transformations of the silylmethyl groups, including the DDQ-promoted oxidative conversion to CHO, CH(2)OH, CH(2)OMe, and CH(2)F functionalities and the fluoride ion-mediated desilylative introduction of carbon-carbon single and double bonds.

  14. Magnetic Pd-Fe{sub 3}O{sub 4} heterodimer nanocrystals as recoverable catalysts for ligand-free hiyama cross-coupling reactions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Woong Sup; Byun, Sang Moon; Kwon, Jung Min; Kim, B. Moon [Dept. of Chemistry, College of Natural Sciences, Seoul National University, Seoul (Korea, Republic of)

    2016-12-15

    Ligand-free Hiyama cross-coupling reaction was achieved through the use of Pd-Fe{sub 3}O{sub 4} heterodimeric nanocrystals (1 mol% in Pd) as recyclable catalysts. The nanocrystal catalysts exhibited good activities accommodating a variety of substrates including aryl bromides and iodides with substituents of varying electronic and steric properties. Furthermore, the nanocrystal catalyst could be conveniently recovered with the aid of an external magnet and recycled five times without the loss of catalytic activity to a considerable degree.

  15. Enzyme oscillation can enhance the thermodynamic efficiency of cellular metabolism: Consequence of anti-phase coupling between reaction flux and affinity

    CERN Document Server

    Himeoka, Yusuke

    2015-01-01

    Cells generally convert nutrient resources to useful products via energy transduction. Accordingly, the thermodynamic efficiency of this conversion process is one of the most essential characteristics of living organisms. However, although these processes occur under conditions of dynamic metabolism, most studies of cellular thermodynamic efficiency have been restricted to examining steady states; thus, the relevance of dynamics to this efficiency has not yet been elucidated. Here, we develop a simple model of metabolic reactions with anabolism-catabolism coupling catalysed by enzymes. Through application of external oscillation in the enzyme abundances, the thermodynamic efficiency of metabolism was found to be improved. This result is in strong contrast with that observed in the oscillatory input, in which the efficiency always decreased with oscillation. This improvement was effectively achieved by separating the anabolic and catabolic reactions, which tend to disequilibrate each other, and taking advantag...

  16. Copper(II)-catalysed oxidative coupling reaction of 3-hydroxyacetanilide with 3-methyl-2-benzothiazolinone hydrazone for the spectrophotometric determination of traces of copper(II).

    Science.gov (United States)

    Kumar, M S Hemantha; Nagaraja, P; Yathirajan, H S

    2003-01-01

    A spectrophotometric method is developed for the determination of traces of copper(II), based on the catalytic oxidative coupling reaction of 3-hydroxyacetanilide with 3-methyl-2-benzothiazolinone hydrazone in the presence of ammonia and hydrochloric acid. Beer's law is obeyed in the copper(II) concentration range of 0.008-0.16 microg mL(-1), and the molar absorptivity at 530 nm is 2.5x10(5) L mol(-1) cm(-1). The Sandell's sensitivity of the product is 0.000254 microg cm(-2). The optimum reaction conditions and other important analytical parameters have been investigated. The proposed method is applied to the analysis of water and soil samples and the results are compared with the literature method.

  17. Coupled CFD analysis of size distributions on indoor secondary organic aerosol derived from ozone/limonene reactions

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Kazuhide [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580 (Japan); Harashima, Hiroshi [Obayashi Co. Ltd., Fukuoka (Japan)

    2011-03-15

    Recently, theoretical analysis and experiment have been initiated to investigate the generation of secondary organic aerosols (SOA) by chemical reactions in indoor air. In particular, it has been confirmed that SOA are generated by the reaction of ozone with various terpenoids. The overarching goal of this work was to better understand ozone, VOC (volatile organic compounds) and generated SOA distributions within rooms. We carried out cylindrical test chamber experiments to measure SOA generation from the chemical reaction of ozone and limonene and discussed numerical models to describe it. In this paper, we propose a method for predicting the particle size distribution of SOA generated by ozone and limonene chemical reactions in air. In particular, we discuss an analytical method that involves a sectional modeling approach governing equations of SOA. Although the changes in particle size distribution in a 40-section model were reproduced to a certain extent, rigorous modeling for the generation and growth of SOA and an increased number of sections are needed for improvement of prediction accuracy. (author)

  18. Use of “Homeopathic” Ligand-Free Palladium as Catalyst for Aryl-Aryl Coupling Reactions

    NARCIS (Netherlands)

    Alimardanov, Asaf; Schmieder-van de Vondervoort, Lizette; Vries, André H.M. de; Vries, Johannes G. de

    2004-01-01

    We have previously shown that the use of ligand-free palladium employing Pd(OAc)2 as catalyst precursor in the Heck reaction of aryl bromides is possible if low catalyst loadings, typically between 0.01 – 0.1 mol % are used. We have now tested this phenomenon, which we have dubbed “homeopathic”

  19. Coupling of collective motions of the protein matrix to vibrations of the non-heme iron in bacterial photosynthetic reaction centers.

    Science.gov (United States)

    Orzechowska, A; Lipińska, M; Fiedor, J; Chumakov, A; Zajac, M; Slezak, T; Matlak, K; Strzałka, K; Korecki, J; Fiedor, L; Burda, K

    2010-10-01

    Non-heme iron is a conservative component of type II photosynthetic reaction centers of unknown function. We found that in the reaction center from Rba. sphaeroides it exists in two forms, high and low spin ferrous states, whereas in Rsp. rubrum mostly in a low spin state, in line with our earlier finding of its low spin state in the algal photosystem II reaction center (Burda et al., 2003). The temperature dependence of the non-heme iron displacement studied by Mössbauer spectroscopy shows that the surrounding of the high spin iron is more flexible (Debye temperature ~165K) than that of the low spin atom (~207K). Nuclear inelastic scattering measurements of the collective motions in the Rba. sphaeroides reaction center show that the density of vibrational states, originating from non-heme iron, has well-separated modes between lower (4-17meV) and higher (17-25meV) energies while in the one from Rsp. rubrum its distribution is more uniform with only little contribution of low energy (~6meV) vibrations. It is the first experimental evidence that the fluctuations of the protein matrix in type II reaction center are correlated to the spin state of non-heme iron. We propose a simple mechanism in which the spin state of non-heme iron directly determines the strength of coupling between the two quinone acceptors (Q(A) and Q(B)) and fast collective motions of protein matrix that play a crucial role in activation and regulation of the electron and proton transfer between these two quinones. We suggest that hydrogen bond network on the acceptor side of reaction center is responsible for stabilization of non-heme iron in different spin states. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. Perchlorate-Coupled Carbon Monoxide (CO Oxidation: Evidence for a Plausible Microbe-Mediated Reaction in Martian Brines

    Directory of Open Access Journals (Sweden)

    Marisa R. Myers

    2017-12-01

    Full Text Available The presence of hydrated salts on Mars indicates that some regions of its surface might be habitable if suitable metabolizable substrates are available. However, several lines of evidence have shown that Mars’ regolith contains only trace levels of the organic matter needed to support heterotrophic microbes. Due to the scarcity of organic carbon, carbon monoxide (CO at a concentration of about 700 parts per million (about 0.4 Pa might be the single most abundant readily available substrate that could support near-surface bacterial activity. Although a variety of electron acceptors can be coupled to CO oxidation, perchlorate is likely the most abundant potential oxidant in Mars’ brines. Whether perchlorate, a potent chaotrope, can support microbial CO oxidation has not been previously documented. We report here the first evidence for perchlorate-coupled CO oxidation based on assays with two distinct euryarchaeal extreme halophiles. CO oxidation occurred readily in 3.8 M NaCl brines with perchlorate concentrations from 0.01 to 1 M. Both isolates were able to couple CO with perchlorate or chlorate under anaerobic conditions with or without nitrate as an inducer for nitrate reductase, which serves as a perchlorate reductase in extreme halophiles. In the presence of perchlorate, CO concentrations were reduced to levels well below those found in Mars’ atmosphere. This indicates that CO could contribute to the survival of microbial populations in hydrated salt formations or brines if water activities are suitably permissive.

  1. Practical synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides via conventional and decarboxylative copper-free Sonogashira coupling reactions

    Directory of Open Access Journals (Sweden)

    Andrea Caporale

    2014-02-01

    Full Text Available Two efficient protocols for the palladium-catalyzed synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides in the absence of copper were developed. A simple catalytic system consisting of Pd(OAc2 and P(p-tol3 using DBU as the base and THF as the solvent was found to be highly effective for the coupling reaction of 2-methyl-3-butyn-2-ol (4 with a wide range of aryl bromides in good to excellent yields. Analogously, the synthesis of aryl-2-methyl-3-butyn-2-ols was performed also through the decarboxylative coupling reaction of 4-hydroxy-4-methyl-2-pentynoic acid with aryl bromides, using a catalyst containing Pd(OAc2 in combination with SPhos or XPhos in the presence of tetra-n-butylammonium fluoride (TBAF as the base and THF as the solvent. Therefore, new efficient approaches to the synthesis of terminal acetylenes from widely available aryl bromides rather than expensive iodides and using 4 or propiolic acid rather than TMS-acetylene as inexpensive alkyne sources are described.

  2. Coupling Instrumented Experiments with Microstructure-based Simulations of Reactant Configuration Effects on Shock-Initiation of Reactions in Intermetallic-Forming Powder Mixtures

    Science.gov (United States)

    Thadhani, Naresh

    2013-06-01

    The shock-initiation of reactions in intermetallic-forming powder mixtures is dominated by the configuration of reactants, which is influenced by the intrinsic and extrinsic properties of constituents. Instrumented experiments coupled with microstructure-based simulations can be used to understand the meso-scale processes and effects of reactant configuration on the onset conditions for reaction initiation. Uniaxial-strain impact experiments are performed to monitor the input and propagated stress-wave profiles and to determine changes in compressibility and wave-velocity associated with powder densification and possible reaction, as a function of impact velocity and different reactant configurations such as size, shape, and distribution of constituent powders. Meso-scale computational simulations through discretely represented constituents with real and synthetically generated microstructures of reactants, imported into CTH simulations, are also used to qualitatively and quantitatively probe the local configuration changes and particle-level processes, following validation of macroscopic properties by correlations with experiments. The simulations reveal the dependence of the starting configuration of reactants on the heterogeneous nature of localized deformation and mixing with processes such as forced or turbulent flow, vortex formation, and dispersion of reactants, influencing the onset conditions for reaction initiation. Understanding of these processes as a function of the effects of starting reactant configuration, and correlating those with synthetically-generated microstructural constructs allows reverse design of reactive powder mixture systems for desired macro-scale performance. This presentation will present an overview of our experimental and modeling approach in understanding the mechanistic aspects of impact-initiation of reactions for design of reactive materials systems. Support provided by AFOSR, DTRA, and ONR.

  3. Remote Migratory Cross-Electrophile Coupling and Olefin Hydroarylation Reactions Enabled by in Situ Generation of NiH.

    Science.gov (United States)

    Chen, Fenglin; Chen, Ke; Zhang, Yao; He, Yuli; Wang, Yi-Ming; Zhu, Shaolin

    2017-10-04

    A highly efficient strategy for remote reductive cross-electrophile coupling has been developed through the ligand-controlled nickel migration/arylation. This general protocol allows the use of abundant and bench-stable alkyl bromides and aryl bromides for the synthesis of a wide range of structurally diverse 1,1-diarylalkanes in excellent yields and high regioselectivities under mild conditions. We also demonstrated that alkyl bromide could be replaced by the proposed olefin intermediate while using n-propyl bromide/Mn(0) as a potential hydride source.

  4. 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.

  5. Higher spin currents in the enhanced N=3 Kazama-Suzuki model

    Science.gov (United States)

    Ahn, Changhyun; Kim, Hyunsu

    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 deter-mined 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.

  6. Exploring possible reaction pathways for the o-atom transfer reactions to unsaturated substrates catalyzed by a [Ni-NO2] ↔ [Ni-NO] redox couple using DFT methods.

    Science.gov (United States)

    Tsipis, Athanassios C

    2017-07-15

    The (nitro)(N-methyldithiocarbamato)(trimethylphospane)nickel(II), [Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] complex catalyses efficiently the O-atom transfer reactions to CO and acetylene. Energetically feasible sequence of elementary steps involved in the catalytic cycle of the air oxidation of CO and acetylene are proposed promoted by the Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] ↔ Ni(NO 2 )(S 2 CNHMe)(PMe 3 ) redox couple using DFT methods both in vacuum and dichloromethane solutions. The catalytic air oxidation of HC≡CH involves formation of a five-member metallacycle intermediate, via a [3 + 2] cyclo-addition reaction of HC≡CH to the Ni-N = O moiety of the Ni(NO 2 )(S 2 CNHMe)(PMe 3 )] complex, followed by a β H-atom migration toward the C α carbon atom of the coordinated acetylene and release of the oxidation product (ketene). The geometric and energetic reaction profile for the reversible [Ni( κN1-NO 2 )(S 2 CNHMe)(PMe 3 )] ⇌ [Ni( κO,O2-ONO)(S 2 CNHMe)(PMe 3 )] linkage isomerization has also been modeled by DFT calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  7. Use of stable isotope dimethyl labeling coupled to selected reaction monitoring to enhance throughput by multiplexing relative quantitation of targeted proteins.

    Science.gov (United States)

    Aye, Thin Thin; Low, Teck Yew; Bjørlykke, Yngvild; Barsnes, Harald; Heck, Albert J R; Berven, Frode S

    2012-06-05

    In this manuscript, we present a proof-of-concept study for targeted relative protein quantitation workflow using chemical labeling in the form of dimethylation, coupled with selected reaction monitoring (dimethyl-SRM). We first demonstrate close to complete isotope incorporation for all peptides tested. The accuracy, reproducibility, and linear dynamic range of quantitation are further assessed based on known ratios of nonhuman standard proteins spiked into human cerebrospinal fluid (CSF) as a model complex matrix. Quantitation reproducibility below 20% (CV proteins. An error of less than 15% was observed when measuring the abundance of 44 out of 45 major human plasma proteins. Dimethyl-SRM was further examined by comparing the relative quantitation of eight proteins in human CSF with the relative quantitation obtained using synthetic heavy peptides coupled to stable isotope dilution-SRM (SID-SRM). Comparison between the two methods reveals that the correlation between dimethyl-SRM and SID-SRM is within 0.3-33% variation, demonstrating the accuracy of relative quantitation using dimethyl-SRM. Dimethyl labeling coupled with SRM provides a fast, convenient, and cost-effective alternative for relative quantitation of a large number of candidate proteins/peptides.

  8. Continuous monitoring of restriction endonuclease cleavage activity by universal molecular beacon light quenching coupled with real-time polymerase chain reaction.

    Science.gov (United States)

    Li, Xiaomin; Song, Chen; Zhao, Meiping; Li, Yuanzong

    2008-10-01

    We describe a method for sensitive monitoring of restriction endonuclease kinetics and activity by use of a universal molecular beacon (U-MB) coupled with real-time polymerase chain reaction (PCR). The method is used to monitor the progress of DNA cleavage in a sealed reaction tube and offers more accurate and high-throughput detection. The template has a universal tail hybridized with the U-MB and the remaining sequence is complementary to one of the restriction endonuclease digestion products. The U-MB is replaced by the extension of digested product and the fluorescence quenches. With this concept, one universal fluorescence probe can be used in different enzyme analytical systems. In the work described here, homogenous assays were performed with the restriction endonucleases AluI, EcoRI, XhoI, and SacI at smoothly controlled temperature. Cleavage efficiencies were determined, and the potential applications of this method were discussed. Furthermore, the AluI and EcoRI cleavage reactions were monitored online at varying substrate concentrations at the molecular level, and K(m), V(max), and K(cat) values were calculated. The results suggest that U-MB monitoring of restriction endonuclease assays based on real-time PCR will be very useful for high-throughput, sensitive, and precise assays for enzyme activity screening and evolutionary biotechnology analysis.

  9. Construction of microbial platform for an energy-requiring bioprocess: practical 2'-deoxyribonucleoside production involving a C-C coupling reaction with high energy substrates.

    Science.gov (United States)

    Horinouchi, Nobuyuki; Sakai, Takafumi; Kawano, Takako; Matsumoto, Seiichiro; Sasaki, Mie; Hibi, Makoto; Shima, Jun; Shimizu, Sakayu; Ogawa, Jun

    2012-06-15

    Reproduction and sustainability are important for future society, and bioprocesses are one technology that can be used to realize these concepts. However, there is still limited variation in bioprocesses and there are several challenges, especially in the operation of energy-requiring bioprocesses. As an example of a microbial platform for an energy-requiring bioprocess, we established a process that efficiently and enzymatically synthesizes 2'-deoxyribonucleoside from glucose, acetaldehyde, and a nucleobase. This method consists of the coupling reactions of the reversible nucleoside degradation pathway and energy generation through the yeast glycolytic pathway. Using E. coli that co-express deoxyriboaldolase and phosphopentomutase, a high amount of 2'-deoxyribonucleoside was produced with efficient energy transfer under phosphate-limiting reaction conditions. Keeping the nucleobase concentration low and the mixture at a low reaction temperature increased the yield of 2'-deoxyribonucleoside relative to the amount of added nucleobase, indicating that energy was efficiently generated from glucose via the yeast glycolytic pathway under these reaction conditions. Using a one-pot reaction in which small amounts of adenine, adenosine, and acetone-dried yeast were fed into the reaction, 75 mM of 2'-deoxyinosine, the deaminated product of 2'-deoxyadenosine, was produced from glucose (600 mM), acetaldehyde (250 mM), adenine (70 mM), and adenosine (20 mM) with a high yield relative to the total base moiety input (83%). Moreover, a variety of natural dNSs were further synthesized by introducing a base-exchange reaction into the process. A critical common issue in energy-requiring bioprocess is fine control of phosphate concentration. We tried to resolve this problem, and provide the convenient recipe for establishment of energy-requiring bioprocesses. It is anticipated that the commercial demand for dNSs, which are primary metabolites that accumulate at very low levels in the

  10. New air-stable planar chiral ferrocenyl monophosphine ligands: Suzuki cross-coupling of aryl chlorides and bromides

    DEFF Research Database (Denmark)

    Jensen, Jakob Feldthusen; Johannsen, Mogens

    2003-01-01

    GraphicA novel class of planar chiral electron-rich monophosphine ligands has been developed. The modular design allows a short and efficient synthesis of an array of aryl-ferrocenyl derivatives carrying the donating bis(dicyclohexyl)phosphino moiety. These new ligands have successfully been...

  11. Best Proximity point for Z-contraction and Suzuki type Z-contraction mappings with an application to fractional calculus

    Directory of Open Access Journals (Sweden)

    Somayya Komal

    2016-10-01

    Full Text Available In this article, we introduced the best proximity point theorems for $\\mathcal{Z}$-contraction and Suzuki type $\\mathcal{Z}$-contraction in the setting of complete metric spaces. Also by the help of weak $P$-property and $P$-property, we proved existence and uniqueness of best proximity point. There is a simple example to show the validity of our results. Our results extended and unify many existing results in the literature. Moreover, an application to fractional order functional differential equation is discussed.

  12. Development and evaluation of materials for thermochemical heat storage based on the CaO/CaCO3 reaction couple

    Science.gov (United States)

    Sakellariou, Kyriaki G.; Tsongidis, Nikolaos I.; Karagiannakis, George; Konstandopoulos, Athanasios G.; Baciu, Diana; Charalambopoulou, Georgia; Steriotis, Theodore; Stubos, Athanasios; Arlt, Wolfgang

    2016-05-01

    The current work relates to the development of synthetic calcium oxide (CaO) based compositions as candidate materials for energy storage under a cyclic carbonation/decarbonation reaction scheme. Although under such a cyclic scheme the energy density of natural lime based CaO is high (˜ 3MJ/kg), the particular materials suffer from notable cycle-to-cycle deactivation. To this direction, pure CaO and CaO/Al2O3 composites have been prepared and preliminarily evaluated under the suggested cyclic carbonation/decarbonation scheme in the temperature range of 600-800°C. For the composite materials, Ca/Al molar ratios were in the range between 95/5 and 52/48 and upon calcination the formation of mixed Ca/Al phases was verified. The preliminary evaluation of materials studied was conducted under 3 carbonation/decarbonation cycles and the loss of activity for the case of natural CaO was obvious. Synthetic materials with superior stability/capture c.f. natural CaO were further subjected to multi-cyclic carbonation/decarbonation, via which the positive effect of alumina addition was made evident. Selected compositions exhibited adequately high CO2 capture capacity and stable performance during multi-cyclic operation. Moreover, this study contains preliminary experiments referring to proof-of-principle validation of a concept based on the utilization of a CaO-based honeycomb reactor/heat exchanger preliminary design. In particular, cordierite monolithic structures were coated with natural CaO and in total 11 cycles were conducted. Upon operation, clear signs of heat dissipation by the imposed flow in the duration of the exothermic reaction step were identified.

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

    KAUST Repository

    Minenkov, Yury

    2017-03-07

    In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) and DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange and association/dissociation reaction enthalpies involving ionic complexes of Li, Be, Na, Mg, Ca, Sr, Ba and Pb(ii). Two strategies were investigated: in the former, only valence electrons were included in the correlation treatment, giving rise to the computationally very efficient FC (frozen core) approach; in the latter, all non-ECP electrons were included in the correlation treatment, giving rise to the AE (all electron) approach. Apart from reactions involving Li and Be, the FC approach resulted in non-homogeneous performance. The FC approach leads to very small errors (<2 kcal mol-1) for some reactions of Na, Mg, Ca, Sr, Ba and Pb, while for a few reactions of Ca and Ba deviations up to 40 kcal mol-1 have been obtained. Large errors are both due to artificial mixing of the core (sub-valence) orbitals of metals and the valence orbitals of oxygen and halogens in the molecular orbitals treated as core, and due to neglecting core-core and core-valence correlation effects. These large errors are reduced to a few kcal mol-1 if the AE approach is used or the sub-valence orbitals of metals are included in the correlation treatment. On the technical side, the CCSD(T) and DLPNO-CCSD(T) results differ by a fraction of kcal mol-1, indicating the latter method as the perfect choice when the CPU efficiency is essential. For completely black-box applications, as requested in catalysis or thermochemical calculations, we recommend the DLPNO-CCSD(T) method with all electrons that are not covered by effective core potentials included in the correlation treatment and correlation-consistent polarized core valence basis sets of cc-pwCVQZ(-PP) quality.

