WorldWideScience

Sample records for catalytic asymmetric synthesis

  1. Catalytic asymmetric synthesis of mycocerosic acid

    NARCIS (Netherlands)

    ter Horst, B.; Feringa, B.L.; J. Minnaard, A.

    2007-01-01

    The first catalytic asymmetric total synthesis of mycocerosic acid was achieved via the application of iterative enantioselective 1,4-addition reactions and allows for the efficient construction of 1,3-polymethyl arrays with full stereocontrol; further exemplified by the synthesis of tetramethyl-dec

  2. Catalytic asymmetric formal synthesis of beraprost

    Science.gov (United States)

    Kobayashi, Yusuke; Kuramoto, Ryuta

    2015-01-01

    Summary The first catalytic asymmetric synthesis of the key intermediate for beraprost has been achieved through an enantioselective intramolecular oxa-Michael reaction of an α,β-unsaturated amide mediated by a newly developed benzothiadiazine catalyst. The Weinreb amide moiety and bromo substituent of the Michael adduct were utilized for the C–C bond formations to construct the scaffold. All four contiguous stereocenters of the tricyclic core were controlled via Rh-catalyzed stereoselective C–H insertion and the subsequent reduction from the convex face. PMID:26734111

  3. Asymmetric catalytic synthesis of the proposed structure of trocheliophorolide B

    OpenAIRE

    Trost, Barry M.; Quintard, Adrien

    2012-01-01

    A concise catalytic asymmetric synthesis of the proposed structure of Trocheliophorolide B is reported. The synthetic sequence notably features an asymmetric acetaldehyde alkynylation, Ru-catalyzed alder-ene reaction and Zn-ProPhenol ynone aldol condensation. Comparison with the reported data suggests a miss-assignment of the natural product structure.

  4. Catalytic Methods in Asymmetric Synthesis Advanced Materials, Techniques, and Applications

    CERN Document Server

    Gruttadauria, Michelangelo

    2011-01-01

    This book covers advances in the methods of catalytic asymmetric synthesis and their applications. Coverage moves from new materials and technologies to homogeneous metal-free catalysts and homogeneous metal catalysts. The applications of several methodologies for the synthesis of biologically active molecules are discussed. Part I addresses recent advances in new materials and technologies such as supported catalysts, supports, self-supported catalysts, chiral ionic liquids, supercritical fluids, flow reactors and microwaves related to asymmetric catalysis. Part II covers advances and milesto

  5. Recent Advances in Catalytic Asymmetric Synthesis

    Institute of Scientific and Technical Information of China (English)

    A. M. P. Koskinen

    2005-01-01

    @@ 1Introduction The rapid development in the genomics and proteomics research has brought about an unprecedented number of potential new drug targets, which translates into an ever-increasing need to rapidly assemble highly pure small molecules (Mr≤850) with an increased structural complexity ‘to identify a small molecule partner for every gene product'[1]. Simultaneously, our increasing awareness of environmental aspects of synthesis places a nearly orthogonal set of requirements for the kinds of syntheses admissible in the future which can be expressed as a rule of 6S' s: selectivity and speed of the syntheses; safety, stability and sustainability of the processes; and scatter of diversity of the attainable products will be the key factors guiding the search for new synthetic organic chemistry.

  6. Catalytic asymmetric total synthesis of (-)-galanthamine and (-)-lycoramine.

    Science.gov (United States)

    Li, Lei; Yang, Qiao; Wang, Yuan; Jia, Yanxing

    2015-05-18

    The catalytic asymmetric total syntheses of (-)-galanthamine (1) and (-)-lycoramine (2) have been achieved by using a conceptually new strategy featuring two metal-catalyzed reactions as the key steps. A new method for the construction of 3,4-fused benzofurans has been developed through a palladium-catalyzed intramolecular Larock annulation reaction, which was successfully applied to the construction of the ABD tricyclic skeleton of 1 and 2. To achieve the asymmetric synthesis of 1 and 2, a Sc(III)/N,N'-dioxide complex was used to catalyze the enantioselective conjugate addition of 3-alkyl-substituted benzofuranone to methyl vinyl ketone for the construction of a chiral quaternary carbon center. PMID:25847447

  7. Catalytic Asymmetric Total Synthesis of Hedyosumins A, B, and C.

    Science.gov (United States)

    Sun, Wang-Bin; Wang, Xuan; Sun, Bing-Feng; Zou, Jian-Ping; Lin, Guo-Qiang

    2016-03-18

    The first and asymmetric total synthesis of hedyosumins A, B, and C was accomplished in 13-14 steps from simple starting materials. The essential tools that allow us to access the tetracyclic skeleton include an organocatalytic [4 + 3] cycloaddition reaction, an intramolecular aldol condensation, and an intramolecular carboxymercuration/demercuration enabled lactonization. A CBS-catalyzed asymmetric reduction was employed to boost the ee of the synthetic natural products to an excellent level. This synthesis established the absolute configurations of hedyosumins A, B, and C. PMID:26925758

  8. A Catalytic, Asymmetric Formal Synthesis of (+)-Hamigeran B

    KAUST Repository

    Mukherjee, Herschel

    2011-03-04

    A concise asymmetric, formal synthesis of (+)-hamigeran B is reported. A Pd-catalyzed, decarboxylative allylic alkylation, employing a trifluoromethylated derivative of t-BuPHOX, is utilized as the enantioselective step to form the critical quaternary carbon center in excellent yield and enantioselectivity. The product is converted in three steps to a late-stage intermediate previously used in the synthesis of hamigeran B.

  9. Catalytic asymmetric synthesis of phthioceranic acid, a heptamethyl-branched acid from Mycobacterium tuberculosis

    NARCIS (Netherlands)

    ter Horst, B.; Feringa, B.L.; J. Minnaard, A.

    2007-01-01

    The first total synthesis of phthioceranic acid (1) has been achieved by an iterative catalytic asymmetric 1,4-addition protocol. This method provides a robust and high-yielding route for the preparation of 1,3-oligomethyl (deoxypropionate) arrays. After the desired number of methyl groups has been

  10. Recent advances in the catalytic asymmetric synthesis of β-amino acids

    NARCIS (Netherlands)

    Weiner, Barbara; Szymanski, Wiktor; Janssen, Dick B.; Minnaard, Adriaan J.; Feringa, Ben L.

    2010-01-01

    In this critical review, the progress in catalytic asymmetric synthesis of β-amino acids is discussed, covering the literature since 2002. The review treats transition metal catalysis, organocatalysis and biocatalysis and covers the most important synthetic methods, such as hydrogenation, the Mannic

  11. De Novo Synthesis of Furanose Sugars: Catalytic Asymmetric Synthesis of Apiose and Apiose-Containing Oligosaccharides.

    Science.gov (United States)

    Kim, Mijin; Kang, Soyeong; Rhee, Young Ho

    2016-08-01

    A de novo synthetic method towards apiose, a structurally unusual furanose, is reported. The key feature is sequential metal catalysis consisting of the palladium-catalyzed asymmetric intermolecular hydroalkoxylation of an alkoxyallene and subsequent ring-closing metathesis (RCM). This strategy enabled the efficient synthesis of various apiose-containing disaccharides and a unique convergent synthesis of trisaccharides. PMID:27381592

  12. Synthesis of Novel Chiral Dibenzo [ a, c ] cycloheptadiene Bis(oxazoline) and Catalytic Asymmetric Reactions

    Institute of Scientific and Technical Information of China (English)

    FU Bin; DU Da-Ming; WANG Jian-Bo

    2003-01-01

    @@ Over the last decade, C2-symmetric chiral oxazoline metal complexes have been recognized as an effective classof chiral catalyst in a variety of transition metal catalyzed asymmetric reactions. [1] High catalytic activities and enantiomeric excesses have been obtained using C2-symmetric chiral ligands in conjunction with suitable transition metal ion, for example, the hydrosilylation of ketone, allylic alkylation, Michael addition, Diels-Alder cycloaddition, and cyclopropanation. Thus, the design and synthesis of new chiral oxazoline ligands have inspired many scientists to work with great efforts.

  13. Ring-Contraction Strategy for the Practical, Scalable, Catalytic Asymmetric Synthesis of Versatile γ-Quaternary Acylcyclopentenes

    KAUST Repository

    Hong, Allen Y.

    2011-02-24

    Contraction action! A simple protocol for the catalytic asymmetric synthesis of highly functionalized γ-quaternary acylcyclopentenes (see schematic) in up to 91 % overall yield and 92 % ee has been developed. The reaction sequence employs a palladium-catalyzed enantioselective alkylation reaction and exploits the unusual stability of β-hydroxy cycloheptanones to achieve a general and robust method for performing two-carbon ring contractions.

  14. Catalytic asymmetric synthesis of spirocyclic azlactones by a double Michael-addition approach.

    Science.gov (United States)

    Weber, Manuel; Frey, Wolfgang; Peters, René

    2013-06-17

    Spirocyclic azlactones are shown to be useful precursors of cyclic quaternary amino acids, such as the constrained cyclohexane analogues of phenylalanine. These compounds are of interest as building blocks for the synthesis of artificial peptide analogues with controlled folds in the peptide backbone. They were prepared in the present study by a step- and atom-economic catalytic asymmetric tandem approach, requiring two steps starting from N-benzoyl glycine and divinylketones. The key of this protocol is the enantioselective formation of the azlactone spirocycles, which involves a PdII-catalyzed double 1,4-addition of an in situ generated azlactone intermediate to the dienone (a formal [5+1] cycloaddition). As the catalyst, a planar chiral ferrocene bispalladacycle was used. Mechanistic studies suggest a monometallic reaction pathway. Although the diastereoselectivity was found to be moderate, the enantioselectivity is usually high for the formation of the azlactone spirocycles, which contain up to three contiguous stereocenters. Spectroscopic studies have shown that the spirocycles often prefer a twist over a chair conformation of the cyclohexanone moiety. PMID:23613333

  15. THE ASYMMETRIC SYNTHESIS OF AMINO ACIDS UNDER POLYMER-SUPPORTED PHASE TRANSFER CATALYTIC CONDITION

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    The optical α-amino acids were synthesized under room temperature by alkylation of N-(diphenyl methylene) glycine t-butyl ester under polymer-supported phase transfer conditions using polymer-supported cinchonine (or quinine) alkaloids as chiral phase transfer catalysts and dichloromethane as solvent, followed by hydrolysis of the above intermediates introduced to the final products-optical α-amino acids. This is a new method for the asymmetric synthesis of α-amino acids. The influences of catalyst,temperature, substrates, and organic solvents on the chemical yield and optical purities of products were studied.

  16. Application of 3-Methyl-2-vinylindoles in Catalytic Asymmetric Povarov Reaction: Diastereo- and Enantioselective Synthesis of Indole-Derived Tetrahydroquinolines.

    Science.gov (United States)

    Dai, Wei; Jiang, Xiao-Li; Tao, Ji-Yu; Shi, Feng

    2016-01-01

    The first application of 3-methyl-2-vinylindoles in catalytic asymmetric Povarov reactions has been established via the three-component reactions of 3-methyl-2-vinylindoles, aldehydes, and anilines in the presence of chiral phosphoric acid, providing easy access to chiral indole-derived tetrahydroquinolines with three contiguous stereogenic centers at high yields (up to 99%) and with excellent diastereo- and enantioselectivities (all >95:5 dr, up to 96% ee). This mode of catalytic asymmetric three-component reaction offers a step-economic and atom-economic strategy for accessing enantioenriched indole-derived tetrahydroquinolines with structural diversity and complexity. PMID:26652222

  17. One-Pot Catalysis Using a Chiral Iridium Complex/Brønsted Base: Catalytic Asymmetric Synthesis of Catalponol.

    Science.gov (United States)

    Suzuki, Takeyuki; Ismiyarto; Ishizaka, Yuka; Zhou, Da-Yang; Asano, Kaori; Sasai, Hiroaki

    2015-11-01

    Tandem asymmetric hydrogen transfer oxidation/aldol condensation under relay catalysis of a chiral iridium complex/achiral Brønsted base binary system is described for the synthesis of α-benzylidene-γ-hydroxytetralones with high ee's. A two-step synthesis of catalponol was achieved using this sequential methodology together with regio- and stereoselective hydroboration. PMID:26496409

  18. Catalytic asymmetric synthesis of a tertiary benzylic carbon center via phenol-directed alkene hydrogenation.

    Science.gov (United States)

    Caille, Seb; Crockett, Rich; Ranganathan, Krishnakumar; Wang, Xiang; Woo, Jacqueline C S; Walker, Shawn D

    2011-07-01

    An expeditious synthetic approach to chiral phenol 1, a key building block in the preparation of a series of drug candidates, is reported. The strategy includes a cost-effective and readily scalable route to cyclopentanone 3 from isobutyronitrile (10). The sterically hindered and enolizable ketone 3 was subsequently employed in a challenging Grignard addition mediated by LaCl(3)·2LiCl. A novel preparation of the lanthanide reagent required for this transformation is described. To complete the process, a highly enantioselective hydrogenation step afforded the target (1). The importance of the phenol group to the success of this asymmetric transformation is discussed. PMID:21630712

  19. Towards a Catalytic Asymmetric Cope Rearrangement and the Synthesis and Self-Assembly of Metal-Coordinated Hosts

    OpenAIRE

    Moehlig, Melissa Padilla

    2013-01-01

    The Cope rearrangement has been used as the key step of several natural products but to date there is only one limited example in the literature that is capable of performing an asymmetric variant of this reaction. The first half of this dissertation focuses on our efforts towards performing a catalytic asymmetric Cope rearrangement to access remote stereocenters. The rearrangement of 2-formyl-1,5-dienes was achieved with both Brønsted and Lewis acid catalysts. The best Lewis acid catalyst wa...

  20. Enantioselective Synthesis of 2,2-Disubstituted Terminal Epoxides via Catalytic Asymmetric Corey-Chaykovsky Epoxidation of Ketones

    Directory of Open Access Journals (Sweden)

    Shigeki Matsunaga

    2012-02-01

    Full Text Available Catalytic asymmetric Corey-Chaykovsky epoxidation of various ketones with dimethyloxosulfonium methylide using a heterobimetallic La-Li3-BINOL complex (LLB is described. The reaction proceeded smoothly at room temperature in the presence of achiral phosphine oxide additives, and 2,2-disubstituted terminal epoxides were obtained in high enantioselectivity (97%–91% ee and yield ( > 99%–88% from a broad range of methyl ketones with 1–5 mol% catalyst loading. Enantioselectivity was strongly dependent on the steric hindrance, and other ketones, such as ethyl ketones and propyl ketones resulted in slightly lower enantioselectivity (88%–67% ee.

  1. Asymmetric synthesis v.4

    CERN Document Server

    Morrison, James

    1984-01-01

    Asymmetric Synthesis, Volume 4: The Chiral Carbon Pool and Chiral Sulfur, Nitrogen, Phosphorus, and Silicon Centers describes the practical methods of obtaining chiral fragments. Divided into five chapters, this book specifically examines initial chiral transmission and extension. The opening chapter describes the so-called chiral carbon pool, the readily available chiral carbon fragments used as building blocks in synthesis. This chapter also provides a list of 375 chiral building blocks, along with their commercial sources, approximate prices, and methods of synthesis. Schemes involving

  2. Catalytic Synthesis Lactobionic Acid

    Directory of Open Access Journals (Sweden)

    V.G. Borodina

    2014-07-01

    Full Text Available Gold nanoparticles are obtained, characterized and deposited on the carrier. Conducted catalytic synthesis of lactobionic acid from lactose. Received lactobionic acid identify on the IR spectrum.

  3. Developing a Practical Chiral Toolbox for Asymmetric Catalytic Reactions

    Institute of Scientific and Technical Information of China (English)

    ZHANG; XuMu

    2001-01-01

    Chiral Quest's Toolbox Approach: During the last several decades, chemists have made major progress in discovering man-made catalysts to perform challenging asymmetric transformations. However, there is no universal chiral ligand or catalyst for solving problems in enantioselective transformations. The focus of Chiral Quest's research is to develop a useful chiral toolbox for strategically important asymmetric catalytic reactions by inventing a diverse set of novel chiral ligands and combining them with transition metals as effective enantioselective catalysts. The toolbox approach addresses significant problems in organic stereochemistry and has resulted in practical methods for the synthesis of chiral pharmaceuticals and agrochemicals  ……

  4. Developing a Practical Chiral Toolbox for Asymmetric Catalytic Reactions

    Institute of Scientific and Technical Information of China (English)

    ZHANG XuMu

    2001-01-01

    @@ Chiral Quest's Toolbox Approach: During the last several decades, chemists have made major progress in discovering man-made catalysts to perform challenging asymmetric transformations. However, there is no universal chiral ligand or catalyst for solving problems in enantioselective transformations. The focus of Chiral Quest's research is to develop a useful chiral toolbox for strategically important asymmetric catalytic reactions by inventing a diverse set of novel chiral ligands and combining them with transition metals as effective enantioselective catalysts. The toolbox approach addresses significant problems in organic stereochemistry and has resulted in practical methods for the synthesis of chiral pharmaceuticals and agrochemicals

  5. Recent advances in catalytic asymmetric hydrogenation:Renaissance of the monodentate phosphorus ligands

    Institute of Scientific and Technical Information of China (English)

    GUO Hongchao; DING Kuiling; DAI Lixin

    2004-01-01

    The history for the development of chiral phosphorus ligands in catalytic asymmetric hydrogenation is briefly highlighted. This review focuses on the recent advances in the synthesis of the monodentate phosphorus ligands and their applications in catalytic asymmetric hydrogenation. The examples highlighted in this article clearly demonstrated the importance and advantages of monodentate phosphorus ligands, which had been ignored for 30 a and experienced a renaissance at the very beginning of this millennium, particularly in the area of asymmetric hydrogenation.

  6. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    FENG; XiaoMing

    2001-01-01

    Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.  ……

  7. Asymmetric Catalytic Reactions Catalyzed by Chiral Titanium Complexes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@ Chiral titanium complexes is very importance catalyst to asymmetric catalytic reactions. A series of catalytic systems based on titanium-chiral ligands complexes has been reported. This presentation will discuss some of our recent progress on asymmetric catalytic reactions catalyzed by chiral titanium complexes.

  8. Asymmetric catalytic aziridination of cyclic enones.

    Science.gov (United States)

    De Vincentiis, Francesco; Bencivenni, Giorgio; Pesciaioli, Fabio; Mazzanti, Andrea; Bartoli, Giuseppe; Galzerano, Patrizia; Melchiorre, Paolo

    2010-07-01

    The first catalytic method for the asymmetric aziridination of cyclic enones is described. The presented organocatalytic strategy is based on the use of an easily available organocatalyst that is able to convert a wide range of cyclic enones into the desired aziridines with very high enantiomeric purity and good chemical yield. Such a method may very well open up new opportunities to stereoselectively prepare complex chiral molecules that possess an indane moiety, a framework that is found in a large number of bioactive and pharmaceutically important molecules. PMID:20512797

  9. Catalytic asymmetric umpolung reactions of imines.

    Science.gov (United States)

    Wu, Yongwei; Hu, Lin; Li, Zhe; Deng, Li

    2015-07-23

    The carbon-nitrogen double bonds in imines are fundamentally important functional groups in organic chemistry. This is largely due to the fact that imines act as electrophiles towards carbon nucleophiles in reactions that form carbon-carbon bonds, thereby serving as one of the most widely used precursors for the formation of amines in both synthetic and biosynthetic settings. If the carbon atom of the imine could be rendered electron-rich, the imine could react as a nucleophile instead of as an electrophile. Such a reversal in the electronic characteristics of the imine functionality would facilitate the development of new chemical transformations that convert imines into amines via carbon-carbon bond-forming reactions with carbon electrophiles, thereby creating new opportunities for the efficient synthesis of amines. The development of asymmetric umpolung reactions of imines (in which the imines act as nucleophiles) remains uncharted territory, in spite of the far-reaching impact such reactions would have in organic synthesis. Here we report the discovery and development of new chiral phase-transfer catalysts that promote the highly efficient asymmetric umpolung reactions of imines with the carbon electrophile enals. These catalysts mediate the deprotonation of imines and direct the 2-azaallyl anions thus formed to react with enals in a highly chemoselective, regioselective, diastereoselective and enantioselective fashion. The reaction tolerates a broad range of imines and enals, and can be carried out in high yield with as little as 0.01 mole per cent catalyst with a moisture- and air-tolerant operational protocol. These umpolung reactions provide a conceptually new and practical approach to chiral amino compounds. PMID:26201597

  10. Asymmetric synthesis of cyclo-archaeol and ß-glucosyl cyclo-archaeol

    NARCIS (Netherlands)

    Ferrer, C.; Fodran, P.; Barroso, S.; Gibson, R.; Hopmans, E.C.; Sinninghe Damsté, J.S.; Schouten, S.; Minnaard, A.J.