  14. Redox zone II. Coupled modeling of groundwater flow, solute transport, chemical reactions and microbial processes in the Aespoe island

    Energy Technology Data Exchange (ETDEWEB)

    Samper, Javier; Molinero, Jorge; Changbing Yang; Guoxiang Zhang [Univ. Da Coruna (Spain)

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behaviour and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by Banwart et al. Later, Banwart presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by Molinero who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulphate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of Molinero and extends the preliminary microbial model of Zhang by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfaphe concentration, thus adding additional evidence for the possibility

  15. Coupled modeling of groundwater flow solute transport, chemical reactions and microbial processes in the 'SP' island

    Energy Technology Data Exchange (ETDEWEB)

    Samper, Javier; Molinero, Jorg; Changbing, Yang; Zhang, Guoxiang

    2003-12-01

    The Redox Zone Experiment was carried out at the Aespoe HRL in order to study the redox behavior and the hydrochemistry of an isolated vertical fracture zone disturbed by the excavation of an access tunnel. Overall results and interpretation of the Redox Zone Project were reported by /Banwart et al, 1995/. Later, /Banwart et al, 1999/ presented a summary of the hydrochemistry of the Redox Zone Experiment. Coupled groundwater flow and reactive transport models of this experiment were carried out by /Molinero, 2000/ who proposed a revised conceptual model for the hydrogeology of the Redox Zone Experiment which could explain simultaneously measured drawdown and salinity data. The numerical model was found useful to understand the natural system. Several conclusions were drawn about the redox conditions of recharge waters, cation exchange capacity of the fracture zone and the role of mineral phases such as pyrite, calcite, hematite and goethite. This model could reproduce the measured trends of dissolved species, except for bicarbonate and sulfate which are affected by microbially-mediated processes. In order to explore the role of microbial processes, a coupled numerical model has been constructed which accounts for water flow, reactive transport and microbial processes. The results of this model is presented in this report. This model accounts for groundwater flow and reactive transport in a manner similar to that of /Molinero, 2000/ and extends the preliminary microbial model of /Zhang, 2001/ by accounting for microbially-driven organic matter fermentation and organic matter oxidation. This updated microbial model considers simultaneously the fermentation of particulate organic matter by yeast and the oxidation of dissolved organic matter, a product of fermentation. Dissolved organic matter is produced by yeast and serves also as a substrate for iron-reducing bacteria. Model results reproduce the observed increase in bicarbonate and sulfate concentration, thus

  16. Graphene-oxide-supported CuAl and CoAl layered double hydroxides as enhanced catalysts for carbon-carbon coupling via Ullmann reaction

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Nesreen S. [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia); Menzel, Robert [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Bio Nano Consulting, The Gridiron Building, One Pancras Square, London N1C 4AG (United Kingdom); Wang, Yifan [Department of Chemistry, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Garcia-Gallastegui, Ainara [Bio Nano Consulting, The Gridiron Building, One Pancras Square, London N1C 4AG (United Kingdom); Bawaked, Salem M.; Obaid, Abdullah Y.; Basahel, Sulaiman N. [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia); Mokhtar, Mohamed, E-mail: mmokhtar2000@yahoo.com [Department of Chemistry, Faculty of Science, King Abdulaziz University (Saudi Arabia); Surface Chemistry and Catalytic Studies Group, King Abdulaziz University (Saudi Arabia)

    2017-02-15

    Two efficient catalyst based on CuAl and CoAl layered double hydroxides (LDHs) supported on graphene oxide (GO) for the carbon-carbon coupling (Classic Ullmann Homocoupling Reaction) are reported. The pure and hybrid materials were synthesised by direct precipitation of the LDH nanoparticles onto GO, followed by a chemical, structural and physical characterisation by electron microscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), surface area measurements and X-ray photoelectron spectroscopy (XPS). The GO-supported and unsupported CuAl-LDH and CoAl-LDH hybrids were tested over the Classic Ullman Homocoupling Reaction of iodobenzene. In the current study CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary and two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH. - Graphical abstract: CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) at very short reaction times (25 min). GO provides a light-weight, charge complementary, two-dimensional material that interacts effectively with the 2D LDHs, in turn enhancing the stability of LDH. - Highlights: • CuAl LDH/GO and CoAl LDH/GO hybrid materials with different LDH compositions were prepared. • Hybrids were fully characterised and their catalytic efficiency over the Classic Ullman Reaction was studied. • CuAl- and CoAl-LDHs have shown excellent yields (91% and 98%, respectively) in 25 min reaction times. • GO provides a light-weight, charge complementary, two-dimensional material that interacts effectively with the 2D LDHs. • After 5 re-use cycles, the catalytic activity of the LDH/GO hybrid is up to 2 times higher than for the unsupported LDH.

  17. The application of inductively coupled plasma dynamic reaction cell mass spectrometry for measurement of selenium isotopes, isotope ratios and chromatographic detection of selenoamino acids

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt

    2000-01-01

    ratios was close to the theoretical values for selenium concentrations at 1 and 10 ng ml(-1). The accuracy of the isotope ratios, however, was improved by correcting the count rate of all selenium isotopes equivalent to the formation of SeH at 9.6 +/- 0.5% one mass unit above the selenium isotopes....... A linear relationship (r mass from the Se-80 reference isotope. This indicated that the error was caused by mass bias. The slope of the curve at -3.0% error per mass unit can be used for correction of the measured......Inductively coupled plasma dynamic reaction cell mass spectrometry (ICP-DRC-MS) was characterised for the detection of the six naturally occurring selenium isotopes. The potentially interfering argon dimers at the selenium masses m/z 74, 76, 78 and 80 were reduced in intensity by approximately five...

  18. Synthesis of palladium nanoparticles with leaf extract of Chrysophyllum cainito (Star apple) and their applications as efficient catalyst for C-C coupling and reduction reactions

    Science.gov (United States)

    Majumdar, Rakhi; Tantayanon, Supawan; Bag, Braja Gopal

    2017-10-01

    A simple green chemical method for the one-step synthesis of palladium nanoparticles (PdNPs) has been described by reducing palladium (II) chloride with the leaf extract of Chrysophyllum cainito in aqueous medium. The synthesis of the palladium nanoparticles completed within 2-3 h at room temperature, whereas on heat treatment (70-80 °C), the synthesis of colloidal PdNPs completed almost instantly. The stabilized PdNPs have been characterized in detail by spectroscopic, electron microscopic and light scattering measurements. The synthesized PdNPs have been utilized as a green catalyst for C-C coupling reactions under aerobic and phosphine-free conditions in aqueous medium. In addition, the synthesized PdNPs have also been utilized as a catalyst for a very efficient sodium borohydride reduction of 3- and 4-nitrophenols. The synthesized PdNPs can retain their catalytic activity for several months.

  19. Determination of ultratrace levels of dissolved metals in seawater by reaction cell inductively coupled plasma mass spectrometry after ammonia induced magnesium hydroxide coprecipitation.

    Science.gov (United States)

    Ardini, Francisco; Magi, Emanuele; Grotti, Marco

    2011-11-07

    A method for the determination of ultratrace amounts of Cr, Fe, Mn, Pb and Zn in seawater has been developed. It combined the low-blank magnesium hydroxide coprecipitation procedure with quadrupole inductively coupled plasma mass spectrometry and used the dynamic reaction cell technique to resolve the polyatomic interferences arising from the residual matrix, the solvent and plasma gases. Detection limits (3σ(B), n=10) for Cr, Fe, Mn, Pb and Zn were 0.02, 0.10, 0.01, 0.002 and 0.19 nM, respectively, using 50 mL of seawater sample. The accuracy of the analytical procedure was verified by the analysis of the seawater reference materials CASS-4, NASS-5, SAFe D2 and SAFe S. The analytical precision ranged from 3% to 16% (n=6), with a sample throughput of about 6 samples h(-1). Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Architecture of β-Graphdiyne-Containing Thin Film Using Modified Glaser-Hay Coupling Reaction for Enhanced Photocatalytic Property of TiO2.

    Science.gov (United States)

    Li, Jiaqiang; Xie, Ziqian; Xiong, Yan; Li, Zhenzhu; Huang, Qunxing; Zhang, Shuqing; Zhou, Jingyuan; Liu, Rong; Gao, Xin; Chen, Changguo; Tong, Lianming; Zhang, Jin; Liu, Zhongfan

    2017-05-01

    β-Graphdiyne (β-GDY) is a member of 2D graphyne family with zero band gap, and is a promising material with potential applications in energy storage, organic electronics, etc. However, the synthesis of β-GDY has not been realized yet, and the measurement of its intrinsic properties remains elusive. In this work, β-GDY-containing thin film is successfully synthesized on copper foil using modified Glaser-Hay coupling reaction with tetraethynylethene as precursor. The as-grown carbon film has a smooth surface and is continuous and uniform. Electrical measurements reveal the conductivity of 3.47 × 10(-6) S m(-1) and the work function of 5.22 eV. TiO2 @β-GDY nanocomposite is then prepared and presented with an enhancement of photocatalytic ability compared to pure TiO2 . © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Sensitive and Quantitative Detection of C-Reaction Protein Based on Immunofluorescent Nanospheres Coupled with Lateral Flow Test Strip.

    Science.gov (United States)

    Hu, Jiao; Zhang, Zhi-Ling; Wen, Cong-Ying; Tang, Man; Wu, Ling-Ling; Liu, Cui; Zhu, Lian; Pang, Dai-Wen

    2016-06-21

    Sensitive and quantitative detection of protein biomarkers with a point-of-care (POC) assay is significant for early diagnosis, treatment, and prognosis of diseases. In this paper, a quantitative lateral flow assay with high sensitivity for protein biomarkers was established by utilizing fluorescent nanospheres (FNs) as reporters. Each fluorescent nanosphere (FN) contains 332 ± 8 CdSe/ZnS quantum dots (QDs), leading to its superstrong luminescence, 380-fold higher than that of one QD. Then a detection limit of 27.8 pM C-reaction protein (CRP) could be achieved with an immunofluorescent nanosphere (IFN)-based lateral flow test strip. The assay was 257-fold more sensitive than that with a conventional Au-based lateral flow test strip for CRP detection. Besides, the fluorescence intensity of FNs and bioactivity of IFNs were stable during 6 months of storage. Hence, the assay owns good reproducibility (intra-assay variability of 5.3% and interassay variability of 6.6%). Furthermore, other cancer biomarkers (PSA, CEA, AFP) showed negative results by this method, validating the excellent specificity of the method. Then the assay was successfully applied to quantitatively detect CRP in peripheral blood plasma samples from lung cancer and breast cancer patients, and healthy people, facilitating the diagnosis of lung cancer. It holds a good prospect of POC protein biomarker detection.

  2. Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Ruth; Bhaumik, Asim [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Dutta, Saikat [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2014-11-01

    A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state {sup 13}C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N{sub 2} sorption, HR-TEM, and NH{sub 3} temperature programmed desorption-thermal conductivity detector (TPD-TCD) analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, β-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H)-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

  3. Carboxylic acid-grafted mesoporous material and its high catalytic activity in one-pot three-component coupling reaction

    Directory of Open Access Journals (Sweden)

    Ruth Gomes

    2014-11-01

    Full Text Available A new carboxylic acid functionalized mesoporous organic polymer has been synthesized via in situ radical polymerization of divinylbenzene and acrylic acid using a mesoporous silica as a seed during the polymerization process under solvothermal conditions. The mesoporous material MPDVAA-1 has been thoroughly characterized employing powder XRD, solid state 13C cross polarization magic angle spinning-nuclear magnetic resonance, FT-IR spectroscopy, N2 sorption, HR-TEM, and NH3 temperature programmed desorption-thermal conductivity detector (TPD-TCD analysis to understand its porosity, chemical environment, bonding, and surface properties. The mesoporous polymer was used as a catalyst for a three comp onent Biginelli condensation between various aldehydes, β-keto esters, and urea/thioureas to give 3,4-dihydropyrimidine-2(1H-ones. The reactions were carried out under conventional heating as well as solvent-free microwave irradiation of solid components, and in both the cases, the mesoporous polymer MPDVAA-1 proved to be a powerful, robust, and reusable catalyst with high catalytic efficiency.

  4. Optimization of an Efficient and Sustainable Sonogashira Cross-Coupling Protocol

    KAUST Repository

    Walter, Philipp E.

    2012-12-01

    Cross coupling reactions are a well-established tool in modern organic synthesis and play a crucial role in the synthesis of a high number of organic compounds. Their importance is highlighted by the Nobel Prize in chemistry to Suzuki, Heck and Negishi in 2010. The increasing importance of sustainability requirements in chemical production has furthermore promoted the development of cross-coupling protocols that comply with the principles of “Green Chemistry”1. The Sonogashira reaction is today the most versatile and powerful way to generate aryl alkynes, a moiety recurring in many pharmaceutical and natural products. Despite many improvements to the original reaction, reports on generally applicable protocols that work under sustainable conditions are scarce. Our group recently reported an efficient protocol for a copperfree Sonogashira cross-coupling at low temperature, in aqueous medium and with no addition of organic solvents or additives2. The goal of this work was to further investigate the effects of different reaction parameters on the catalytic activity in order to optimize the protocol. Limitations of the protocol were tested in respect to reaction temperature, heating method, atmosphere, base type and amount, catalyst loading, reaction time and work up procedure. The reaction worked successfully under air and results were not affected by the presence of oxygen in the water phase. Among a variety of bases tested, triethylamine was confirmed to give the best results and its required excess could be reduced from nine to four equivalents. Catalyst loading could also be reduced by up to 90%: Good to near quantitative yields for a broad range of substrates were achieved using a catalyst concentration of 0.25mol% and 5 eq of Et3N at 50°C while more reactive substrates could be coupled with a catalyst concentration as low as 0.025mol%. Filtration experiments showed the possibility of a simplified work up procedure and a protocol completely free of organic

  5. Study of W boson polarisations and Triple Gauge boson Couplings in the reaction $e^{+}e^{-} \\to W^{+}W^{-}$ at LEP 2

    CERN Document Server

    Abdallah, J.; Adam, W.; Adzic, P.; Albrecht, T.; Alemany-Fernandez, R.; Allmendinger, T.; Allport, P.P.; Amaldi, U.; Amapane, N.; Amato, Sandra F.; Anashkin, E.; Andreazza, A.; Andringa, Sofia; Anjos, N.; Antilogus, Pierre; Apel, W-D.; Arnoud, Y.; Ask, S.; Asman, B.; Augustin, Jean-Eudes; Augustinus, A.; Baillon, P.; Ballestrero, A.; Bambade, P.; Barbier, R.; Bardin, D.; Barker, G.J.; Baroncelli, Antonio; Battaglia, Marco; Baubillier, M.; Becks, K-H.; Begalli, M.; Behrmann, A.; Ben-Haim, Eli; Benekos, N.; Benvenuti, A.; Berat, C.; Berggren, Mikael; Bertrand, D.; Besancon, Marc; Besson, N.; Bloch, Daniel; Blom, M.; Bluj, Michal; Bonesini, Maurizio; Boonekamp, M.; Booth, P.S.L.; Borisov, G.; Botner, Olga; Bouquet, B.; Bowcock, T.J.V.; Boyko, I.; Bracko, Marko; Brenner, R.; Brodet, E.; Bruckman, P.; Brunet, J.M.; Buschbeck, B.; Buschmann, P.; Calvi, M.; Camporesi, Tiziano; Canale, V.; Carena, F.; Castro, Nuno Filipe; Cavallo, F.; Chapkin, M.; Charpentier, Ph.; Checchia, Paolo; Chierici, R.; Chliapnikov, P.; Chudoba, J.; Chung, Suh-Urk; Cieslik, K.; Collins, P.; Contri, Roberto; Cosme, G.; Cossutti, Fabio; Costa, M.J.; Crennell, D.; Cuevas, Javier; D'Hondt, J.; da Silva, T.; Da Silva, W.; Della Ricca, Giuseppe; De Angelis, Alessandro; De Boer, W.; De Clercq, C.; De Lotto, Barbara; De Maria, N.; De Min, A.; de Paula, L.; Di Ciaccio, L.; Di Simone, A.; Doroba, K.; Eigen, G.; Ekelof, Tord; Ellert, Mattias; Elsing, M.; Espirito Santo, Maria Catarina; Fanourakis, George K.; Feindt, Michael; Fernandez, J.; Ferrer, Antonio; Ferro, F.; Flagmeyer, U.; Foeth, H.; Fokitis, E.; Fulda-Quenzer, F.; Fuster, J.; Gandelman, Miriam; Garcia, C.; Gavillet, Philippe; Gazis, Evangelos; Gomez-Ceballos, G.; Goncalves, P.; Graziani, E.; Grosdidier, G.; Grzelak, K.; Guy, J.; Haag, C.; Hallgren, A.; Hamacher, Klaus; Hamilton, K.; Haug, S.; Hauler, F.; Hedberg, Vincent; Hennecke, M.; Herr, H.; Hoffman, J.; Holmgren, S-O.; Holt, P.J.; Houlden, M.A.; Jackson, John Neil; Jarlskog, Goran; Jarry, P.; Jeans, D.; Johansson, E.K.; Jonsson, P.; Joram, C.; Jungermann, L.; Kapusta, Frederic; Katsanevas, S.; Katsoufis, E.; Kernel, Gabrijel; Kerzel, U.; King, B.T.; Kjaer, N.J.; Kluit, Peter; Kokkinias, P.; Kourkoumelis, C.; Kouznetsov, O.; Krumstein, Z.; Kucharczyk, M.; Lamsa, J.; Leder, G.; Ledroit, F.; Leinonen, L.; Leitner, R.; Lemonne, Jacques; Lepeltier, V.; Lesiak, T.; Liebig, W.; Liko, D.; Lipniacka, A.; Lopes, J.H.; Lopez, J.M.; Loukas, D.; Lutz, Pierre; Lyons, Louis; MacNaughton, J.; Malek, A.; Maltezos, S.; Mandl, F.; Marco, J.; Marco, R.; Marechal, B.; Margoni, M.; Marin, J-C.; Mariotti, C.; Markou, A.; Martinez-Rivero, C.; Masik, J.; Mastroyiannopoulos, N.; Matorras, F.; Matteuzzi, C.; Mazzucato, F.; Mazzucato, M.; Nulty, R.Mc; Meroni, C.; Migliore, E.; Mitaroff, W.; Mjoernmark, U.; Moa, T.; Moch, M.; Monge, R.; Montenegro, J.; Moraes, D.; Moreno, S.; Morettini, P.; Muller, Ulrich; Muenich, K.; Mulders, M.; Mundim Filho, Luiz Martins; Murray, W.; Muryn, B.; Myatt, G.; Myklebust, T.; Nassiakou, M.; Navarria, F.; Nawrocki, K.; Nicolaidou, R.; Oblakowska-Mucha, A.; Obraztsov, V.; Olshevski, A.; Onofre, A.; Orava, R.; Osterberg, K.; Ouraou, A.; Oyanguren, A.; Paganoni, M.; Paiano, S.; Palacios, J.P.; Palka, Henryk; Papadopoulou, Th.D.; Pape, L.; Parkes, C.; Parodi, F.; Parzefall, U.; Passeri, A.; Passon, O.; Peralta, L.; Perepelitsa, V.; Perrotta, Andrea; Petrolini, Alessandro; Piedra, Jonatan; Pieri, L.; Pierre, Francois; Pimenta, M.; Piotto, E.; Poireau, V.; Pol, M.E.; Polok, G.; Pozdniakov, V.; Pukhaeva, N.; Pullia, A.; Radojicic, D.; Rames, J.; Read, A.; Rebecchi, P.; Rehn, J.; Reid, D.; Reinhardt, R.; Renton, Peter; Richard, F.; Ridky, Jan; Rivero, M.; Rodriguez, D.; Romero, A.; Ronchese, Paolo; Roudeau, P.; Rovelli, T.; Ruhlmann, Vanina; Ryabtchikov, D.; Sadovsky, A.; Salmi, L.; Salt, J.; Sander, C.; Savoy-Navarro, A.; Schwickerath, U.; Segar, A.; Sekulin, R.; Siebel, Martin; Sisakian, A.; Smadja, G.; Smirnova, O.; Sokolov, Andrei Valerevich; Sopczak, A.; Sosnowski, R.; Spassov, T.; Stanitzki, M.; Stocchi, A.; Strauss, J.; Stugu, B.; Szczekowski, M.; Szeptycka, M.; Szumlak, T.; Tabarelli de Fatis, T.; Taffard, A.C.; Tegenfeldt, F.; Timmermans, Jan; Tkatchev, L.; Tobin, M.; Todorovova, S.; Tome, B.; Tonazzo, A.; Tortosa, P.; Travnicek, Petr; Treille, D.; Tristram, G.; Trochimczuk, M.; Troncon, Clara; Turluer, M-L.; Tyapkin, I.A.; Tyapkin, P.; Tzamarias, S.; Uvarov, V.; Valenti, Giovanni; Van Dam, P.; Van Eldik, J.; Van Lysebetten, A.; van Remortel, N.; Van Vulpen, I.; Vegni, G.; Veloso, Filipe; Venus, W.; Verdier, Patrice; Verzi, V.; Vilanova, D.; Vitale, Lorenzo; Vrba, V.; Wahlen, H.; Washbrook, A.J.; Weiser, C.; Wicke, D.; Wickens, J.; Wilkinson, G.; Winter, M.; Witek, M.; Yushchenko, O.; Zalewska, A.; Zalewski, P.; Zavrtanik, Danilo; Zhuravlov, V.; Zimine, N.I.; Zintchenko, Alexandre

    2008-01-01

    A determination of the single W Spin Density Matrix (SDM) elements in the reaction e+e- -> W+W- -> l nu q qbar (l=e/mu) is reported at centre-of-mass energies between 189 and 209 GeV. The data sample used corresponds to an integrated luminosity of 520 pb^{-1} taken by DELPHI between 1998 and 2000. The single W SDM elements, rho_{tau tau'}^{W+-} (tau,tau' = +/-1 or 0), are determined as a function of the W- production angle with respect to the e- beam direction and are obtained from measurements of the W decay products by the application of suitable projection operators, Lambda_{tau tau'}, which assume the V-A coupling of the W boson to fermions. The measured SDM elements are used to obtain the fraction of longitudinally polarised Ws, with the result: sigma_L/sigma_tot = 24.9 +/- 4.5(stat) +/- 2.2(syst) % at a mean energy of 198 GeV. The SDM elements are also used to determine the Triple Gauge Couplings Delta g_1^Z, Delta kappa_gamma, lambda_gamma and g_4^Z, ~kappa_Z and ~lambda_Z. For the CP-violating couplin...

  6. Multiplex-Polymerase Chain Reaction for Detecting Microdeletions in The Azoospermia Factor Region of Y Chromosome in Iranian Couples with Non-Obstructive Infertility and Recurrent Pregnancy Loss

    Directory of Open Access Journals (Sweden)

    Afsaneh Mojtabanezhad Shariatpanahi

    2017-10-01

    Full Text Available Background Approximately 15% of couples are infertile with the male factor explaining approximately 50% of the cases. One of the main genetic factors playing a role in male infertility is Y chromosomal microdeletions within the proximal long arm of the Y chromosome (Yq11, named the azoospermia factor (AZF region. Recent studies have shown there is a potential connection between deletions of the AZF region and recurrent pregnancy loss (RPL. The aim of this study is to examine this association by characterizing AZF microdeletions in two infertile groups: in men with non-obstructive infertility and in men with wives displaying RPL. Materials and Methods In this is a case-control study, genomic DNA was extracted from 80 male samples including 40 non-obstructive infertile men, 20 males from couples with RPL and 20 fertile males as controls. Multiplex polymerase chain reaction was used to amplify 19 sequence tagged sites (STS to detect AZF microdeletions. Differences between the case and control groups were evaluated by two-tailed unpaired t test. P<0.05 were considered statistically significant. Results Only one subject was detected to have Y chromosome microdeletions in SY254, SY157 and SY255 among the 40 men with non-obstructive infertility. No microdeletion was detected in the males with wives displaying RPL and in 20 control males. Y chromosome microdeletion was neither significantly associated with non-obstructive infertility (P=0.48 nor with recurrent pregnancy loss. Conclusion Performing Testing for Y chromosome microdeletions in men with non-obstructive infertility and couples with RPL remains inconclusive in this study.

  7. The effect of pH on coupled mass transfer and sol-gel reaction in a two-phase system.

    Science.gov (United States)

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

    2007-11-01

    The coupled mass transfer and chemical reactions of a gel-forming compound in a two-phase system were recently analyzed in detail [Castelijns et al. J. Appl. Phys. 2006, 100, 024916]. In this successive work, the gel-forming chemical tetramethylorthosilicate (TMOS) was dissolved in a mineral oil and placed together with heavy water (D2O) in small cylinders. The transfer of TMOS from the oleic phase to the aqueous phase was monitored through nuclear magnetic resonance (NMR) relaxation time measurements of hydrogen in the oleic phase. The rate of gelation was measured through NMR relaxation time measurements of deuterium in the aqueous phase. The temperature, the initial concentration of TMOS, and the type of buffer in the aqueous phase were varied in the experiments. The mass transfer is driven by the rate of hydrolysis, which increases with temperature. The hydrolysis rate is the lowest at a neutral pH and is the highest at a low pH. In the aqueous phase, a sharp decrease in the transverse relaxation time (T2) of 2H is observed, which is attributed to the gel reaction. The plateau in T2 indicates the gel transition point. The gel rates increase with increasing temperature and increasing concentration, and are the highest at a neutral pH.

  8. Effect of a weak magnetic field on the Mizoroki–Heck coupling reaction in the presence of wicker-like palladium-poly(N-vinylpyrrolidone)-iron nanocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Rafiee, Ezzat, E-mail: ezzat_rafiee@yahoo.com [Department of Inorganic Chemistry, Faculty of Chemistry, Razi University, Kermanshah 67149 (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, Razi University, Kermanshah 67149 (Iran, Islamic Republic of); Joshaghani, Mohammad [Department of Inorganic Chemistry, Faculty of Chemistry, Razi University, Kermanshah 67149 (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, Razi University, Kermanshah 67149 (Iran, Islamic Republic of); Abadi, Parvaneh Ghaderi-Shekhi [Institute of Nano Science and Nano Technology, Razi University, Kermanshah 67149 (Iran, Islamic Republic of)

    2016-06-15

    The wicker-like Pd-PVP-Fe (palladium-poly(N-vinylpyrrolidone)-iron) was synthesized by the external magnetic field (EMF). The Pd-based catalyst with nano and the face-centered cubic (fcc) structure was obtained at room temperature without using any additive. The resulting composite was characterized. The results show that EMF has a great influence on morphology, particle size, and crystalline structure of the Pd-PVP-Fe composite. The resulting composite (Pd-PVP-Fe), was found to be an effective catalyst for the Mizoroki–Heck reaction while is exposed to EMF with the intensity at 486 µT. The reused catalyst for at least five repeating cycles, shows excellent activity. - Highlights: • The wicker-like Pd-PVP-Fe nanocatalyst was synthesized via external magnetic field. • The resulting catalyst composite was characterized. • The C–C coupling reaction was carried out at magnetic field and room temperature. • Magnetic field affects on the morphology and size of the catalyst. • The catalyst could be reused without significant degradation in activity.

  9. Pd nanoparticles deposited on poly(lactic acid) grafted carbon nanotubes: synthesis, characterization and application in Heck C-C coupling reaction.

    Science.gov (United States)

    Neelgund, Gururaj M; Oki, Aderemi

    2011-05-31

    Herein we described the synthesis of a novel f-CNTs-Pd nanocatalyst by covalent grafting of poly(lactic acid) (PLA) onto carbon nanotubes (CNTs) and subsequent deposition of Pd nanoparticles. Prior to grafting of PLA, CNTs were oxidized with a mixture of HNO(3)/H(2)SO(4) and successively activated with thionyl chloride. The PLA grafted CNTs (f-CNTs) were then used as platform for in-situ deposition of Pd nanoparticles. The formation of f-CNTs-Pd nanocatalyst was analyzed by UV-vis, FTIR and Raman spectroscopy, powder XRD, energy dispersive spectroscopy and thermogravimetric analysis. The morphologies of the nanocatalyst were characterized using scanning and transmission electron microscopes. The f-CNTs stabilized Pd nanoparticles are found to be more effective in the promotion of Heck cross-coupling reaction between aryl halides and n-butyl acrylate. The f-CNTs-Pd nanocatalyst was regenerated for three cycles of reaction without any significant loss in its activity.

  10. New insights into the nonadiabatic state population dynamics of model proton-coupled electron transfer reactions from the mixed quantum-classical Liouville approach

    Energy Technology Data Exchange (ETDEWEB)

    Shakib, Farnaz A.; Hanna, Gabriel, E-mail: gabriel.hanna@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada)

    2016-01-14

    In a previous study [F. A. Shakib and G. Hanna, J. Chem. Phys. 141, 044122 (2014)], we investigated a model proton-coupled electron transfer (PCET) reaction via the mixed quantum-classical Liouville (MQCL) approach and found that the trajectories spend the majority of their time on the mean of two coherently coupled adiabatic potential energy surfaces. This suggested a need for mean surface evolution to accurately simulate observables related to ultrafast PCET processes. In this study, we simulate the time-dependent populations of the three lowest adiabatic states in the ET-PT (i.e., electron transfer preceding proton transfer) version of the same PCET model via the MQCL approach and compare them to the exact quantum results and those obtained via the fewest switches surface hopping (FSSH) approach. We find that the MQCL population profiles are in good agreement with the exact quantum results and show a significant improvement over the FSSH results. All of the mean surfaces are shown to play a direct role in the dynamics of the state populations. Interestingly, our results indicate that the population transfer to the second-excited state can be mediated by dynamics on the mean of the ground and second-excited state surfaces, as part of a sequence of nonadiabatic transitions that bypasses the first-excited state surface altogether. This is made possible through nonadiabatic transitions between different mean surfaces, which is the manifestation of coherence transfer in MQCL dynamics. We also investigate the effect of the strength of the coupling between the proton/electron and the solvent coordinate on the state population dynamics. Drastic changes in the population dynamics are observed, which can be understood in terms of the changes in the potential energy surfaces and the nonadiabatic couplings. Finally, we investigate the state population dynamics in the PT-ET (i.e., proton transfer preceding electron transfer) and concerted versions of the model. The PT

  11. KO(t)Bu-Mediated, Three-Component Coupling Reaction of Indoles, [60]Fullerene, and Haloalkanes: One-Pot, Transition-Metal-Free Synthesis of Various 1,4-(3-Indole)(organo)[60]fullerenes.

    Science.gov (United States)

    Li, Fei; Wang, Lianghui; Wang, Junjie; Peng, Dan; Zhao, Yuqi; Li, Shengli; Zhou, Hongping; Wu, Jieying; Tian, Xiaohe; Tian, Yupeng

    2017-03-03

    The KO(t)Bu-mediated three-component coupling reaction of indoles, [60]fullerene, and haloalkane has been developed as a practical and efficient protocol for the one-pot synthesis of various 1,4-(3-indole)(organo)[60]fullerenes. The reaction exhibits high regioselectivity at the 3-position of indoles and the 1,4-position on the [60]fullerene core. Furthermore, this methodology features excellent functional group tolerance, such as chloro, ester, cyano, and nitro on indole.

  12. Long-Gradient Separations Coupled with Selected Reaction Monitoring for Highly Sensitive, Large Scale Targeted Protein Quantification in a Single Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Tujin; Fillmore, Thomas L.; Gao, Yuqian; Zhao, Rui; He, Jintang; Schepmoes, Athena A.; Nicora, Carrie D.; Wu, Chaochao; Chambers, Justin L.; Moore, Ronald J.; Kagan, Jacob; Srivastava, Sudhir; Liu, Alvin Y.; Rodland, Karin D.; Liu, Tao; Camp, David G.; Smith, Richard D.; Qian, Weijun

    2013-10-01

    Long-gradient separations coupled to tandem MS were recently demonstrated to provide a deep proteome coverage for global proteomics; however, such long-gradient separations have not been explored for targeted proteomics. Herein, we investigate the potential performance of the long-gradient separations coupled with selected reaction monitoring (LG-SRM) for targeted protein quantification. Direct comparison of LG-SRM (5 h gradient) and conventional LC-SRM (45 min gradient) showed that the long-gradient separations significantly reduced background interference levels and provided an 8- to 100-fold improvement in LOQ for target proteins in human female serum. Based on at least one surrogate peptide per protein, an LOQ of 10 ng/mL was achieved for the two spiked proteins in non-depleted human serum. The LG-SRM detection of seven out of eight endogenous plasma proteins expressed at ng/mL or sub-ng/mL levels in clinical patient sera was also demonstrated. A correlation coefficient of >0.99 was observed for the results of LG-SRM and ELISA measurements for prostate-specific antigen (PSA) in selected patient sera. Further enhancement of LG-SRM sensitivity was achieved by applying front-end IgY14 immunoaffinity depletion. Besides improved sensitivity, LG-SRM offers at least 3 times higher multiplexing capacity than conventional LC-SRM due to ~3-fold increase in average peak widths for a 300-min gradient compared to a 45-min gradient. Therefore, LG-SRM holds great potential for bridging the gap between global and targeted proteomics due to its advantages in both sensitivity and multiplexing capacity.

  13. Determination of Cd, Cr, Hg and Pb in plastics from waste electrical and electronic equipment by inductively coupled plasma mass spectrometry with collision-reaction interface technology

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Mirian C. [Grupo de Espectrometria Atomica, Institute of Chemistry, University of Campinas, P.O. Box 6154, 13083-970 Campinas, SP (Brazil); Nobrega, Joaquim A. [Grupo de Analise Instrumental Aplicada, Departamento de Quimica, Universidade Federal de Sao Carlos, Sao Carlos, SP (Brazil); Cadore, Solange, E-mail: cadore@iqm.unicamp.br [Grupo de Espectrometria Atomica, Institute of Chemistry, University of Campinas, P.O. Box 6154, 13083-970 Campinas, SP (Brazil)

    2011-06-15

    Highlights: {yields} New procedures for determination of Cd, Cr, Hg and Pb in WEEE are required considering both recent legislation and instrumentation. {yields} It is shown here how an inductively coupled plasma mass spectrometer with a collision-reaction interface can be used for this analytical task. {yields} Experimental conditions for microwave-assisted sample digestion followed by ICP-MS measurements are fully described and discussed. - Abstract: A procedure based on the use of a quadrupole inductively coupled plasma-mass spectrometer equipped with a collision-reaction interface (CRI) for control of spectral overlap interferences was developed for simultaneous determination of Cd, Cr, Hg, and Pb in plastics from waste electrical and electronic equipment (WEEE). The injection of H{sub 2} and He (80 and 60 mL min{sup -1}, respectively) into the sampled plasma, colliding and reacting with potentially interfering polyatomic ions, allows interference-free determination of chromium via its isotopes {sup 52}Cr and {sup 53}Cr that are freed from overlap due to the occurrence of {sup 40}Ar{sup 12}C{sup +}, {sup 40}Ar{sup 12}C{sup 1}H{sup +}, {sup 36}S{sup 16}O{sup +} or {sup 1}H{sup 36}S{sup 16}O{sup +}. Cadmium, Hg and Pb were directly determined via their isotopes {sup 110}Cd, {sup 111}Cd, {sup 112}Cd, {sup 199}Hg, {sup 200}Hg, {sup 201}Hg, {sup 202}Hg, {sup 206}Pb, {sup 207}Pb, and {sup 208}Pb, without using CRI. The CRI can be quickly activated or deactivated before each analyte measurement. Limits of detection for {sup 52}Cr were 0.04 or 0.14 {mu}g L{sup -1} with He or H{sub 2} injected in CRI. Cadmium and Pb have LODs between 0.02 and 0.08 {mu}g L{sup -1} and Hg had 0.93-0.98 {mu}g L{sup -1}, without using CRI. Analyte concentrations for samples varied from 16 to 43, 1 to 11, 4 to 12, and 5 to 13 mg kg{sup -1} for Cr, Cd, Hg and Pb, respectively.

  14. Exploiting dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) for sequential determination of trace elements in blood using a dilute-and-shoot procedure

    Energy Technology Data Exchange (ETDEWEB)

    Lemos Batista, Bruno; Lisboa Rodrigues, Jairo; Andrade Nunes, Juliana; Oliveira Souza, Vanessa Cristina de [Departamento de Analises Clinicas, Toxicologicas e Bromatologicas, Faculdade de Ciencias Farmaceuticas de Ribeirao Preto - FCFRP - USP - Avenida do Cafe, s/n, Monte Alegre, 14040-903 Ribeirao Preto, SP (Brazil); Barbosa, Fernando, E-mail: fbarbosa@fcfrp.usp.br [Departamento de Analises Clinicas, Toxicologicas e Bromatologicas, Faculdade de Ciencias Farmaceuticas de Ribeirao Preto - FCFRP - USP - Avenida do Cafe, s/n, Monte Alegre, 14040-903 Ribeirao Preto, SP (Brazil)

    2009-04-20

    Inductively coupled plasma mass spectrometry with quadrupole (q-ICP-MS) and dynamic reaction cell (DRC-ICP-MS) were evaluated for sequential determination of As, Cd, Co, Cr, Cu, Mn, Pb, Se, Tl, V and Zn in blood. The method requires as little as 100 {mu}L of blood. Prior to analysis, samples (100 {mu}L) were diluted 1:50 in a solution containing 0.01% (v/v) Triton X-100 and 0.5% (v/v) nitric acid. The use of the DRC was only mandatory for Cr, Cu, V and Zn. For the other elements the equipment may be operated in a standard mode (q-ICP-MS). Ammonia was used as reaction gas. Selection of best flow rate of ammonium gas and optimization of the quadrupole dynamic band-pass tuning parameter (RPq) were carried out, using a ovine base blood for Cr and V and a synthetic matrix solution (SMS) for Zn and Cu diluted 1:50 and spiked to contain 1 {mu}g L{sup -1} of each element. Method detection limits (3 s) for {sup 75}As, {sup 114}Cd, {sup 59}Co, {sup 51}Cr, {sup 63}Cu {sup 55}Mn, {sup 208}Pb, {sup 82}Se, {sup 205}Tl, {sup 51}V, and {sup 64}Zn were 14.0, 3.0, 11.0, 7.0, 280, 9.0, 3.0, 264, 0.7, 6.0 and 800 ng L{sup -1}, respectively. Method validation was accomplished by the analysis of blood Reference Materials produced by the L'Institut National de Sante Publique du Quebec (Canada).

  15. Preventive Effect of Pine Bark Extract (Flavangenol on Metabolic Disease in Western Diet-Loaded Tsumura Suzuki Obese Diabetes Mice

    Directory of Open Access Journals (Sweden)

    Tsutomu Shimada

    2011-01-01

    Full Text Available It is known that the metabolic syndrome has a multi-factorial basis involving both genetic and environmental risk factors. In this study, Tsumura Suzuki Obese Diabetes (TSOD mice, a mouse model of multi-factorial, hereditary, obese type II diabetes, were given a Western diet (WTD as an environmental factor to prepare a disease model (TSOD-WTD and to investigate the preventive effects of Pine bark extract (Flavangenol against obesity and various features of metabolic disease appearing in this animal model. In contrast to control Tsumura Suzuki Non-obesity (TSNO mice, TSOD mice were obese and suffered from other metabolic complications. WTD-fed TSOD mice developed additional features such as hyperinsulinemia, abnormal glucose/lipid metabolism and fatty liver. The treatment with Flavangenol had a suppressive effect on increase in body weight and accumulation of visceral and subcutaneous fat, and also showed preventive effects on symptoms related to insulin resistance, abnormal glucose/lipid metabolism and hypertension. Flavangenol also increased the plasma concentration of adiponectin and decreased the plasma concentration of TNF-α. We next investigated the effect of Flavangenol on absorption of meal-derived lipids. Flavangenol suppressed absorption of neutral fat in an olive-oil-loading test (in vivo and showed an inhibitory effect on pancreatic lipase (in vitro. The above results suggest that Flavangenol has a preventive effect on severe metabolic disease due to multiple causes that involve both genetic and environmental risk factors. The mechanism of action might involve a partial suppressive effect of meal-derived lipids on absorption.

  16. KANTBP: A program for computing energy levels, reaction matrix and radial wave functions in the coupled-channel hyperspherical adiabatic approach

    Science.gov (United States)

    Chuluunbaatar, O.; Gusev, A. A.; Abrashkevich, A. G.; Amaya-Tapia, A.; Kaschiev, M. S.; Larsen, S. Y.; Vinitsky, S. I.

    2007-10-01

    A FORTRAN 77 program is presented which calculates energy values, reaction matrix and corresponding radial wave functions in a coupled-channel approximation of the hyperspherical adiabatic approach. In this approach, a multi-dimensional Schrödinger equation is reduced to a system of the coupled second-order ordinary differential equations on the finite interval with homogeneous boundary conditions of the third type. The resulting system of radial equations which contains the potential matrix elements and first-derivative coupling terms is solved using high-order accuracy approximations of the finite-element method. As a test desk, the program is applied to the calculation of the energy values and reaction matrix for an exactly solvable 2D-model of three identical particles on a line with pair zero-range potentials. Program summaryProgram title: KANTBP Catalogue identifier: ADZH_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZH_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 4224 No. of bytes in distributed program, including test data, etc.: 31 232 Distribution format: tar.gz Programming language: FORTRAN 77 Computer: Intel Xeon EM64T, Alpha 21264A, AMD Athlon MP, Pentium IV Xeon, Opteron 248, Intel Pentium IV Operating system: OC Linux, Unix AIX 5.3, SunOS 5.8, Solaris, Windows XP RAM: depends on (a) the number of differential equations; (b) the number and order of finite-elements; (c) the number of hyperradial points; and (d) the number of eigensolutions required. Test run requires 30 MB Classification: 2.1, 2.4 External routines: GAULEG and GAUSSJ [W.H. Press, B.F. Flanery, S.A. Teukolsky, W.T. Vetterley, Numerical Recipes: The Art of Scientific Computing, Cambridge University Press, Cambridge, 1986] Nature of problem: In the hyperspherical adiabatic

  17. DNA-binding, catalytic oxidation, C—C coupling reactions and antibacterial activities of binuclear Ru(II thiosemicarbazone complexes: Synthesis and spectral characterization

    Directory of Open Access Journals (Sweden)

    Arumugam Manimaran

    2012-07-01

    Full Text Available New hexa-coordinated binuclear Ru(II thiosemicarbazone complexes of the type {[(B(EPh3(COClRu]2L} (where, E = P or As; B = PPh3 or AsPh3 or pyridine; L = mononucleating NS donor of N-substituted thiosemicarbazones have been synthesized and characterized by elemental analysis, FT-IR, UV–vis and 31P{1H} NMR cyclic voltammetric studies. The DNA-binding studies of Ru(II complexes with calf thymus DNA (CT-DNA were investigated by UV–vis, viscosity measurements, gel-electrophoresis and fluorescence spectroscopy. The new complexes have been used as catalysts in C—C coupling reaction and in the oxidation of alcohols to their corresponding carbonyl compounds by using NMO as co-oxidant and molecular oxygen (O2 atmosphere at ambient temperature. Further, the new binucleating thiosemicarbazone ligands and their Ru(II complexes were also screened for their antibacterial activity against Klebsiella pneumoniae, Shigella sp., Micrococcus luteus, Escherichia coli and Salmonella typhi. From this study, it was found out that the activity of the complexes almost reaches the effectiveness of the conventional bacteriocide.

  18. A DFT study on photoinduced surface catalytic coupling reactions on nanostructured silver: selective formation of azobenzene derivatives from para-substituted nitrobenzene and aniline.

    Science.gov (United States)

    Zhao, Liu-Bin; Huang, Yi-Fan; Liu, Xiu-Min; Anema, Jason R; Wu, De-Yin; Ren, Bin; Tian, Zhong-Qun

    2012-10-05

    We propose that aromatic nitro and amine compounds undergo photochemical reductive and oxidative coupling, respectively, to specifically produce azobenzene derivatives which exhibit characteristic Raman signals related to the azo group. A photoinduced charge transfer model is presented to explain the transformations observed in para-substituted ArNO(2) and ArNH(2) on nanostructured silver due to the surface plasmon resonance effect. Theoretical calculations show that the initial reaction takes place through excitation of an electron from the filled level of silver to the lowest unoccupied molecular orbital (LUMO) of an adsorbed ArNO(2) molecule, and from the highest occupied molecular orbital (HOMO) of an adsorbed ArNH(2) molecule to the unoccupied level of silver, during irradiation with visible light. The para-substituted ArNO(2)(-)˙ and ArNH(2)(+)˙ surface species react further to produce the azobenzene derivatives. Our results may provide a new strategy for the syntheses of aromatic azo dyes from aromatic nitro and amine compounds based on the use of nanostructured silver as a catalyst.

  19. Detection of genetically modified crops using multiplex asymmetric polymerase chain reaction and asymmetric hyperbranched rolling circle amplification coupled with reverse dot blot.

    Science.gov (United States)

    Wang, Xiumin; Teng, Da; Guan, Qingfeng; Tian, Fang; Wang, Jianhua

    2015-04-15

    To meet the ever-increasing demand for detection of genetically modified crops (GMCs), low-cost, high-throughput and high-accuracy detection assays are needed. The new multiplex asymmetric polymerase chain reaction and asymmetric hyper-branched rolling circle amplification coupled with reverse dot blot (RDB) systems were developed to detect GMCs. Thirteen oligonucleotide probes were designed to identify endogenous targets (Lec1, Hmg and Sad1), event-specific targets (RRS-5C, RRS-3C, Bt176-3C and MON810-3C), screening targets (35S promoter and NOS terminator), and control targets (18S and PLX). Optimised conditions were as follows: tailed hybridization probes (1-2 pmol/l) were immobilized on a membrane by baking for 2h, and a 10:1 ratio of forward to reverse primers was used. The detection limits were 0.1 μg/l of 2% RRS and 0.5 ng/l of DNA from genetically modified (GM) soybean. These results indicate that the RDB assay could be used to detect multiplex target genes of GMCs rapidly and inexpensively. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Ab initio calculations on 2,6-dimethylphenol and 4-(2,6-dimethylphenoxy)-2,6-dimethylphenol. Evidence of an important role for the phenoxonium cation in the copper-catalyzed oxidative phenol coupling reaction

    NARCIS (Netherlands)

    Baesjou, PJ; Driessen, WL; Challa, G; Reedijk, J

    1997-01-01

    Ab initio unrestricted Hartree-Fock calculations with a 6-31G* basis set were performed on 2, 6-dimethylphenol (DMP or monomer) and 4-(2, 6-dimethylphenoxy)-2, 6-dimethylphenol (dimer) to gain more insight into the mechanism of the copper-catalyzed oxidative phenol coupling reaction. Atomic charges

  1. Multi-element analysis of urine using dynamic reaction cell inductively coupled plasma mass spectrometry (ICP-DRC-MS — A practical application

    Directory of Open Access Journals (Sweden)

    Renata Brodzka

    2013-04-01

    Full Text Available Objectives: The method for the determination of As, Al, Cd, Ni, Pb (toxic elements and Cr, Co, Cu, Fe, Mn, Zn (essential elements in human urine by the use of Inductively Coupled Plasma Mass Spectrometry (quadrupole ICP-MS DRCe Elan, Perkin Elmer with the dynamic reaction cell (DRC was developed. Materials and Methods: The method has been applied for multi-element analysis of the urine of 16 non-exposed healthy volunteers and 27 workers employed in a copper smelter. The analysis was conducted after initial 10-fold dilution of the urine samples with 0,1% nitric acid. Rhodium was used as an internal standard. The method validation parameters such as detection limit, sensitivity, precision were described for all elements. Accuracy of the method was checked by the regular use of certified reference materials ClinCheck®-Control Urine (Recipe as well as by participation of the laboratory in the German External Quality Assessment Scheme (G-EQUAS. Results: The detection limits (DL 3s of the applied method were 0.025, 0.007, 0.002, 0.004, 0.004, 0.086, 0.037, 0.009, 0.016, 0.008, 0.064 (μg/l for Al, As, Cd, Cr, Co, Cu, Fe, Mn, Ni, Pb, Zn in urine, respectively. For each element linearity with correlation coefficient of at least 0.999 was determined. Spectral interferences from some of the ions were removed using DRC-e with addition of alternative gas: methane for cobalt, copper, cadmium, chromium, iron, manganese, nickel and rhodium, and oxygen for arsenic. Conclusions: The developed method allows to determine simultaneously eleven elements in the urine with low detection limits, high sensitivity and good accuracy. Moreover, the method is appropriate for the assessment of both environmental and occupational exposure.

  2. Generalized semi-analytical solutions to multispecies transport equation coupled with sequential first-order reaction network in arbitrary heterogenious medium using GITT

    Science.gov (United States)

    Suk, Heejun

    2017-04-01

    This paper presents a semi-analytical procedure for solving coupled the multispecies reactive solute transport equations, with a sequential first-order reaction network in arbitrary heterogeneous media using General Integral Transformation Tecgnique(GITT).This proposed approach was developed to describe behavior of reactive multicpecise transport on spatially or temporally varying flow velocities and dispersion coefficients with distinct retardation factors, which might be function of space and time. This proposed approach deals with general initial conditions, and arbitrary temporal variable inlet concentration as well as arbitrary heterogenous media. The proposed approach sequentially calculates the concentration distributions of each species by employing only the generalized integral transform technique (GITT). Because the proposed solutions for each species' concentration distributions have separable forms in space and time, the solution for subsequent species (daughter species) can be obtained using only the GITT without the decomposition by change-of-variables method imposing the limitation of identical retarda- tion values for all the reactive species by directly substituting solutions for the preceding species (parent species) into the transport equation of subsequent species (daughter species). The proposed solutions were compared with previously published analytical solutions or numerical solutions of the numerical code of the Two-Dimensional Subsurface Flow, Fate and Transport of Microbes and Chemicals (2DFATMIC) in all verification examples. In these examples, the proposed solutions were well matched with previous analytical solutions and the numerical solutions obtained by 2DFATMIC model. A hypothetical single-well push-pull test example and a scale-dependent dispersion example were designed to demonstrate the practical application of the proposed solution to a real field problem.