    2013-01-01

    An efficient asymmetric synthesis of cyclo-archaeol and beta-glucosyl cyclo-archaeol is presented employing catalytic asymmetric conjugate addition and catalytic epoxide ring opening as the key steps. Their occurrence in deep sea hydrothermal vents has been confirmed by chromatographic comparison wi

  11. Asymmetric synthesis of cyclo-archaeol and beta-glucosyl cyclo-archaeol

    NARCIS (Netherlands)

    Ferrer, Catalina; Fodran, Peter; Barroso, Santiago; Gibson, Robert; Hopmans, Ellen C.; Damste, Jaap Sinninghe; Schouten, Stefan; Minnaard, Adriaan J.

    2013-01-01

    An efficient asymmetric synthesis of cyclo-archaeol and beta-glucosyl cyclo-archaeol is presented employing catalytic asymmetric conjugate addition and catalytic epoxide ring opening as the key steps. Their occurrence in deep sea hydrothermal vents has been confirmed by chromatographic comparison wi

  12. Special Issue of "Asymmetric Synthesis"%Special Issue of "Asymmetric Synthesis"

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Organic chemistry exploring the world at a molecu- lar level remains essential for our society in the 21st century. Asymmetric synthesis, particularly those em- ploying catalytic approach, is one of the most important research fields in organic synthesis providing chiral compounds in an enantiopure form. The latter is critical since the two enantiomers of one chiral compound, in many cases, have a different response in biological sys- tems. The huge markets of non-racemic chiral com- pounds as synthetic intermediates, pharmaceuticals,

  13. Hydroxamic acids in asymmetric synthesis.

    Science.gov (United States)

    Li, Zhi; Yamamoto, Hisashi

    2013-02-19

    Metal-catalyzed stereoselective reactions are a central theme in organic chemistry research. In these reactions, the stereoselection is achieved predominantly by introducing chiral ligands at the metal catalyst's center. For decades, researchers have sought better chiral ligands for asymmetric catalysis and have made great progress. Nevertheless, to achieve optimal stereoselectivity and to catalyze new reactions, new chiral ligands are needed. Because of their high metal affinity, hydroxamic acids play major roles across a broad spectrum of fields from biochemistry to metal extraction. Dr. K. Barry Sharpless first revealed their potential as chiral ligands for asymmetric synthesis in 1977: He published the chiral vanadium-hydroxamic-acid-catalyzed, enantioselective epoxidation of allylic alcohols before his discovery of Sharpless asymmetric epoxidation, which uses the titanium-tartrate complex as the chiral reagent. However, researchers have reported few highly enantioselective reactions using metal-hydroxamic acid as catalysts since then. This Account summarizes our research on metal-catalyzed asymmetric epoxidation using hydroxamic acids as chiral ligands. We designed and synthesized a series of new hydroxamic acids, most notably the C2-symmetric bis-hydroxamic acid (BHA) family. V-BHA-catalyzed epoxidation of allylic and homoallylic alcohols achieved higher activity and stereoselectivity than Sharpless asymmetric epoxidation in many cases. Changing the metal species led to a series of unprecedented asymmetric epoxidation reactions, such as (i) single olefins and sulfides with Mo-BHA, (ii) homoallylic and bishomoallylic alcohols with Zr- and Hf-BHA, and (iii) N-alkenyl sulfonamides and N-sulfonyl imines with Hf-BHA. These reactions produce uniquely functionalized chiral epoxides with good yields and enantioselectivities. PMID:23157425

  14. Cyclodextrins in Asymmetric and Stereospecific Synthesis

    Directory of Open Access Journals (Sweden)

    Fliur Macaev

    2015-09-01

    Full Text Available Since their discovery, cyclodextrins have widely been used as green and easily available alternatives to promoters or catalysts of different chemical reactions in water. This review covers the research and application of cyclodextrins and their derivatives in asymmetric and stereospecific syntheses, with their division into three main groups: (1 cyclodextrins promoting asymmetric and stereospecific catalysis in water; (2 cyclodextrins’ complexes with transition metals as asymmetric and stereospecific catalysts; and (3 cyclodextrins’ non-metallic derivatives as asymmetric and stereospecific catalysts. The scope of this review is to systematize existing information on the contribution of cyclodextrins to asymmetric and stereospecific synthesis and, thus, to facilitate further development in this direction.

  15. Total Synthesis of Chiral Biaryl Natural Products by Asymmetric Biaryl Coupling ‡

    OpenAIRE

    Kozlowski, Marisa C.; Morgan, Barbara J.; Linton, Elizabeth C.

    2009-01-01

    This tutorial review highlights the use of catalytic asymmetric 2-naphthol couplings in total synthesis. The types of chirality, chiral biaryl natural products, prior approaches to chiral biaryl natural products, and other catalytic asymmetric biaryl couplings are outlined. The three main categories of chiral catalysts for 2-naphthol coupling (Cu, V, Fe) are described with discussion of their limitations and advantages. Applications of the copper catalyzed couplings in biomimetic syntheses ar...

  16. Design and synthesis of chiral Ti-1,1'-bi-2-naphthol coordination polymers for heterogeneous catalytic asymmetric oxidation of sulfides

    Institute of Scientific and Technical Information of China (English)

    YUAN Xiao-ya; WANG Xiao-tian

    2008-01-01

    Polymer-immobilized catalysis has many advantages such as easy recovery and reuse of catalyst. We prepared three novel chiral 1,1'-bi-2-naphthol-Ti coordination polymers with properly designed ligands and Ti(OiPr)4 under mild conditions. The prepared polymers exhibited good activity and excellent enantioselectivity (over 99%ee) in catalyzing the asymmetric oxidation of sulfides. The bridge linker in the polymer and the reaction solvent noticeably affected the enantioselectivity. The chiral coordination polymer was very stable and easy to separate from catalyzed reaction systems, with no significant loss of activity or enantioselectivity after reuse for at least ten times. These findings suggest a promising type of catalysts for synthesizing the widely used sulfoxides by asymmetrically oxidizing sulfides.

  17. Synthesis of Asymmetric Propanetriol Analogues

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    From natural tartaric acid, (R)-2-benzyloxy-3-(2-tetrahydropyranyloxy) propanol 3 was designed and synthesized, and (R)-2-benzyloxy-3-(4-methoxybenzyloxy) propanol 7 was prepared in a new method. They can be used as chiral synthons of lysophosphatidic acid and other compounds with asymmetric propanetriol backbone.

  18. Asymmetric Synthesis via Chiral Aziridines

    DEFF Research Database (Denmark)

    Tanner, David Ackland; Harden, Adrian; Wyatt, Paul; Andersson, Pher G.; Johansson, Fredrik

    1996-01-01

    A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines)]. In the...

  19. Catalytic asymmetric addition of Grignard reagents to alkenyl-substituted aromatic N-heterocycles.

    Science.gov (United States)

    Jumde, Ravindra P; Lanza, Francesco; Veenstra, Marieke J; Harutyunyan, Syuzanna R

    2016-04-22

    Catalytic asymmetric conjugate addition reactions represent a powerful strategy to access chiral molecules in contemporary organic synthesis. However, their applicability to conjugated alkenyl-N-heteroaromatic compounds, of particular interest in medicinal chemistry, has lagged behind applications to other substrates. We report a highly enantioselective and chemoselective catalytic transformation of a wide range of β-substituted conjugated alkenyl-N-heteroaromatics to their corresponding chiral alkylated products. This operationally simple methodology can introduce linear, branched, and cyclic alkyl chains, as well as a phenyl group, at the β-carbon position. The key to this success was enhancement of the reactivity of alkenyl-heteroaromatic substrates via Lewis acid activation, in combination with the use of readily available and highly reactive Grignard reagents and a copper catalyst coordinated by a chiral chelating diphosphine ligand. PMID:27102477

  20. Asymmetric catalytic cascade reactions for constructing diverse scaffolds and complex molecules.

    Science.gov (United States)

    Wang, Yao; Lu, Hong; Xu, Peng-Fei

    2015-07-21

    With the increasing concerns about chemical pollution and sustainability of resources, among the significant challenges facing synthetic chemists are the development and application of elegant and efficient methods that enable the concise synthesis of natural products, drugs, and related compounds in a step-, atom- and redox-economic manner. One of the most effective ways to reach this goal is to implement reaction cascades that allow multiple bond-forming events to occur in a single vessel. This Account documents our progress on the rational design and strategic application of asymmetric catalytic cascade reactions in constructing diverse scaffolds and synthesizing complex chiral molecules. Our research is aimed at developing robust cascade reactions for the systematic synthesis of a range of interesting molecules that contain structural motifs prevalent in natural products, pharmaceuticals, and biological probes. The strategies employed to achieve this goal can be classified into three categories: bifunctional base/Brønsted acid catalysis, covalent aminocatalysis/N-heterocyclic carbene catalysis, and asymmetric organocatalytic relay cascades. By the use of rationally designed substrates with properly reactive sites, chiral oxindole, chroman, tetrahydroquinoline, tetrahydrothiophene, and cyclohexane scaffolds were successfully assembled under bifunctional base/Brønsted acid catalysis from simple and readily available substances such as imines and nitroolefins. We found that some of these reactions are highly efficient since catalyst loadings as low as 1 mol % can promote the multistep sequences affording complex architectures with high stereoselectivities and yields. Furthermore, one of the bifunctional base/Brønsted acid-catalyzed cascade reactions for the synthesis of chiral cyclohexanes has been used as a key step in the construction of the tetracyclic core of lycorine-type alkaloids and the formal synthesis of α-lycorane. Guided by the principles of

  1. Asymmetric Imine Isomerisation in the Enantioselective Synthesis of Chiral Amines from Prochiral Ketones

    NARCIS (Netherlands)

    Willems, Johannes G.H.; Vries, Johannes G. de; Nolte, Roeland J.M.; Zwanenburg, Binne

    1995-01-01

    An asymmetric catalytic synthesis of chiral amines using a chiral base catalysed [1,3]-proton shift reaction of imines is described. The isomerisation reaction of N-benzylimines derived from prochiral ketones (benzylacetone, acetophenone) and p-substituted benzylamines, is catalysed by chiral alcoho

  2. Direct Asymmetric Aldol Type Reaction with Ethyl Diazoacetate: Stereoselective Synthesis of α, β-Dihydroxy Esters

    Institute of Scientific and Technical Information of China (English)

    LIAO Ming-Yi; YAO Wen-Gang; FENG Hai-Tao; WANG Jian-Bo

    2003-01-01

    @@ Enantioselective aldol condensation under catalytic condition remains a challenging task in modern organic synthesis, and numerous efforts have been directed to this area. In particular, the direct catalytic asymmetric aldol reaction is very attractive considering the requirement of atom efficiency. This has been studied only recently, and several very practical processes have been developed. We have recently initiated a study on the direct asymmetric aldol type reaction with ethyl diazoacetate as nucleophile. Moderate enantioselectivities (65% ~91% ee ) were achieved in the condensation of aldehydes with ethyl diazoacetate catalyzed by the chiral complex of BINOL derivatives-Zr (OBu- t )4. [1

  3. Asymmetric catalysis in organic synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Reilly, S.D.; Click, D.R.; Grumbine, S.K.; Scott, B.L.; Watkins, J.G.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of the project was to prepare new catalyst systems, which would perform chemical reactions in an enantioselective manner so as to produce only one of the possible optical isomers of the product molecule. The authors have investigated the use of lanthanide metals bearing both diolate and Schiff-base ligands as catalysts for the enantioselective reduction of prochiral ketones to secondary alcohols. The ligands were prepared from cheap, readily available starting materials, and their synthesis was performed in a ''modular'' manner such that tailoring of specific groups within the ligand could be carried out without repeating the entire synthetic procedure. In addition, they have developed a new ligand system for Group IV and lanthanide-based olefin polymerization catalysts. The ligand system is easily prepared from readily available starting materials and offers the opportunity to rapidly prepare a wide range of closely related ligands that differ only in their substitution patterns at an aromatic ring. When attached to a metal center, the ligand system has the potential to carry out polymerization reactions in a stereocontrolled manner.

  4. Asymmetric Synthesis of Both Enantiomers of Disparlure

    Institute of Scientific and Technical Information of China (English)

    王志刚; 郑剑峰; 黄培强

    2012-01-01

    Starting from propargyl alcohol (12), and on the basis of Zhou's modified Sharpless asymmetric epoxidation, the sex pheromone of the Gypsy moth, disparlure (+)-8 and its enantiomer (-)-8 have been synthesized, each in six steps, with overall yields of 29% for (+)-8 and 27% for (-)-8 (ee〉98%). The use of the sequential coupling tactic renders the method flexible, which is applicable to the synthesis of other cis-epoxy pheromones.

  5. A novel and practical asymmetric synthesis of dapoxetine hydrochloride

    Science.gov (United States)

    Zhu, Yijun; Liu, Zhenren; Li, Hongyan

    2015-01-01

    Summary A novel and practical asymmetric synthesis of dapoxetine hydrochloride by using the chiral auxiliary (S)-tert-butanesulfinamide was explored. The synthesis was concise, mild, and easy to perform. The overall yield and stereoselectivity were excellent. PMID:26734109

  6. Some Remarks on Asymmetric Syntheses from Recent Studies

    OpenAIRE

    Baba, Naomichi

    1990-01-01

    Some asymmetric syntheses were presented here and discussed briefly including NADH model reactions, phase transfer-catalyzed asymmetric epoxidation, enantiotopic group-selective hydrolysis of a malonic anhydride with alkoxide anion, intramolecular acid-catalyzed lactonizations, catalytic asymmetric Diels-Alder synthesis, asymmetric aldol condensation, chiral homoallyl alcohol synthesis, asymmetric addition of diethylzinc to aldehyde, kinetic resolution of racemic hydroperoxides and binaphthol...

  7. Asymmetric Synthesis of ( - ) -(2R, 3R, 6S ) -Irnigaine

    Institute of Scientific and Technical Information of China (English)

    MA, Nan; MA, Da-Wei

    2003-01-01

    Asymmetric synthesis of irnigaine was achieved starting from an enantiopure β-amino ester 5 using the condensation of amino alcohol 2 with acetylacetone and the subsequent intramolecular cyclization as the key steps.

  8. Enantioselective approach to polycyclic polyprenylated acylphloroglucinols via catalytic asymmetric intramolecular cyclopropanation.

    Science.gov (United States)

    Uetake, Yuta; Uwamori, Masahiro; Nakada, Masahisa

    2015-02-01

    The formal enantioselective total synthesis of nemorosone, garsubellin A, clusianone, and hyperforin is described. The catalytic asymmetric intramolecular cyclopropanation (CAIMCP) of an α-diazo ketone, a common synthetic intermediate for the above four polycyclic polyprenylated acylphloroglucinols previously reported by us, exhibited low enantioselectivity. However, CAIMCP of the corresponding α-diazo β-keto sulfone afforded the desired product in 79% yield with 84% ee. Investigation of the CAIMCP of the α-diazo β-keto sulfone demonstrated the formation of a rearrangement product in the presence of molecular sieves 4 Å, whereas, in the presence of H2O, the byproduct derived from ring-opening of the desired cyclopropane was observed. X-ray crystallographic analysis suggested that the above two products are derived from the same chiral intermediate. The product derived from ring-opening of the cyclopropane was successfully transformed to the respective synthetic intermediates for the total syntheses of nemorosone, garsubellin A, clusianone, and hyperforin, which had previously been reported by us. PMID:25581002

  9. Absolute Asymmetric Synthesis: The Origin, Control, and Amplification of Chirality

    OpenAIRE

    Delden, Richard A. van; Feringa, Bernard

    1999-01-01

    One of the fundamental and intriguing aspects of life is the homochirality of the essential molecules. From the early days of stereochemistry, the origin of chirality in biological systems has been a challenge to the chemical sciences and numerous theories and experiments have been reported. Despite the great progress in asymmetric synthesis, there are only a few genuine absolute asymmetric syntheses known today. Novel approaches based on the interplay of molecular biology, organic chemistry,...

  10. Catalytic Synthesis Methods for Triazolopyrimidine Derivatives

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new method for catalyzed synthesis of triazolopyrimidine derivatives is reported. Aikylamine reaction with dialkyl cyanodithioiminocarbonate was catalyzed by quaternary ammonium salts at room temperature to yield 3-alkylamine-5-amino-1,2,4-triazole in good quality and high yields. After imidization and reaction with an α,β-unsaturated acid derivative, the reaction intermediate was hydrolyzed in the presence of a Lewis acid to obtain the target product. This novel catalytic method for triazolopyrimidine derivatives can be carried out under inexpen-sive and mild conditions, and is safe and environmentally friendly. IH NMR results for all intermediates are re-ported.

  11. Biomimetic, Catalytic Oxidation in Organic Synthesis

    Institute of Scientific and Technical Information of China (English)

    Shun-lchi Murahashi

    2005-01-01

    @@ 1Introduction Oxidation is one of the most fundamental reactions in organic synthesis. Owing to the current need to develop forward-looking technology that is environmentally acceptable with respect many aspects. The most attractive approaches are biomimetic oxidation reactions that are closely related to the metabolism of living things. The metabolisms are governed by a variety of enzymes such as cytochrome P-450 and flavoenzyme.Simulation of the function of these enzymes with simple transition metal complex catalyst or organic catalysts led to the discovery of biomimetic, catalytic oxidations with peroxides[1]. We extended such biomimetic methods to the oxidation with molecular oxygen under mild conditions.