  3. Generalized semi-analytical solutions to multispecies transport equation coupled with sequential first-order reaction network with spatially or temporally variable transport and decay coefficients

    Science.gov (United States)

    Suk, Heejun

    2016-08-01

    This paper presents a semi-analytical procedure for solving coupled the multispecies reactive solute transport equations, with a sequential first-order reaction network on spatially or temporally varying flow velocities and dispersion coefficients involving distinct retardation factors. This proposed approach was developed to overcome the limitation reported by Suk (2013) regarding the identical retardation values for all reactive species, while maintaining the extensive capability of the previous Suk method involving spatially variable or temporally variable coefficients of transport, general initial conditions, and arbitrary temporal variable inlet concentration. The proposed approach sequentially calculates the concentration distributions of each species by employing only the generalized integral transform technique (GITT). Because the proposed solutions for each species' concentration distributions have separable forms in space and time, the solution for subsequent species (daughter species) can be obtained using only the GITT without the decomposition by change-of-variables method imposing the limitation of identical retardation values for all the reactive species by directly substituting solutions for the preceding species (parent species) into the transport equation of subsequent species (daughter species). The proposed solutions were compared with previously published analytical solutions or numerical solutions of the numerical code of the Two-Dimensional Subsurface Flow, Fate and Transport of Microbes and Chemicals (2DFATMIC) in three verification examples. In these examples, the proposed solutions were well matched with previous analytical solutions and the numerical solutions obtained by 2DFATMIC model. A hypothetical single-well push-pull test example and a scale-dependent dispersion example were designed to demonstrate the practical application of the proposed solution to a real field problem.

  4. Detection of influenza viruses by coupling multiplex reverse-transcription loop-mediated isothermal amplification with cascade invasive reaction using nanoparticles as a sensor

    Science.gov (United States)

    Ge, Yiyue; Zhou, Qiang; Zhao, Kangchen; Chi, Ying; Liu, Bin; Min, Xiaoyan; Shi, Zhiyang; Zou, Bingjie; Cui, Lunbiao

    2017-01-01

    Influenza virus infections represent a worldwide public health and economic problem due to the significant morbidity and mortality caused by seasonal epidemics and pandemics. Sensitive and convenient methodologies for detection of influenza viruses are essential for further disease control. Loop-mediated isothermal amplification (LAMP) is the most commonly used method of nucleic acid isothermal amplification. However, with regard to multiplex LAMP, differentiating the ladder-like LAMP products derived from multiple targets is still challenging today. The requirement of specialized instruments has further hindered the on-site application of multiplex LAMP. We have developed an integrated assay coupling multiplex reverse transcription LAMP with cascade invasive reaction using nanoparticles (mRT-LAMP-CIRN) as a sensor for the detection of three subtypes of influenza viruses: A/H1N1pdm09, A/H3 and influenza B. The analytic sensitivities of the mRT-LAMP-CIRN assay were 101 copies of RNA for both A/H1N1pdm09 and A/H3, and 102 copies of RNA for influenza B. This assay demonstrated highly specific detection of target viruses and could differentiate them from other genetically or clinically related viruses. Clinical specimen analysis showed the mRT-LAMP-CIRN assay had an overall sensitivity and specificity of 98.3% and 100%, respectively. In summary, the mRT-LAMP-CIRN assay is highly sensitive and specific, and can be used as a cost-saving and instrument-free method for the detection of influenza viruses, especially for on-site use. PMID:28435249

  5. FAKTOR PSIKOLOGIS, LINGKUNGAN DAN BAURAN PEMASARAN YANG MEMPENGARUHI PEMBELIAN SEPEDA MOTOR Studi Pada Konsumen Sepeda Motor Bebek 4-tak Merk Suzuki dan Honda di Kota Banjarmasin

    Directory of Open Access Journals (Sweden)

    Taufiq Adi Rahmanie

    2012-05-01

    Full Text Available ABSTRAK Penelitian ini dilakukan untuk mengetahui faktor psikologis, lingkungan dan bauran pemasaran yang mempengaruhi pembelian sepeda motor bebek 4-tak merk Suzuki dan Honda di Kota Banjarmasin, dan untuk mengetahui variabel yang dominan terhadap keputusan pembelian. Penelitian ini dilakukan di Kota Banjarmasin. Pengambilan sampel dilakukan dengan teknik non random sampling dengan motode convenience sampling, dengan jumlah sampel 706 responden (355 konsumen Suzuki dan  351 konsumen Honda. Tingkat signifikansi yang ditetapkan dalam penelitian ini adalah 5%. Sebanyak 49 item dalam daftar pertanyaan yang diuraikan dalam 12 variabel dalam faktor psikologis, lingkungan dan bauran pemasaran. Pengujian terhadap semua instrumen penelitian menunjukkan tingkat reliabilitas dan validitas yang tinggi. Hasil penelitian ini semua variabel bebas yaitu persepsi (X1, sikap (X2, gaya hidup (X3, kepribadian (X4, budaya (X5, kelas sosial (X6, kelompok referensi (X7, situasi penentu (X8, produk (X9, harga (X10, promosi (X11 dan distribusi (X12 mempunyai korelasi yang signifikan terhadap keputusan pembelian sepeda motor bebek 4-tak merk Suzuki dan Honda. Diantara keduabelas variabel tersebut, variabel persepsi (X1, sikap (X2, gaya hidup (X3, kelompok referensi (X7, situasi penentu (X8 dan produk (X9 berpengaruh secara nyata terhadap keputusan pembelian sepeda motor bebek 4-tak merk Suzuki dan Honda di Kota Banjarmasin. Koefisien determinasi (R2 sebesar 0.591 menunjukkan kontribusi variabel-variabel independen untuk menjelaskan variabel dependen sebesar 59.1%. Sedangkan variabel yang paling dominan pengaruhnya adalah sikap sebesar 39.6%.   Kata kunci: pemasaran, bauran, psikologis ABSTRACT This research has been done to know psychological, environmental, marketing mix to influence 4 stroke bebek motorcycle (Honda and Suzuki buying in Banjarmasin, and also to know the dominant variable on buying decision. This research has been done in Banjarmasin. Writer uses non

  6. Total Synthesis of the Anti-inflammatory and Pro-resolving Lipid Mediator MaR1n-3 DPA Utilizing an sp3-sp3 Negishi Cross-coupling Reaction**

    Science.gov (United States)

    Tungen, Jørn Eivind; Aursnes, Marius; Dalli, Jesmond; Arnardottir, Hildur; Serhan, Charles Nicholas

    2014-01-01

    The first total synthesis of the lipid mediator MaR1n-3 DPA (5) has been achieved in 12% overall yield over 11 steps. The stereoselective preparation of 5 was based on a Pd-catalyzed sp3-sp3 Negishi cross-coupling reaction and a stereo controlled Evans-Nagao acetate aldol reaction. LC-MS/MS results with synthetic material matched the biologically product 5. This novel lipid mediator displayed potent pro-resolving properties stimulating macrophage efferocytosis of apoptotic neutrophils. PMID:25225129

  7. Cross-coupling reactions of unprotected halopurine bases, nucleosides, nucleotides and nucleoside triphosphates with 4-boronophenylalanine in water. Synthesis of (purin-8-yl)- and (purin-6-yl)phenylalanines

    Czech Academy of Sciences Publication Activity Database

    Čapek, Petr; Pohl, Radek; Hocek, Michal

    2006-01-01

    Roč. 4, č. 11 (2006), s. 2278-2284 ISSN 1477-0520 R&D Projects: GA AV ČR(CZ) 1QS400550501; GA MŠk(CZ) 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : amino acids * purines * nucleosides * cross-coupling reactions Subject RIV: CC - Organic Chemistry Impact factor: 2.874, year: 2006

  8. disubstituted indazoles and their AKT inhibition activity

    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.

  9. 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.

  10. Synthesis and photophysics of fully π-conjugated heterobis-functionalized polymeric molecular wires via Suzuki chain-growth polymerization.

    Science.gov (United States)

    Elmalem, Einat; Biedermann, Frank; Johnson, Kerr; Friend, Richard H; Huck, Wilhelm T S

    2012-10-24

    We present a fast and efficient in situ synthetic approach to obtain fully π-conjugated polymers with degrees of polymerization up to 23 and near quantitative (>95%) heterobis-functionalization. The synthesis relies on the key advantages of controlled Suzuki chain-growth polymerization: control over molecular weight, narrow polydispersity, and ability to define polymer end groups. The first end group is introduced through the initiator metal complex tBu(3)PPd(X)Br, while the second end group is added by quenching of the chain-growth polymerization with the desired boronic esters. In all cases, polymers obtained at 50% conversion showed excellent end group fidelity and high purity following a simple workup procedure, as determined by MALDI-TOF, GPC, and (1)H and 2D NMR. End group functionalization altered the optoelectronic properties of the bridge polymer. Building on a common fluorene backbone, and guided by DFT calculations, we introduced donor and acceptor end groups to create polymeric molecular wires exhibiting charge transfer and energy transfer as characterized by fluorescence, absorption, and transient absorption spectroscopy as well as by fluorescence lifetime measurements.

  11. Ultrasound-assisted synthesis of novel 1,2,3-triazoles coupled diaryl sulfone moieties by the CuAAC reaction, and biological evaluation of them as antioxidant and antimicrobial agents.

    Science.gov (United States)

    Mady, Mohamed F; Awad, Ghada E A; Jørgensen, Kåre B

    2014-09-12

    A series of 1,2,3-triazoles coupled diaryl sulfone containing compounds were synthesized by the copper-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC) reaction in benign solvents under ultrasound irradiation. In situ formation of azides from α-bromoketones together with the CuAAC reaction in one pot allowed safe handling and good availability of azides for the development of a small library of compounds. The sonication reduced reaction time and increased yields compared to otherwise same conditions. All synthesized compounds were evaluated for antibacterial, antifungal and antioxidant activities. Compounds 3b, 6b and 9e-9g were found to be the most potent antifungal agents with minimal inhibitory concentration (MIC) at 25 μg/mL; moreover other compounds revealed good to moderate antimicrobial activity. Compound 8e showed an excellent antioxidant activity using a DPPH free radical scavenging assay. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  12. 2-ARYL-6,8-DIBROMO-2,3-DIHYDROQUINAZOLIN-4(1H)

    African Journals Online (AJOL)

    Preferred Customer

    case, no product resulting from possible N-bromination was detected or isolated from the reaction ... catalyzed Suzuki-Miyaura cross-coupling with arylboronic acids as coupling partners. As a .... treatment of diabetes and obesity [33]. (i). N. O.

  13. 4R- and 4S-iodophenyl hydroxyproline, 4R-pentynoyl hydroxyproline, and S-propargyl-4-thiolphenylalanine: conformationally biased and tunable amino acids for bioorthogonal reactions.

    Science.gov (United States)

    Forbes, Christina R; Pandey, Anil K; Ganguly, Himal K; Yap, Glenn P A; Zondlo, Neal J

    2016-02-21

    Bioorthogonal reactions allow the introduction of new functionalities into peptides, proteins, and other biological molecules. The most readily accessible amino acids for bioorthogonal reactions have modest conformational preferences or bases for molecular interactions. Herein we describe the synthesis of 4 novel amino acids containing functional groups for bioorthogonal reactions. (2S,4R)- and (2S,4S)-iodophenyl ethers of hydroxyproline are capable of modification via rapid, specific Suzuki and Sonogashira reactions in water. The synthesis of these amino acids, as Boc-, Fmoc- and free amino acids, was achieved through succinct sequences. These amino acids exhibit well-defined conformational preferences, with the 4S-iodophenyl hydroxyproline crystallographically exhibiting β-turn (ϕ, ψ∼-80°, 0°) or relatively extended (ϕ, ψ∼-80°, +170°) conformations, while the 4R-diastereomer prefers a more compact conformation (ϕ∼-60°). The aryloxyproline diastereomers present the aryl groups in a highly divergent manner, suggesting their stereospecific use in molecular design, medicinal chemistry, and catalysis. Thus, the 4R- and 4S-iodophenyl hydroxyprolines can be differentially applied in distinct structural contexts. The pentynoate ester of 4R-hydroxyproline introduces an alkyne functional group within an amino acid that prefers compact conformations. The propargyl thioether of 4-thiolphenylalanine was synthesized via copper-mediated cross-coupling reaction of thioacetic acid with protected 4-iodophenylalanine, followed by thiolysis and alkylation. This amino acid combines an alkyne functional group with an aromatic amino acid and the ability to tune aromatic and side chain properties via sulfur oxidation. These amino acids provide novel loci for peptide functionalization, with greater control of conformation possible than with other amino acids containing these functional groups.

  14. An efficient synthesis of 8-substituted Odoratine derivatives by the ...

    Indian Academy of Sciences (India)

    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 ...

  15. In-line near-infrared (NIR) and Raman spectroscopy coupled with principal component analysis (PCA) for in situ evaluation of the transesterification reaction.

    Science.gov (United States)

    Fontalvo-Gómez, Miriam; Colucci, José A; Velez, Natasha; Romañach, Rodolfo J

    2013-10-01

    Biodiesel was synthesized from different commercially available oils while in-line Raman and near-infrared (NIR) spectra were obtained simultaneously, and the spectral changes that occurred during the reaction were evaluated with principal component analysis (PCA). Raman and NIR spectra were acquired every 30 s with fiber optic probes inserted into the reaction vessel. The reaction was performed at 60-70 °C using magnetic stirring. The time of reaction was 90 min, and during this time, 180 Raman and NIR spectra were collected. NIR spectra were collected using a transflectance probe and an optical path length of 1 mm at 8 cm(-1) spectral resolution and averaging 32 scans; for Raman spectra a 3 s exposure time and three accumulations were adequate for the analysis. Raman spectroscopy showed the ester conversion as evidenced by the displacement of the C=O band from 1747 to 1744 cm(-1) and the decrease in the intensity of the 1000-1050 cm(-1) band and the 1405 cm(-1) band as methanol was consumed in the reaction. NIR spectra also showed the decrease in methanol concentration with the band in the 4750-5000 cm(-1) region; this signal is present in the spectra of the transesterification reaction but not in the neat oils. The variations in the intensity of the methanol band were a main factor in the in-line monitoring of the transesterification reaction using Raman and NIR spectroscopy. The score plot of the first principal component showed the progress of the reaction. The final product was analyzed using (1)H nuclear magnetic resonance ((1)H NMR) spectroscopy and using mid-infrared spectroscopy, confirming the conversion of the oils to biodiesel.

  16. Highly selective biaryl cross-coupling reactions between aryl halides and aryl Grignard reagents: a new catalyst combination of N-heterocyclic carbenes and iron, cobalt, and nickel fluorides.

    Science.gov (United States)

    Hatakeyama, Takuji; Hashimoto, Sigma; Ishizuka, Kentaro; Nakamura, Masaharu

    2009-08-26

    Combinations of N-heterocyclic carbenes (NHCs) and fluoride salts of the iron-group metals (Fe, Co, and Ni) have been shown to be excellent catalysts for the cross-coupling reactions of aryl Grignard reagents (Ar(1)MgBr) with aryl and heteroaryl halides (Ar(2)X) to give unsymmetrical biaryls (Ar(1)-Ar(2)). Iron fluorides in combination with SIPr, a saturated NHC ligand, catalyze the biaryl cross-coupling between various aryl chlorides and aryl Grignard reagents in high yield and high selectivity. On the other hand, cobalt and nickel fluorides in combination with IPr, an unsaturated NHC ligand, exhibit interesting complementary reactivity in the coupling of aryl bromides or iodides; in contrast, with these substrates the iron catalysts show a lower selectivity. The formation of homocoupling byproducts is suppressed markedly to less than 5% in most cases by choosing the appropriate metal fluoride/NHC combination. The present catalyst combinations offer several synthetic advantages over existing methods: practical synthesis of a broad range of unsymmetrical biaryls without the use of palladium catalysts and phosphine ligands. On the basis of stoichiometric control experiments and theoretical studies, the origin of the unique catalytic effect of the fluoride counterion can be ascribed to the formation of a higher-valent heteroleptic metalate [Ar(1)MF(2)]MgBr as the key intermediate in our proposed catalytic cycle. First, stoichiometric control experiments revealed the stark differences in chemical reactivity between the metal fluorides and metal chlorides. Second, DFT calculations indicate that the initial reduction of di- or trivalent metal fluoride in the wake of transmetalation with PhMgCl is energetically unfavorable and that formation of a divalent heteroleptic metalate complex, [PhMF(2)]MgCl (M = Fe, Co, Ni), is dominant in the metal fluoride system. The heteroleptic ate-complex serves as a key reactive intermediate, which undergoes oxidative addition with Ph

  17. Transport of sugars and amino acids in bacteria. XV. Comparative studies on the effects of various energy poisons on the oxidative and phosphorylating activities and energy coupling reactions for the active transport systems for amino acids in E. coli.

    Science.gov (United States)

    Anraku, Y; Kin, E; Tanaka, Y

    1975-07-01

    The effects of various energy poisons on oxidation of respiratory substrate, synthesis of cellular ATP, and energy transformation reaction in intact Escherichia coli cells were studied systematically. Various mutants were, therefore, used in which specific functions in the energy-transducing reactions were defective or altered. The energy poisons examined were: sodium azide. DPPA and azidebenzenes which are inhibitors of respiratory-chain phosphorylation, SF6847, and CCCP which are known to be uncouplers, zinc sulfate which is an inhibitor for certain dehydrogenases, and sodium arsenate and sodium fluoride which are inhibitors of glycolytic synthesis of ATP. The preferential inhibitions occurred in the oxidation reactions with certain respiratory substrates by energy poisons used. DPPA inhibited glycerol oxidation much more strongly than succinate oxidation. However, DPPA could inhibit the oxidation of both glycerol 3-phosphate and succinate by membrane fraction strongly while the oxidation of NADH and D-lactate slightly. It inhibited glycerol 3-phosphate dehydrogenase [EC 1.1.2.1] strongly as well as succinate dehydrogenase [EC 1.3.99.1],.but not D-lactate dehydrogenase of membrane fraction. MAB and other azidebenzene derivatives inhibited succinate oxidation preferentially. SF6847 and CCCP inhibited succinate oxidation strongly, while sodium azide inhibited it weakly and these three poisons were less inhibitory for glycerol oxidation. DPPA, sodium azide, SF6847, and CCCP inhibited the synthesis of ATP coupled with respiration but not with glycolysis. Zinc sulfate inhibited the cellular ATP synthesis coupled with either respiration or glycolysis.

  18. Combined effects of chemical reaction and temperature dependent heat source on MHD mixed convective flow of a couple-stress fluid in a vertical wavy porous space with travelling thermal waves

    Directory of Open Access Journals (Sweden)

    Muthuraj R.

    2012-01-01

    Full Text Available A mathematical model is developed to examine the effect of chemical reaction on MHD mixed convective heat and mass transfer flow of a couple-stress fluid in vertical porous space in the presence of temperature dependent heat source with travelling thermal waves. The dimensionless governing equations are assumed to be made up of two parts: a mean part corresponding to the fully developed mean flow, and a small perturbed part, using amplitude as a small parameter. The analytical solution of perturbed part have been carried out by using the long-wave approximation. The expressions for the zeroth-order and the first order solutions are obtained and the results of the heat and mass transfer characteristics are presented graphically for various values of parameters entering into the problem. It is noted that velocity of the fluid increases with the increase of the couple stress parameter and increasing the chemical reaction parameter leads suppress the velocity of the fluid. Cross velocity decreases with an increase of the phase angle. The increase of the chemical reaction parameter and Schmidt number lead to decrease the fluid concentration. The hydrodynamic case for a non-porous space in the absence of the temperature dependent heat source for Newtonian fluid can be captured as a limiting case of our analysis by taking, and α1→0, Da→∞, a→∞.

  19. Development and characterization of "push-pull" sampling device with fast reaction quenching coupled to high-performance liquid chromatography for pharmaceutical process analytical technologies.

    Science.gov (United States)

    Chisolm, Claire N; Evans, Charles R; Jennings, Colin; Black, Will A; Antosz, Frederick J; Qiang, Yangqiao; Diaz, Angel R; Kennedy, Robert T

    2010-11-26

    A push-pull sampling system interfaced on-line to high-performance liquid chromatography (HPLC) was developed for micro-volume real-time monitoring of reaction mixtures. The device consists of concentric tubes wherein sample was continuously withdrawn through the outer tube and reaction quenchant continuously delivered through a recessed inner tube. The device allowed sampling rates of 0.1-6.0 μL/min from a reaction vessel and stopped the reaction by passive mixing with quenchant to preserve the conditions observed in the reaction vessel. A finite element model of the system showed that reaction mixtures could be completely mixed with quenchant within 4.3s at a flow rate of 1.0 μL/min. The model also showed that an offset distance of 1mm between the push capillary and sample capillary tips is sufficient to avoid leakage of quenchant/diluent into the bulk sample for push flow rates up to 95% of the pull flow rate. The maximum relative push flow rate was determined to be 90% of the pull flow rate experimentally. Delay between sampling and delivery to the HPLC was from 111±3s to 317±9s for pull flow rates from 1.0 to 3.0 μL/min in agreement with expected delays based on tubing volume. Response times were from 27±1s to 52±6s over the same flow rate range. The sampler was tested to determine the effects of sample viscosity. The sampler was also used to demonstrate periodic sampling capabilities. As a test of the system, it was used to monitor the base-catalyzed hydrolysis of aspirin for 1.5h, demonstrating its utility for monitoring an ongoing reaction. Copyright © 2010 Elsevier B.V. All rights reserved.

  20. An efficient method for the construction of functionalized DNA bearing amino acid groups through cross-coupling reactions of nucleoside triphosphates followed by primer extension or PCR

    Czech Academy of Sciences Publication Activity Database

    Čapek, Petr; Cahová, Hana; Pohl, Radek; Hocek, Michal; Gloeckner, Ch.; Marx, A.

    2007-01-01

    Roč. 13, č. 21 (2007), s. 6196-6203 ISSN 0947-6539 R&D Projects: GA MŠk LC512; GA ČR GA203/05/0043 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleoside triphosphates * cross-coupling * DNA Subject RIV: CC - Organic Chemistry Impact factor: 5.330, year: 2007

  1. The taxonomic implication of frontal tubercles in Polypedilum subgenera diagnoses, with re-description of Polypedilum isigabeceum Sasa & Suzuki (Diptera, Chironomidae).

    Science.gov (United States)

    Yamamoto, Nao; Yamamoto, Masaru

    2016-11-15

    Polypedilum isigabeceum Sasa et Suzuki, 2000 was described as belonging to subgenus Polypedilum s. str. However, if we accept the conclusion of Sæther et al. (2010), the species might be placed into Kribionympha with P. unagiquartum Sasa, 1985 because of the presence of distinct frontal tubercles in the adult males. However, other taxonomic characters do not support their treatment. P. isigabeceum is re-described and reconfirmed to be assigned to the subgenus Polypedilum s. str. The taxonomic meaning of frontal tubercles is discussed for defining the subgeneric rankings within genus Polypedilum.

  2. The study of CaO and MgO heterogenic nano-catalyst coupling on transesterification reaction efficacy in the production of biodiesel from recycled cooking oil.

    Science.gov (United States)

    Tahvildari, Kambiz; Anaraki, Yasaman Naghavi; Fazaeli, Reza; Mirpanji, Sogol; Delrish, Elham

    2015-01-01

    Fossil fuels' pollution and their non-renewability have motivated the search for alternative fuels. Some common example of seed oils are sunflower oil, date seed oil, soy bean oil. For instance, soy methyl and soy-based biodiesel are the main biodiesel. Biodiesel is a clean diesel fuel that can be produced through transesterification reaction. Recycled cooking oil, on the other hand, is one of the inexpensive, easily available sources for producing biodiesel. This article is aimed at production of biodiesel via trans-esterification method, Nano CaO synthesis using sol-gel method, and Nano MgO synthesis using sol-gel self-combustion. Two catalysts' combination affecting the reaction's efficacy was also discussed. Optimum conditions for the reaction in the presence of Nano CaO are 1.5 % weight fracture, 1:7 alcohol to oil proportion and 6 h in which biodiesel and glycerin (the byproduct) are produced. Moreover, the optimum conditions for this reaction in the presence of Nano CaO and Nano MgO mixture are 3 % weight fracture (0.7 g of Nano CaO and 0.5 g of Nano MgO), 1:7 alcohols to oil proportion and 6 h. Nano MgO is not capable of catalyzing the transesterification by itself, because it has a much weaker basic affinity but when used with Nano CaO due to its surface structure, the basic properties increase and it becomes a proper base for the catalyst so that CaO contact surface increases and transesterification reaction yield significantly increases as well. This study investigates the repeatability of transesterification reaction in the presence of these Nano catalysts as well.

  3. Reaction Mechanism of Cu(I)-Mediated Reductive CO2 Coupling for the Selective Formation of Oxalate: Cooperative CO2 Reduction To Give Mixed-Valence Cu2(CO2•-) and Nucleophilic-Like Attack.