  12. Asymmetric Synthesis of Spiropyrazolones by Sequential Organo- and Silver Catalysis

    Science.gov (United States)

    Hack, Daniel; Dürr, Alexander B; Deckers, Kristina; Chauhan, Pankaj; Seling, Nico; Rübenach, Lukas; Mertens, Lucas; Raabe, Gerhard; Schoenebeck, Franziska; Enders, Dieter

    2016-01-01

    A stereoselective one-pot synthesis of spiropyrazolones through an organocatalytic asymmetric Michael addition and a formal Conia-ene reaction has been developed. Depending on the nitroalkene, the 5-exo-dig-cyclization could be achieved by silver-catalyzed alkyne activation or by oxidation of the intermediate enolate. The mechanistic pathways have been investigated using computational chemistry and mechanistic experiments. PMID:26676875

  13. Asymmetric Synthesis of Spiropyrazolones by Sequential Organo- and Silver Catalysis.

    Science.gov (United States)

    Hack, Daniel; Dürr, Alexander B; Deckers, Kristina; Chauhan, Pankaj; Seling, Nico; Rübenach, Lukas; Mertens, Lucas; Raabe, Gerhard; Schoenebeck, Franziska; Enders, Dieter

    2016-01-26

    A stereoselective one-pot synthesis of spiropyrazolones through an organocatalytic asymmetric Michael addition and a formal Conia-ene reaction has been developed. Depending on the nitroalkene, the 5-exo-dig-cyclization could be achieved by silver-catalyzed alkyne activation or by oxidation of the intermediate enolate. The mechanistic pathways have been investigated using computational chemistry and mechanistic experiments. PMID:26676875

  14. Catalytic aerobic oxidation and tandem enantioselective cycloaddition in cascade multicomponent synthesis.

    Science.gov (United States)

    Potowski, Marco; Merten, Christian; Antonchick, Andrey P; Waldmann, Herbert

    2015-03-23

    An efficient multicomponent cascade transformation for the highly diastereo- and enantioselective synthesis of complex natural product inspired polycyclic products from simple starting materials is described. The cascade is initiated by copper-catalyzed aerobic CH oxidation of cyclopentadiene to cyclopentadienone followed by double catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides. The cascade synthesis efficiently yields structurally complex 5,5,5-tricyclic products with eight stereocenters with good yields and excellent diastereo- and enantiocontrol using one catalyst. PMID:25676025

  15. Plasma Catalytic Synthesis of Silver Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu-Tao; GUO Ying; MA Teng-Cai

    2011-01-01

    We present the experimental results of plasma catalytic synthesis of colloidal silver nanoparticles, using AgNO3 as the precursor, ethanol as the solvent and reducing agent, and poly vinyl pyrrolidone (PVP) as the macromolecular surfactant. The plasma is generated by an atmospheric argon dielectric barrier discharge jet. Silver nanoparticles are produced instantly once the plasma is ignited. The system is not heated so it is necessary to use traditional chemical methods. The samples are characterized by UV-visible absorbance and transmission electron microscopy. For glow discharge mode no obvious silver nanoparticles are observed. For low voltage filamentary streamer discharge mode a lot of silver nanoparticles with the mean diameter of ~3.5nm are generated and a further increase of the voltage causes the occurrence of agglomeration.%We present the experimental results of plasma catalytic synthesis of colloidal silver nanoparticles,using AgNO3 as the precursor,ethanol as the solvent and reducing agent,and poly vinyl pyrrolidone (PVP) as the macromolecular surfactant.The plasma is generated by an atmospheric argon dielectric barrier discharge jet.Silver nanoparticles are produced instantly once the plasma is ignited.The system is not heated so it is necessary to use traditional chemical methods.The samples are characterized by UV-visible absorbance and transmission electron microscopy.For glow discharge mode no obvious silver nanoparticles are observed.For low voltage filamentary streamer discharge mode a lot of silver nanoparticles with the mean diameter of ~3.5nm are generated and a further increase of the voltage causes the occurrence of agglomeration.The study of silver nanoparticles has been an extremely active area in recent years because of their important physical and chemical properties as a catalyst and antimicrobial reagent,for example.A number of methods for silver nanoparticle preparation have been developed,[1-3] among them chemical reduction is

  16. Nanosheet-enhanced asymmetric induction of chiral α-amino acids in catalytic aldol reaction.

    Science.gov (United States)

    Zhao, Li-Wei; Shi, Hui-Min; Wang, Jiu-Zhao; He, Jing

    2012-11-26

    An efficient ligand design strategy towards boosting asymmetric induction was proposed, which simply employed inorganic nanosheets to modify α-amino acids and has been demonstrated to be effective in vanadium-catalyzed epoxidation of allylic alcohols. Here, the strategy was first extended to zinc-catalyzed asymmetric aldol reaction, a versatile bottom-up route to make complex functional compounds. Zinc, the second-most abundant transition metal in humans, is an environment-friendly catalytic center. The strategy was then further proved valid for organocatalyzed metal-free asymmetric catalysis, that is, α-amino acid catalyzed asymmetric aldol reaction. Visible improvement of enantioselectivity was experimentally achieved irrespective of whether the nanosheet-attached α-amino acids were applied as chiral ligands together with catalytic Zn(II) centers or as chiral catalysts alone. The layered double hydroxide nanosheet was clearly found by theoretical calculations to boost ee through both steric and H-bonding effects; this resembles the role of a huge and rigid substituent. PMID:23074138

  17. An efficient asymmetric synthesis of (-)-wodeshiol

    Indian Academy of Sciences (India)

    Soon Ho Lee; Jae-Chul Jung; Oee Sook Park

    2011-05-01

    An efficient synthesis of (-)-wodeshiol 1 is described. The key reactions include highly stereoselective aldol condensation of piperonal with the dianion of chiral oxazolidinone, subsequent intramolecular ring cyclization of the aldol product 8 and a diastereocontrolled oxygenation of dilactone 7 in good yield.

  18. Asymmetric synthesis using chiral-encoded metal.

    Science.gov (United States)

    Yutthalekha, Thittaya; Wattanakit, Chularat; Lapeyre, Veronique; Nokbin, Somkiat; Warakulwit, Chompunuch; Limtrakul, Jumras; Kuhn, Alexander

    2016-01-01

    The synthesis of chiral compounds is of crucial importance in many areas of society and science, including medicine, biology, chemistry, biotechnology and agriculture. Thus, there is a fundamental interest in developing new approaches for the selective production of enantiomers. Here we report the use of mesoporous metal structures with encoded geometric chiral information for inducing asymmetry in the electrochemical synthesis of mandelic acid as a model molecule. The chiral-encoded mesoporous metal, obtained by the electrochemical reduction of platinum salts in the presence of a liquid crystal phase and the chiral template molecule, perfectly retains the chiral information after removal of the template. Starting from a prochiral compound we demonstrate enantiomeric excess of the (R)-enantiomer when using (R)-imprinted electrodes and vice versa for the (S)-imprinted ones. Moreover, changing the amount of chiral cavities in the material allows tuning the enantioselectivity. PMID:27562028

  19. Asymmetric Synthesis of (R)-and (S)-Moprolol

    Institute of Scientific and Technical Information of China (English)

    WANG Zhao-yang; WANG Yan; SUN Li-wen; ZHU Jin-tao

    2008-01-01

    A simple and effective procedure for the enantioselective synthesis of (R)-and (S)-moprolol was described.The key step was the asymmetric synthesis of enantiopure (R)-and (S)-guaifenesin,which were synthesized from enantioenriched (R)-3-chloro-1,2-propanediol and (S)-epichlorohydrin via kinetics of hydrolysis resolution of racemic epichlorohydrin by chiral Salen-CoIIII complex.The e.e.values of both the optical compounds were above 98%,and the chemical structures of the target compounds were confirmed by 1H NMR,13C NMR,IR,and MS.

  20. Asymmetric Synthesis of Fluoroamines from Chiral Aziridines

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hyeonjeong; Yoon, Dooha; Ha, Hyunjoon [Hankuk Univ. of Foreign Studies, Yongin (Korea, Republic of); Son, Se In; Lee, Won Koo [Sogang Univ., Seoul (Korea, Republic of)

    2014-03-15

    We described an efficient preparation of fluoroamines by the ring-opening reactions of chiral aziridines with Et{sub 3}N·3HF. At most cases both regioisomers were obtained from the ring openings at C2 and C3 positions depending on the substituents at C2 of the starting substrates.The fluorinated organic molecules have attracted great attentions from synthetic and medicinal chemists with wide use of various agrochemicals and pharmaceuticals. Their uniqueness is originated from its electronic characteristics and the small size without altering the molecular conformations of non-fluorinated compounds. The fluorine is the second most widely used atom in the commercial drugs following the amine. Thereby, the elaboration of fluoro-amines bearing two most widely used atoms in drugs is one of the most challenging problems in drug synthesis and its development.

  1. Simulation for Synthesis of TAME with Catalytic Distillation Process

    Institute of Scientific and Technical Information of China (English)

    Liu Boxue; Deng Zhengyong; Weng Huixin; Gao Buliang

    2008-01-01

    The triangular matrixing modified relaxation model equation was established for the synthesis of TAME with catalytic distillation process, and a new accelerated convergence technique was adopted. The simulation on the synthesis of TAME showed that the calculated data agreed well with the experimental results.

  2. Asymmetric Synthesis Using Enzymes in Supercritical CO2

    Institute of Scientific and Technical Information of China (English)

    T. Matsuda

    2005-01-01

    @@ 1Introduction Great efforts have been extended to catalysis in supercritical CO2 (scCO2) since the early 1990's due to the environmental friendliness, high diffusivity, high solubilizing power, easiness of the product separation,etc.. A combined process of scCO2 and enzymatic catalyst system would be a promising synthetic tool to produce optically active compounds because the enzyme has advantages of being natural and having high enantioselectivity in nature. Here we report asymmetric synthesis using lipase and alcohol dehydrogenase in scCO2[1,2].

  3. Catalytic synthesis of ammonia using vibrationally excited nitrogen molecules

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Henriksen, Niels Engholm; Billing, Gert D.; Guldberg, Annette

    The dissociation of nitrogen is the rate-limiting step in the catalytic synthesis of ammonia. Theoretical calculations have shown that the dissociative sticking probability of molecular nitrogen on catalytic active metal surfaces is enhanced by orders of magnitude when the molecules are vibration......The dissociation of nitrogen is the rate-limiting step in the catalytic synthesis of ammonia. Theoretical calculations have shown that the dissociative sticking probability of molecular nitrogen on catalytic active metal surfaces is enhanced by orders of magnitude when the molecules are...... vibrationally excited to states with quantum numbers 3-10. The rate and equilibrium constants for the process using vibrationally excited nitrogen molecules are calculated and expressions for the reaction rates are derived. A comparison with the ordinary process, where the nitrogen molecules are in the...

  4. Controlled synthesis of porous platinum nanostructures for catalytic applications.

    Science.gov (United States)

    Cao, Yanqin; Zhang, Junwei; Yang, Yong; Huang, Zhengren; Long, Nguyen Viet; Nogami, Masayuki

    2014-02-01

    Porous platinum, that has outstanding catalytic and electrical properties and superior resistant characteristics to corrosion, has been widely applied in chemical, petrochemical, pharmaceutical, electronic, and automotive industries. As the catalytic activity and selectivity depend on the size, shape and structure of nanomaterials, the strategies for controlling these factors of platinum nanomaterials to get excellent catalytic properties are discussed. Here, recent advances in the design and preparation of various porous platinum nanostructures are reviewed, including wet-chemical synthesis, electro-deposition, galvanic replacement reaction and de-alloying technology. The applications of various platinum nanostructures are also discussed, especially in fuel cells. PMID:24749422

  5. Catalytic synthesis of ammonia using vibrationally excited nitrogen

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Billing, Gert D.; Hansen, Flemming Yssing

    1992-01-01

    In a previous study we have considered the catalytic synthesis of ammonia in the presence of vibrationally excited nitrogen. The distribution over vibrational states was assumed to be maintained during the reaction, and it was shown that the yield of ammonia increased considerably compared to tha...

  6. Asymmetric catalytic formation of quaternary carbons by iminium ion trapping of radicals

    Science.gov (United States)

    Murphy, John J.; Bastida, David; Paria, Suva; Fagnoni, Maurizio; Melchiorre, Paolo

    2016-04-01

    An important goal of modern organic chemistry is to develop new catalytic strategies for enantioselective carbon–carbon bond formation that can be used to generate quaternary stereogenic centres. Whereas considerable advances have been achieved by exploiting polar reactivity, radical transformations have been far less successful. This is despite the fact that open-shell intermediates are intrinsically primed for connecting structurally congested carbons, as their reactivity is only marginally affected by steric factors. Here we show how the combination of photoredox and asymmetric organic catalysis enables enantioselective radical conjugate additions to β,β-disubstituted cyclic enones to obtain quaternary carbon stereocentres with high fidelity. Critical to our success was the design of a chiral organic catalyst, containing a redox-active carbazole moiety, that drives the formation of iminium ions and the stereoselective trapping of photochemically generated carbon-centred radicals by means of an electron-relay mechanism. We demonstrate the generality of this organocatalytic radical-trapping strategy with two sets of open-shell intermediates, formed through unrelated light-triggered pathways from readily available substrates and photoredox catalysts—this method represents the application of iminium ion activation (a successful catalytic strategy for enantioselective polar chemistry) within the realm of radical reactivity.

  7. Asymmetric catalytic formation of quaternary carbons by iminium ion trapping of radicals.

    Science.gov (United States)

    Murphy, John J; Bastida, David; Paria, Suva; Fagnoni, Maurizio; Melchiorre, Paolo

    2016-04-14

    An important goal of modern organic chemistry is to develop new catalytic strategies for enantioselective carbon-carbon bond formation that can be used to generate quaternary stereogenic centres. Whereas considerable advances have been achieved by exploiting polar reactivity, radical transformations have been far less successful. This is despite the fact that open-shell intermediates are intrinsically primed for connecting structurally congested carbons, as their reactivity is only marginally affected by steric factors. Here we show how the combination of photoredox and asymmetric organic catalysis enables enantioselective radical conjugate additions to β,β-disubstituted cyclic enones to obtain quaternary carbon stereocentres with high fidelity. Critical to our success was the design of a chiral organic catalyst, containing a redox-active carbazole moiety, that drives the formation of iminium ions and the stereoselective trapping of photochemically generated carbon-centred radicals by means of an electron-relay mechanism. We demonstrate the generality of this organocatalytic radical-trapping strategy with two sets of open-shell intermediates, formed through unrelated light-triggered pathways from readily available substrates and photoredox catalysts--this method represents the application of iminium ion activation (a successful catalytic strategy for enantioselective polar chemistry) within the realm of radical reactivity. PMID:27075098

  8. Simulation of Suspension Catalytic Distillation for Synthesis of Linear Alkylbenzene

    Institute of Scientific and Technical Information of China (English)

    王二强; 李成岳

    2003-01-01

    Suspension catalytic distillation (SCD) has been developed recently as an innovative technology in catalytic distillation. In this paper, a brief introduction to SCD is given and an equilibrium stage (EQ) model is developed to simulate this new process for synthesis of linear alkylbenzene (LAB) from benzene and 1-dodecene.Since non-ideality of this reaction system is not strong, EQ model developed could be applied to it successfully.Simulation results agree well with experimental data, and indicate some characteristics of SCD process as an advanced technology for the production of LAB: 100% conversion of olefins, low temperature (90-100℃) and low benzene/olefin mole ratio.

  9. An efficient catalytic method for fulvene synthesis

    OpenAIRE

    Coşkun, Necdet; Erden, Ihsan

    2011-01-01

    The effects of the nature and amount of base, substrate structure, amount of added water and solvent on the condensation of carbonyl compounds with cyclopentadiene in the presence of secondary amines were investigated. Based on these studies, a new efficient and green synthesis of fulvenes was developed.

  10. Electrophilic Activation of α,β-Unsaturated Amides: Catalytic Asymmetric Vinylogous Conjugate Addition of Unsaturated γ-Butyrolactones.

    Science.gov (United States)

    Zhang, Ming; Kumagai, Naoya; Shibasaki, Masakatsu

    2016-04-11

    Although catalytic asymmetric conjugate addition reactions have remarkably advanced over the last two decades, the application of less electrophilic α,β-unsaturated carboxylic acid derivatives in this useful reaction manifold remains challenging. Herein, we report that α,β-unsaturated 7-azaindoline amides act as reactive electrophiles to participate in catalytic diastereo- and enantioselective vinylogous conjugate addition of γ-butyrolactones in the presence of a cooperative catalyst comprising of a soft Lewis acid and a Brønsted base. Reactions mostly reached completion with as little as 1 mol % of catalyst loading to give the desired conjugate adducts in a highly stereoselective manner. PMID:26970428

  11. Catalytic synthesis of long-chained alcohols from syngas

    DEFF Research Database (Denmark)

    Christensen, Jakob Munkholt

    This work has been an investigation of the catalytic conversion of syngas into mixed alcohols with Mo-based catalysts. The primary focus has been on the use of alkali promoted cobalt-molybdenum sulfide as a catalyst for the alcohol synthesis. The alcohol synthesis is a possibility for the...... production of gasoline additives/replacements from biomass via a gasification process. It is observed that the sulfide catalyst is able to operate both with and without a sulfur source in the syngas feed, but the presence of a sulfur source like H2S can exert a significant influence on the catalytic...... crystalline Co9S8, which is considered to be inactive, can be observed in the spent catalyst. It is hypothesized that the loss of sulfur from the catalyst in the reducing atmosphere is driving the conversion of cobalt from its active form (possibly a mixed cobalt-molybdenum sulfide) into larger, more sulfur...

  12. The Catalytic Enantioselective Total Synthesis of (+)‐Liphagal

    DEFF Research Database (Denmark)

    Day, Joshua J.; McFadden, Ryan M.; Virgil, Scott C.;

    2011-01-01

    Ring a ding: The first catalytic enantioselective total synthesis of the meroterpenoid natural product (+)-liphagal is disclosed. The approach showcases a variety of technology including enantioselective enolate alkylation, a photochemical alkyne-alkene [2+2] reaction, microwaveassisted metal...... establish the trans homodecalin system found in the natural product...... catalysis, and an intramolecular aryne capture cyclization reaction. Pivotal to the successful completion of the synthesis was a sequence involving ring expansion from a [6-5-4] tricycle to a [6-7] bicyclic core followed by stereoselective hydrogenation of a sterically occluded tri-substituted olefin to...

  13. Developments in catalytic asymmetric Strecker reaction of aldimines%醛亚胺的不对称Strecker反应研究进展

    Institute of Scientific and Technical Information of China (English)

    唐贝; 李高伟

    2013-01-01

    α-Aminonitriles can be easily converted to α-amino acids, and is an important intermediate for the synthesis of many biologically active natural products and drugs. The asymmetric Strecker reaction of the aldimine as a direct and affective method of synthesis of optically active α-aminonitriles has been widely accepted. In this current paper, the developments in catalytic asymmetric Strecker reaction of aldimines is introduced.%α-氨基腈不仅可以很容易地转化为α-氨基酸,而且是合成许多具有生物活性的天然产物和药物的重要中间体.醛亚胺的不对称Strecker反应作为制备光学活性α-氨基腈的直接而有效的方法之一,已被广泛接受.作者介绍了醛亚胺的不对称Strecker反应研究进展.

  14. Diastereodivergent Catalytic Asymmetric Michael Addition of 2-Oxindoles to α,β-Unsaturated Ketones by Chiral Diamine Catalysts.

    Science.gov (United States)

    Wei, Yuan; Wen, Shigang; Liu, Zunwu; Wu, Xinxin; Zeng, Bubing; Ye, Jinxing

    2015-06-01

    A diastereodivergent catalytic asymmetric Michael addition of 2-oxindoles to α,β-unsaturated ketones has been successfully developed with two complementary chiral diamine catalysts, affording chiral 3,3-disubstituted oxindoles with two adjacent chiral centers. Diastereodivergence has been realized through modifying substrates and utilizing different catalysts. Either anti-or syn-configured products possessing vicinal quaternary and tertiary stereogenic centers were produced with high enantioselectivities. PMID:25973971

  15. Substrate-Controlled Asymmetric Total Synthesis and Structure Revision of (-)-Bisezakyne A.

    Science.gov (United States)

    Shin, Iljin; Lee, Dongjoo; Kim, Hyoungsu

    2016-09-01

    The first asymmetric total synthesis and subsequent structure revision of (-)-bisezakyne A, a Laurencia C15 acetogenin from Alpysia oculifera, has been accomplished. Our substrate-controlled synthesis of this oxolane natural product features a highly stereoselective "protecting-group-dependent" intramolecular amide enolate alkylation strategy for the synthesis of the key 9,10-trans-9,12-cis-10-hydroxytetrahydrofuran intermediate through "nonchelate" control. In addition, our synthesis determined the absolute configuration of the halogenated marine natural product. PMID:27551943

  16. Shape tailored green synthesis and catalytic properties of gold nanocrystals

    Science.gov (United States)

    Rajan, Anish; MeenaKumari, M.; Philip, Daizy

    2014-01-01

    The use of environmentally benign procedures is highly desirable for the synthesis of nanoparticles. Here we report a simple, versatile, economic, ecofriendly and reproducible green method for the size-tunable synthesis of stable and crystalline gold nanoparticles of varied shape using aqueous extract of Garcinia Combogia fruit. The predominant anisotropic nature in the morphology of synthesized particles at lower quantities of extract gradually shifted to spherical particles with larger quantity of extract and increase of temperature. The onset of reduction, the time-evolution of the Surface Plasmon Resonance (SPR) and the catalytic activity are studied using UV-Visible spectroscopy. The Selected Area Diffraction (SAED) pattern, the lattice fringes in the High Resolution Transmission Electron Microscopic (HRTEM) image and the X-ray Diffraction (XRD) pattern clearly show the pure crystalline nature of the synthesized gold nanoparticles. The role of carboxyl group present in Garcinia Combogia fruit extract in the reduction of chloroaurate ions is established using Fourier Transform Infrared (FTIR) spectra. The size dependent catalytic activity of the green synthesized gold nanoparticles on the reduction of 4-Nitrophenol to 4-Aminophenol using sodium borohydride is studied and reported for the first time. The first order kinetics is fitted and rate constants are calculated. Catalytically active green synthesized gold nanoparticles with controllable size and shape presents an advanced step in future biomedical and chemical applications.