    Science.gov (United States)

    Lan, Jialing; Liao, Tao; Zhang, Tonghuan; Chung, Lung Wa

    2017-06-19

    A dinuclear, Cu(I)-catalyzed reductive CO2 coupling reaction was recently developed to selectively yield a metal-oxalate product through electrochemical means, instead of the usual formation of carbonate and CO ( Science 2010 , 327 , 313 ). To shed light on the mechanism of this important and unusual reductive coupling reaction, extensive and systematic density functional theory (DFT) calculations on several possible pathways and spin states were performed in which a realistic system up to 164 atoms was adopted. Our calculations support the observation that oxalate formation is energetically more favorable than the formation of carbonate and CO products in this cationic Cu(I) complex. Spatial confinement of the realistic catalyst (a long metal-metal distance) was found to further destabilize the carbonate formation, whereas it slightly promotes oxalate formation. Our study does not support the proposed diradical coupling mechanism. Instead, our calculations suggest a new mechanism in which one CO2 molecule is first reduced cooperatively by two Cu(I) metals to give a new, fully delocalized mixed-valence Cu2I/II(CO2•-) radical anion intermediate (analogues to Type 4 Cu center, CuA), followed by further partial reduction of the metal-ligated CO2 molecule and (metal-mediated) nucleophilic-like attack on the carbon atom of an incoming second CO2 molecule to afford the dinuclear Cu(II)-oxalate product. Overall, our proposed reaction mechanism involves a closed-shell reactant as well as two open-shell transition states and products. The effects of size, charge, and catalyst metal on the oxalate formation were also investigated and compared.

  4. Coupling between reactions and transport for the modelling and simulation of CO{sub 2} geological storage; Couplage reactions-transport pour la modelisation et la simulation du stockage geologique de CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Tillier, E

    2007-09-15

    In this work, we present some results about the coupling between transport and geochemistry for the modelling and the simulation of CO{sub 2} geological storage. We present a multiphase flow model and a geochemical model which enables to describe a coupled reactive multiphase flow problem. We then propose two methods of resolution, the first one is a global method, the other one is a splitting method which is used at the IFP in the software COORES. The splitting is based on physical assumptions. The coupling method used is a non iterative method, in which the splitting error is corrected by adding a penalization term. A convergence study shows that this scheme converges to the same solution as the global scheme. A part of this PhD is dedicated to diffusion and dispersion phenomena. We are interested in this term because it cannot be integrated easily in a splitting scheme, if the reactive transport is solved locally (which is necessary to use local time-step). After having highlighted the importance of this term on a representative test case, we show some difficulties encountered to integrate it in a splitting scheme. Finally, we study a miscible multiphase flow problem in 1D from a mathematical point of view. The difficulties arise with the non linearity due to the non zero gas solubility in water. We propose a definition for the weak solution of this problem and its existence is shown thanks to the convergence of a finite volume scheme. (O.M.)

  5. Chemical properties of water-soluble porphyrins. 4. The reaction of a 'picket-fence-like' iron (III) complex with the superoxide oxygen couple.

    Science.gov (United States)

    Faraggi, M; Peretz, P; Weinraub, D

    1986-06-01

    Solution properties of the iron-(III) 'picket-fence-like' porphyrin, Fe(III)-alpha,alpha,alpha, beta-tetra-ortho (N-methyl-isonicotinamidophenyl) porphyrin, (Fe(III)PFP) were investigated. These were acid/base properties of the aquo complex with pKa of 3.9 and its aggregation (formation of dimer with K = 1 X 10(-10) dm3 mol-1), complex formation with cyanide ions and 1-methyl imidazole (1-MeIm), spectral properties of the three iron complexes in their ferric and ferrous form and the one-electron reduction potential of these complexes. Knowing these properties, the reaction of the ferric complexes, aquo, dicyano and bis (1-MeIm), with the superoxide radical and other reducing radicals were studied using the pulse radiolysis technique. The second-order reaction rate constant of O2- with the iron (III) aquo complex which governs the catalytic efficiency of the metalloporphyrin upon the disproportionation of the superoxide radical was 7.6 X 10(7) dm3 mol-1 s-1, two orders of magnitude faster when compared to the reaction of each of the other complexes. The reduction by other radicals with all iron (III) complexes had similar second-order rate constants (10(9) to 10(10) dm3 mol-1 s-1). The reduction reaction in all cases produced Fe(II)PEP and no intermediate was found. The oxidation reaction of Fe(II)PEP by O2- was one order of magnitude faster when compared to the reduction of Fe(III)PFP by the same radical. Since the reactivity of O2- toward the three iron (III) porphyrin complexes follows their reduction potentials, it is suggesting the formation of a peroxo Fe(II) porphyrin as an intermediate. The reactions of the Fe(II)PFP complexes with dioxygen were also studied. The aquo complex was found to be first order in O2 and second order in Fe(II)PFP, suggesting the formation of a peroxo Fe(II) porphyrin as an intermediate. The intermediate formation was corroborated by evidence of the rapid CO binding reaction to the aquo complex of Fe(II)PFP. The two other complexes

  6. Efficient C-O and C-N bond forming cross-coupling reactions catalyzed by core-shell structured Cu/Cu2O nanowires

    KAUST Repository

    Elshewy, Ahmed M.

    2013-12-01

    Oxygen and Nitrogen containing compounds are of utmost importance due to their interesting and diverse biological activities. The construction of the C-O and C–N bonds is of significance as it opens avenues for the introduction of ether and amine linkages in organic molecules. Despite significant advancements in this field, the construction of C-O and C–N bonds is still a major challenge for organic chemists, due to the involvement of harsh reaction conditions or the use of expensive catalysts or ligands in many cases. Thus, it is a challenge to develop alternative, milder, cheaper and more reproducible methodologies for the construction of these types of bonds. Herein, we introduce a new efficient ligand free catalytic system for C-O and C-N bond formation reactions.

  7. Straightforward Access to Hexahydropyrrolo[2,3-b]indole Core by a Regioselective C3-Azo Coupling Reaction of Arenediazonium Compounds with Tryptamines.

    Science.gov (United States)

    Stephens, David E; Larionov, Oleg V

    2014-06-01

    A base-mediated regioselective electrophilic addition of arenediazonium salts at the C3-position of tryptamines followed by cyclization provides an efficient entry to C3-nitrogenated hexahydropyrrolo[2,3-b]indoles (HPIs) that can subsequently be transformed into 3-arylhexahydropyrrolo[2,3-b]indoles and other HPI derivatives. The reaction is the first example of a 1,2-diamination that utilizes easily accessible arenediazonium salts as nitrogenous electrophiles.

  8. Efficient one-pot synthesis of new 1-amino substituted pyrrolo[1,2-a]quinoline-4-carboxylate esters via copper-free Sonogashira coupling reactions.

    Science.gov (United States)

    Keivanloo, Ali; Kazemi, Shaghayegh Sadat; Nasr-Isfahani, Hossein; Bamoniri, Abdolhamid

    2017-02-01

    The reactions of several 2-chloroquinoline-3-carboxylate esters with propargyl alcohol and a secondary amine in the presence of palladium catalyst leads to the formation of new alkyl 1-amino substituted pyrrolo[1,2-a]quinoline-4-carboxylate derivatives. This one-pot process, carried out in the absence of any copper salt, provides an efficient method for the synthesis of functionalized pyrrolo[1,2-a]quinolines in good-to-high yields.

  9. Importance of considering the coupling between transfer properties, alkali leaching and expansion in the modelling of concrete beams affected by internal swelling reactions

    OpenAIRE

    MARTIN, Renaud Pierre; OMIKRINE METALSSI, Othman; TOUTLEMONDE, François

    2013-01-01

    Alkali aggregat reaction (AAR) and delayed ettringite formation (DEF) cause expansion of the affected concrete that generally leads to cracking and decrease of its mechanical properties. Consequently, these pathologies raise severe problems regarding serviceability, sustainable operation and structural integrity. Thus it is necessary to provide predictive models able to re-assess the mechanical state of the affected structures. Since cracking may alter diffusion properties of concrete, and si...

  10. Mo-II Cluster Complex-Based Coordination Polymer as an Efficient Heterogeneous Catalyst in the Suzuki–Miyaura Coupling Reaction

    Czech Academy of Sciences Publication Activity Database

    Bůžek, Daniel; Hynek, Jan; Kučeráková, Monika; Kirakci, Kaplan; Demel, Jan; Lang, Kamil

    2016-01-01

    Roč. 2016, č. 28 (2016), s. 4668-4673 ISSN 1434-1948 R&D Projects: GA ČR GA13-05114S; GA ČR GA15-12653S EU Projects: European Commission(XE) CZ.2.16/3.1.00/24510 Institutional support: RVO:61388980 ; RVO:68378271 Keywords : C–C coupling * Heterogeneous catalysis * Molybdenum * Palladium * Polymers Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (FZU-D) Impact factor: 2.444, year: 2016

  11. First cross-coupling reaction of potassium aryltrifluoroborates with organic chlorides in aqueous media catalyzed by an oxime-derived palladacycle.

    Science.gov (United States)

    Alacid, Emilio; Nájera, Carmen

    2008-11-06

    Potassium aryltrifluoroborates are cross-coupled with aryl and heteroaryl chlorides using a 4-hydroxyacetophenone oxime-derived palladacycle as precatalyst, K2CO3 as base, and TBAB as additive in refluxing water under conventional and microwave heating affording the corresponding biphenyls under phosphine-free conditions. For the arylation of allyl and benzyl chlorides, KOH is used as base in acetone-water (3:2) at rt or 50 degrees C using 0.1 mol % Pd loading providing allylbenzenes and diarylmethanes, respectively.

  12. Renaissance of Sandmeyer-Type Reactions: Conversion of Aromatic C-N Bonds into C-X Bonds (X = B, Sn, P, or CF3).

    Science.gov (United States)

    Mo, Fanyang; Qiu, Di; Zhang, Yan; Wang, Jianbo

    2018-02-20

    -induced reactions, aqueous-phase diazotization methods, and reactions with aryltriazenes as the arene diazonium salt surrogates. In addition to the borylation, we have also demonstrated the corresponding stannylation and phosphorylation of arylamines with similar Sandmeyer-type approaches. The stannylation of arylamines was achieved by the reaction of in situ generated diazonium salts with a distannane reagent, while phosphorylation is the reaction of arylamines with trimethyl phosphite in the presence of tert-butyl nitrite (t-BuONO). With the sequential borylation and stannylation approaches, the aromatic compounds bearing two amino groups are easily converted into trimethylstannyl arylboronates, which can be further used in consecutive Stille and Suzuki-Miyaura cross-couplings. Finally, direct conversion of the amino group of arylamines to the trifluoromethyl group has been developed through aryl diazonium salts almost simultaneously by several groups. These reactions represent a novel strategy to achieve trifluoromethylation of aromatic compounds. These developments show the revivification of this age-old chemistry, and this Account will summarize the Sandmeyer reaction-related transformations that have been developed since 2010.

  13. New High-Performance Liquid Chromatography Coupled Mass Spectrometry Method for the Detection of Lobster and Shrimp Allergens in Food Samples via Multiple Reaction Monitoring and Multiple Reaction Monitoring Cubed.

    Science.gov (United States)

    Korte, Robin; Monneuse, Jean-Marc; Gemrot, Elodie; Metton, Isabelle; Humpf, Hans-Ulrich; Brockmeyer, Jens

    2016-08-10

    Crustacean shellfish allergy ranks among the most frequent and severe food allergies for adults, demanding rugged and sensitive analytical routine methods. The objective of this study was therefore to develop a mass spectrometric approach for the detection of contamination with shrimp and lobster, two economically important types of crustaceans, in complex food matrices. Following a biomarker approach, we identified proteotypic peptides and developed a multiple reaction monitoring (MRM) method allowing for the identification and differentiation of shrimp and lobster in the food matrix at concentrations down to 0.1%. To further enhance sensitivity, we employed the MRM-cubed (MRM(3)) mode, which allowed us to detect crustaceans down to concentrations of 25 μg/g (crustacean/food, 0.0025%). We hereby present the first mass spectrometric method for the detection of shrimp and lobster in food matrices.

  14. The $e^+ e^- \\to Z\\gamma\\gamma \\to q\\overline{q}\\gamma\\gamma$ Reaction at LEP and Constraints on Anomalous Quartic Gauge Boson Couplings

    CERN Document Server

    Achard, P; Aguilar-Benítez, M; Alcaraz, J; Alemanni, G; Allaby, James V; Aloisio, A; Alviggi, M G; Anderhub, H; Andreev, V P; Anselmo, F; Arefev, A; Azemoon, T; Aziz, T; Bagnaia, P; Bajo, A; Baksay, G; Baksay, L; Baldew, S V; Banerjee, S; Banerjee, Sw; Barczyk, A; Barillère, R; Bartalini, P; Basile, M; Batalova, N; Battiston, R; Bay, A; Becattini, F; Becker, U; Behner, F; Bellucci, L; Berbeco, R; Berdugo, J; Berges, P; Bertucci, B; Betev, B L; Biasini, M; Biglietti, M; Biland, A; Blaising, J J; Blyth, S C; Bobbink, Gerjan J; Böhm, A; Boldizsar, L; Borgia, B; Bottai, S; Bourilkov, D; Bourquin, Maurice; Braccini, S; Branson, J G; Brochu, F; Burger, J D; Burger, W J; Cai, X D; Capell, M; Cara Romeo, G; Carlino, G; Cartacci, A M; Casaus, J; Cavallari, F; Cavallo, N; Cecchi, C; Cerrada, M; Chamizo-Llatas, M; Chang, Y H; Chemarin, M; Chen, A; Chen, G; Chen, G M; Chen, H F; Chen, H S; Chiefari, G; Cifarelli, Luisa; Cindolo, F; Clare, I; Clare, R; Coignet, G; Colino, N; Costantini, S; de la Cruz, B; Cucciarelli, S; van Dalen, J A; De Asmundis, R; Déglon, P L; Debreczeni, J; Degré, A; Dehmelt, K; Deiters, K; Della Volpe, D; Delmeire, E; Denes, P; De Notaristefani, F; De Salvo, A; Diemoz, M; Dierckxsens, M; Dionisi, C; Dittmar, Michael; Doria, A; Dova, M T; Duchesneau, D; Echenard, B; Eline, A; El-Mamouni, H; Engler, A; Eppling, F J; Ewers, A; Extermann, Pierre; Falagán, M A; Falciano, S; Favara, A; Fay, J; Fedin, O; Felcini, Marta; Ferguson, T; Fesefeldt, H S; Fiandrini, E; Field, J H; Filthaut, Frank; Fisher, P H; Fisher, W; Fisk, I; Forconi, G; Freudenreich, Klaus; Furetta, C; Galaktionov, Yu; Ganguli, S N; García-Abia, P; Gataullin, M; Gentile, S; Giagu, S; Gong, Z F; Grenier, G; Grimm, O; Grünewald, M W; Guida, M; van Gulik, R; Gupta, V K; Gurtu, A; Gutay, L J; Haas, D; Hakobyan, R S; Hatzifotiadou, D; Hebbeker, T; Hervé, A; Hirschfelder, J; Hofer, H; Hohlmann, M; Holzner, G; Hou, S R; Hu, Y; Jin, B N; Jones, L W; de Jong, P; Josa-Mutuberria, I; Käfer, D; Kaur, M; Kienzle-Focacci, M N; Kim, J K; Kirkby, Jasper; Kittel, E W; Klimentov, A; König, A C; Kopal, M; Koutsenko, V F; Kräber, M H; Krämer, R W; Krenz, W; Krüger, A; Kunin, A; Ladrón de Guevara, P; Laktineh, I; Landi, G; Latt, J; Lebeau, M; Lebedev, A; Lebrun, P; Lecomte, P; Lecoq, P; Le Coultre, P; Le Goff, J M; Leiste, R; Levtchenko, M; Levchenko, P M; Li, C; Likhoded, S A; Lin, C H; Lin, W T; Linde, Frank L; Lista, L; Liu, Z A; Lohmann, W; Longo, E; Lü, Y S; Lübelsmeyer, K; Luci, C; Luminari, L; Lustermann, W; Ma Wen Gan; Malgeri, L; Malinin, A; Maña, C; Mangeol, D J J; Mans, J; Martin, J P; Marzano, F; Mazumdar, K; McNeil, R R; Mele, S; Merola, L; Meschini, M; Metzger, W J; Mihul, A; Milcent, H; Mirabelli, G; Mnich, J; Mohanty, G B; Muanza, G S; Muijs, A J M; Musicar, B; Musy, M; Nagy, S; Natale, S; Napolitano, M; Nessi-Tedaldi, F; Newman, H; Niessen, T; Nisati, A; Nowak, H; Ofierzynski, R A; Organtini, G; Palomares, C; Pandoulas, D; Paolucci, P; Paramatti, R; Passaleva, G; Patricelli, S; Paul, T; Pauluzzi, M; Paus, C; Pauss, Felicitas; Pedace, M; Pensotti, S; Perret-Gallix, D; Petersen, B; Piccolo, D; Pierella, F; Pioppi, M; Piroué, P A; Pistolesi, E; Plyaskin, V; Pohl, M; Pozhidaev, V; Pothier, J; Prokofiev, D O; Prokofev, D; Quartieri, J; Rahal-Callot, G; Rahaman, M A; Raics, P; Raja, N; Ramelli, R; Rancoita, P G; Ranieri, R; Raspereza, A V; Razis, P A; Ren, D; Rescigno, M; Reucroft, S; Riemann, S; Riles, K; Roe, B P; Romero, L; Rosca, A; Rosier-Lees, S; Roth, S; Rosenbleck, C; Roux, B; Rubio, Juan Antonio; Ruggiero, G; Rykaczewski, H; Sakharov, A; Saremi, S; Sarkar, S; Salicio, J; Sánchez, E; Sanders, M P; Schäfer, C; Shchegelskii, V; Schmidt-Kärst, S; Schmitz, D; Schopper, Herwig Franz; Schotanus, D J; Schwering, G; Sciacca, C; Servoli, L; Shevchenko, S; Shivarov, N; Shoutko, V; Shumilov, E; Shvorob, A V; Siedenburg, T; Son, D; Souga, C; Spillantini, P; Steuer, M; Stickland, D P; Stoyanov, B; Strässner, A; Sudhakar, K; Sultanov, G G; Sun, L Z; Sushkov, S V; Suter, H; Swain, J D; Szillási, Z; Tang, X W; Tarjan, P; Tauscher, Ludwig; Taylor, L; Tellili, B; Teyssier, D; Timmermans, C; Ting, Samuel C C; Ting, S M; Tonwar, S C; Tóth, J; Tully, C; Tung, K L; Ulbricht, J; Valente, E; Van de Walle, R T; Vásquez, R P; Veszpremi, V; Vesztergombi, G; Vetlitskii, I; Vicinanza, D; Viertel, Gert M; Villa, S; Vivargent, M; Vlachos, S; Vodopyanov, I; Vogel, H; Vogt, H; Vorobev, I; Vorobyov, A A; Wadhwa, M; Wallraff, W; Wang, X L; Wang, Z M; Weber, M; Wienemann, P; Wilkens, H; Wynhoff, S; Xia, L; Xu, Z Z; Yamamoto, J; Yang, B Z; Yang, C G; Yang, H J; Yang, M; Yeh, S C; Zalite, A; Zalite, Yu; Zhang, Z P; Zhao, J; Zhu, G Y; Zhu, R Y; Zhuang, H L; Zichichi, A; Zimmermann, B; Zöller, M

    2002-01-01

    The cross section of the process e^+ e^- -> Z \\gamma\\gamma -> qq~ \\gamma \\gamma is measured with 215 pb^-1 of data collected with the L3 detector during the final LEP run at centre-of-mass energies around 205 GeV and 207 GeV. No deviation from the Standard Model expectation is observed. The full data sample of 713 pb^-1, collected above the Z resonance, is used to constrain the coefficients of anomalous quartic gauge boson couplings to: -0.02 GeV^-2 < a_0/\\Lambda^2 < 0.03 GeV^-2 and -0.07 GeV^-2 < a_c/\\Lambda^2 < 0.05 GeV^-2, at 95% confidence level.

  15. Role of self-assembly coated Er(3+): YAlO3/TiO2 in intimate coupling of visible-light-responsive photocatalysis and biodegradation reactions.

    Science.gov (United States)

    Dong, Shanshan; Dong, Shuangshi; Tian, Xiadi; Xu, Zhengxue; Ma, Dongmei; Cui, Bin; Ren, Nanqi; Rittmann, Bruce E

    2016-01-25

    Conventionally used ultraviolet light can result in dissolved organic carbon (DOC) increasing and biofilm damage in intimate coupling of photocatalysis and biodegradation (ICPB). Visible-light-responsive photocatalysis offers an alternative for achieving ICPB. In this study, composite-cubes were developed using self-assembly to coat a thin and even layer of visible-light-responsive photocatalyst (Er(3+): YAlO3/TiO2) on sponge-type carriers, followed by biofilm cultivation. The degradations of phenol (50 mg L(-1)) were compared for four protocols in circulating beds: adsorption (AD), visible-light-responsive photocatalysis (VPC), biodegradation (B), and intimately coupled visible-light-responsive photocatalysis and biodegradation (VPCB). The phenol and DOC removal efficiencies using VPCB in 16 h were 99.8% and 65.2%, respectively, i.e., higher than those achieved using VPC (71.6% and 50.0%) or B (99.4% and 58.2%). The phenol removal of 96.3% could be obtained even after 3 additional cycles. The 6.17-min intermediate detected by HPLC, continuously accumulated for VPC, appeared at 1-6 h and then was completely removed for VPCB in 10 h. ICPB was further illustrated in that most of the biofilm was protected in the carrier interiors, with less protection on the carrier exterior in VPCB. A self-regulation mechanism that helped photocatalyst exposure to visible-light irradiation was identified, promoting the combined photocatalysis and biodegradation. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Determination of {sup 90}Sr in soil samples using inductively coupled plasma mass spectrometry equipped with dynamic reaction cell (ICP-DRC-MS)

    Energy Technology Data Exchange (ETDEWEB)

    Feuerstein, J.; Boulyga, S.F.; Galler, P.; Stingeder, G. [Department of Chemistry, Division of Analytical Chemistry-VIRIS Laboratory, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna (Austria); Prohaska, T. [Department of Chemistry, Division of Analytical Chemistry-VIRIS Laboratory, University of Natural Resources and Applied Life Sciences, Muthgasse 18, A-1190 Vienna (Austria)], E-mail: thomas.prohaska@boku.ac.at

    2008-11-15

    A rapid method is reported for the determination of {sup 90}Sr in contaminated soil samples in the vicinity of the Chernobyl Nuclear Power Plant by ICP-DRC-MS. Sample preparation and measurement procedures focus on overcoming the isobaric interference of {sup 90}Zr, which is present in soils at concentrations higher by more than six orders of magnitude than {sup 90}Sr. Zirconium was separated from strontium in two steps to reduce the interference by {sup 90}Zr{sup +} ions by a factor of more than 10{sup 7}: (i) by ion exchange using a Sr-specific resin and (ii) by reaction with oxygen as reaction gas in a dynamic reaction cell (DRC) of a quadrupole ICP-MS. The relative abundance sensitivity of the ICP-MS was studied systematically and the peak tailing originating from {sup 88}Sr on mass 90 u was found to be about 3 x 10{sup -9}. Detection limits of 4 fg g{sup -1} (0.02 Bq g{sup -1}) were achieved when measuring Sr solutions containing no Zr. In digested uncontaminated soil samples after matrix separation as well as in a solution of 5 {mu}g g{sup -1} Sr and 50 ng g{sup -1} Zr a detection limit of 0.2 pg g{sup -1} soil (1 Bq g{sup -1} soil) was determined. {sup 90}Sr concentrations in three soil samples collected in the vicinity of the Chernobyl Nuclear Power Plant were 4.66 {+-} 0.27, 13.48 {+-} 0.68 and 12.9 {+-} 1.5 pg g{sup -1} corresponding to specific activities of 23.7 {+-} 1.3, 68.6 {+-} 3.5 and 65.6 {+-} 7.8 Bq g{sup -1}, respectively. The ICP-DRC-MS results were compared to the activities measured earlier by radiometry. Although the ICP-DRC-MS is inferior to commonly used radiometric methods with respect to the achievable minimum detectable activity it represents a time- and cost-effective alternative technique for fast monitoring of high-level {sup 90}Sr contamination in environmental or nuclear industrial samples down to activities of about 1 Bq g{sup -1}.

  17. Multi-elements (aluminium, copper, magnesium, manganese, selenium and zinc) determination in serum by dynamic reaction cell-inductively coupled plasma-mass spectrometry.