  17. Synthesis of the tetracyclic core of Illicium sesquiterpenes using an organocatalyzed asymmetric Robinson annulation

    OpenAIRE

    Trzoss, Lynnie; Xu, Jing; Lacoske, Michelle H.; Theodorakis, Emmanuel A.

    2013-01-01

    An enantioselective synthesis of the core framework of neurotrophic Illicium majucin-type sesquiterpenes is described here. This strategy is based on an organocatalyzed asymmetric Robinson annulation and provides an efficient approach for a diversity-oriented synthesis of Illicium natural products that holds remarkable therapeutic potential for neurodegenerative diseases.

  18. Highly Selective Synthesis of Catalytically Active Monodisperse Rhodium Nanocubes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Grass, M.E.; Kuhn, J.N.; Tao, F.; Habas, S.E.; Huang, W.; Yang, P.; Somorjai, G.A.

    2009-02-21

    Synthesis of monodisperse and shape-controlled colloidal inorganic nanocrystals (NCs) is of increasing scientific interest and technological significance. Recently, shape control of Pt, Pd, Ag, Au, and Rh NCs has been obtained by tuning growth kinetics in various solution-phase approaches, including modified polyol methods, seeded growth by polyol reduction, thermolysis of organometallics, and micelle techniques. Control of reduction kinetics of the noble metal precursors and regulation of the relative growth rates of low-index planes (i.e. {l_brace}100{r_brace} and {l_brace}111{r_brace}) via selective adsorption of selected chemical species are two keys for achieving shape modification of noble metal NCs. One application for noble metal NCs of well-defined shape is in understanding how NC faceting (determines which crystallographic planes are exposed) affects catalytic performance. Rh NCs are used in many catalytic reactions, including hydrogenation, hydroformylation, hydrocarbonylation, and combustion reactions. Shape manipulation of Rh NCs may be important in understanding how faceting on the nanoscale affects catalytic properties, but such control is challenging and there are fewer reports on the shape control of Rh NCs compared to other noble metals. Xia and coworkers obtained Rh multipods exhibiting interesting surface plasmonic properties by a polyol approach. The Somorjai and Tilley groups synthesized crystalline Rh multipods, cubes, horns and cuboctahedra, via polyol seeded growth. Son and colleagues prepared catalytically active monodisperse oleylamine-capped tetrahedral Rh NCs for the hydrogenation of arenes via an organometallic route. More recently, the Somorjai group synthesized sizetunable monodisperse Rh NCs using a one-step polyol technique. In this Communication, we report the highly selective synthesis of catalytically active, monodisperse Rh nanocubes of < 10 nm by a seedless polyol method. In this approach, Br{sup -} ions from trimethyl

  19. Assessing the reliability of calculated catalytic ammonia synthesis rates

    DEFF Research Database (Denmark)

    Medford, Andrew James; Wellendorff, Jess; Vojvodic, Aleksandra; Studt, Felix; Abild-Pedersen, Frank; Jacobsen, Karsten Wedel; Bligaard, Thomas; Nørskov, Jens K.

    2014-01-01

    We introduce a general method for estimating the uncertainty in calculated materials properties based on density functional theory calculations. We illustrate the approach for a calculation of the catalytic rate of ammonia synthesis over a range of transition-metal catalysts. The correlation...... between errors in density functional theory calculations is shown to play an important role in reducing the predicted error on calculated rates. Uncertainties depend strongly on reaction conditions and catalyst material, and the relative rates between different catalysts are considerably better described...

  20. Catalytic synthesis of ammonia-a "never-ending story"?

    Science.gov (United States)

    Schlögl, Robert

    2003-05-01

    Nitrogen atoms are essential for the function of biological molecules and thus are and important component of fertilizers and medicaments. Bonds to nitrogen also find nonbiological uses in dyes, explosives, and resins. The synthesis of all these materials requires ammonia as an activated nitrogen building block. This situation is true for natural processes and the chemical industry. Knowledge of the various techniques for the preparation of ammonia is thus of fundamental importance for chemistry. The Haber-Bosch synthesis was the first heterogeneous catalytic system employed in the chemical industry and is still in use today. Understanding the mechanism and the translation of the knowledge into technical perfection has become a fundamental criterion for scientific development in catalysis research. PMID:12746811

  1. Synthesis and catalytic applications of combined zeolitic/mesoporous materials

    Directory of Open Access Journals (Sweden)

    Jarian Vernimmen

    2011-11-01

    Full Text Available In the last decade, research concerning nanoporous siliceous materials has been focused on mesoporous materials with intrinsic zeolitic features. These materials are thought to be superior, because they are able to combine (i the enhanced diffusion and accessibility for larger molecules and viscous fluids typical of mesoporous materials with (ii the remarkable stability, catalytic activity and selectivity of zeolites. This review gives an overview of the state of the art concerning combined zeolitic/mesoporous materials. Focus is put on the synthesis and the applications of the combined zeolitic/mesoporous materials. The different synthesis approaches and formation mechanisms leading to these materials are comprehensively discussed and compared. Moreover, Ti-containing nanoporous materials as redox catalysts are discussed to illustrate a potential implementation of combined zeolitic/mesoporous materials.

  2. Catalytic synthesis of alcoholic fuels for transportation from syngas

    DEFF Research Database (Denmark)

    Wu, Qiongxiao

    This work has investigated the catalytic conversion of syngas into methanol and higher alcohols. Based on input from computational catalyst screening, an experimental investigation of promising catalyst candidates for methanol synthesis from syngas has been carried out. Cu-Ni alloys of different...... composition have been identified as potential candidates for methanol synthesis. These Cu-Ni alloy catalysts have been synthesized and tested in a fixed-bed continuous-flow reactor for CO hydrogenation. The metal area based activity for a Cu-Ni/SiO2 catalyst is at the same level as a Cu/ZnO/Al2O3 model...... catalyst. The high activity and selectivity of silica supported Cu-Ni alloy catalysts agrees with the fact that the DFT calculations identified Cu-Ni alloys as highly active and selective catalysts for the hydrogenation of CO to form methanol. This work has also provided a systematic study of Cu...

  3. Self-Assembly of a Library of Polyborate Chiral Anions for Asymmetric Catalytic Quinoline Reduction

    Science.gov (United States)

    Desai, Aman A.; Guan, Yong; Odom, Aaron L.; Majumder, Supriyo; Wulff, William D.

    2015-01-01

    The ‘template’ polyborate BOROX catalysts are shown to mediate the asymmetric transfer hydrogenation of 2-quinolines. The rapid and simple generation of a large family of BOROX catalysts with significantly altered asymmetric pockets is described. A transition state model that explains the enantioselectivity is proposed. PMID:26034335

  4. Catalytic Phosphination and Arsination

    Institute of Scientific and Technical Information of China (English)

    Kwong Fuk Yee; Chan Kin Shing

    2004-01-01

    The catalytic, user-friendly phosphination and arsination of aryl halides and triflates by triphenylphosphine and triphenylarsine using palladium catalysts have provided a facile synthesis of functionalized aryl phosphines and arsines in neutral media. Modification of the cynaoarisne yielded optically active N, As ligands which will be screened in various asymmetric catalysis.

  5. Asymmetric Shaped-Pattern Synthesis for Planar Antenna Arrays

    Directory of Open Access Journals (Sweden)

    T. M. Bruintjes

    2016-01-01

    Full Text Available A procedure to synthesize asymmetrically shaped beam patterns is developed for planar antenna arrays. As it is based on the quasi-analytical method of collapsed distributions, the main advantage of this procedure is the ability to realize a shaped (null-free region with very low ripple. Smooth and asymmetrically shaped regions can be used for Direction-of-Arrival estimation and subsequently for efficient tracking with a single output (fully analog beamformer.

  6. Enantioconvergent synthesis by sequential asymmetric Horner-Wadsworth-Emmons and palladium-catalyzed allylic substitution reactions

    DEFF Research Database (Denmark)

    Pedersen, Torben Møller; Hansen, E. Louise; Kane, John;

    2001-01-01

    A new method for enantioconvergent synthesis has been developed. The strategy relies on the combination of an asymmetric Horner-Wadsworth-Emmons (HWE) reaction and a palladium-catalyzed allylic substitution. Different $alpha@-oxygen-substituted, racemic aldehydes were initially transformed by...... asymmetric HWE reactions into mixtures of two major $alpha@,$beta@-unsaturated esters, possessing opposite configurations at their allylic stereocenters as well as opposite alkene geometry. Subsequently, these isomeric mixtures of alkenes could be subjected to palladium-catalyzed allylic substitution...

  7. Palladium-catalyzed asymmetric alkylation in the synthesis of cyclopentanoid and cycloheptanoid core structures bearing all-carbon quaternary stereocenters

    KAUST Repository

    Hong, Allen Y.

    2011-12-01

    General catalytic asymmetric routes toward cyclopentanoid and cycloheptanoid core structures embedded in numerous natural products have been developed. The central stereoselective transformation in our divergent strategies is the enantioselective decarboxylative alkylation of seven-membered β-ketoesters to form α-quaternary vinylogous esters. Recognition of the unusual reactivity of β-hydroxyketones resulting from the addition of hydride or organometallic reagents enabled divergent access to γ-quaternary acylcyclopentenes through a ring contraction pathway or γ-quaternary cycloheptenones through a carbonyl transposition pathway. Synthetic applications of these compounds were explored through the preparation of mono-, bi-, and tricyclic derivatives that can serve as valuable intermediates for the total synthesis of complex natural products. This work complements our previous work with cyclohexanoid systems.

  8. Synthesis, structure characterization and catalytic activity of nickel tungstate nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Pourmortazavi, Seied Mahdi, E-mail: pourmortazavi@yahoo.com [Faculty of Material and Manufacturing Technologies, Malek Ashtar University of Technology, Tehran (Iran, Islamic Republic of); Rahimi-Nasrabadi, Mehdi, E-mail: rahiminasrabadi@gmail.com [Department of Chemistry, Imam Hossein University, Tehran (Iran, Islamic Republic of); Khalilian-Shalamzari, Morteza [Department of Chemistry, Imam Hossein University, Tehran (Iran, Islamic Republic of); Zahedi, Mir Mahdi; Hajimirsadeghi, Seiedeh Somayyeh [Islamic Azad University, Varamin Pishva Branch, Varamin (Iran, Islamic Republic of); Omrani, Ismail [Department of Chemistry, Imam Hossein University, Tehran (Iran, Islamic Republic of)

    2012-12-15

    Graphical abstract: NiWO{sub 4} nanoparticles were prepared via precipitation technique. Experimental parameters of procedure were optimized statistically. Highlights: Black-Right-Pointing-Pointer NiWO{sub 4} spherical nanoparticles were synthesized via direct precipitation method. Black-Right-Pointing-Pointer Taguchi robust design was used for optimization of synthesis reaction parameters. Black-Right-Pointing-Pointer Composition and structural properties of NiWO{sub 4} nanoparticles were characterized. Black-Right-Pointing-Pointer EDAX, XRD, SEM, FT-IR, UV-vis and photoluminescence techniques were employed. Black-Right-Pointing-Pointer Catalytic activity of the product in a cyclo-addition reaction was investigated. - Abstract: Taguchi robust design was applied to optimize experimental parameters for controllable, simple and fast synthesis of nickel tungstate nanoparticles. NiWO{sub 4} nanoparticles were synthesized by precipitation reaction involving addition of nickel ion solution to the tungstate aqueous reagent and then formation of nickel tungstate nucleolus which are insoluble in aqueous media. Effects of various parameters such as nickel and tungstate concentrations, flow rate of reagent addition and reactor temperature on diameter of synthesized nickel tungstate nanoparticles were investigated experimentally by the aid of orthogonal array design. The results for analysis of variance (ANOVA) showed that particle size of nickel tungstate can be effectively tuned by controlling significant variables involving nickel and tungstate concentrations and flow rate; while, temperature of the reactor has a no considerable effect on the size of NiWO{sub 4} particles. The ANOVA results proposed the optimum conditions for synthesis of nickel tungstate nanoparticles via this technique. Also, under optimum condition nanoparticles of NiWO{sub 4} were prepared and their structure and chemical composition were characterized by means of EDAX, XRD, SEM, FT-IR spectroscopy, UV

  9. Synthesis, structure characterization and catalytic activity of nickel tungstate nanoparticles

    International Nuclear Information System (INIS)

    Graphical abstract: NiWO4 nanoparticles were prepared via precipitation technique. Experimental parameters of procedure were optimized statistically. Highlights: ► NiWO4 spherical nanoparticles were synthesized via direct precipitation method. ► Taguchi robust design was used for optimization of synthesis reaction parameters. ► Composition and structural properties of NiWO4 nanoparticles were characterized. ► EDAX, XRD, SEM, FT-IR, UV–vis and photoluminescence techniques were employed. ► Catalytic activity of the product in a cyclo-addition reaction was investigated. - Abstract: Taguchi robust design was applied to optimize experimental parameters for controllable, simple and fast synthesis of nickel tungstate nanoparticles. NiWO4 nanoparticles were synthesized by precipitation reaction involving addition of nickel ion solution to the tungstate aqueous reagent and then formation of nickel tungstate nucleolus which are insoluble in aqueous media. Effects of various parameters such as nickel and tungstate concentrations, flow rate of reagent addition and reactor temperature on diameter of synthesized nickel tungstate nanoparticles were investigated experimentally by the aid of orthogonal array design. The results for analysis of variance (ANOVA) showed that particle size of nickel tungstate can be effectively tuned by controlling significant variables involving nickel and tungstate concentrations and flow rate; while, temperature of the reactor has a no considerable effect on the size of NiWO4 particles. The ANOVA results proposed the optimum conditions for synthesis of nickel tungstate nanoparticles via this technique. Also, under optimum condition nanoparticles of NiWO4 were prepared and their structure and chemical composition were characterized by means of EDAX, XRD, SEM, FT-IR spectroscopy, UV–vis spectroscopy, and photoluminescence. Finally, catalytic activity of the nanoparticles in a cycloaddition reaction was examined.

  10. Catalytic Synthesis of Oxygenates: Mechanisms, Catalysts and Controlling Characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Klier, Kamil; Herman, Richard G

    2005-11-30

    This research focused on catalytic synthesis of unsymmetrical ethers as a part of a larger program involving oxygenated products in general, including alcohols, ethers, esters, carboxylic acids and their derivatives that link together environmentally compliant fuels, monomers, and high-value chemicals. The catalysts studied here were solid acids possessing strong Brnsted acid functionalities. The design of these catalysts involved anchoring the acid groups onto inorganic oxides, e.g. surface-grafted acid groups on zirconia, and a new class of mesoporous solid acids, i.e. propylsulfonic acid-derivatized SBA-15. The former catalysts consisted of a high surface concentration of sulfate groups on stable zirconia catalysts. The latter catalyst consists of high surface area, large pore propylsulfonic acid-derivatized silicas, specifically SBA-15. In both cases, the catalyst design and synthesis yielded high concentrations of acid sites in close proximity to one another. These materials have been well-characterization in terms of physical and chemical properties, as well as in regard to surface and bulk characteristics. Both types of catalysts were shown to exhibit high catalytic performance with respect to both activity and selectivity for the bifunctional coupling of alcohols to form ethers, which proceeds via an efficient SN2 reaction mechanism on the proximal acid sites. This commonality of the dual-site SN2 reaction mechanism over acid catalysts provides for maximum reaction rates and control of selectivity by reaction conditions, i.e. pressure, temperature, and reactant concentrations. This research provides the scientific groundwork for synthesis of ethers for energy applications. The synthesized environmentally acceptable ethers, in part derived from natural gas via alcohol intermediates, exhibit high cetane properties, e.g. methylisobutylether with cetane No. of 53 and dimethylether with cetane No. of 55-60, or high octane properties, e.g. diisopropylether with

  11. Asymmetric silica encapsulation toward colloidal Janus nanoparticles: a concave nanoreactor for template-synthesis of an electocatalytic hollow Pt nanodendrite

    Science.gov (United States)

    Koo, Jung Hun; Kim, Daun; Kim, Jin Goo; Jeong, Hwakyeung; Kim, Jongwon; Lee, In Su

    2016-07-01

    A novel reverse microemulsion strategy was developed to asymmetrically encapsulate metal-oxide nanoparticles in silica by exploiting the self-catalytic growth of aminosilane-containing silica at a single surface site. This strategy produced various colloidal Janus nanoparticles, including Au/Fe3O4@asy-SiO2, which were converted to an Au-containing silica nanosphere, Au@con-SiO2, by reductive Fe3O4 dissolution. The use of Au@con-SiO2 as a metal-growing nanoreactor allowed the templated synthesis of various noble-metal nanocrystals, including a hollow dendritic Pt nanoshell which exhibits significantly better electrocatalytic activities for the oxygen reduction reaction than commercial Pt/C catalysts.A novel reverse microemulsion strategy was developed to asymmetrically encapsulate metal-oxide nanoparticles in silica by exploiting the self-catalytic growth of aminosilane-containing silica at a single surface site. This strategy produced various colloidal Janus nanoparticles, including Au/Fe3O4@asy-SiO2, which were converted to an Au-containing silica nanosphere, Au@con-SiO2, by reductive Fe3O4 dissolution. The use of Au@con-SiO2 as a metal-growing nanoreactor allowed the templated synthesis of various noble-metal nanocrystals, including a hollow dendritic Pt nanoshell which exhibits significantly better electrocatalytic activities for the oxygen reduction reaction than commercial Pt/C catalysts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03557d

  12. Size Controlled Synthesis of Transition Metal Nanoparticles for Catalytic Applications

    KAUST Repository

    Esparza, Angel

    2011-07-07

    Catalysis offers cleaner and more efficient chemical reactions for environmental scientists. More than 90% of industrial processes are performed with a catalyst involved, however research it is still required to improve the catalyst materials. The purpose of this work is to contribute with the development of catalysts synthesis with two different approaches. First, the precise size control of non-noble metals nanoparticles. Second, a new one-pot synthesis method based on a microemulsion system was developed to synthesize size-controlled metal nanoparticles in oxide supports. The one-pot method represents a simple approach to synthesize both support and immobilized nanometer-sized non-noble metal nanoparticles in the same reaction system. Narrow size distribution nickel, cobalt, iron and cobalt-nickel nanoparticles were obtained. High metal dispersions are attainable regardless the metal or support used in the synthesis. Thus, the methodology is adaptable and robust. The sizecontrolled supported metal nanoparticles offer the opportunity to study size effects and metal-support interactions on different catalytic reactions with different sets of metals and supports.

  13. Synthesis, characterization and exploration of the catalytic, supramolecular and biological applications of dinuclear complexes

    OpenAIRE

    Johnpeter, Justin Paul Raj; Therrien, Bruno

    2014-01-01

    The work presented in this thesis involves the synthesis and characterization of dinuclear ruthenium, rhodium and iridium complexes. The catalytic, supramolecular and biological applications of these dinuclear complexes will be discussed. In the first part, the synthesis of sawhorse-type diruthenium tetracarbonyl complexes and their catalytic applications in the supercritical carbon dioxide (scCO2) are presented. Synthesis of sawhorse-type molecular tweezers derived from pyrenyl and porphyrin...

  14. Synthesis, characterization and catalytic activity of CdO nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Singh, G., E-mail: gsingh4us@yahoo.com [Department of Chemistry, D.D.U. Gorakhpur University, Gorakhpur 273009 (India); Kapoor, I.P.S.; Dubey, Reena; Srivastava, Pratibha [Department of Chemistry, D.D.U. Gorakhpur University, Gorakhpur 273009 (India)

    2011-02-15

    In this paper, we report the synthesis of nanocrystalline cadmium oxide (CdO) and its characterization by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Its catalytic activity was investigated on the thermal decomposition of 1,2,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), ammonium perchlorate (AP), hydroxyl terminated polybutadiene (HTPB) and composite solid propellants (CSPs) using thermogravimetric analysis (TG), simultaneous thermogravimerty and differential scanning calorimetry (TG-DSC) and ignition delay measurements. Kinetics of thermal decomposition of AP + CdO has also been investigated using model free (isoconversional) and model-fitting approaches which have been applied to data for isothermal TG decomposition. All these studies show enhancement in the rate of decomposition of AP, HTPB and CSPs but no effect on HMX. The burning rate of CSPs has also been found to be increased with CdO nanocrystals.

  15. Resonant active sites in catalytic ammonia synthesis: A structural model

    Science.gov (United States)

    Cholach, Alexander R.; Bryliakova, Anna A.; Matveev, Andrey V.; Bulgakov, Nikolai N.

    2016-03-01

    Adsorption sites Mn consisted of n adjacent atoms M, each bound to the adsorbed species, are considered within a realistic model. The sum of bonds Σ lost by atoms in a site in comparison with the bulk atoms was used for evaluation of the local surface imperfection, while the reaction enthalpy at that site was used as a measure of activity. The comparative study of Mn sites (n = 1-5) at basal planes of Pt, Rh, Ir, Fe, Re and Ru with respect to heat of N2 dissociative adsorption QN and heat of Nad + Had → NHad reaction QNH was performed using semi-empirical calculations. Linear QN(Σ) increase and QNH(Σ) decrease allowed to specify the resonant Σ for each surface in catalytic ammonia synthesis at equilibrium Nad coverage. Optimal Σ are realizable for Ru2, Re2 and Ir4 only, whereas other centers meet steric inhibition or unreal crystal structure. Relative activity of the most active sites in proportion 5.0 × 10- 5: 4.5 × 10- 3: 1: 2.5: 3.0: 1080: 2270 for a sequence of Pt4, Rh4, Fe4(fcc), Ir4, Fe2-5(bcc), Ru2, Re2, respectively, is in agreement with relevant experimental data. Similar approach can be applied to other adsorption or catalytic processes exhibiting structure sensitivity.

  16. Asymmetric Synthesis of β, γ-β-Hydroxyl-γ-butyrolactones

    Institute of Scientific and Technical Information of China (English)

    WANG Jin-Xin; ZHANG Chao-Xin; LI Ying

    2003-01-01

    @@ Chiral β-hydroxyl-γ-butyrolactones have attracted substantial interest in recent years due to their presence inmany strongly active natural products having antitumor, fungicidal, anti-inflammatory activity, and their use as important precursors in natural product synthesis. [1] In the course of the total synthesis of the natural product Tuxpano lide ,[2] we found a concise and efficient strategy on the stereocontrolled synthesis of β-hydroxyl-γ-butyrolactonederivatives from cheap and achiral starting material.

  17. Synthesis of Main-Chain Chiral Quaternary Ammonium Polymers for Asymmetric Catalysis Using Quaternization Polymerization

    Directory of Open Access Journals (Sweden)

    Md. Masud Parvez

    2012-06-01

    Full Text Available Main-chain chiral quaternary ammonium polymers were successfully synthesized by the quaternization polymerization of cinchonidine dimer with dihalides. The polymerization occurred smoothly under optimized conditions to give novel type of main-chain chiral quaternary ammonium polymers. The catalytic activity of the polymeric chiral organocatalysts was investigated on the asymmetric benzylation of N-(diphenylmethylideneglycine tert-butyl ester.

  18. Fructose derived pyridyl alcohol ligands: synthesis and application in the asymmetric diethylzinc addition to aldehydes

    Institute of Scientific and Technical Information of China (English)

    ZHOU, Yong-Gui; DAI, Li-Xin; HOU, Xue-Long

    2000-01-01

    Easily available chiral ketones were employed for the synthesis of optically active pyridyl alcohols, which were applied in the asymmetric diethylzinc addition to aldehydes, up to 89.4%e.e. was obtained using D-fructose-derived pyridyl alcohol.

  19. Organocatalytic One-Pot Asymmetric Synthesis of Thiolated Spiro-γ-lactam Oxindoles Bearing Three Stereocenters.

    Science.gov (United States)

    Huang, Xin; Liu, Miao; Pham, Kenny; Zhang, Xiaofeng; Yi, Wen-Bin; Jasinski, Jerry P; Zhang, Wei

    2016-07-01

    The first asymmetric synthesis of spiro-γ-lactam oxindoles bearing three stereocenters is reported. One-pot thiol-Michael/Mannich/lactamization reactions promoted by a recyclable fluorous bifunctional cinchona alkaloid/thiourea organocatalyst afford products in moderate to good yields with up to 95% ee and 6:1 dr. PMID:27258150

  20. The Taumycin A Macrocycle: Asymmetric Total Synthesis and Revision of Relative Stereochemistry

    OpenAIRE

    deGruyter, Justine N.; Maio, William A.

    2014-01-01

    The first asymmetric total synthesis and revision of the relative configuration of the 12-membered taumycin A macrocycle is described. Key to the success of this work was a novel α-keto ketene macrocyclization that provided an efficient means by which to access two diastereomers of the desired macrolide without the need to employ additional coupling agents or unnecessary oxidation state adjustments.

  1. Synthesis of Borohydride and Catalytic Dehydrogenation by Hydrogel Based Catalyst

    Science.gov (United States)

    Boynuegri, Tugba Akkas; Karabulut, Ahmet F.; Guru, Metin

    2016-08-01

    This paper deals with the synthesis of calcium borohydride (Ca(BH4)2) as hydrogen storage material. Calcium chloride salt (CaCl2), magnesium hydride (MgH2), and boron oxide (B2O3) were used as reactants in the mechanochemical synthesis of Ca(BH4)2. The mechanochemical reaction was carried out by means of Spex type ball milling without applying high pressure and temperature. Parametric studies have been established at different reaction times and for different amounts of reactants at a constant ball to powder ratio (BPR) 4:1. The best combination was determined by Fourier Transform Infrared (FT-IR) analysis. According to the FT-IR analysis, reaction time, the first reaction parameter, was found as 1600 min. After the reaction time was fixed at 1600 min, the difference of the B-H peak areas was dependent on the amount of reactant MgH2 that was investigated. The amount of the reactant (MgH2), the second reaction parameter, was measured to be 2.85 times more than the stoichiometric amount of MgH2. According to our previous studies, BPR was selected as 4:1 for all experiments. Samples were prepared in a glove box under argon atmosphere but the time that elapsed for FT-IR analysis highly affected B-H bonds. B-H peak areas clearly decreased with time because of negative effect of ambient atmosphere. A catalyst was prepared by absorbing cobalt fluoride (CoF2) in poly (acrylamide-co-acrylic acid) hydrogel matrices type and its catalytic dehydrogenation performance that has been characterized by the catalytic reaction of sodium borohydride's known hydrogen capacity in an alkaline medium. The metal amount of hydrogel catalyst was determined as 135.82 mg Co by Atomic Absorption Spectroscopy (AAS). The specific dehydrogenation capacity of the Co active compound in the catalyst thanks to catalytic dehydrogenation of commercial sodium borohydride was measured as 1.66 mL H2/mg Co.

  2. Asymmetric Total Synthesis of Soraphen A: a Flexible Alkyne Strategy**

    OpenAIRE

    Trost, Barry M.; Sieber, Joshua D.; Qian, Wei; Dhawan, Rajiv; Ball, Zachary T.

    2009-01-01

    The alkyne functional group can be a valuable handle for organic synthesis since the alkyne can function both as a nucleophile or as an electrophile when activated with an appropriate metal catalyst. Herein, we exploit this dual nature of the alkyne moiety for the concise total synthesis of the natural product soraphen A.

  3. Cysteine functionalized copper organosol: synthesis, characterization and catalytic application

    International Nuclear Information System (INIS)

    We herein report a facile one-pot synthesis, stabilization, redispersion and Cu-S interaction of L-cysteine and dodecanethiol (DDT) protected copper organosol in toluene from precursor copper stearate using sodium borohydride in toluene under a nitrogen atmosphere. Surface modification of the synthesized copper organosol with an amino acid L-cysteine and an alkanethiol (dodecanethiol, DDT) is accomplished by a thiolate bond between the used ligands and nanoparticle surface. The cysteine molecule binds the copper surface via a thiolate and amine linkage but not through electrostatic interaction with the carboxylate group due to the solvent polarity and dielectric medium. Fourier transform infrared (FTIR) analysis was performed to confirm the surface functionalization of the amino acid and DDT to the copper surface. Copper organosol has been characterized by optical spectroscopy (UV/vis), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD). The as-synthesized particles are spherical in shape and exhibit a Mie scattering profile with an absorption maxima in the visible range. Copper nanoparticles capped by cysteine and/or DDT in non-aqueous media are found to represent an interesting catalytic approach for the synthesis of octylphenyl ether

  4. Synthesis of antidepressant duloxetine via asymmetric transfer hydrogenation

    Institute of Scientific and Technical Information of China (English)

    Shan Zhen He; Xue Ming Li; Jia Dai; Ming Yan

    2008-01-01

    Antidepressant duloxetine (1) was prepared via asymmetric transfer hydrogenation of 3-(dimethylamino)-1-(thiophen-2-yl)propan-1-one (3). The Ru(Ⅱ), Rh(Ⅲ) and Ir(Ⅲ) complexes of several chiral ligands were examined as the catalyst and(S,S)-N-tosyl-1,2-diphenyl ethylenediamine (TsDPEN)-Ru(Ⅱ) complex was found to provide good yield and excellent enantios-electivity.

  5. Catalytic asymmetric allylation of aliphatic aldehydes by chiral bipyridine N,N'-dioxides

    Czech Academy of Sciences Publication Activity Database

    Hrdina, R.; Boyd, T.; Valterová, Irena; Hodačová, Jana; Kotora, Martin

    -, č. 20 (2008), s. 3141-3144. ISSN 0936-5214 Grant ostatní: GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40550506 Keywords : allylations * aldehydes * Lewis base * asymmetric catalysis * solvent effect Subject RIV: CC - Organic Chemistry Impact factor: 2.659, year: 2008

  6. Preparation of MCM-41-supported chiral Salen Mn (Ⅲ) catalysts and their catalytic properties in the asymmetric epoxidation of olefins

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A secondary amino-modified mesoporous molecular sieve MCM-41 was obtained by reaction of bis(3-(triethoxysilyl)propyl)amine with MCM-41. The chiral Salen-Mn (Ⅲ) complex was anchored onto the modified MCM-41 by a multi-step grafting method and two heterogenized catalysts with different Mn contents were obtained. The catalysts were characterized by XRD, N2 adsorption, ICP, FT-IR and DR UV-Vis. Their catalysis on asymmetric epoxidation of several olefins was studied with NaClO and m-CPBA as oxidants respectively. It was found that both the activity and enantioselectivity of the catalysts decreased after the homogeneous catalyst was heterogenized. The reasons resulting in the decrease of catalytic performance were discussed.

  7. A Series of Asymmetrical Phthalocyanines: Synthesis and Near Infrared Properties

    Directory of Open Access Journals (Sweden)

    Xiguang Du

    2013-04-01

    Full Text Available We report here the preparation of asymmetrical phthalocyanine dimers 1a–3a, which are endowed with novel charge transfer bands at 1,151–1,154 nm and strong NIR luminescences at 840–860 nm and 1,600–1,650 nm. Through H-bonding interaction, 1a–3a are inclined to self-assemble into hexrod nanotubes at the interface of CHCl3 and CH3OH. Our results provide further insights into the interaction in molecular dimers, and suggest that 1a–3a have potential application in magnets and supramolecular architectures.

  8. Catalytic Asymmetric [4 + 1] Annulation of Sulfur Ylides with Copper-Allenylidene Intermediates.

    Science.gov (United States)

    Wang, Qiang; Li, Tian-Ren; Lu, Liang-Qiu; Li, Miao-Miao; Zhang, Kai; Xiao, Wen-Jing

    2016-07-13

    The first copper-catalyzed asymmetric decarboxylative [4 + 1] cycloaddition of propargylic carbamates and sulfur ylides was successfully developed. This strategy led to a series of chiral indolines with synthetically flexible alkyne groups in good yields and with high enantio- and diastereoselectivities (up to 99% yield, 98% ee, and >95:5 dr). A possible mechanism and stereoinduction mode with copper-allenylidenes were proposed as the possible dipolar intermediate. PMID:27355096

  9. Microbially supported synthesis of catalytically active bimetallic Pd-Au nanoparticles

    DEFF Research Database (Denmark)

    Hosseinkhani, Baharak; Søbjerg, Lina Sveidal; Rotaru, Amelia-Elena;

    2012-01-01

    Bimetallic nanoparticles are considered the next generation of nanocatalysts with increased stability and catalytic activity. Bio-supported synthesis of monometallic nanoparticles has been proposed as an environmentally friendly alternative to the conventional chemical and physical protocols. In ...

  10. New Chiral Metal Cluster Systems for Catalytic Asymmetric Syntheses of Chiral Alcohols

    Institute of Scientific and Technical Information of China (English)

    LI Yan-yun; CHEN Jian-shan; YANG Chuan-bo; DONG Zhen-rong; LI Bao-zhu; ZHANG Hui; GAO Jing-xing; TAKAO Ikariya

    2004-01-01

    The efficient chiral Ru3(CO)12 systems were prepared in situ from Ru3(CO)12 and various chiral diiminoor diamino-diphosphine tetradentate ligands. The systems have been used for the asymmetric transfer hydrogenation of propiophenone in 2-propanol, leading to 1-phenyl-1-propanol in a 98% yield and 96% e.e. The IR study suggests that the carbonyl hydride anion [HRu3(CO)11]- most probably exists as a principal species under the reaction conditions. The high chiral efficiency may be due to the synergetic effect produced by the neighboring ruthenium atoms and a special chiral micro-environment involving the polydentate ligand and the Ru3 framework.

  11. Catalytic Asymmetric Reduction of a 3,4-Dihydroisoquinoline for the Large-Scale Production of Almorexant: Hydrogenation or Transfer Hydrogenation?

    OpenAIRE

    Verzijl, Gerard K.M.; Vries, André H.M. de; Vries, Johannes G. de; Kapitan, Peter; Dax, Thomas; Helms, Matthias; Nazir, Zarghun; Skranc, Wolfgang; Imboden, Christoph; Stichler, Juergen; Ward, Richard A.; Abele, Stefan; Lefort, Laurent

    2013-01-01

    Several methods are presented for the enantioselective synthesis of the tetrahydroisoquinoline core of almorexant (ACT-078573A), a dual orexin receptor antagonist. Initial clinical supplies were secured by the Noyori Ru-catalyzed asymmetric transfer hydrogenation (Ru-Noyori ATH) of the dihydroisoquinoline precursor. Both the yield and enantioselectivity eroded upon scale-up. A broad screening exercise identified TaniaPhos as ligand for the iridium-catalyzed asymmetric hydrogenation with a ded...

  12. IMMOBILIZATION OF Saccharomyces Cerevisiae USING POLY(ACRYLAMIDE) GEL FOR ASYMMETRIC SYNTHESIS OF R(-)-MANDELIC ACID

    Institute of Scientific and Technical Information of China (English)

    LI Zhongqin; GUO Daiping; HUANG Xinghua; YANG Kai; XU Xiaoping

    2006-01-01

    In this paper, the poly(acrylamide) hydrogel used to immobilize saccharomyces cerevisiae for asymmetric synthesis of R(-)-mandelic acid was prepared with free radical ploymerization in deionized water at room temperature under nitrogen atmosphere. The influence of the composition of hydrogel, loading amount of cells and culture conditions on the asymmetric synthesis was investigated. Results show that PAAm hydrogel is a feasible carrier for immobilization of cells which is a potential alternative method to prepare enantiomerically pure R(-)-mandelic acid.

  13. Group-assisted purification (GAP) chemistry for the synthesis of Velcade via asymmetric borylation of N-phosphinylimines

    OpenAIRE

    Jian-bo Xie; Jian Luo; Winn, Timothy R; David B. Cordes; Guigen Li

    2014-01-01

    A new approach to the anticancer drug Velcade was developed by performing asymmetric borylation of an imine anchored with a chiral N-phosphinyl auxiliary. Throughout the 7-step synthesis, especially in the imine’s synthesis and in the asymmetric borylation reactions, operations and work-up were conducted in simple and easy ways without any column chromatographic purification, which defines the GAP (group-assisted purification) chemistry concept. It was found that the optically pure isomer (dr...

  14. A Facile Method for Asymmetric Synthesis of β-Hydroxy-α-amino Acids

    Institute of Scientific and Technical Information of China (English)

    LI,Shuo; LI,Lei; ZHANG,Zhi-Hui; XU,Peng-Fei

    2004-01-01

    @@ β-Hydroxy-a-amino acids are an important class of amino acids due to their inherent biological investigations[1] and as structural components of more complex biomolecules.[2] β-Hydroxy-a-amino acids have been used as intermediates in the asymmetric synthesis of other compounds.[3] An efficient and convenient concise method for the preparation of optically pure enantiomers of β-hydroxy-α-amino acids would be of general interest.

  15. SYNTHESIS AND CHARACTERIZATION OF ASYMMETRIC ULTRAFILTRATION MEMBRANE MADE WITH RECYCLED POLYSTYRENE FOAM AND DIFFERENT ADDITIVES

    OpenAIRE

    RAUDEL RAMOS-OLMOS; EDUARDO ROGEL-HERNÁNDEZ; LUCÍA Z FLORES-LÓPEZ; SHUI WAI LIN; HERIBERTO ESPINOZA-GÓMEZ

    2008-01-01

    This paper reports the synthesis and characterization of asymmetric ultrafiltration membrane made from recycled polystyrene foam (PS) with different additives and polyvinylpyrrolidone (PVP). The polystyrene is currently employed as packing, in fabrication of glasses and dishes. The recycled polystyrene is inexpensive and easy to acquire and, at less in Mexico, not a conscience exists of recycled. The membranes where prepared by phase inversion process from casting solution containing polystyr...

  16. Synthesis of a small molecule walker and the application of mechanically interlocked ligands in asymmetric catalysis

    OpenAIRE

    Hoekman, Steven

    2016-01-01

    This thesis reports the synthesis of a novel synthetic small molecule walker, a chiral [2]rotaxane and a single-handed trefoil knot. The last two were employed as ligands for metal catalysed asymmetric reactions.Chapter 1 explains what small molecule walkers are and their resemblance to nature’s walking proteins. The motor protein myosin is discussed in more detail, followed by a section about small molecules that diffuse along a surface and recent advances in dynamic covalent walker systems....

  17. Collagen synthesis, nitric oxide and asymmetric dimethylarginine in diabetic subjects undergoing hyperbaric oxygen therapy

    OpenAIRE

    Gürdöl, Figen; Cimsit, M; Öner-Iyidoğan, Yıldız; Koçak, Hikmet; Sengun, S; Yalçınkaya-Demirsöz, S

    2010-01-01

    The main pathological condition in patients with impaired wound healing is diabetes mellitus. These patients have significantly low circulating nitric oxide (NO) levels because the stimulatory action of insulin on NO synthesis is absent. Additionally, asymmetric dimethylarginine (ADMA), an inhibitor of NO synthase, is increased owing to the generation of oxidative stress. NO was thought to contribute to wound healing. Hyperbaric oxygen (HBO) treatment is generally used in order to accelerate ...