    Science.gov (United States)

    Wah Fong, Bonnie Mei; Siu, Tak Shing; Kit Lee, Joseph Sai; Tam, Sidney

    2009-01-01

    Trace element determination in laboratory medicine is widely carried out by atomic absorption or emission spectroscopy. In the last decade, there has been a rapid growth in the use of inductively coupled plasma-mass spectrometry because of its strong detection power, and the possibility of multi-elements analysis in a single run. Having the advantages of smaller sample volume and better detection limit, we developed a method for the simultaneous determinations of six trace elements by using 100 microL serum, and the assay can be accomplished within 3 min. The method developed gave recovery of the six elements ranging from 97% to 117%. The method covered a wide dynamic range with manganese in the range of nmol/L, while magnesium was in the range of mmol/L. The detection limits were 0.001 mmol/L, 0.05 micromol/L, 2.0 nmol/L, 0.2 micromol/L, 0.05 micromol/L, and 0.01 micromol/L for magnesium, aluminium, manganese, copper, zinc, and selenium, respectively. All the six elements had intra-assay imprecision of less than 5%, and inter-assay imprecision of less than 8%. This fast and robust method is suitable for use in the clinical laboratory where short turnaround time is needed for managing patients with trace element deficiency or toxicity.

  18. Serial processing of biological reactions using flow-through microfluidic devices: coupled PCR/LDR for the detection of low-abundant DNA point mutations.

    Science.gov (United States)

    Hashimoto, Masahiko; Barany, Francis; Xu, Feng; Soper, Steven A

    2007-09-01

    We have fabricated a flow-through biochip consisting of passive elements for the analysis of single base mutations in genomic DNA using polycarbonate (PC) as the substrate. The biochip was configured to carry out two processing steps on the input sample, a primary polymerase chain reaction (PCR) followed by an allele-specific ligation detection reaction (LDR) for scoring the presence of low abundant point mutations in genomic DNA. The operation of the device was demonstrated by detecting single nucleotide polymorphisms in gene fragments (K-ras) that carry high diagnostic value for colorectal cancers. The effect of carryover from the primary PCR on the subsequent LDR was investigated in terms of LDR yield and fidelity. We found that a post-PCR treatment step prior to the LDR phase of the assay was not essential. As a consequence, a thermal cycling microchip was used for a sequential PCR/LDR in a simple continuous-flow format, in which the following three steps were carried out: (1) exponential amplification of the gene fragments from genomic DNA; (2) mixing of the resultant PCR product(s) with an LDR cocktail via a Y-shaped passive micromixer; and (3) ligation of two primers (discriminating primer that carried the complement base to the mutation locus being interrogated and a common primer) only when the particular mutation was present in the genomic DNA. We successfully demonstrated the ability to detect one mutant DNA in 1000 normal sequences with the integrated microfluidic system. The PCR/LDR assay using the microchip performed the entire assay at a relatively fast processing speed: 18.7 min for 30 rounds of PCR, 4.1 min for 13 rounds of LDR (total processing time = ca. 22.8 min) and could screen multiple mutations simultaneously in a multiplexed format. In addition, the low cost of the biochip due to the fact that it was fabricated from polymers using replication technologies and consisted of passive elements makes the platform amenable to clinical diagnostics

  19. A revised method for determination of serum mercaptalbumin and non-mercaptalbumin by high-performance liquid chromatography coupled with postcolumn bromocresol green reaction.

    Science.gov (United States)

    Ueyama, Jun; Ishikawa, Yusuke; Kondo, Takaaki; Motoyama, Megumi; Matsumoto, Hiroyuki; Matsushita, Tadashi

    2015-01-01

    Previously, high-performance liquid chromatography (HPLC) equipped with ultraviolet or fluorescence detectors has been used for separation of human mercaptalbumin (HMA) and human non-mercaptalbumin (HNA). However, it is difficult to perform reliable chromatographic analysis due to peak interference of such serum compounds as uric acid and bilirubin. The aim of this study is to explore a selective and simple analytical method for the determination of HMA and HNA. HMA and HNA in serum sample were separated by HPLC and reacted with bromocresol green using a postcolumn reaction scheme. A complete separation of HMA and HNA is achieved in less than 30 min by using weak anion exchange columns and isocratic elution. Within-run and between-day precisions at albumin concentration of 45 g/L were 4.2 and 1.7% for HMA and 4.5 and 4.6% for HNA, respectively. There was no interference in HMA and HNA peaks when bilirubin-, haemoglobin- or chyle-spiked pooled serum samples were analysed. Our method is reliable and not labour-intensive and, therefore, might be applicable for clinical and epidemiological studies. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  20. Multiplex Reverse-Transcription Loop-Mediated Isothermal Amplification Coupled with Cascade Invasive Reaction and Nanoparticle Hybridization for Subtyping of Influenza A Virus

    Science.gov (United States)

    Chi, Ying; Ge, Yiyue; Zhao, Kangchen; Zou, Bingjie; Liu, Bin; Qi, Xian; Bian, Qian; Shi, Zhiyang; Zhu, Fengcai; Zhou, Minghao; Cui, Lunbiao; Su, Chuan

    2017-01-01

    Considering the fatal human victims and economic loss caused by influenza virus infection every year, methodologies for rapid and on-site detection of influenza viruses are urgently needed. LAMP is the most commonly used nucleic acid isothermal amplification technology suitable for on-site use. However, for multiplex LAMP, differentiation of the amplicons derived from multiple targets is still challengeable currently. Here we developed a multiplex RT-LAMP assay for simultaneous amplification of three prominent subtypes of influenza viruses (A/H5, A/H7 and 2009A/H1). The amplicons were further identified by cascade invasive reaction and nanoparticle hybridization in separate target-specific detection tubes (referred to as mRT-LAMP-IRNH). The analytic sensitivities of the assay are 10 copies of RNA for all the three HA subtypes, and the specificity reached 100%. Clinical specimen analysis showed this assay had a combined sensitivity and specificity of 98.1% and 100%, respectively. Overall, the mRT-LAMP-IRNH assay can be used as a cost-saving method that utilizes a simple instrument to detect A/H5, A/H7, and 2009A/H1 influenza viruses, especially in resource-limited settings. PMID:28322309

  1. Silica-acac-supported palladium nanoparticles as an efficient and ...

    Indian Academy of Sciences (India)

    -supported palladium nanoparticles as an efficient and reusable heterogeneous catalyst in the Suzuki-Miyaura cross-coupling reaction in water. Abdol Reza Hajipour Zohre Shirdashtzade Ghobad Azizi. Volume 126 Issue 1 January 2014 pp ...

  2. Synthesis of Monochlorosilyl Derivatives of Dialkyloligothiophenes for Self-Assembling Mono layer Field-Effect Transistors

    NARCIS (Netherlands)

    Ponomarenko, Sergei A.; Borshchev, Oleg V.; Meyer-Friedrichsen, Timo; Pleshkova, Alexandra P.; Setayesh, Sepas; Smits, Edsger C. P.; Mathijssen, Simon G. J.; de Leeuw, Dago M.; Kirchmeyer, Stephan; Muzafarov, Aziz M.

    2010-01-01

    Unsymmetrical dimethylchlorosilyl-substituted alpha,alpha'-dialkylquater-, quinque-, and sexithiophenes were designed and successfully synthesized by a combination of Kumada and Suzuki cross-coupling reactions followed by hydrosilylation. Optimization possibilities of the hydrosilylation of

  3. Synthesis of monochlorosilyl derivatives of dialkyloligothiophenes for self-assembling monolayer field-effect transistors

    NARCIS (Netherlands)

    Ponomarenko, S.A.; Borshchev, O.V.; Meyer-Friedrichsen, T.; Pleshkova, A.P.; Setayesh, S.; Smits, E.C.P.; Mathijssen, S.G.J.; Leeuw, D.M. de; Kirchmeyer, S.; Muzafarov, A.M.

    2010-01-01

    Unsymmetrical dimethylchlorosilyl-substituted α, α′- dialkylquater-, quinque-, and sexithiophenes were designed and successfully synthesized by a combination of Kumada and Suzuki cross-coupling reactions followed by hydrosilylation. Optimization possibilities of the hydrosilylation of low-soluble

  4. Beyond Born-Oppenheimer theory for ab initio constructed diabatic potential energy surfaces of singlet H3+ to study reaction dynamics using coupled 3D time-dependent wave-packet approach.

    Science.gov (United States)

    Ghosh, Sandip; Mukherjee, Saikat; Mukherjee, Bijit; Mandal, Souvik; Sharma, Rahul; Chaudhury, Pinaki; Adhikari, Satrajit

    2017-08-21

    The workability of beyond Born-Oppenheimer theory to construct diabatic potential energy surfaces (PESs) of a charge transfer atom-diatom collision process has been explored by performing scattering calculations to extract accurate integral cross sections (ICSs) and rate constants for comparison with most recent experimental quantities. We calculate non-adiabatic coupling terms among the lowest three singlet states of H3+ system (11A', 21A', and 31A') using MRCI level of calculation and solve the adiabatic-diabatic transformation equation to formulate the diabatic Hamiltonian matrix of the same process [S. Mukherjee et al., J. Chem. Phys. 141, 204306 (2014)] for the entire region of nuclear configuration space. The nonadiabatic effects in the D+ + H2 reaction has been studied by implementing the coupled 3D time-dependent wave packet formalism in hyperspherical coordinates [S. Adhikari and A. J. C. Varandas, Comput. Phys. Commun. 184, 270 (2013)] with zero and non-zero total angular momentum (J) on such newly constructed accurate (ab initio) diabatic PESs of H3+. We have depicted the convergence profiles of reaction probabilities for the reactive non-charge transfer, non-reactive charge transfer, and reactive charge transfer processes for different collisional energies with respect to the helicity (K) and total angular momentum (J) quantum numbers. Finally, total and state-to-state ICSs are calculated as a function of collision energy for the initial rovibrational state (v = 0, j = 0) of the H2 molecule, and consequently, those quantities are compared with previous theoretical and experimental results.

  5. A field-scale reactive transport model for U(VI) migration influenced by coupled multirate mass transfer and surface complexation reactions

    Science.gov (United States)

    Ma, R.; Zheng, C.; Prommer, H.; Greskowiak, J.; Liu, C.; Zachara, J.; Rockhold, M.

    2010-05-01

    This study explores field-scale modeling of U(VI) reactive transport through incorporation of laboratory and field data. A field-scale reactive transport model was developed on the basis of laboratory-characterized U(VI) surface complexation reactions (SCRs) and multirate mass transfer processes, as well as field-measured hydrogeochemical conditions at the U.S. Department of Energy, Hanford 300 Area (300 A), Washington. The model was used to assess the importance of multirate mass transfer processes on U(VI) reactive transport and to evaluate the effect of variable geochemical conditions caused by dynamic river water-groundwater interactions on U(VI) plume migration. Model simulations revealed complex spatiotemporal relationships between groundwater composition and U(VI) speciation, adsorption, and plume migration. In general, river water intrusion enhances uranium adsorption and lowers aqueous uranium concentration because river water dilution increases pH and decreases aqueous bicarbonate concentration, leading to overall enhanced U(VI) surface complexation. Strong U(VI) retardation was computed for the field-measured hydrogeochemical conditions, suggesting a slow dissipation of the U(VI) plume, a phenomenon consistent with field observations. The simulations also showed that SCR-retarded U(VI) migration becomes more dynamic and synchronous with the groundwater flow field when multirate mass transfer processes are involved. Breakthrough curves at selected locations and the temporal changes in the calculated mass during the 20 year simulation period indicated that uranium adsorption/desorption never attained steady state because of the dynamic flow field and groundwater composition variations caused by river water intrusion. Thus, the multirate SCR model appears to be a crucial consideration for future reactive transport simulations of uranium contaminants at the Hanford 300 A site and elsewhere under similar hydrogeochemical conditions.

  6. Optimized synthesis of π-extended squaraine dyes relevant to organic electronics by direct (hetero)arylation and Sonogashira coupling reactions.

    Science.gov (United States)

    Payne, Abby-Jo; Welch, Gregory C

    2017-04-11

    This study reports on the synthesis and characterization of four molecular π-extended squaraine compounds relevant to the field of organic electronics. The compounds each consist of a bis-indole squaraine core end-capped with indoloquinoxaline units employing three different bridging units, namely thiophene, thiazole, and acetylene. Compound 10 bears a thiophene bridge, 11 consists of a thiophene bridge and fluorinated indoloquinoxaline terminal units, and compounds 12 and 13 are bridged by thiazole and acetylene, respectively. The final compounds are constructed using the atom economical direct (hetero)arylation or the classic Sonogashira carbon-carbon bond formation protocols. Each carbon-carbon bond forming reaction employing thiophene bridges (i.e. synthesis of compounds 10 and 11) has been optimized using the stable and reusable silica supported Pd catalyst, SiliaCat® DPP-Pd, streamlining the synthetic procedure. While compounds 12 and 13 were also accessible using the SiliaCat® DPP-Pd catalyst, the use of Herrmann-Beller and Pd(PPh3)4 catalysts, respectively, lead to improved isolated yields of the final materials. Compounds 10-13 were characterized by thermal gravimetric analysis, cyclic voltammetry, optical absorption spectroscopy, photoluminescence spectroscopy, and each structure was analysed using density functional theory. All compounds exhibit high thermal stability and good solubility in common organic solvents, including in the greener alternative 2-methyl tetrahydrofuran. The reported compounds display stable ambipolar redox behaviour, furthermore, we have demonstrated that the frontier molecular energy levels can be effectively tuned by changing the bridging unit as predicted by density functional theory. Most striking is the drastic optical absorption profile changes observed from this class of materials upon post-deposition film annealing, suggesting molecular rearrangement in the solid-state. The induced changes and fine structure observed

  7. Simultaneous quantification of 17 trace elements in blood by dynamic reaction cell inductively coupled plasma mass spectrometry (DRC-ICP-MS) equipped with a high-efficiency sample introduction system.

    Science.gov (United States)

    D'Ilio, S; Violante, N; Di Gregorio, M; Senofonte, O; Petrucci, F

    2006-10-10

    A quadrupole inductively coupled plasma mass spectrometer (Q-ICP-MS) equipped with a dynamic reaction cell (DRC) and coupled with a desolvating nebulization system (APEX-IR) was employed to determine 17 elements (Al, As, Ba, Cd, Co, Cr, Li, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, V, and Zr) in blood samples. Ammonia (for Al, Cr, Mn, and V) and O2 (for As and Se) were used as reacting gases. Selection of the best flow rate of the gases and optimization of the quadrupole dynamic bandpass tuning parameter (RPq) were carried out, using digested blood diluted 1+9 with deionized water and spiked with 1 microg L(-1) of Al, Cr, Mn, V and 5 microgL(-1) of As and Se. Detection limits were determined in digested blood using the 3sigma criterion. The desolvating system allowed a sufficient sensitivity to be achieved to determine elements at levels of ng L(-1) without detriment of signal stability. The accuracy of the method was tested with the whole blood certified reference material (CRM), certified for Al, As, Cd, Co, Cr, Mn, Mo, Ni, Pb, Sb, Se, and V, and with indicative values for Ba, Li, Sn, Sr, and Zr. The addition calibration approach was chosen for analysis. In order to confirm the DRC data, samples were also analyzed by means of sector field inductively coupled plasma mass spectrometry (SF-ICP-MS), operating in medium (m/Deltam=4000) and high (m/Deltam=10,000) resolution mode and achieving a good agreement between the two techniques.

  8. A surface enhanced Raman scattering quantitative analytical platform for detection of trace Cu coupled the catalytic reaction and gold nanoparticle aggregation with label-free Victoria blue B molecular probe.

    Science.gov (United States)

    Li, Chongning; Ouyang, Huixiang; Tang, Xueping; Wen, Guiqing; Liang, Aihui; Jiang, Zhiliang

    2017-01-15

    With development of economy and society, there is an urgent need to develop convenient and sensitive methods for detection of Cu2+ pollution in water. In this article, a simple and sensitive SERS sensor was proposed to quantitative analysis of trace Cu2+ in water. The SERS sensor platform was prepared a common gold nanoparticle (AuNP)-SiO2 sol substrate platform by adsorbing HSA, coupling with the catalytic reaction of Cu2+-ascorbic acid (H2A)-dissolved oxygen, and using label-free Victoria blue B (VBB) as SERS molecular probes. The SERS sensor platform response to the AuNP aggregations by hydroxyl radicals (•OH) oxidizing from the Cu2+ catalytic reaction, which caused the SERS signal enhancement. Therefore, by monitoring the increase of SERS signal, Cu2+ in water can be determined accurately. The results show that the SERS sensor platforms owns a linear response with a range from 0.025 to 25μmol/L Cu2+, and with a detection limit of 0.008μmol/L. In addition, the SERS method demonstrated good specificity for Cu2+, which can determined accurately trace Cu2+ in water samples, and good recovery and accuracy are obtained for the water samples. With its high selectivity and good accuracy, the sensitive SERS quantitative analysis method is expected to be a promising candidate for determining copper ions in environmental monitoring and food safety. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Oxidative coupling of methane over a La{sub 2}O{sub 3}/CaO catalyst. Optimization of reaction conditions in a bubbling fluidized-bed reactor

    Energy Technology Data Exchange (ETDEWEB)

    Mleczko, L.; Pannek, U.; Rothaemel, M.; Baerns, M. [Bochum Univ. (Germany). Technische Chemie

    1996-04-01

    Oxidative coupling of methane (OCM) over a La{sub 2}O{sub 3}/CaO catalyst was investigated in laboratory-scale fluidized-bed reactors in various ranges of reaction conditions. The catalyst proved to be a very active and selective material for OCM. It was fluidizable in the whole range of operating conditions, and catalytically stable. Axial gas concentration profiles showed that C{sub 2}+ selectivity was not only influenced by oxidative consecutive reactions, but also by steam reforming of ethylene. Two methods for improving C{sub 2}+ selectivity were tested: (1) dilution of the catalytic bed, and (2) operation with lean feed. Dilution of the catalyst led to a slight (1-2%) decrease in selectivity. Dilution of the feed gas with nitrogen resulted in a small improvement (<2%) in C{sub 2}+ selectivity. Although not currently viable economically, given certain changes in the future, this catalyst may find application in OCM, which is the potentially prospective route for the direct conversion of methane. 33 refs., 5 figs.

  10. Nanosheet Array-Like Palladium-Catalysts Pdx/rGO@CoAl-LDH via Lattice Atomic-Confined in Situ Reduction for Highly Efficient Heck Coupling Reaction.

    Science.gov (United States)

    Wang, Yanna; Dou, Liguang; Zhang, Hui

    2017-11-08

    A series of novel nanosheet array-like catalysts Pdx/rGO@CoAl-LDH (x = 0.0098-1.9, refers to Pd loading in wt % on ICP, rGO: reduced graphene oxide, LDH: layered double hydroxide) were first prepared via a simple and green lattice atomic-confined in situ reduction of oxidative Pd precursors by the evenly atomic-dispersed reductive Co2+ sites on LDH layers of a nanohybrid rGO@CoAl-LDH with hexagonal LDH nanoplates (∼73 × 7 nm) interdigitated vertical to the surfaces of rGO layer in both sides, fabricated through a simple citric acid-assisted aqueous-phase coprecipitation method. The as-obtained Pd catalysts possess clean Pd nanoclusters (NCs) with tunable sizes in 1.3-1.8 nm on varied Pd loadings. All the Pdx/rGO@CoAl-LDH catalysts show excellent activities for the Heck reaction, and the Pd0.0098/rGO@CoAl-LDH with the ultrafine Pd NCs of 1.3 ± 0.2 nm yields a maximum turnover frequency of 160 000 h-1 over a heterogeneous catalyst so far. The excellent activities can be attributed to the ultrasmall Pd NCs with high dispersion and clean Pd surfaces, increased electron transfer capacity and surface area, and remarkable Pd-CoAl-LDH-rGO three-phase synergistic effect of the present unique nanosheet array-like Pd NCs catalysts. Moreover, the catalyst Pd0.33/rGO@CoAl-LDH shows a broad range of substrate applicability and can be reused more than five runs without obvious loss of activity, giving the present catalysts long-term stability. These findings make the rGO@CoAl-LDH hybrid prepared by a facile and scalable synthesis route a universal green platform to support other noble or nonprecious metal NCs via lattice atomic-confined in situ reduction strategy to construct more desired heterogeneous catalysts.

  11. Energy-Storage Applications for a pH Gradient between Two Benzimidazole-Ligated Ruthenium Complexes That Engage in Proton-Coupled Electron-Transfer Reactions in Solution.

    Science.gov (United States)

    Motoyama, Daisuke; Yoshikawa, Kai; Ozawa, Hiroaki; Tadokoro, Makoto; Haga, Masa-Aki

    2017-06-05

    The judicious selection of pairs of benzimidazole-ligated ruthenium complexes allowed the construction of a rechargeable proton-coupled electron-transfer (PCET)-type redox battery. A series of ruthenium(II) and -(III) complexes were synthesized that contain substituted benzimidazoles that engage in PCET reactions. The formation of intramolecular Ru-C cyclometalation bonds stabilized the resulting ruthenium(III) complexes, in which pK a values of the imino N-H protons on the benzimidazoles are usually lower than those for the corresponding ruthenium(II) complexes. As a proof-of-concept study for a solution redox battery based on such PCET reactions, the charging/discharging cycles of several pairs of ruthenium complexes were examined by chronopotentiometry in an H-type device with half-cells separated by a Nafion membrane in unbuffered CH 3 CN/H 2 O (1/1, v/v) containing 0.1 M NaCl. During the charging/discharging cycles, the pH value of the solution gradually changed accompanied by a change of the open-circuit potential (OCP). The changes for the OCP and pH value of the solution in the anodic and cathodic half-cells were in good agreement with the predicted values from the Pourbaix diagrams for the pairs of ruthenium complexes used. Accordingly, the careful selection of pairs of ruthenium complexes with a sufficient potential gradient and a suitably large pK a difference is crucial: the charge generated between the two ruthenium complexes changes the OCP and the pH difference between the two cells in an unbuffered solution, given that the PCET reactions occur at both electrodes and that discharging leads to the original state. Because the electric energy is stored as a pH gradient between the half-cells, new possibilities for PCET-type rocking-chair redox batteries arise.

  12. A Polyphenylene Support for Pd Catalysts with Exceptional Catalytic Activity

    DEFF Research Database (Denmark)

    Wang, Feng; Mielby, Jerrik Jørgen; Richter, Felix Herrmann

    2014-01-01

    We describe a solid polyphenylene support that serves as an excellent platform for metal-catalyzed reactions that are normally carried out under homogeneous conditions. The catalyst is synthesized by palladium-catalyzed Suzuki coupling which directly results in formation of palladium nanoparticles...... confined to a porous polyphenylene network. The composite solid is in turn highly active for further Suzuki coupling reactions, including non-activated substrates that are challenging even for molecular catalysts....

  13. 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.

  14. Optimization of collision/reaction gases for determination of 90Sr in atmospheric particulate matter by inductively coupled plasma tandem mass spectrometry after direct introduction of air via a gas-exchange device

    Science.gov (United States)

    Suzuki, Yoshinari; Ohara, Ryota; Matsunaga, Kirara

    2017-09-01

    Nuclear power plant accidents release radioactive strontium 90 (90Sr) into the environment. Monitoring of 90Sr, although important, is difficult and time consuming because it emits only beta radiation. We have developed a new analytical system that enables real-time analysis of 90Sr in atmospheric particulate matter with an analytical run time of only 10 min. Briefly, after passage of an air sample through an impactor, a small fraction of the sample is introduced into a gas-exchange device, where the air is replaced by Ar. Then the sample is directly introduced into an inductively coupled plasma tandem mass spectrometry (ICP-MS/MS) system equipped with a collision/reaction cell to eliminate isobaric interferences on 90Sr from 90Zr+, 89Y1H+, and 90Y+. Experiments with various reaction gas conditions revealed that these interferences could be minimized under the following optimized conditions: 1.0 mL min- 1 O2, 10.0 mL min- 1 H2, and 1.0 mL min- 1 NH3. The estimated background equivalent concentration and estimated detection limit of the system were 9.7 × 10- 4 and 3.6 × 10- 4 ng m- 3, respectively, which are equivalent to 4.9 × 10- 6 and 1.8 × 10- 6 Bq cm- 3. Recoveries of Sr in PM2.5 measured by real-time analysis compared to those obtained by simultaneously collection on filter was 53 ± 23%, and using this recovery, the detection limit as PM2.5 was estimated to be 3.4 ± 1.5 × 10- 6 Bq cm- 3. That is, this system enabled detection of 90Sr at concentrations < 5 × 10- 6 Bq cm- 3 even considering the insufficient fusion/vaporization/ionization efficiency of Sr in PM2.5.