  18. Catalytic asymmetric exo-selective [6+3] cycloaddition of iminoesters with fulvenes.

    Science.gov (United States)

    Potowski, Marco; Antonchick, Andrey P; Waldmann, Herbert

    2013-09-14

    A novel exo-selective [6+3] cycloaddition approach for the highly enantioselective synthesis of polysubstituted piperidines was developed. The developed methodology was applied in a one-pot [6+3]-[4+2] dicycloaddition, allowing the construction of structurally and stereochemically rich polycyclic compounds from simple building blocks. PMID:23884088

  19. Synthesis and optical properties of novel asymmetric perylene bisimides

    International Nuclear Information System (INIS)

    A novel series of asymmetric perylene bisimides, 1-amino-7-nitroperylene bisimides (1a–1c), was synthesized and fully characterized. These molecules undergo an excited-state intramolecular electron transfer reaction, resulting in a unique charge transfer emission in the near-infrared region, of which the peak wavelength exhibits strong solvatochromism. The dipole moments of these compounds have been estimated using the Lippert–Mataga equation, and upon excitation, the molecules show larger dipole moment changes than those of the symmetric 1,7-diaminoperylene bisimides (2a–2c). Furthermore, these dyes undergo two quasi-reversible one-electron oxidations and two quasi-reversible one-electron reductions in dichloromethane at modest potentials. They display good thermal stability and optical stability that can be used as stable near-infrared fluorescent dyes. Their spectroscopic properties in various conditions and complementary time-dependent density functional theory calculations are reported. - Highlights: • 1-amino-7-nitroperylene bisimide dyes were synthesized. • These molecules undergo an excited-state intramolecular electron transfer reaction. • They can be used as stable near-infrared fluorescent dyes

  20. Synthesis and optical properties of novel asymmetric perylene bisimides

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Hsing-Yang; Chen, Kew-Yu, E-mail: kyuchen@fcu.edu.tw

    2014-05-01

    A novel series of asymmetric perylene bisimides, 1-amino-7-nitroperylene bisimides (1a–1c), was synthesized and fully characterized. These molecules undergo an excited-state intramolecular electron transfer reaction, resulting in a unique charge transfer emission in the near-infrared region, of which the peak wavelength exhibits strong solvatochromism. The dipole moments of these compounds have been estimated using the Lippert–Mataga equation, and upon excitation, the molecules show larger dipole moment changes than those of the symmetric 1,7-diaminoperylene bisimides (2a–2c). Furthermore, these dyes undergo two quasi-reversible one-electron oxidations and two quasi-reversible one-electron reductions in dichloromethane at modest potentials. They display good thermal stability and optical stability that can be used as stable near-infrared fluorescent dyes. Their spectroscopic properties in various conditions and complementary time-dependent density functional theory calculations are reported. - Highlights: • 1-amino-7-nitroperylene bisimide dyes were synthesized. • These molecules undergo an excited-state intramolecular electron transfer reaction. • They can be used as stable near-infrared fluorescent dyes.

  1. Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones

    Science.gov (United States)

    Di Mola, Antonia; Tiffner, Maximilian; Scorzelli, Francesco; Palombi, Laura; Filosa, Rosanna; De Caprariis, Paolo

    2015-01-01

    Summary New bifunctional chiral ammonium salts were investigated in an asymmetric cascade synthesis of a key building block for a variety of biologically relevant isoindolinones. With this chiral compound in hand, the development of further transformations allowed for the synthesis of diverse derivatives of high pharmaceutical value, such as the Belliotti (S)-PD172938 and arylated analogues with hypnotic sedative activity, obtained in good overall total yield (50%) and high enantiomeric purity (95% ee). The synthetic routes developed herein are particularly convenient in comparison with the current methods available in literature and are particularly promising for large scale applications. PMID:26734105

  2. Electroenzymatic strategies for deracemization, stereoinversion and asymmetric synthesis of amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Maerkle, Wolfgang [Institut fuer Biotechnologie 2, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany); Luetz, Stephan [Institut fuer Biotechnologie 2, Forschungszentrum Juelich GmbH, D-52425 Juelich (Germany)], E-mail: s.luetz@fz-juelich.de

    2008-02-25

    A combination of a selective enzymatic oxidation with an unselective electrochemical reduction step was applied for deracemization, stereoinversion and asymmetric synthesis of L-leucine (starting from racemic leucine, D-leucine or 4-methyl-2-oxovaleric acid) in a batch reactor. D-Amino acid oxidase (D-AAO) from Trigonopsis variabilis was used as enzyme. Reaction conditions for the electrochemical and enzymatic reactions were investigated separately and finally combined to an electroenzymatic synthesis, yielding 3.5 mmol L{sup -1} d{sup -1} of L-leucine (ee 91%)

  3. Bifunctional phase-transfer catalysis in the asymmetric synthesis of biologically active isoindolinones.

    Science.gov (United States)

    Di Mola, Antonia; Tiffner, Maximilian; Scorzelli, Francesco; Palombi, Laura; Filosa, Rosanna; De Caprariis, Paolo; Waser, Mario; Massa, Antonio

    2015-01-01

    New bifunctional chiral ammonium salts were investigated in an asymmetric cascade synthesis of a key building block for a variety of biologically relevant isoindolinones. With this chiral compound in hand, the development of further transformations allowed for the synthesis of diverse derivatives of high pharmaceutical value, such as the Belliotti (S)-PD172938 and arylated analogues with hypnotic sedative activity, obtained in good overall total yield (50%) and high enantiomeric purity (95% ee). The synthetic routes developed herein are particularly convenient in comparison with the current methods available in literature and are particularly promising for large scale applications. PMID:26734105

  4. Development of a strategy for the asymmetric synthesis of polycyclic polyprenylated acylphloroglucinols via N-amino cyclic carbamate hydrazones: application to the total synthesis of (+)-clusianone.

    Science.gov (United States)

    Garnsey, Michelle R; Lim, Daniel; Yost, Julianne M; Coltart, Don M

    2010-11-19

    A broadly applicable asymmetric synthetic strategy utilizing N-amino cyclic carbamate alkylation that provides access to the various stereochemical permutations of a common structural motif found in many polycyclic polyprenylated acylphloroglucinols is described. The utility of this methodology is demonstrated through the first asymmetric total synthesis of the antiviral agent (+)-clusianone. PMID:20977254

  5. Catalytic synthesis of alcoholic fuels for transportation from syngas

    Energy Technology Data Exchange (ETDEWEB)

    Qiongxiao Wu

    2012-12-15

    consequently on the catalytic activity. (3) Addition of 3 mol % CO{sub 2} to the H2/CO feed stream leads to a significant loss of activity for the Cu-Ni/SiO2 catalyst contrary to the case for the Cu/ZnO/Al2O3 catalyst. DFT calculations show in accordance with previous surface science studies that oxygen on the surface could lead to an enrichment of the Ni-content in the surface. (4) Silica supported bimetallic Cu-Ni catalysts with different ratios of Cu to Ni have been prepared by impregnation. In situ reduction of Cu-Ni alloys with combined synchrotron XRD and XAS reveal a strong interaction between Cu and Ni, resulting in improved reducibility of Ni as compared to monometallic Ni. At high nickel concentrations silica supported Cu-Ni alloys form a homogeneous solid solution of Cu and Ni, whereas at lower nickel contents, copper and nickel are separately aggregated and form metallic Cu and Cu-Ni alloy phases. At the same reduction conditions, the particle sizes of reduced Cu-Ni alloys decrease with increasing in Ni content. A maximum methanol productivity of 0.66 kg kgcat-1 h-1 with methanol selectivity up to 99.2 mol % has been achieved for a Cu-Ni/SiO2 catalyst prepared by the deposition-co-precipitation method. There is no apparent catalyst deactivation observed during the tested time on stream (40-100 h), contrary to the observation for the industrial Cu/ZnO/Al2O3 catalyst. For higher alcohol synthesis, the main work has been performed on CO hydrogenation over supported Mo2C. Mo2C supported on active carbon, carbon nanotubes, and titanium dioxide, and promoted by K2CO3, has been prepared and tested for higher alcohol synthesis from syngas. At optimal conditions, the activity and selectivity to alcohols (methanol and higher alcohols) over supported Mo2C are significantly higher compared to bulk Mo2C. The CO conversion reaches a maximum, when about 20 wt % Mo2C is loaded on active carbon. The selectivity to higher alcohols increases with increasing Mo2C loading on active

  6. Primary amine/CSA ion pair: A powerful catalytic system for the asymmetric enamine catalysis

    KAUST Repository

    Liu, Chen

    2011-05-20

    A novel ion pair catalyst containing a chiral counteranion can be readily derived by simply mixing cinchona alkaloid-derived diamine with chiral camphorsulfonic acid (CSA). A mixture of 9-amino(9-deoxy)epi-quinine 8 and (-)-CSA was found to be the best catalyst with matching chirality, enabling the direct amination of α-branched aldehydes to proceed in quantitative yields and with nearly perfect enantioselectivities. A 0.5 mol % catalyst loading was sufficient to catalyze the reaction, and a gram scale enantioselective synthesis of biologically important α-methyl phenylglycine has been successfully demonstrated. © 2011 American Chemical Society.

  7. Direct Catalytic Asymmetric Mannich-Type Reaction of α- and β-Fluorinated Amides.

    Science.gov (United States)

    Brewitz, Lennart; Arteaga, Fernando Arteaga; Yin, Liang; Alagiri, Kaliyamoorthy; Kumagai, Naoya; Shibasaki, Masakatsu

    2015-12-23

    The last two decades have witnessed the emergence of direct enolization protocols providing atom-economical and operationally simple methods to use enolates for stereoselective C-C bond-forming reactions, eliminating the inherent drawback of the preformation of enolates using stoichiometric amounts of reagents. In its infancy, direct enolization relied heavily on the intrinsic acidity of the latent enolates, and the reaction scope was limited to readily enolizable ketones and aldehydes. Recent advances in this field enabled the exploitation of carboxylic acid derivatives for direct enolization, offering expeditious access to synthetically versatile chiral building blocks. Despite the growing demand for enantioenriched fluorine-containing small molecules, α- and β-fluorinated carbonyl compounds have been neglected in direct enolization chemistry because of the competing and dominating defluorination pathway. Herein we present a comprehensive study on direct and highly stereoselective Mannich-type reactions of α- and β-fluorine-functionalized 7-azaindoline amides that rely on a soft Lewis acid/hard Brønsted base cooperative catalytic system to guarantee an efficient enolization while suppressing undesired defluorination. This protocol contributes to provide a series of fluorinated analogs of enantioenriched β-amino acids for medicinal chemistry. PMID:26652911

  8. Quantitative study of catalytic activity and catalytic deactivation of Fe–Co/Al2O3 catalysts for multi-walled carbon nanotube synthesis by the CCVD process

    OpenAIRE

    Pirard, Sophie; Heyen, Georges; Pirard, Jean-Paul

    2010-01-01

    The catalytic deactivation during multi-walled carbon nanotube (MWNT) synthesis by the CCVD process and the influence of hydrogen on it were quantified. Initial specific reaction rate, relative specific productivity and catalytic deactivation were studied. Carbon source was ethylene, and a bimetallic iron–cobalt catalyst supported on alumina was used. The catalytic deactivation was modeled by a decreasing hyperbolic law, reflecting the progressive accumulation of amorphous carbon on active si...

  9. Catalytic Asymmetric Reduction of a 3,4-Dihydroisoquinoline for the Large-Scale Production of Almorexant : Hydrogenation or Transfer Hydrogenation?

    NARCIS (Netherlands)

    Verzijl, Gerard K.M.; Vries, André H.M. de; Vries, Johannes G. de; Kapitan, Peter; Dax, Thomas; Helms, Matthias; Nazir, Zarghun; Skranc, Wolfgang; Imboden, Christoph; Stichler, Juergen; Ward, Richard A.; Abele, Stefan; Lefort, Laurent

    2013-01-01

    Several methods are presented for the enantioselective synthesis of the tetrahydroisoquinoline core of almorexant (ACT-078573A), a dual orexin receptor antagonist. Initial clinical supplies were secured by the Noyori Ru-catalyzed asymmetric transfer hydrogenation (Ru-Noyori ATH) of the dihydroisoqui

  10. Synthesis of sulphonated mesoporous phenolic resins and their application in esterification and asymmetric aldol reactions

    International Nuclear Information System (INIS)

    Mesoporous phenolic resins were functionalized with sulphonic acid groups by four different types of sulphonation procedures: (i) direct sulphonation on the aromatic ring, (ii) alkyl sulphonation of the aromatic ring, and functionalizations of the phenolic hydroxyl surface by using an aryl silane, 2-(4-chlorosulphonylphenyl)ethyl trichlorosilane (iii) or a propyl silane, 3-mercaptopropyltrimethoxysilane (iv). The highest acidity loadings were obtained through direct sulphonation with fuming sulphuric acid (1.90 mmol H+ g−1) or chlorosulphonic acid (1.31 mmol H+ g−1) and these materials showed the highest conversion (97+ %) in Fischer esterification of acetic acid with propanol. However, the alkyl sulphonic groups, obtained through sulphonation procedure (ii) showed the highest stability in terms of maintenance of their acidity after use in consecutive catalytic runs or leaching treatments. This was demonstrated both through evaluation of the regenerated catalysts in a consecutive esterification run and during a leaching resistance test in aqueous medium. Moreover, the developed sulphonated mesoporous phenolic resins are presented as novel support for the non-covalent immobilization of an L-phenylalanine derived chiral diamine organocatalyst for asymmetric aldol reactions. The immobilization is established by an acid–base interaction between the sulphonic acid group and the amine function. The acidity and in particular the electronic withdrawing environment of the sulphonic acid groups influence enormously the catalytic performance of the non-covalent immobilized chiral diamine catalyst (aromatic > aliphatic). - Highlights: ► Different types of sulphonation procedures for mesoporous phenolic resins. ► Influence of acidity and electronic withdrawing environment. ► Novel support for non-covalent immobilization of chiral diamine catalyst. ► Catalytic performance in esterification and asymmetric aldol condensation. ► Demonstration of leaching resistance

  11. Synthesis of sulphonated mesoporous phenolic resins and their application in esterification and asymmetric aldol reactions

    Energy Technology Data Exchange (ETDEWEB)

    Muylaert, Ilke [Department of Inorganic and Physical Chemistry, Ghent University, Center for Ordered Materials, Organometallics and Catalysis (COMOC), Krijgslaan 281-S3, 9000 Ghent (Belgium); Verberckmoes, An, E-mail: an.verberckmoes@hogent.be [Department of Inorganic and Physical Chemistry, Ghent University, Center for Ordered Materials, Organometallics and Catalysis (COMOC), Krijgslaan 281-S3, 9000 Ghent (Belgium); Associated Faculty of Applied Engineering Sciences, University College Ghent, Valentin Vaerwyckweg 1, 9000 Ghent (Belgium); Spileers, Jeremy [Associated Faculty of Applied Engineering Sciences, University College Ghent, Valentin Vaerwyckweg 1, 9000 Ghent (Belgium); Demuynck, Anneleen; Peng, Li; De Clippel, Filip; Sels, Bert [Katholieke Universiteit Leuven, Centre for Surface Chemistry and Catalysis (COK), Kasteelpark Arenberg 23, 3001 Heverlee (Belgium); Van Der Voort, Pascal, E-mail: pascal.vandervoort@ugent.be [Department of Inorganic and Physical Chemistry, Ghent University, Center for Ordered Materials, Organometallics and Catalysis (COMOC), Krijgslaan 281-S3, 9000 Ghent (Belgium)

    2013-02-15

    Mesoporous phenolic resins were functionalized with sulphonic acid groups by four different types of sulphonation procedures: (i) direct sulphonation on the aromatic ring, (ii) alkyl sulphonation of the aromatic ring, and functionalizations of the phenolic hydroxyl surface by using an aryl silane, 2-(4-chlorosulphonylphenyl)ethyl trichlorosilane (iii) or a propyl silane, 3-mercaptopropyltrimethoxysilane (iv). The highest acidity loadings were obtained through direct sulphonation with fuming sulphuric acid (1.90 mmol H{sup +} g{sup −1}) or chlorosulphonic acid (1.31 mmol H{sup +} g{sup −1}) and these materials showed the highest conversion (97+ %) in Fischer esterification of acetic acid with propanol. However, the alkyl sulphonic groups, obtained through sulphonation procedure (ii) showed the highest stability in terms of maintenance of their acidity after use in consecutive catalytic runs or leaching treatments. This was demonstrated both through evaluation of the regenerated catalysts in a consecutive esterification run and during a leaching resistance test in aqueous medium. Moreover, the developed sulphonated mesoporous phenolic resins are presented as novel support for the non-covalent immobilization of an L-phenylalanine derived chiral diamine organocatalyst for asymmetric aldol reactions. The immobilization is established by an acid–base interaction between the sulphonic acid group and the amine function. The acidity and in particular the electronic withdrawing environment of the sulphonic acid groups influence enormously the catalytic performance of the non-covalent immobilized chiral diamine catalyst (aromatic > aliphatic). - Highlights: ► Different types of sulphonation procedures for mesoporous phenolic resins. ► Influence of acidity and electronic withdrawing environment. ► Novel support for non-covalent immobilization of chiral diamine catalyst. ► Catalytic performance in esterification and asymmetric aldol condensation. ► Demonstration

  12. Asymmetric Total Synthesis of Propindilactone G, Part 3: The Final Phase and Completion of the Synthesis.

    Science.gov (United States)

    Liang, Xin-Ting; You, Lin; Li, Yuan-He; Yu, Hai-Xin; Chen, Jia-Hua; Yang, Zhen

    2016-05-01

    Two independent synthetic approaches were evaluated for the final phase of the asymmetric total synthesis of propindilactone G (1). The key steps that led to the completion of the asymmetric total synthesis included: 1) an intermolecular oxidative heterocoupling reaction of enolsilanes to link the core structure to the side chain; 2) an intermolecular Wittig reaction for the formation of the α,β,γ,δ-unsaturated ester; and 3) a regio- and stereoselective OsO4 -catalyzed dihydroxylation of an α,β,γ,δ-unsaturated enone, followed by an intramolecular lactonization reaction to afford the final product. These reactions enabled the synthesis of (+)-propindilactone G in only 20 steps. As a consequence of our synthetic studies, the structure of (+)-propindilactone G has been revised. Furthermore, the direct oxidative coupling strategy for ligation of the core of propindilactone G with its side chain may find application in the syntheses of other natural products and complex molecules. PMID:26991640

  13. Asymmetric synthesis of -aminophosphonates: The bio-isosteric analogs of -aminobutyric acid

    Indian Academy of Sciences (India)

    Kalisankar Bera; Dwayaja Nadkarni; Iirishi N N Namboothiri

    2013-05-01

    The properties of aminophosphonates as transition state analogs of amino acids, and as antibacterial, antifungal and antiHIV agents attracted considerable attention in recent years. Although many reviews appeared in the literature covering - and -aminophosphonates, -aminophosphonates did not receive sufficient attention despite the fact that parent -aminophosphonic acid and its derivatives are bio-isosteric analogs of GABA (-amino butyric acid). This review provides a critical summary of the significance of -aminophosphonates and various approaches to their synthesis, with particular emphasis to asymmetric versions.

  14. One-Pot, Four-Step Organocatalytic Asymmetric Synthesis of Functionalized Nitrocyclopropanes.

    Science.gov (United States)

    Zaghi, Anna; Bernardi, Tatiana; Bertolasi, Valerio; Bortolini, Olga; Massi, Alessandro; De Risi, Carmela

    2015-09-18

    The asymmetric synthesis of functionalized nitrocyclopropanes has been achieved by a one-pot, four-step method catalyzed by (S)-diphenylprolinol TMS ether, which joins two sequential domino reactions, namely a domino sulfa-Michael/aldol condensation of α,β-unsaturated aldehydes with 1,4-dithiane-2,5-diol, and a domino Michael/α-alkylation reaction of the derived chiral dihydrothiophenes with bromonitromethane. The title compounds were obtained in 27-45% yields, with high levels of diastereoselectivity (93:7 to 100:0 dr) and generally good enantioselectivities (up to 95:5 er). PMID:26317611

  15. Chiral Borated Esters in Asymmetric Synthesis:1.The First Asymmetric Reaction Catalyzed by Chiral Spiroborated Esters with an O3BN Framework

    Institute of Scientific and Technical Information of China (English)

    LIU, De-Jun(刘德军); SHAN, Zi-Xing(单自兴); QIN, Jin-Gui(秦金贵)

    2004-01-01

    The first asymmetric reaction catalyzed by chiral spiroborated esters with an O3BN framework was reported. In the presence of 0.1 equivalent of (R,S)-1 or (S,S)-1, acetophenone was reduced by 0.6 equivalent of borane in THF at 0-5 ℃ for 2 h to give (R)-1-phenylethanol of up to 76% ee and 73% isolated yield. Influence of reaction conditions on the stereoselectivity of the reduction was investigated and a possible catalytic mechanism of the chiral spiroborated esters toward the reduction was also suggested.