  15. A Focused Multiple Reaction Monitoring (MRM Quantitative Method for Bioactive Grapevine Stilbenes by Ultra-High-Performance Liquid Chromatography Coupled to Triple-Quadrupole Mass Spectrometry (UHPLC-QqQ

    Directory of Open Access Journals (Sweden)

    Elías Hurtado-Gaitán

    2017-03-01

    Full Text Available Grapevine stilbenes are a family of polyphenols which derive from trans-resveratrol having antifungal and antimicrobial properties, thus being considered as phytoalexins. In addition to their diverse bioactive properties in animal models, they highlight a strong potential in human health maintenance and promotion. Due to this relevance, highly-specific qualitative and quantitative methods of analysis are necessary to accurately analyze stilbenes in different matrices derived from grapevine. Here, we developed a rapid, sensitive, and specific analysis method using ultra-high-performance liquid chromatography coupled to triple-quadrupole mass spectrometry (UHPLC-QqQ in MRM mode to detect and quantify five grapevine stilbenes, trans-resveratrol, trans-piceid, trans-piceatannol, trans-pterostilbene, and trans-ε-viniferin, whose interest in relation to human health is continuously growing. The method was optimized to minimize in-source fragmentation of piceid and to avoid co-elution of cis-piceid and trans-resveratrol, as both are detected with resveratrol transitions. The applicability of the developed method of stilbene analysis was tested successfully in different complex matrices including cellular extracts of Vitis vinifera cell cultures, reaction media of biotransformation assays, and red wine.

  16. Profile and quantification of human stratum corneum ceramides by normal-phase liquid chromatography coupled with dynamic multiple reaction monitoring of mass spectrometry: development of targeted lipidomic method and application to human stratum corneum of different age groups.

    Science.gov (United States)

    Jia, Zhi-Xin; Zhang, Jin-Lan; Shen, Chun-Ping; Ma, Lin

    2016-09-01

    Skin, the largest organ of the human body, serves as the primary barrier to the external environment. Ceramides are one of the main constituents of stratum corneum (SC), playing an important role in skin barrier function. Therefore, comprehensive profiling and quantification of SC ceramide is important. Herein, a new targeted lipidomic method for human SC ceramide profiling and quantification is presented and tested. Normal-phase high-performance liquid chromatography coupled with dynamic multiple reaction monitoring mass spectrometry (NP-HPLC-dMRM-MS) was used to separate ceramides into subclasses and then characterize different ceramides within each subclass on the basis of their characteristics. In total, 483 ceramides were quantified in a single run within 20 min, covering 12 subclasses as well as some glycosylated ceramides not previously reported. Each subclass had typical standard substances (if available) that served to establish representative standard curves and were used for related substances with no standards. Linearity range, limit of quantification (LOQ), limit of detection (LOD), precision, accuracy, stability, and matrix effects were validated. dMRM increased sensitivity and accuracy greatly compared with common MRM (cMRM). This method was successfully applied to the study of human SC from different age groups. A total of 193 potential biomarkers were found to indicate age differences between children and adults. This method is an innovative approach for high-throughput quantification of SC ceramide. Graphical Abstract Method establishment (MRM spectra by the established method) and method application (score scatter plots of authentic samples).

  17. Reaction Automata

    OpenAIRE

    Okubo, Fumiya; Kobayashi, Satoshi; YOKOMORI, Takashi

    2011-01-01

    Reaction systems are a formal model that has been introduced to investigate the interactive behaviors of biochemical reactions. Based on the formal framework of reaction systems, we propose new computing models called reaction automata that feature (string) language acceptors with multiset manipulation as a computing mechanism, and show that reaction automata are computationally Turing universal. Further, some subclasses of reaction automata with space complexity are investigated and their la...

  18. Autocatalysis in Reaction Networks

    OpenAIRE

    Deshpande, Abhishek; Gopalkrishnan, Manoj

    2013-01-01

    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view to...

  19. The Glaser–Hay reaction

    DEFF Research Database (Denmark)

    Vilhelmsen, Mie Højer; Jensen, Jonas; Tortzen, Christian

    2013-01-01

    . This unfavorable change in reaction profile could be avoided by adding molecular sieves to the reaction mixture, thereby removing the water that is accumulated from the air and produced in the reaction in which dioxygen acts as the oxidizing agent. Not unexpectedly, the stirring rate, and hence uptake of air (O2......), was found to have a significant effect on the rate of the reaction: The percentage of alkyne remaining after a certain time decreased linearly with the rate of stirring. On the basis of systematic studies, the optimized conditions for the coupling reaction using CuCl/TMEDA as the catalyst system......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...

  20. Synthesis of diverse indole libraries on polystyrene resin – Scope and limitations of an organometallic reaction on solid supports

    Directory of Open Access Journals (Sweden)

    Kerstin Knepper

    2012-07-01

    Full Text Available The synthesis of diverse substituted indole structures on solid supports is described. The immobilization of nitrobenzoic acid onto Merrifield resin and the subsequent treatment with alkenyl Grignard reagents delivered indole carboxylates bound to solid supports. In contrast to results in the liquid phase, ortho,ortho-unsubstituted nitroarenes also delivered indole moieties in good yields. Subsequent palladium-catalyzed reactions (Suzuki, Heck, Sonogashira, Stille delivered, after cleavage, the desired molecules in moderate to good yields over four steps. The scope and limitations are presented.

  1. Daily Coffee Intake Inhibits Pancreatic Beta Cell Damage and Nonalcoholic Steatohepatitis in a Mouse Model of Spontaneous Metabolic Syndrome, Tsumura-Suzuki Obese Diabetic Mice.

    Science.gov (United States)

    Watanabe, Syunsuke; Takahashi, Tetsuyuki; Ogawa, Hirohisa; Uehara, Hisanori; Tsunematsu, Takaaki; Baba, Hayato; Morimoto, Yuki; Tsuneyama, Koichi

    2017-05-01

    Metabolic syndrome is one of the most important health issues worldwide. Obesity causes insulin resistance, hyperlipidemia, diabetes, and various diseases throughout the body. The liver phenotype, which is called nonalcoholic steatohepatitis (NASH), frequently progresses to hepatocellular carcinoma. We recently established a new animal model, Tsumura-Suzuki obese diabetic (TSOD) mice, which spontaneously exhibit obesity, diabetes, hyperlipidemia, and NASH with liver nodules. We examined the effects of coffee intake on various conditions of the metabolic syndrome using TSOD mice. The daily volume of coffee administered was limited so that it reflected the appropriate quantities consumed in humans. To clarify the effects of the specific components, animals were divided into two coffee-intake groups that included with and without caffeine. Coffee intake did not significantly affect obesity and hyperlipidemia in TSOD mice. In contrast, coffee intake caused various degrees of improvement in the pancreatic beta cell damage and steatohepatitis with liver carcinogenesis. Most of the effects were believed to be caused by a synergistic effect of caffeine with other components such as polyphenols. However, the antifibrotic effects of coffee appeared to be due to the polyphenols rather than the caffeine. A daily habit of drinking coffee could possibly play a role in the prevention of metabolic syndrome.

  2. Studies of the thermal dissolution process of the Suzuki phase of the Eu{sup 2+} ion in KBr single crystals by analysis of photoacoustic signals

    Energy Technology Data Exchange (ETDEWEB)

    MejIa-Uriarte, E V [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Laboratorio de FotofIsica, Universidad Nacional Autonoma de Mexico, AP 70-186, CP 04510 Mexico, DF (Mexico); Castaneda-Guzman, R [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Laboratorio de FotofIsica, Universidad Nacional Autonoma de Mexico, AP 70-186, CP 04510 Mexico, DF (Mexico); Villagran-Muniz, M [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Laboratorio de FotofIsica, Universidad Nacional Autonoma de Mexico, AP 70-186, CP 04510 Mexico, DF (Mexico); Camarillo, E [Instituto de FIsica, Universidad Nacional Autonoma de Mexico, AP 20-364, CP 01000 Mexico, DF (Mexico); A, J Hernandez [Instituto de FIsica, Universidad Nacional Autonoma de Mexico, AP 20-364, CP 01000 Mexico, DF (Mexico); S, H Murrieta [Instituto de FIsica, Universidad Nacional Autonoma de Mexico, AP 20-364, CP 01000 Mexico, DF (Mexico); Navarrete, M [Instituto de IngenierIa, Coordinacion de IngenierIa Mecanica Termica y Fluidos, Universidad Nacional Autonoma de Mexico, AP 70-543, Mexico, DF (Mexico)

    2003-10-15

    An experimental investigation of the thermal behaviour of the dissolution process of the Suzuki phase (SP) by continuous heating (1 deg. C min{sup -1}) of KBr:Eu{sup 2+} crystals is reported in this work. The thermal profiles were determined by the correlation functions between subsequent photoacoustic (PA) signals registered during the dissolution process. The behaviour of the thermal profile is directly related to the absorption coefficient of the Eu{sup 2+} ion in precipitated states that are present in the crystal. The PA signal is detected as a consequence of the non-radiative processes that take place after the excitation of the low-energy band of the Eu{sup 2+} ion by means of a focused laser pulse at 355 nm. The results obtained by this method are compared with those simultaneously obtained by the photoluminescence (PL) technique. The samples were heated from room temperature to 205 deg. C. The PA signal and PL spectrum were obtained every 6 deg. C. The temperature range of the SP dissolution process was from 77 to 115 deg. C. These results are in agreement with those obtained by the PL technique and with the data reported in the literature.

  3. Ion-exchange reactions on clay minerals coupled with advection/dispersion processes. Application to Na+/Ca2+ exchange on vermiculite: Reactive-transport modeling, batch and stirred flow-through reactor experiments

    Science.gov (United States)

    Tertre, E.; Hubert, F.; Bruzac, S.; Pacreau, M.; Ferrage, E.; Prêt, D.

    2013-07-01

    The present study aims at testing the validity of using an Na+/Ca2+ ion-exchange model, derived from batch data to interpret experimental Ca2+-for-Na+ exchange breakthrough curves obtained on vermiculite (a common swelling clay mineral in surface environments). The ion-exchange model was constructed considering the multi-site nature of the vermiculite surface as well as the exchange of all aqueous species (Mg2+ derived from the dissolution of the solid and H+). The proposed ion-exchange model was then coupled with a transport model, and the predicted breakthrough curves were compared with the experimental ones obtained using a well stirred flow-through reactor. For a given solute residence time in the reactor (typically 50 min), our thermodynamic model based on instantaneous equilibrium was found to accurately reproduce several of the experimental breakthrough curves, depending on the Na+ and Ca2+ concentrations of the influents pumped through the reactor. However the model failed to reproduce experimental breakthrough curves obtained at high flow rates and low chemical gradient between the exchanger phase and the solution. An alternative model based on a hybrid equilibrium/kinetic approach was thus used and allowed predicting experimental data. Based on these results, we show that a simple parameter can be used to differentiate between thermodynamic and kinetic control of the exchange reaction with water flow. The results of this study are relevant for natural systems where two aquatic environments having contrasted chemistries interact. Indeed, the question regarding the attainment of a full equilibrium in such a system during the contact time of the aqueous phase with the particle/colloid remains most often open. In this context, we show that when a river (a flow of fresh water) encounters marine colloids, a systematic full equilibrium can be assumed (i.e., the absence of kinetic effects) when the residence time of the solute in 1 m3 of the system is ⩾6200 h.

  4. Effects of coupled homogeneous chemical reactions on the response of large-amplitude AC voltammetry: extraction of kinetic and mechanistic information by Fourier transform analysis of higher harmonic data.

    Science.gov (United States)

    Lee, Chong-Yong; Bullock, John P; Kennedy, Gareth F; Bond, Alan M

    2010-09-23

    Large-amplitude ac voltammograms contain a wealth of kinetic information concerning electrode processes and can provide unique mechanistic insights compared to other techniques. This paper describes the effects homogeneous chemical processes have on ac voltammetry in general and provides experimental examples using two well-known chemical systems: one simple and one complex. Oxidation of [Cp*Fe(CO)(2)](2) (Cp* = η(5)-pentamethylcyclopentadienyl) in noncoordinating media is a reversible one-electron process; in the presence of nucleophiles, however, the resulting ligand-induced disproportionation changes the process to a multiple step regeneration. The chemical kinetic parameters of the regeneration mechanism were discerned via analysis of the third and higher harmonics of Fourier-transformed ac voltammetry data. Comparison of experimental data to digital simulations provides clear evidence that the reaction proceeds via a rapid pre-equilibrium between the electrogenerated monocation and the coordinating ligand; simultaneous fitting of the first nine harmonics indicates that k(f) = 7500 M(-1) s(-1) and k(r) = 100 s(-1), and that the unimolecular decomposition of the corresponding intermediate occurs with a rate constant of 2.2 s(-1). The rapid cis(+) → trans(+) isomerization of the electrogenerated cis-[W(CO)(2)(dpe)(2)](+), where dpe = 1,2-diphenylphosphinoethane, was examined to illustrate the effects of a simpler EC mechanism on the higher harmonics; a rate constant of 280 s(-1) was determined. These results not only shed new light on the chemistry of these systems, but provide a clear demonstration that the higher harmonics of ac voltammetry provide mechanistic insights into coupled homogeneous processes far more detailed than those that are readily accessible with dc techniques.

  5. Autocatalysis in reaction networks.

    Science.gov (United States)

    Deshpande, Abhishek; Gopalkrishnan, Manoj

    2014-10-01

    The persistence conjecture is a long-standing open problem in chemical reaction network theory. It concerns the behavior of solutions to coupled ODE systems that arise from applying mass-action kinetics to a network of chemical reactions. The idea is that if all reactions are reversible in a weak sense, then no species can go extinct. A notion that has been found useful in thinking about persistence is that of "critical siphon." We explore the combinatorics of critical siphons, with a view toward the persistence conjecture. We introduce the notions of "drainable" and "self-replicable" (or autocatalytic) siphons. We show that: Every minimal critical siphon is either drainable or self-replicable; reaction networks without drainable siphons are persistent; and nonautocatalytic weakly reversible networks are persistent. Our results clarify that the difficulties in proving the persistence conjecture are essentially due to competition between drainable and self-replicable siphons.

  6. Drug Reactions

    Science.gov (United States)

    ... or diabetes. But medicines can also cause unwanted reactions. One problem is interactions, which may occur between ... more serious. Drug allergies are another type of reaction. They can be mild or life-threatening. Skin ...

  7. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    2015-01-01

    We study possible motivations for co-entreprenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes...... with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse – most commonly the female – has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female...

  8. Multicomponent Hetero-[4 + 2] Cycloaddition/Allylboration Reaction: From Natural Product Synthesis to Drug Discovery.

    Science.gov (United States)

    Hall, Dennis G; Rybak, Taras; Verdelet, Tristan

    2016-11-15

    chemical diversity. Biological screening of these druglike imidopiperidine libraries unveiled promising bioactive agents such as A12B4C3, the first reported inhibitor of the human DNA repair enzyme, polynucleotide kinase-phosphatase (hPNKP). Related applications of this MCR in target-oriented synthesis also led to total syntheses of palustrine alkaloids. The inverse electron-demand oxa[4 + 2] cycloaddition/allyboration variant can take advantage of Jacobsen's chiral Cr(III)salen catalyst, affording a rare example of catalytic enantioselective MCR, one that provides a rapid access to α-hydroxyalkyl dihydropyrans in high enantio- and diastereoselectivity. This process exploits 3-boronoacrolein pinacolate as the heterodiene with ethyl vinyl ether or various 2-substituted enol ethers, along with a wide variety of aldehydes in the allylation stage. This versatile methodology was deployed in total syntheses of thiomarinol antibiotics, goniodiol and its derivatives, and the complex anticancer macrolide palmerolide A. More recent work from our laboratory centered on the regio- and stereoselective Suzuki-Miyaura cross-coupling of the dihydropyranyl boronates, thus providing a glimpse of the potential for new multicomponent variants that merge hetero[4 + 2] cycloadditions of 1-borylated heterodienes with transition metal-catalyzed transformations. This stereoselective MCR strategy holds great promise for provoking continuing applications in complex molecule synthesis and drug discovery, and is likely to inspire new and innovative MCR-based approaches to nonaromatic heterocycles.

  9. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    2015-01-01

    a labor market position for (female) spouses with limited alternative opportunities. This decision has positive effects: the financial benefits for each of the spouses, and especially the fe-male, are larger in co-entrepreneurial firms, both during the life of the business and post-dissolution. This also......We study motivations for and outcomes of couples starting up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010, while comparing them to a set of comparable firms and couples. The main motivation for joint entrepreneurship is to create...

  10. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse - most commonly the female - has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female......We study possible motivations for co-entrepenurial couples to start up a joint firm, us-ing a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and post-dissolution private and financial outcomes......, are larger in co-entrepreneurial firms, both during the life of the business and post-dissolution. The start-up of co-entrepreneurial firms seems therefore a sound in-vestment in the human capital of both spouses as well as in the reduction of income inequality in the household. We find no evidence of non...

  11. Entrepreneurial Couples

    DEFF Research Database (Denmark)

    Dahl, Michael S.; Van Praag, Mirjam; Thompson, Peter

    with a selected set of comparable firms and couples. We find evidence that couples often establish a business together because one spouse – most commonly the female – has limited outside opportunities in the labor market. However, the financial benefits for each of the spouses, and especially the female......We study possible motivations for co-entrepenurial couples to start up a joint firm, using a sample of 1,069 Danish couples that established a joint enterprise between 2001 and 2010. We compare their pre-entry characteristics, firm performance and postdissolution private and financial outcomes......, are larger in co-entrepreneurial firms, both during the life of the business and post-dissolution. The start-up of co-entrepreneurial firms seems therefore a sound investment in the human capital of both spouses as well as in the reduction of income inequality in the household. We find no evidence of non...

  12. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, October 1, 1994--December 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, E.; Perry, D.L.; Heinemann, H.

    1994-12-01

    This report describes research on the oxidative coupling of methane and catalysts involved in coal gasification. Topics include methane pyrolysis and catalysts, and magnetic properties of the coal gasification catalyst Ca-Ni-K-O system.

  13. 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...

  14. Application of quinoxaline based diimidazolium salt in palladium ...

    Indian Academy of Sciences (India)

    The diimidazolium salt was found to be efficient in catalyzing Suzuki-Miyaura cross-coupling reaction in ethanol under ambient conditions. Moderate to good selectivity of the trans product was observed in the Heck cross-coupling reaction. The molecular structure of 1 was confirmed by single crystal X-ray diffraction study.

  15. Neuron-glia metabolic coupling: Role in plasticity and neuroprotection

    KAUST Repository

    Magistretti, Pierre J.

    2017-12-02

    A tight metabolic coupling between astrocytes and neurons is a key feature of brain energy metabolism (Magistretti and Allaman, Neuron, 2015). Over the years we have described two basic mechanisms of neurometabolic coupling. First the glycogenolytic effect of VIP and of noradrenaline indicating a regulation of brain homeostasis by neurotransmitters acting on astrocytes, as glycogen is exclusively localized in these cells. Second, the glutamate-stimulated aerobic glycolysis in astrocytes. Both the VIP-and noradrenaline-induced glycogenolysis and the glutamate-stimulated aerobic glycolysis result in the release of lactate from astrocytes as an energy substrate for neurons (Magistretti and Allaman, Neuron, 2015). We have recently shown that lactate is necessary not only as an energy substrate but is also a signaling molecule for long-term memory consolidation and for maintenance of LTP (Suzuki et al, Cell, 2011). At the molecular level we have found that L-lactate stimulates the expression of synaptic plasticity-related genes such as Arc, Zif268 and BDNF through a mechanism involving NMDA receptor activity and its downstream signaling cascade Erk1/2 (Yang et al, PNAS, 2014). L-lactate potentiates NMDA receptor-mediated currents and the ensuing increases in intracellular calcium. These results reveal a novel action of L-lactate as a signaling molecule for neuronal plasticity. We have also recently shown that peripheral administration of lactate exerts antidepressant-like effects in three animal models of depression (Carrard et al, Mol.Psy., 2016).

  16. Di(1H-benzo[d][1,2,3]triazol-1-yl)methane

    Indian Academy of Sciences (India)

    Negishi, Suzuki and Sonogashira coupling reactions.3. The conjugated π systems resulting from alkynylation reactions are building blocks often encountered within natural products, pharmaceutical molecules, synthetic agrochemicals, and molecular materials.4,5 During last decade Sonogashira reaction has become one ...

  17. A Green Multicomponent Reaction for the Organic Chemistry Laboratory: The Aqueous Passerini Reaction

    Science.gov (United States)

    Hooper, Matthew M.; DeBoef, Brenton

    2009-01-01

    Water is the ideal green solvent for organic reactions. However, most organic molecules are insoluble in it. Herein, we report a laboratory module that takes advantage of this property. The Passerini reaction, a three-component coupling involving an isocyanide, aldehyde, and carboxylic acid, typically requires [similar to] 24 h reaction times in…

  18. cycloaddition reactions

    Indian Academy of Sciences (India)

    Unknown

    models of regioselectivity in pericyclic reactions. In addition, local hard and soft acid base (HSAB) princi- ples have been also employed to predict the observed regioselectivity.2 In recent years, the conceptual density functional theory has been remarkably successful in explaining the reactivity and site selectivity.3 The.

  19. 新型氮杂环卡宾-钯配合物的设计、制备及在Buchwald-Hartwig交叉偶联反应中的应用%Novel Pd-N-Heterocyclic Carbene Complexes: Design, Synthesis and Applyment in Buchwald-Hartwig Cross Coupling Reaction

    Institute of Scientific and Technical Information of China (English)

    王凡; 胡宇才; 沈安; 曹育才

    2017-01-01

    发展了一类含有不同亚胺配体的氮杂环卡宾-钯配合物,并将其应用到Buchwald-Hartwig交叉偶联反应中.研究发现亚胺配体的结构对催化活性有明显的影响,尤其带有强吸电子基团的亚胺配体表现最佳.利用该类配合物可以在低至0.5 mol%的催化剂用量下实现不同氯代芳烃和各种胺的高效偶联反应.%N-Heterocyclic carbene (NHC) palladium complexes with different imine ligands have been developed and applied in Buchwald-Hartwig cross coupling reaction.The structure of imine ligand would influence the catalytic activity apparently.Especially,the imine ligand with electron withdrawing group performed best.Low to 0.5 mol% catalyst loading could realize effective Buchwald-Hartwig cross coupling reaction between various aryl chlorides and amines.

  20. KINETICS AND MECHANISM OF THE DIAZO COUPLING ...

    African Journals Online (AJOL)

    rates of this acid catalyzed reaction in dioxane — water, ethanol — water. and propan—2—ol — water ... Recently we proposed a mechanism for the diazo coupling reaction of arenediazo methyl others with B—naphthol, as a ... The available results emphasise the highly basic character of water when compared to dioxane ...

  1. Comparison of DSMC Reaction Models with QCT Reaction Rates for Nitrogen

    Science.gov (United States)

    2016-07-17

    include area code) N/A Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18 Comparison of DSMC Reaction Models with QCT Reaction Rates ...controls vibration coupling A is adjusted to match thermal reaction rate Simplest to implement, not tied to any other model Distribution A: Approved for...General trend: reaction rate increases with v • TCE, QK: lack of vibrational favoring results in much lower slope as compared to the benchmark QCT • VFD: φ

  2. Nuclear structure of weakly bound radioactive nuclei through elastic and and inelastic scattering on proton. Impacts of the couplings induced by these exotic nuclei on direct reactions; Structure de noyaux radioactifs faiblement lies par diffusions elastiques et inelastiques sur proton. Effets des couplages induits par ces noyaux exotiques sur les reactions directes

    Energy Technology Data Exchange (ETDEWEB)

    Lapoux, V

    2005-09-15

    Information on the structure, spectroscopy and target interaction potentials of exotic nuclei can be inferred by interpreting measured data from direct reactions on proton such as elastic or inelastic scattering of proton (p,p') or one-nucleon transfer reaction (p,d). A series of experimental results has been obtained at the GANIL facilities on the setting composed of the MUST telescope array used for the detection of light charged-particles and of CATS beam detectors. This setting aims at measuring reactions on light proton or deuteron targets through reverse kinematics. Particularly, results on C{sup 10}, C{sup 11} and on direct reactions with the He{sup 8} beam of Spiral are presented. The first chapter is dedicated to the description of the most important theories concerning the nucleus. The experimental tools used to probe the nucleus are reported in the second chapter. The third and fourth chapters present the framework that has allowed us to analyse results from (p,p') and (p,d) reactions on weakly bound exotic nuclei. The last chapter is dedicated to the description of future experimental programs. (A.C.)