  16. Synthesis, characterization and catalytic activity of chromium substituted cobalt ferrospinels

    International Nuclear Information System (INIS)

    Chromium substituted cobalt ferrospinels were prepared by soft citrate gel method. The synthesized material was characterized by various physico-chemical methods. All the samples showed a single-phase cubic structure. Lattice constant varies from 8.389 to 8.323 A. Transmission electron microscopic study indicated the nanostructure of the catalysts while homogenous grain distribution was presented by scanning electron microscopic studies. The catalytic activity of the samples was investigated towards acetylation of phenols. The presence of active centers on the surface of the material was confirmed through pyridine adsorption studies. The surface acidity of the catalyst is responsible for better catalytic performance. The material was found to serve as a promising catalyst for acylation and benzoylation of phenols under solvent free condition. These catalysts are ∼100% selective towards o-acylation of phenols, a promising reaction for perfumery intermediates. The catalysts were seen to be reusable without any further treatment. Catalytic activities of cobalt, chromium and iron oxides were also investigated for comparison. The cobalt ferrospinel was found to have better catalytic activity as compared to the Cr-substituted ferrospinels and the pure oxides. Cobalt ferrite catalyst offers high yields in a short reaction time under solvent-free conditions.

  17. Synthesis, characterization and catalytic activity of chromium substituted cobalt ferrospinels

    Energy Technology Data Exchange (ETDEWEB)

    Hankare, P.P., E-mail: p_hankarep@rediffmail.com [Department of Chemistry, Shivaji University, Kolhapur, Maharashtra, 416 004 (India); Sankpal, U.B., E-mail: sankpalumesh@gmail.com [Department of Chemistry, Shivaji University, Kolhapur, Maharashtra, 416 004 (India); Patil, R.P. [Department of Chemistry, Shivaji University, Kolhapur, Maharashtra, 416 004 (India); Lokhande, P.D. [Department of Chemistry, University of Pune, Pune, Maharashtra, 411 007 (India); Sasikala, R. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

    2011-02-15

    Chromium substituted cobalt ferrospinels were prepared by soft citrate gel method. The synthesized material was characterized by various physico-chemical methods. All the samples showed a single-phase cubic structure. Lattice constant varies from 8.389 to 8.323 A. Transmission electron microscopic study indicated the nanostructure of the catalysts while homogenous grain distribution was presented by scanning electron microscopic studies. The catalytic activity of the samples was investigated towards acetylation of phenols. The presence of active centers on the surface of the material was confirmed through pyridine adsorption studies. The surface acidity of the catalyst is responsible for better catalytic performance. The material was found to serve as a promising catalyst for acylation and benzoylation of phenols under solvent free condition. These catalysts are {approx}100% selective towards o-acylation of phenols, a promising reaction for perfumery intermediates. The catalysts were seen to be reusable without any further treatment. Catalytic activities of cobalt, chromium and iron oxides were also investigated for comparison. The cobalt ferrospinel was found to have better catalytic activity as compared to the Cr-substituted ferrospinels and the pure oxides. Cobalt ferrite catalyst offers high yields in a short reaction time under solvent-free conditions.

  18. Investigation of the By-products Formed during the Catalytic Synthesis of 4,4'-Methylenedimethyldiphenylcarbamate

    Institute of Scientific and Technical Information of China (English)

    QIU, Ze-Gang; WANG, Jun-Wei; KANG, Mao-Qing; LI, Qi-Feng; DU, Hui; WANG, Xin-Kui

    2007-01-01

    The structures of the by-products formed during the catalytic synthesis of 4,4'-methylenedimethyldiphenylcarbamate (MDC) by the reaction of 4,4'-methylenedianiline (MDA) with dimethyl carbonate (DMC) were identified and then the mechanisms of their formation were proposed.

  19. Competitive exclusion principle in ecology and absolute asymmetric synthesis in chemistry.

    Science.gov (United States)

    Ribó, Josep M; Hochberg, David

    2015-10-01

    The key concepts underlying the Frank model (1953) for spontaneous asymmetric synthesis in chemistry are traced back to the pioneering works of Volterra (1926) and Lotka (1932) on biological species competition. The Lotka-Volterra (L-V) two-species exclusive competition model reduces to the Frank model for the special case of distinguishable but degenerate species (i.e., the enantiomers). The important ecological principle of competitive exclusion, originally derived from the L-V two-competitors model, is a consequence of sufficiently antagonistic interactions between the species competing for limited common resources, or mutual inhibition, as the term is known in the chemical literature on absolute asymmetric synthesis. The L-V and Frank models are described by the same general differential equations, nevertheless a crucial thermodynamic distinction between these models is necessary to correlate ecological selection and chemical selectivity arising from 1) the absence of reversibility in biological transformations, in marked contrast to chemical reactions, and 2) the constraints in chemical scenarios on the reaction rate constants required to fulfill the principle of micro-reversibility. PMID:26301597

  20. Synthesis and characterization of type silicoaluminophosphates catalytic support

    International Nuclear Information System (INIS)

    The refining processes, the catalytic hydrocracking is the future of diesel oil in Brazil and the first units are already scheduled to be inaugurated. Among the catalysts used in this process, silicoaluminophosphates (SAPO's) have considerable potential for use as they have been effective in the isomerization of n-alkanes, the isomerization of olefins and alkylation of aromatics. Because of this, the objective is to develop catalysts that will be used in hydrocracking reactions. The media like SAPO-5 were synthesized with different ratios silicon/aluminum, which is used as a catalytic support and have the function of crack organic molecules, since it has acidic character. The materials were characterized by techniques: X-ray diffraction, chemical analysis and textural by BET. After summarizing the media found that they had agreements with the crystalline phases presented in the literature.(author)

  1. Catalytic fluorination s: the synthesis of hydro fluorocarbon (HFCs)

    International Nuclear Information System (INIS)

    Catalytic processes in the fluorine chemistry are developed for example in the selective preparation of substitutes of chlorofluorocarbons, such as the hydro-fluorocarbon CF3CH2F used as a refrigeration agent to replace the CF2CICCIF2. A better understanding of the catalyst and of the various mechanisms involved is required in order to increase the selectivity towards the wanted fluorinated products. (authors)

  2. Synthesis and Catalytic Evaluation of Dendrimer-Encapsulated Cu Nanoparticles: An Undergraduate Experiment Exploring Catalytic Nanomaterials

    Science.gov (United States)

    Feng, Z. Vivian; Lyon, Jennifer L.; Croley, J. Sawyer; Crooks, Richard M.; Vanden Bout, David A.; Stevenson, Keith J.

    2009-01-01

    Copper nanoparticles were synthesized using generation 4 hydroxyl-terminated (G4-OH) poly(amidoamine) (PAMAM) dendrimers as templates. The synthesis is conducted by coordinating copper ions with the interior amines of the dendrimer, followed by chemical reduction to form dendrimer-encapsulated copper nanoparticles (Cu-DEN). The catalytic…

  3. Environmentally Benign Synthesis of Enamides via Waste-Free Catalytic Addition of Amides to Terminal Alkynes

    OpenAIRE

    Salih, Kifah S. M.

    2010-01-01

    A number of natural products are known that contain an enamide as a key structural feature. This functionality is a very important subunit in various biologically active products and pharmaceutical drug lead compounds. In addition, enamides serve as highly versatile synthetic intermediates, particularly in the pericyclic reaction, formation of heterocycles, cross-coupling and in asymmetric synthesis. As a result, several protocols have been devised for the preparation of enamides. Traditional...

  4. Synthesis, characterization and catalytic properties of CuO nanocrystals with various shapes

    International Nuclear Information System (INIS)

    CuO nanocrystals with different shapes, i.e. irregular nanoparticles, nanobelts and nanoplatelets, have been synthesized by controlling a few critical synthesis parameters to explore their catalytic properties. It was found that the rate of CO oxidation on the nanoplatelets is over six times higher than that on the nanoparticles and about three times higher than that on the nanobelts at 110 deg. C. Based on combined characterizations, such as BET, XRD, TEM, HRTEM and CO temperature-programmed reduction, the relationship between the catalytic reactivity and the shape as well as the predominantly exposed crystal planes of the CuO nanocrystals has been discussed

  5. Chiral linker-bridged bis-N-heterocyclic carbenes: design, synthesis, palladium complexes, and catalytic properties.

    Science.gov (United States)

    Zhang, Dao; He, Yu; Tang, Junkai

    2016-08-01

    A series of chiral bis(benzimidazolium) salts 10-19 with (1R,2R)-cyclohexene, (1R,2R)-diphenylethylene and (aR)-binaphthylene linkers have been designed and synthesized in 30-94% yield. Ten chiral bis(NHC) palladium complexes 20-28 have been synthesized and characterized by NMR, HRMS, elemental analysis and further confirmed by X-ray single crystal analysis. These bis(NHC)-Pd complexes showed obviously different catalytic properties in the asymmetric Suzuki-Miyaura coupling reactions. The (1R,2R)-cyclohexene-bridged bis(NHC)-Pd complex, (R,R)-23, achieved the highest yield of 90%, while complex (aR)-28, with a binaphthylene linker, showed the best enantioselectivity of 60 ee%. The structural analysis of these complexes suggested that such difference of catalytic performance has a close relationship with their coordination surroundings around metal centres. PMID:27230553

  6. Microwave-Assisted SynthesisCatalytic Applications in Aqueous Media

    Science.gov (United States)

    The development of sustainable methods directed towards the synthesis of molecules is due to the heightened awareness and recognition of alternative eco-friendly and economical protocols that have minimum impact on environment. Among others, microwave (MW)-assisted methodology ha...

  7. Asymmetric total synthesis of (-)-lingzhiol via a Rh-catalysed [3+2] cycloaddition.

    Science.gov (United States)

    Long, Rong; Huang, Jun; Shao, Wenbin; Liu, Song; Lan, Yu; Gong, Jianxian; Yang, Zhen

    2014-01-01

    The development of efficient reactions for the one-pot construction of bicyclic ring systems bearing two quaternary carbon centres at their bridgehead positions represents a significant challenge to synthetic chemistry. The development of new methods capable of overcoming this challenge is highly desirable, because this motif can be found in a wide range of natural products with significant biological activities. Herein, we report an efficient [3+2] cycloaddition reaction between an enal and an alleno rhodium species, which was generated in situ from the corresponding enynol via a retro metal-propargylation reaction, to give [3.3.0] and [3.4.0] bicyclic systems bearing two quaternary atoms at their bridgehead positions. The developed chemistry has been successfully applied to the asymmetric total synthesis of natural product (-)-lingzhiol (4) for the first time in 17 steps. PMID:25483390

  8. Synthesis of asymmetric supramolecular compounds using a Ni(0) catalysed homo-coupling approach.

    Science.gov (United States)

    Cassidy, Lynda; Horn, Sabine; Cleary, Laura; Halpin, Yvonne; Browne, Wesley R; Vos, Johannes G

    2009-05-28

    The synthesis and characterisation of a series of dinuclear ruthenium and osmium polypyridyl metal complexes based on the bridging ligands [5-(5'-bipyridin-2',2''-yl)-3-(pyridin-2-yl)]-1,2,4-triazole (Hpytr-bipy), 2,2'-bis(pyridin-2''yl)-5,5'-bis(pyridin-3''-yl) (bipy-bipy) and 5,5'-bis(pyridin-2''-yl)-3,3'-bis(1,2,4-triazole) (Hpytr-Hpytr) are reported. The dinuclear complexes have been synthesised via a Ni(0) catalysed cross-coupling reaction from brominated precursors. With this approach a mixture of three products is obtained, which are separated by chromatographic methods. The compounds obtained are characterised by elemental analysis, (1)H NMR, absorption and emission spectroscopy. The synthetic approach developed offers a new route to asymmetric multinuclear supramolecular structures that is complimentary to the complexes as ligands/complexes as metal approaches. PMID:19440590

  9. Facile synthesis and catalytic property of porous tin dioxide nanostructures.

    Science.gov (United States)

    Zhao, Qingrui; Zhang, Zhigao; Dong, Ting; Xie, Yi

    2006-08-10

    Porous tin dioxide (SnO(2)) nanostructures consisting of nanoplates are prepared through thermal decomposition of the mixed solution composed of dibutyltin dilaurate and acetic acid. The aggregations of the nanoplates give rise to large macropores with the size of about 100-300 nm. These nanoplates have a wormhole-like porous structure with the size of about 4 nm and possess high surface area. X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, infrared spectroscopy, and nitrogen sorption have been employed to characterize the obtained porous structures. It is found that the obtained nanostructures exhibit excellent catalytic activity toward methanol decomposition. Such porous structures with high surface area have promising industrial applications as catalysts. PMID:16884229

  10. Synthesis of polyaniline nanotubes through UV light catalytic method

    Directory of Open Access Journals (Sweden)

    Chuanyu Sun

    2015-03-01

    Full Text Available In this study, nitrocellulose (NC fiber blanket prepared by electrostatic spinning method has been used as a template, and copper nitrate (Cu(NO32 as an oxidant to synthesise polyaniline nanotubes doped with heteropolyacid (H4SiW12O40, SiW12 using UV light catalytic method. Infrared spectroscopy (IR, X-ray powder diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM technologies were applied to characterize the prepared samples of polyaniline nanotubes. The results show that the external diameter of the tube is about 200 nm, and the internal diameter about 170 nm. We also give a reasonable speculation and explanation about the formation mechanism of the nanotubes.

  11. Incorporation of catalytic dehydrogenation into fischer-tropsch synthesis to significantly reduce carbon dioxide emissions

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, Gerald P.

    2012-11-13

    A new method of producing liquid transportation fuels from coal and other hydrocarbons that significantly reduces carbon dioxide emissions by combining Fischer-Tropsch synthesis with catalytic dehydrogenation is claimed. Catalytic dehydrogenation (CDH) of the gaseous products (C1-C4) of Fischer-Tropsch synthesis (FTS) can produce large quantities of hydrogen while converting the carbon to multi-walled carbon nanotubes (MWCNT). Incorporation of CDH into a FTS-CDH plant converting coal to liquid fuels can eliminate all or most of the CO.sub.2 emissions from the water-gas shift (WGS) reaction that is currently used to elevate the H.sub.2 level of coal-derived syngas for FTS. Additionally, the FTS-CDH process saves large amounts of water used by the WGS reaction and produces a valuable by-product, MWCNT.

  12. Green synthesis, characterization and catalytic activity of palladium nanoparticles by xanthan gum

    Science.gov (United States)

    Santoshi kumari, Amrutham; Venkatesham, Maragoni; Ayodhya, Dasari; Veerabhadram, Guttena

    2015-03-01

    Here, we report the synthesis, characterization and catalytic evaluation of palladium nanoparticles (PdNPs) using xanthan gum, acting as both reducing and stabilizing agent without using any synthetic reagent. The uniqueness of our method lies in its fast synthesis rates using hydrothermal method in autoclave at a pressure of 15 psi and at 120 °C temperature by 10 min time. The formation and size of the PdNPs were characterized by UV-visible spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. The catalytic activity of PdNPs was evaluated on the reduction of 4-nitrophenol to 4-aminophenol by sodium borohydride using spectrophotometry.

  13. MWW-type titanosilicate synthesis, structural modification and catalytic applications to green oxidations

    CERN Document Server

    Wu, Peng; Xu, Le; Liu, Yueming; He, Mingyuan

    2013-01-01

    This book provides a comprehensive review of a new generation of selective oxidation titanosilicate catalysts with the MWW topology (Ti-MWW) based on the research achievements of the past 12 years. It gives an overview of the synthesis, structure modification and catalytic properties of Ti-MWW. Ti-MWW can readily be prepared by means of direct hydrothermal synthesis with crystallization-supporting agents, using dual-structure-directing agents and a dry-gel conversion technique. It also can be post-synthesized through unique reversible structure transformation and liquid-phase isomorphous subst

  14. Advances in Study on Catalysts for Phenol Synthesis via Catalytic Hydroxylation of Benzene in China

    Institute of Scientific and Technical Information of China (English)

    Zheng Zhaohui

    2004-01-01

    Synthesis of phenol via direct hydroxylation of benzene as a typical reaction of atomic economy has attracted extensive attention worldwide and has also become an actively investigated domain in China. This article refers to the recent domestic advances in study on phenol synthesis via hydroxylation of benzene from the viewpoint of catalysts, and considers the TS-1/H2O2 and FeZSM-5/N2O catalytic systems to be promising ones with good prospects for commercialization along with some suggestions on future research work.

  15. Synthesis and properties of epoxydized cooligomers obtained from petroleum resins synthesized by heterogeneous catalytic oligomerization

    OpenAIRE

    Voronchak, Taras; Nykulyshyn, Irena; Pikh, Zorian; Rypka, Anna

    2012-01-01

    Synthesis of cooligomers with epoxy groups was studied. They were synthesized by epoxidation of unsaturated petroleum resins obtained by heterogeneous catalytic oligomerization of liquid pyrolysis products С9 fraction. The degree of unsaturated bonds conversion and the selectivity of epoxidation process were calculated. The properties of epoxydized cooligomers were determined and analyzed. The structurization of synthesized products in the composition of composites with epoxy resin ED-20 ...

  16. Mössbauer study of nanodimensional nickel ferrite-mechanochemical synthesis and catalytic properties

    OpenAIRE

    Manova, Elina; Estournès, Claude; Paneva, Daniela; Rehspringer, Jean Luc; Tsoncheva, Tanya; Kunev, Boris; Mitov, Ivan

    2005-01-01

    Iron-nickel spinel oxide NiFe2O4 nanoparticles have been prepared by the combination of chemical precipitation and subsequent mechanical milling. For comparison, their analogue obtained by thermal synthesis is also studied. Phase composition and structural properties of iron-nickel oxides are investigated by X-ray diffraction and Mössbauer spectroscopy. Their catalytic behavior in methanol decomposition to CO and methane is tested. An influence of the preparation method on the reduction and c...

  17. Asymmetric Synthesis of Decahydroquinolines via Organocatalysis: Total Synthesis of (+)-Lycoposerramine Z and (-)-Cermizine B

    OpenAIRE

    Luque Corredera, Carlos

    2014-01-01

    [eng] 1) The treatment of a tert-butyl beta-keto ester tethered to an omega-amino monoprotected group with crotonaldehyde using LiOH as the base, furnishes domino reactions involving the consecutive formation of two C-C bonds and one C-N bond in a sequence that comprises an intermolecular Michael process, followed by intramolecular aldol and aza-Michael reactions. This general methodology for the diastereoselective synthesis of 5-oxodecahydroquinolines implies a biscyclization and the format...