  3. Anomalous subdiffusion with multispecies linear reaction dynamics.

    Science.gov (United States)

    Langlands, T A M; Henry, B I; Wearne, S L

    2008-02-01

    We have introduced a set of coupled fractional reaction-diffusion equations to model a multispecies system undergoing anomalous subdiffusion with linear reaction dynamics. The model equations are derived from a mesoscopic continuous time random walk formulation of anomalously diffusing species with linear mean field reaction kinetics. The effect of reactions is manifest in reaction modified spatiotemporal diffusion operators as well as in additive mean field reaction terms. One consequence of the nonseparability of reaction and subdiffusion terms is that the governing evolution equation for the concentration of one particular species may include both reactive and diffusive contributions from other species. The general solution is derived for the multispecies system and some particular special cases involving both irreversible and reversible reaction dynamics are analyzed in detail. We have carried out Monte Carlo simulations corresponding to these special cases and we find excellent agreement with theory.

  4. 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.

  5. Fundamental studies of the mechanism of catalytic reactions with catalysts effective in the gasification of carbon solids and the oxidative coupling of methane. Quarterly report, April 1, 1993--June 30, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Heinemann, H.; Somorjai, G.A.; Perry, D.L.

    1993-08-01

    The last quarterly report (LBL-33769) summarized results obtained with ternary catalysts; e.g., K-Ca-Ni oxide and K-Ca-Co oxide. It was also shown that chars prepared in e presence of NAOH were more easily gasified than the base char, even if the chars were washed to remove all residual free NAOH. During the present report quarter, three variables were investigated: (1) The effect of varying the atomic ratio of different catalyst components (alkali vs. transition metal); (2) The effect of steam partial pressure and of temperature on the reaction; (3) Determination of activation energy of the reaction over K-Ca-Co oxide. It was also found that if the water (steam) used for gasification contains a small amount of NAOH, gasification rates are greatly improved. Figure 1 shows that the gasification rate improves with increasing Co content of the catalyst, though the differences between different Co contents are relatively small. A very similar effect was observed for different concentrations of Fe{sup 3+} in KCa-Fe oxide catalysts. Figure 2 presents conversion vs. time plots for gasification of an Ill {number_sign}6 char (which had been charred in the presence of 0.5% caustic) over a K-Ca-Co oxide catalyst at four temperatures. As expected the gasification rate increases with temperature, although there is little difference between our standard 640{degree}C and 680{degree}C. Figure 3 investigates the effect of partial pressure of water on the conversion using an Ill {number_sign}6 char (prepared in the presence of 0.5% caustic) and a K-Ca-Co oxide catalyst at 640{degree}C. There is an improvement in rate with increasing water partial pressure.

  6. Reaction of tin(iv) phthalocyanine dichloride with decamethylmetallocenes (M = CrII and CoII). Strong magnetic coupling of spins in (Cp*2Co+){SnIVCl2(Pc˙3-)}˙-·2C6H4Cl2.

    Science.gov (United States)

    Konarev, Dmitri V; Troyanov, Sergey I; Shestakov, Alexander F; Yudanova, Evgeniya I; Otsuka, Akihiro; Yamochi, Hideki; Kitagawa, Hiroshi; Lyubovskaya, Rimma N

    2018-01-23

    The reaction of tin(iv) phthalocyanine dichloride {SnIVCl2(Pc2-)} with decamethylmetallocenes (Cp*2M, M = Co, Cr) has been studied. Decamethylcobaltocene reduces SnIVCl2(Pc2-) to form the (Cp*2Co+){SnIVCl2(Pc˙3-)}˙-·2C6H4Cl2 (1) complex. The negative charge of {SnIVCl2(Pc˙3-)}˙- is delocalized over the Pc macrocycle providing the alternation of the C-N(imine) bonds, the appearance of new bands in the NIR range and a strong blue shift of both the Soret and Q-bands in the spectrum of 1. The magnetic moment of 1 is equal to 1.68μB at 300 K, indicating the contribution of one S = 1/2 spin of the Pc˙3- macrocycles. These macrocycles form closely packed double stacks in 1 with effective π-π interactions providing strong antiferromagnetic coupling of spins at a Weiss temperature of -80 K. Decamethylchromocene initially also reduces SnIVCl2(Pc2-) to form the [(Cp*2Cr+){SnVICl2(Pc˙3-)}˙- complex but further reaction between the ions is observed. This reaction is accompanied by the substitution of one Cp* ligand of Cp*2Cr by chloride anions originating from {SnIVCl2(Pc˙3-)}˙- to form the complex {(Cp*CrCl2)(SnIV(μ-Cl)(Pc2-))}·C6H4Cl2 (2) in which the (Cp*CrCl2) and {SnIV(Pc2-)} species are bonded through the μ-bridged Cl- anion. According to the DFT calculations, this reaction proceeds via an intermediate [(Cp*2CrCl)(SnClPc)] complex.

  7. Journal of Chemical Sciences

    Indian Academy of Sciences (India)

    0008471

    In the presence of hydrogen peroxide as oxidant and ascorbic acid as reductant, .... The transition metal Schiff base complexes synthesized and characterized by ... Suzuki–Miyaura cross-coupling reactions and optimized to enhance the yield of the Suzuki reaction. Regular Article. Axially chiral benzimidazolium based ...

  8. HandaPhos

    DEFF Research Database (Denmark)

    Handa, Sachin; Andersson, Martin Peter; Gallou, Fabrice

    2016-01-01

    The new monophosphine ligand HandaPhos has been identified such that when complexed in a 1:1 ratio with Pd(OAc)2, enables Pd-catalyzed cross-couplings to be run using ≤1000 ppm of this pre-catalyst. Applications to Suzuki-Miyaura reactions involving highly funtionalized reaction partners...

  9. Application of bisphosphomide-palladium (II) pincer complex in ...

    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.

  10. Spallation reactions; Reactions de spallation

    Energy Technology Data Exchange (ETDEWEB)

    Cugon, J.

    1996-12-31

    Spallation reactions dominate the interactions of hadrons with nuclei in the GeV range (from {approx} 0.1 to {approx} 10 GeV). They correspond to a sometimes important ejection of light particles leaving most of the time a residue of mass commensurate with the target mass. The main features of the experimental data are briefly reviewed. The most successful theoretical model, namely the intranuclear cascade + evaporation model, is presented. Its physical content, results and possible improvements are critically discussed. Alternative approaches are shortly reviewed. (author). 84 refs.

  11. Synthesis of Hydrocarbons from H2-Deficient Syngas in Fischer-Tropsch Synthesis over Co-Based Catalyst Coupled with Fe-Based Catalyst as Water-Gas Shift Reaction

    Directory of Open Access Journals (Sweden)

    Ting Ma

    2015-01-01

    Full Text Available The effects of metal species in an Fe-based catalyst on structural properties were investigated through the synthesis of Fe-based catalysts containing various metal species such, as Mn, Zr, and Ce. The addition of the metal species to the Fe-based catalyst resulted in high dispersions of the Fe species and high surface areas due to the formation of mesoporous voids about 2–4 nm surrounded by the catalyst particles. The metal-added Fe-based catalysts were employed together with Co-loaded beta zeolite for the synthesis of hydrocarbons from syngas with a lower H2/CO ratio of 1 than the stoichiometric H2/CO ratio of 2 for the Fischer-Tropsch synthesis (FTS. Among the catalysts, the Mn-added Fe-based catalyst exhibited a high activity for the water-gas shift (WGS reaction with a comparative durability, leading to the enhancement of the CO hydrogenation in the FTS in comparison with Co-loaded beta zeolite alone. Furthermore, the loading of Pd on the Mn-added Fe-based catalyst enhanced the catalytic durability due to the hydrogenation of carbonaceous species by the hydrogen activated over Pd.

  12. Study of the kinetics of palladium catalysts with 2-metoxy-naphtyl-diferrocenyl-, 2-tert-butyl-oxiphenyl-diferrocenyl-phosphine and 1,1’-diphenyl-phosphin-ferrocene ligands

    Directory of Open Access Journals (Sweden)

    Alibek Khabiyev

    2014-08-01

    Full Text Available The article presents results of the study on kinetic of palladium catalyst with 2-metoxy-naphtyl-diferrocenyl-, 2-tret-butyl-oxiphenyl-diferrocenyl-phosphin and 1,1’-diphenyl-phosphin-ferrocen ligands in Suzuki-Miyara test-reactions. The advantage of Suzuki reactions in difference from other cross-coupling reactions is the use of insensitive to water and oxygen thermostable organoboron compounds. As boronic acid was used phenylboronic acid and as weak base – potassium phosphate. All used catalysts showed good activity with arylbromides and weak activity with arylchlorides.

  13. Stickland reactions of dental plaque.

    Science.gov (United States)

    Curtis, M A; Kemp, C W; Robrish, S A; Bowen, W H

    1983-01-01

    Dental plaque samples from monkeys (Macaca fascicularis) were shown to contain proline reduction activity in coupled Stickland reactions with other amino acids and also with certain end products of bacterial glucose metabolism. The unusually high concentration of bound and free proline in the oral environment may be of importance in both the production of base and in the removal of acid from the tooth surface after dietary carbohydrate ingestion. PMID:6618673

  14. Liquid-liquid transfer phenomena studies coupled with redox reactions: back-extraction of nitrous acid in the presence of scavengers in aqueous phase; Etude de reactions d`oxydoreduction couplees a des phenomenes de transfert liquide-liquide: cas de la desextraction de l`acide nitreux en presence de composes antinitreux en phase aqueuse

    Energy Technology Data Exchange (ETDEWEB)

    K`zerho, R

    1998-12-31

    This work deals with the investigation of redox reaction contribution to the kinetics of liquid-liquid transfer, in relation with PUREX reprocessing of spent nuclear fuel. The chemical system chosen concerns the tripping of nitrous acid from tributylphosphate organic phase into a nitric acid aqueous solution containing an `anti-nitrous` component, namely hydrazinium nitrate. According to the abundant literature, a major attention is devoted to the very important role of interfacial phenomena on the kinetics of solvent extraction with tributylphosphate. Although, a suitable experimental technique is chosen, using a constant interfacial area cell of the ARMOLLEX-type. Furthermore, the effects of the hydrodynamical and the physico-chemical parameters on the extraction rate led to the identification of the extraction regime nature: diffusional, then chemical limitation. When no `anti-nitrous` component is used, the diffusional resistance is found to be mainly located in the aqueous diffusion layer. The presence of hydrazinium nitrate into the aqueous solution has an overall accelerating effect on the rate of extraction, related to both a complete suppression of the aqueous diffusional resistance, and a very significant enhancement of the interfacial transfer of the nitrous acid, as a function of hydrazinium concentration. If the first effect could be expected because of the well known fast redox reaction in aqueous phase, the second phenomenon represents a quite original and new result which has never been explored before, to the best of our knowledge. A reaction mechanism is postulated and validated, taking into account the reactive effect of hydrazinium on the interfacial step. In order to support the drawn general patterns, different complementary studies were attempted. When hydroxyl-ammonium nitrate is used, a surprising interfacial transfer blockage is observed, pointing out the extreme performance and specificity of the common hydrazinium component. (author) 99

  15. Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system; Modelisation couplee (transport - reaction) des interactions fluides - argiles et de leurs effets en retour sur les proprietes physiques de barrieres ouvragees en bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Marty, N

    2006-11-15

    The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

  16. 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.

  17. Anaphylaxis-Like Reactions

    Science.gov (United States)

    ... Home Conditions Anaphylaxis Anaphylaxis-Like Reactions Anaphylaxis-Like Reactions Make an Appointment Refer a Patient Ask a ... exposed to a foreign substance, some people suffer reactions identical to anaphylaxis, but no allergy (IgE antibody) ...

  18. Catalysis of Photochemical Reactions.

    Science.gov (United States)

    Albini, A.

    1986-01-01

    Offers a classification system of catalytic effects in photochemical reactions, contrasting characteristic properties of photochemical and thermal reactions. Discusses catalysis and sensitization, examples of catalyzed reactions of excepted states, complexing ground state substrates, and catalysis of primary photoproducts. (JM)

  19. On Thermonuclear Reaction Rates

    OpenAIRE

    Haubold, H. J.; Mathai, A. M.

    1996-01-01

    Nuclear reactions govern major aspects of the chemical evolution of galaxies and stars. Analytic study of the reaction rates and reaction probability integrals is attempted here. Exact expressions for the reaction rates and reaction probability integrals for nuclear reactions in the cases of nonresonant, modified nonresonant, screened nonresonant and resonant cases are given. These are expressed in terms of H-functions, G-functions and in computable series forms. Computational aspects are als...

  20. Ligand-controlled Iron-catalyzed Cross Coupling of Benzylic Chlorides with Aryl Grignard Reagents

    National Research Council Canada - National Science Library

    Kawamura, Shintaro; Nakamura, Masaharu

    2013-01-01

    .... Although electron-deficient ligands promoted the reductive homocoupling of benzylic halides, electron-rich ligands effectively promoted the desired cross-coupling reaction to afford the corresponding...

  1. Fast, greener and scalable direct coupling of organolithium compounds with no additional solvents

    National Research Council Canada - National Science Library

    Pinxterhuis, Erik B; Giannerini, Massimo; Hornillos, Valentin; Feringa, Ben L

    2016-01-01

    Although the use of catalytic rather than stoichiometric amounts of metal mediator in cross-coupling reactions between organic halides and organometallic counterparts improves significantly the atom...

  2. Reaction-Diffusion in the NEURON Simulator

    Directory of Open Access Journals (Sweden)

    Robert A. McDougal

    2013-11-01

    Full Text Available In order to support research on the role of cell biological principles (genomics, proteomics, signaling cascades and reaction dynamics on the dynamics of neuronal response in health and disease, NEURON has developed a Reaction-Diffusion (rxd module in Python which provides specification and simulation for these dynamics, coupled with the electrophysiological dynamics of the cell membrane. Arithmetic operations on species and parameters are overloaded, allowing arbitrary reaction formulas to be specified using Python syntax. These expressions are then transparently compiled into bytecode that uses NumPy for fast vectorized calculations. At each time step, rxd combines NEURON's integrators with SciPy’s sparse linear algebra library.

  3. Nanocatalysis in Ionic Liquids - Syntheses, Characterisation and Application of Nanoscale Catalysts

    OpenAIRE

    Keßler, Michael

    2014-01-01

    In this work, immobilized metal- and metaloxide nanoparticles were used as nanoscale catalysts in chemical reactions. Palladium nanoparticles, which catalyze classical CC cross-coupling reactions (Heck-, Suzuki- or Sonogashira reactions), were grafted in the pores of carbonized wood. Several recycling reactions with remarkable performance could be realized. Furthermore, Cu2O nanoparticles were synthesized in tetra-n-butylphosphonium acetate, an ionic liquid with high stabilizin...

  4. Atmospheric gas phase reactions

    Science.gov (United States)

    Platt, Ulrich

    This chapter introduces the underlying physicochemical principles and the relevance of atmospheric gas phase reactions. In particular, reaction orders, the concept of elementary reactions, definition of and factors determining reaction rates (kinetic theory of chemical reactions), and photochemical reactions are discussed. Sample applications of the pertinent reaction pathways in tropospheric chemistry are presented, particularly reactions involving free radicals (OH, NO3, halogen oxides) and their roles in the self-cleaning of the troposphere. The cycles of nitrogen and sulfur species as well as the principles of tropospheric ozone formation are introduced. Finally, the processes governing the stratospheric ozone layer (Chapman Cycle and extensions) are discussed.

  5. Fulltext PDF

    Indian Academy of Sciences (India)

    1157–1162. Pd supported on amidoxime (AO)-functionalized Fe3O4 nanoparticles (Fe3O4/AO/Pd) showed high catalytic activity in Suzuki and Ullmann coupling reaction. Molecular docking, MM/GBSA and 3D-QSAR studies on EGFR inhibitors. Raju Bathini, Sree Kanth Sivan, Sabiha Fatima and Vijjulatha Manga .

  6. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. MARUTHAI KUMARAVEL. Articles written in Journal of Chemical Sciences. Volume 126 Issue 3 May 2014 pp 711-716 Regular Articles. Application of bisphosphomide-palladium(II) pincer complex in Suzuki-Miyaura cross-coupling reaction under microwave irradiation.

  7. 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...

  8. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences. Jaya Shree A. Articles written in Journal of Chemical Sciences. Volume 128 Issue 3 March 2016 pp 441-450 Regular Articles. An efficient synthesis of 8-substituted Odoratine derivatives by the Suzuki coupling reaction · Ravi Kumar P Balakrishna C Murali B Ramakrishna ...

  9. Novel Dodecaarylporphyrins: Synthesis and Variable Temperature NMR Studies

    Energy Technology Data Exchange (ETDEWEB)

    Cancilla, Mark; Lebrilla, Carlito; Ma, Jian-Guo; Medforth, Craig J.; Muzzi, Cinzia M.; Shelnutt, John A.; Smith, Kevin M.; Voss, Lisa

    1999-05-05

    An investigation of the synthesis of novel dodecaarylporphyrins using the Suzuki coupling reaction of arylboronic acids with octabromotetraarylporphyrins is reported. Studies of the dynamic properties of these new porphyrins using variable temperature (VT) 1H NMR spectroscopy and molecular mechanics provide interesting insights into their dynamic properties, including the first determination of {beta} aryl rotation in a porphyrin system.

  10. A doubly 2,6-pyridylene-bridged porphyrin-perylene-porphyrin triad.

    OpenAIRE

    IKEDA, SHIN; Aratani, Naoki; Osuka, Atsuhiro

    2012-01-01

    A doubly 2, 6-pyridylene-bridged porphyrin-perylene-porphyrin triad was synthesized via Suzuki-Miyaura cross coupling reaction, which captures a tetrakis(3-pyridyl)porphyrin guest in a 2 : 1 manner to form a supramolecular complex that undergoes photo-induced electron transfer.

  11. High catalytic activity of palladium nanoparticle clusters supported on a spherical polymer network.

    Science.gov (United States)

    Sultanova, Elza D; Salnikov, Vadim V; Mukhitova, Rezeda K; Zuev, Yuriy F; Osin, Yuriy N; Zakharova, Lucia Ya; Ziganshina, Albina Y; Konovalov, Alexander I

    2015-09-04

    In this communication we report the synthesis of Pd nanoparticle clusters achieved via the assembly of Pd nanoparticles on the surface of a spherical polymer network. The network exhibits flexibility and adapts to the cluster formation. The nanoclusters display high catalytic activity toward p-nitrophenol reduction and the Suzuki-Miyaura coupling reaction.

  12. Pd immobilized on modified magnetic Fe3O4 nanoparticles ...

    Indian Academy of Sciences (India)

    J. Chem. Sci. Vol. 128, No. 7, July 2016, pp. 1157–1162. c Indian Academy of Sciences. DOI 10.1007/s12039-016-1098-9. 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.

  13. Scalable BDDC Algorithms for Cardiac Electromechanical Coupling

    KAUST Repository

    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.

  14. Electrode reactions in slowly relaxing media

    Science.gov (United States)

    Matyushov, Dmitry V.; Newton, Marshall D.

    2017-11-01

    Standard models of reaction kinetics in condensed materials rely on the Boltzmann-Gibbs distribution for the population of reactants at the top of the free energy barrier separating them from the products. While energy dissipation and quantum effects at the barrier top can potentially affect the transmission coefficient entering the rate pre-exponential factor, much stronger dynamical effects on the reaction barrier are caused by the breakdown of ergodicity for populating the reaction barrier (violation of the Boltzmann-Gibbs statistics). When the spectrum of medium modes coupled to the reaction coordinate includes fluctuations slower than the reaction rate, such nuclear motions dynamically freeze on the reaction time scale and do not contribute to the activation barrier. Here we consider the consequences of this scenario for electrode reactions in slowly relaxing media. Changing the electrode overpotential speeds the electrode electron transfer up, potentially cutting through the spectrum of nuclear modes coupled to the reaction coordinate. The reorganization energy of electrochemical electron transfer becomes a function of the electrode overpotential, switching between the thermodynamic value at low rates to the nonergodic limit at higher rates. The sharpness of this transition depends on the relaxation spectrum of the medium. The reorganization energy experiences a sudden drop with increasing overpotential for a medium with a Debye relaxation but becomes a much shallower function of the overpotential for media with stretched exponential dynamics. The latter scenario characterizes the electron transfer in ionic liquids. The analysis of electrode reactions in room-temperature ionic liquids shows that the magnitude of the free energy of nuclear solvation is significantly below its thermodynamic limit. This result applies to reaction times faster than microseconds and is currently limited by the available dielectric relaxation data.

  15. Concept and progress in coupling of dehydrogenation and ...

    Indian Academy of Sciences (India)

    in the area of coupled reactions and also helps future researchers or engineers to find out the improvements required in areas such as advancements in .... of nitrobenzene using supported Pt catalysts.25 Studies on coupling of EB and ..... www/chemicalvision2020.com/ pdfs/chem vision.pdf. 2. Ioana F, Ye W and Jacques ...

  16. Continuous Consecutive Reactions with Inter-Reaction Solvent Exchange by Membrane Separation.

    Science.gov (United States)

    Peeva, Ludmila; Da Silva Burgal, Joao; Heckenast, Zsofia; Brazy, Florine; Cazenave, Florian; Livingston, Andrew

    2016-10-17

    Pharmaceutical production typically involves multiple reaction steps with separations between successive reactions. Two processes which complicate the transition from batch to continuous operation in multistep synthesis are solvent exchange (especially high-boiling- to low-boiling-point solvent), and catalyst separation. Demonstrated here is membrane separation as an enabling platform for undertaking these processes during continuous operation. Two consecutive reactions are performed in different solvents, with catalyst separation and inter-reaction solvent exchange achieved by continuous flow membrane units. A Heck coupling reaction is performed in N,N-dimethylformamide (DMF) in a continuous membrane reactor which retains the catalyst. The Heck reaction product undergoes solvent exchange in a counter-current membrane system where DMF is continuously replaced by ethanol. After exchange the product dissolved in ethanol passes through a column packed with an iron catalyst, and undergoes reduction (>99 % yield). © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  17. Oxidative Dehydrogenative Couplings of Pyrazol-5-amines Selectively Forming Azopyrroles

    Science.gov (United States)

    2015-01-01

    New oxidative dehydrogenative couplings of pyrazol-5-amines for the selective synthesis of azopyrrole derivatives have been described. The former reaction simultaneously installs C–I and N–N bonds through iodination and oxidation, whereas the latter involved a copper-catalyzed oxidative coupling process. The resulting iodo-substituted azopyrroles were employed by treatment with various terminal alkynes through Sonogashira cross-coupling leading to new azo compounds. PMID:24731223

  18. Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling

    KAUST Repository

    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.

  19. Electromagnetic clutches and couplings

    CERN Document Server

    Vorob'Yeva, T M; Fry, D W; Higinbotham, W

    2013-01-01

    Electromagnetic Clutches and Couplings contains a detailed description of U.S.S.R. electromagnetic friction clutches, magnetic couplings, and magnetic particle couplings. This book is divided into four chapters. The first chapter discusses the design and construction of magnetic (solenoid-operated) couplings, which are very quick-acting devices and used in low power high-speed servo-systems. Chapter 2 describes the possible fields of application, design, construction, and utilization of magnetic particle couplings. The aspects of construction, design, and utilization of induction clutches (sli

  20. Metabolic anchor reactions for robust biorefining.

    Science.gov (United States)

    Jouhten, Paula; Huerta-Cepas, Jaime; Bork, Peer; Patil, Kiran Raosaheb

    2017-03-01

    Microbial cell factories based on renewable carbon sources are fundamental to a sustainable bio-economy. The economic feasibility of producer cells requires robust performance balancing growth and production. However, the inherent competition between these two objectives often leads to instability and reduces productivity. While algorithms exist to design metabolic network reduction strategies for aligning these objectives, the biochemical basis of the growth-product coupling has remained unresolved. Here, we reveal key reactions in the cellular biochemical repertoire as universal anchor reactions for aligning cell growth and production. A necessary condition for a reaction to be an anchor is that it splits a substrate into two or more molecules. By searching the currently known biochemical reaction space, we identify 62 C-C cleaving anchor reactions, such as isocitrate lyase (EC 4.1.3.1) and L-tryptophan indole-lyase (EC 4.1.99.1), which are relevant for biorefining. The here identified anchor reactions mark network nodes for basing growth-coupled metabolic engineering and novel pathway designs. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.