  18. Polymer supported nickel complex: Synthesis, structure and catalytic application

    Indian Academy of Sciences (India)

    Alekha Kumar Sutar; Tungabidya Maharana; Yasobanta Das; Prasanta Rath

    2014-11-01

    In the present investigation, a new synthetic route for a novel recyclable free [3-MOBdMBn-Ni] and polystyrene-anchored [P-3-MOBdMBn-Ni] nickel complexes is presented. The free and polymer-anchored metal complexes were synthesized by the reaction of nickel (II) with one molar equivalent of unsupported N N′-bis (2-Hydroxy-3-methoxybenzaldehyde) 4-Methylbenzene-1,2-diamine (3-MOBdMBn) or polymersupported (P-3-MOBdMBn) Schiff-base ligand in methanol under nitrogen atmosphere. The advantages of these polymer-supported catalysts are the low cost of catalyst and recyclability up to six times, due to easy availability of materials and simple synthetic route. The higher efficiency of complexation of nickel on the polymer-anchored 3-MOBdMBn Schiff base than the unsupported analogue is another advantage of this catalyst system. The structural study reveals that nickel(II) complex of 3-MOBdMBn is square planar in geometry. The catalytic activity of nickel complex towards the oxidation of phenol was investigated in the presence of hydrogen peroxide. Experimental results indicate that the reactivity of P-3-MOBdMBn-Ni was dramatically affected by the polymer support compared to free 3-MOBdMBn-Ni. The rates of oxidation (R) for unsupported and supported catalysts are 1.37 × 10-6 mole dm-3 s-1 and 2.33 × 10-6 mole dm-3 s-1 respectively.

  19. Synthesis and catalytic activity of polysaccharide templated nanocrystalline sulfated zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Sherly, K. B.; Rakesh, K. [Mahatma Gandhi University Regional Research Center in Chemistry, Department of Chemistry, Mar Athanasius College, Kothamangalam-686666, Kerala (India)

    2014-01-28

    Nanoscaled materials are of great interest due to their unique enhanced optical, electrical and magnetic properties. Sulfate-promoted zirconia has been shown to exhibit super acidic behavior and high activity for acid catalyzed reactions. Nanocrystalline zirconia was prepared in the presence of polysaccharide template by interaction between ZrOCl{sub 2}⋅8H{sub 2}O and chitosan template. The interaction was carried out in aqueous phase, followed by the removal of templates by calcination at optimum temperature and sulfation. The structural and textural features were characterized by powder XRD, TG, SEM and TEM. XRD patterns showed the peaks of the diffractogram were in agreement with the theoretical data of zirconia with the catalytically active tetragonal phase and average crystalline size of the particles was found to be 9 nm, which was confirmed by TEM. TPD using ammonia as probe, FTIR and BET surface area analysis were used for analyzing surface features like acidity and porosity. The BET surface area analysis showed the sample had moderately high surface area. FTIR was used to find the type species attached to the surface of zirconia. UV-DRS found the band gap of the zirconia was found to be 2.8 eV. The benzylation of o-xylene was carried out batchwise in atmospheric pressure and 433K temperature using sulfated zirconia as catalyst.

  20. Asymmetric Total Synthesis of Propindilactone G, Part 2: Enantioselective Construction of the Fully Functionalized BCDE Ring System.

    Science.gov (United States)

    Zhang, Jia-Jun; You, Lin; Wang, Yue-Fan; Li, Yuan-He; Liang, Xin-Ting; Zhang, Bo; Yang, Shou-Liang; Su, Qi; Chen, Jia-Hua; Yang, Zhen

    2016-05-01

    The enantioselective synthesis of the fully functionalized BCDE tetracyclic ring system of propindilactone G (A) is reported. Several synthetic methods were developed and applied to achieve this goal, including: 1) an asymmetric Diels-Alder reaction in the presence of Hayashi's catalyst for the synthesis of optically pure key intermediate 3; 2) an intramolecular Pauson-Khand reaction (PKR) for the stereoselective synthesis of the BCDE ring with an all-carbon chiral quaternary center at the C13 position by using the TMS-substituted acetylene as the substrate; and 3) Pd-catalyzed reductive hydrogenolysis for the stereoselective synthesis of the fully functionalized BCDE tetracyclic ring system. The chemistry developed herein provided a greater understanding of the total synthesis propindilactone G (A) and its analogues. PMID:26991420

  1. Catalytic Enantioselective Functionalization of Unactivated Terminal Alkenes.

    Science.gov (United States)

    Coombs, John R; Morken, James P

    2016-02-01

    Terminal alkenes are readily available functional groups which appear in α-olefins produced by the chemical industry, and they appear in the products of many contemporary synthetic reactions. While the organic transformations that apply to alkenes are amongst the most studied reactions in all of chemical synthesis, the number of reactions that apply to nonactivated terminal alkenes in a catalytic enantioselective fashion is small in number. This Minireview highlights the cases where stereocontrol in catalytic reactions of 1-alkenes is high enough to be useful for asymmetric synthesis. PMID:26764019

  2. Structure Investigation of Ti(IV)BODOLates Involved in the Catalytic Asymmetric Reduction of Ketones Using Catecholborane

    DEFF Research Database (Denmark)

    Sarvary, Ian; Norrby, Per-Ola; Frejd, Torbjörn

    2004-01-01

    The complexes formed on mixing Ti(OiPr)4 and bicyclo-octanediols (BODOLs) 1 and 2 (1:1) are useful as chiral catalysts in asymmetric reductions and were investigated by 1HNMR-spectroscopy and by computational methods. A consistent picture emerged of head-to-tail dimers being kept together via a Ti...

  3. DIFLUORPHOS and SYNPHOS in asymmetric catalysis: Synthetic applications

    Indian Academy of Sciences (India)

    Sebastien Prevost; Tahar Ayad; Jean-Pierre Genet; Phannarath Phansavath; Virginie Ratovelomanana-Vidal

    2014-03-01

    Enantiomerically pure diphosphines play an important role in various homogeneous metalcatalyzed asymmetric reactions. Over the last few years, our group has been involved in the design and synthesis of atropisomeric ligands named SYNPHOS and DIFLUORPHOS with complementary stereoelectronic properties. This paper shows the high catalytic performances of DIFLUORPHOS, SYNPHOS and SYNPHOS analogues for some C-H and C-C bond forming processes as well as for the synthesis of biorelevant targets.

  4. One-Pot Synthesis of (S)-Baclofen via Aldol Condensation of Acetaldehyde with Diphenylprolinol Silyl Ether Mediated Asymmetric Michael Reaction as a Key Step.

    Science.gov (United States)

    Hayashi, Yujiro; Sakamoto, Daisuke; Okamura, Daichi

    2016-01-01

    An efficient asymmetric total synthesis of (S)-baclofen was accomplished via a one-pot operation from commercially available materials using sequential reactions, such as aldol condensation of acetaldehyde, diphenylprolinol silyl ether mediated asymmetric Michael reaction of nitromethane, Kraus-Pinnick oxidation, and Raney Ni reduction. Highly enantioenriched baclofen was obtained in one pot with a good yield over four reactions. PMID:26636719

  5. Asymmetric Total Synthesis of (+)- and (−)-Clusianone and (+)- and (−)Clusianone Methyl Enol Ether via ACC Alkylation and Evaluation of their Anti-HIV Activity

    OpenAIRE

    Garnsey, Michelle R.; Matous, James A.; Kwiek, Jesse J; Coltart, Don M.

    2011-01-01

    The total asymmetric synthesis of (+)- and (−)-clusianone and (+)- and (−)-clusianone methyl enol ether is reported. Asymmetric induction is achieved through the use of ACC alkylation, providing the key intermediates with an er of 99:1. The four synthetic compounds were evaluated for their anti-HIV activity. Both (+)- and (−)-clusianone displayed significant anti-HIV activity.

  6. Synthesis of MoO{sub 3} nanoparticles for azo dye degradation by catalytic ozonation

    Energy Technology Data Exchange (ETDEWEB)

    Manivel, Arumugam; Lee, Gang-Juan [Department of Environmental Engineering and Science, Feng Chia University, Taiwan (China); Chen, Chin-Yi [Department of Material Science and Engineering, Feng Chia University, Taiwan (China); Chen, Jing-Heng; Ma, Shih-Hsin [Department of Photonics, Feng Chia University, Taiwan (China); Horng, Tzzy-Leng [Department of Applied Mathematics, Taiwan (China); Wu, Jerry J., E-mail: jjwu@fcu.edu.tw [Department of Environmental Engineering and Science, Feng Chia University, Taiwan (China)

    2015-02-15

    Highlights: • Synthesis of one-dimensional MoO{sub 3} nanostructures using hydrothermal, microwave, and sonochemical methods. • Sonochemical synthesized MoO{sub 3} presents the best efficiency for the dye removal by catalytic ozonation. • Efficient environmental remediation process. - Abstract: One-dimensional molybdenum trioxide nanostructures were prepared in three different approaches, including thermal, microwave, and sonochemical methods. The physicochemical properties of the obtained MoO{sub 3} nanoparticles were investigated by diffused reflectance spectroscopy, X-ray diffraction analysis, field emission scanning electron microscopy, high resolution transmission electron microscopy, and Brunauer–Emmett–Teller surface area analysis. Among the methods as investigated, sonochemical synthesis gave well-dispersed fine MoO{sub 3} nanoparticles compared with the other approaches. All the synthesized MoO{sub 3} nanostructures were examined for the catalytic ozonation to degrade azo dye in aqueous environment. Different performances were obtained for the catalyst prepared in different methods and the catalytic efficiencies were found to be the order of sonochemical, microwave, and then thermal methods. The sonochemical MoO{sub 3} catalyst allowed the total dye removal within 20 min and its good performance was justified according to their higher surface area with higher number of active sites that provide effective dye interaction for better degradation.

  7. Synthesis of MoO3 nanoparticles for azo dye degradation by catalytic ozonation

    International Nuclear Information System (INIS)

    Highlights: • Synthesis of one-dimensional MoO3 nanostructures using hydrothermal, microwave, and sonochemical methods. • Sonochemical synthesized MoO3 presents the best efficiency for the dye removal by catalytic ozonation. • Efficient environmental remediation process. - Abstract: One-dimensional molybdenum trioxide nanostructures were prepared in three different approaches, including thermal, microwave, and sonochemical methods. The physicochemical properties of the obtained MoO3 nanoparticles were investigated by diffused reflectance spectroscopy, X-ray diffraction analysis, field emission scanning electron microscopy, high resolution transmission electron microscopy, and Brunauer–Emmett–Teller surface area analysis. Among the methods as investigated, sonochemical synthesis gave well-dispersed fine MoO3 nanoparticles compared with the other approaches. All the synthesized MoO3 nanostructures were examined for the catalytic ozonation to degrade azo dye in aqueous environment. Different performances were obtained for the catalyst prepared in different methods and the catalytic efficiencies were found to be the order of sonochemical, microwave, and then thermal methods. The sonochemical MoO3 catalyst allowed the total dye removal within 20 min and its good performance was justified according to their higher surface area with higher number of active sites that provide effective dye interaction for better degradation

  8. In Situ Synthesis of Bimetallic Hybrid Nanocatalysts on a Paper-Structured Matrix for Catalytic Applications

    Directory of Open Access Journals (Sweden)

    Hirotaka Koga

    2011-11-01

    Full Text Available Bimetallic nanoparticles have attracted significant attention as their electrochemical and catalytic properties being superior to those of the individual component nanoparticles. In this study, gold-silver hybrid nanoparticles (AuAgNPs with an Aucore-Agshell nanostructure were successfully synthesized on zinc oxide (ZnO whiskers. The as-prepared nanocatalyst, denoted AuAgNPs@ZnO whisker, exhibits an excellent catalytic efficiency in the aqueous reduction of 4-nitrophenol to 4-aminophenol; the turnover frequency was up to 40 times higher than that of each component nanoparticle. Their unique features were attributed to the electronic ligand effect at the bimetallic interface. In addition, the AuAgNPs were synthesized on a ZnO whisker-containing paper with a fiber-network microstructure, which was prepared via a papermaking technique. The paper-structured AuAgNPs composite possessed both a paper-like practical utility and a good catalytic performance. Furthermore, the on-paper synthesis process for these bimetallic nanocatalysts is facile. These easy-to-handle nanocatalyst hybrid composites are expected to find a wide range of applications in various chemical and catalytic processes.

  9. Catalytic performance of Fe3O4 nanoparticles for cyclocondensation synthesis of thiacrown ethers

    International Nuclear Information System (INIS)

    The catalytic function of nanoparticles is one the most successful applications of nanotechnologies so far. A novel and mild one-pot cyclocondensation reaction catalyzed by Fe3O4 nanoparticles is achieved for the first time in this work. By the function of those nanoparticles, the thiacrown ethers, including both 1,4-dithiane and 1,4,7-trithiacyclononane were obtained with considerable yield and turnover in a milder condition than that of the conventional routes. The excellent dehydrating ability and acid sensitivity of Fe3O4 nanoparticles were discovered in a series of experiments of esterification of DL-malic acid. The catalytic reaction mechanism of Fe3O4 nanoparticles was explored through the investigation of morphology evolution of those nanoparticles by transmission electron microscopy. Interestingly, the as-prepared big nanoparticles were decomposed into hollow or loose bounded aggregates of smaller nanoparticles after catalytic cycles. The result shown in this work claims promising utilization of Fe3O4 nanoparticles with big potential in catalytic synthesis. (paper)

  10. Catalytic Synthesis of Isopropyl Benzene over SO42-/ZrO2 -MCM-41

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Super acid catalyst SO2-4-/ZrO2 was introduced into pure silicone MCM-41 via the impregnation method and the catalyst samples obtained at different temperatures were characterized by means of XRD, IR, and Py-IR techniques.The selectively catalytic gas-phase flow reactions of benzene with propene over the catalyst samples were carried out in a made-to-measure high-pressure flow reactor equipped with a thermostat and a condenser. Effect of the preparative condition on the catalytic synthesis of isopropyl benzene over the catalyst samples was tested. The results show that SO2-4/ZrO2-MCM-41 (SZM-41) can be used as a catalyst for the title reaction, in which there are a higher conversion (97%) for the propene and a higher selectivity(93%) for the isopropyl benzene.

  11. Highly asymmetrical glycerol diether bolalipids: synthesis and temperature-dependent aggregation behavior.

    Science.gov (United States)

    Markowski, Thomas; Drescher, Simon; Förster, Günter; Lechner, Bob-Dan; Meister, Annette; Blume, Alfred; Dobner, Bodo

    2015-10-01

    In the present work, we describe the synthesis and temperature-dependent aggregation behavior of two examples of a new class of highly asymmetrical glycerol diether bolaphospholipids. The bolalipids contain a long alkyl chain (C32) bound to glycerol in the sn-3 position, carrying a hydroxyl group at the ω position. The C16 alkyl chain in the sn-2 position either possesses a racemic methyl branch at the 10 position of the short alkyl chain (lipid II) or does not (lipid I). The sn-1 position of the glycerol is linked to a zwitterionic phosphocholine moiety. The temperature-dependent aggregation behavior of both bolalipids was studied using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and X-ray scattering. Aggregate structures were visualized by transmission electron microscopy (TEM). We show that both bolalipids self-assemble into large lamellar sheetlike aggregates. Closed lipid vesicles or other aggregate structures such as tubes or nanofibers, as usually found for diglycerol tetraether lipids, were not observed. Within the lamellae the bolalipid molecules are arranged in an antiparallel (interdigitated) orientation. Lipid I, without an additional methyl moiety in the short alkyl chain, shows a lamellar phase with high crystallinity up to a temperature of 34 °C, which was not observed before for other phospholipids. PMID:26366715

  12. Catalytic Role of Manganese Oxides in Prebiotic Nucleobases Synthesis from Formamide

    Science.gov (United States)

    Bhushan, Brij; Nayak, Arunima; Kamaluddin

    2016-06-01

    Origin of life processes might have begun with the formation of important biomonomers, such as amino acids and nucleotides, from simple molecules present in the prebiotic environment and their subsequent condensation to biopolymers. While studying the prebiotic synthesis of naturally occurring purine and pyrimidine derivatives from formamide, the manganese oxides demonstrated not only good binding for formamide but demonstrated novel catalytic activity. A novel one pot manganese oxide catalyzed synthesis of pyrimidine nucleobases like thymine is reported along with the formation of other nucleobases like purine, 9-(hydroxyacetyl) purine, cytosine, 4(3 H)-pyrimidinone and adenine in acceptable amounts. The work reported is significant in the sense that the synthesis of thymine has exhibited difficulties especially under one pot conditions and also such has been reported only under the catalytic activity of TiO2. The lower oxides of manganese were reported to show higher potential as catalysts and their existence were favored by the reducing atmospheric conditions prevalent on early Earth; thereby confirming the hypothesis that mineral having metals in reduced form might have been more active during the course of chemical evolution. Our results further confirm the role of formamide as a probable precursor for the formation of purine and pyrimidine bases during the course of chemical evolution and origin of life.

  13. Catalytic Role of Manganese Oxides in Prebiotic Nucleobases Synthesis from Formamide.

    Science.gov (United States)

    Bhushan, Brij; Nayak, Arunima; Kamaluddin

    2016-06-01

    Origin of life processes might have begun with the formation of important biomonomers, such as amino acids and nucleotides, from simple molecules present in the prebiotic environment and their subsequent condensation to biopolymers. While studying the prebiotic synthesis of naturally occurring purine and pyrimidine derivatives from formamide, the manganese oxides demonstrated not only good binding for formamide but demonstrated novel catalytic activity. A novel one pot manganese oxide catalyzed synthesis of pyrimidine nucleobases like thymine is reported along with the formation of other nucleobases like purine, 9-(hydroxyacetyl) purine, cytosine, 4(3 H)-pyrimidinone and adenine in acceptable amounts. The work reported is significant in the sense that the synthesis of thymine has exhibited difficulties especially under one pot conditions and also such has been reported only under the catalytic activity of TiO2. The lower oxides of manganese were reported to show higher potential as catalysts and their existence were favored by the reducing atmospheric conditions prevalent on early Earth; thereby confirming the hypothesis that mineral having metals in reduced form might have been more active during the course of chemical evolution. Our results further confirm the role of formamide as a probable precursor for the formation of purine and pyrimidine bases during the course of chemical evolution and origin of life. PMID:26758444

  14. Monodisperse metal nanoparticle catalysts on silica mesoporous supports: synthesis, characterizations, and catalytic reactions

    Energy Technology Data Exchange (ETDEWEB)

    Somorjai, G.A.

    2009-09-14

    The design of high performance catalyst achieving near 100% product selectivity at maximum activity is one of the most important goals in the modern catalytic science research. To this end, the preparation of model catalysts whose catalytic performances can be predicted in a systematic and rational manner is of significant importance, which thereby allows understanding of the molecular ingredients affecting the catalytic performances. We have designed novel 3-dimensional (3D) high surface area model catalysts by the integration of colloidal metal nanoparticles and mesoporous silica supports. Monodisperse colloidal metal NPs with controllable size and shape were synthesized using dendrimers, polymers, or surfactants as the surface stabilizers. The size of Pt, and Rh nanoparticles can be varied from sub 1 nm to 15 nm, while the shape of Pt can be controlled to cube, cuboctahedron, and octahedron. The 3D model catalysts were generated by the incorporation of metal nanoparticles into the pores of mesoporous silica supports via two methods: capillary inclusion (CI) and nanoparticle encapsulation (NE). The former method relies on the sonication-induced inclusion of metal nanoparticles into the pores of mesoporous silica, whereas the latter is performed by the encapsulation of metal nanoparticles during the hydrothermal synthesis of mesoporous silica. The 3D model catalysts were comprehensively characterized by a variety of physical and chemical methods. These catalysts were found to show structure sensitivity in hydrocarbon conversion reactions. The Pt NPs supported on mesoporous SBA-15 silica (Pt/SBA-15) displayed significant particle size sensitivity in ethane hydrogenolysis over the size range of 1-7 nm. The Pt/SBA-15 catalysts also exhibited particle size dependent product selectivity in cyclohexene hydrogenation, crotonaldehyde hydrogenation, and pyrrole hydrogenation. The Rh loaded SBA-15 silica catalyst showed structure sensitivity in CO oxidation reaction. In

  15. Synthesis, Characterization and Catalytic Activity of Cu/Cu2O Nanoparticles Prepared in Aqueous Medium

    Directory of Open Access Journals (Sweden)

    Sayed M. Badawy

    2015-07-01

    Full Text Available Copper/Copper oxide (Cu/Cu2O nanoparticles were synthesized by modified chemical reduction method in an aqueous medium using hydrazine as reducing agent and copper sulfate pentahydrate as precursor. The Cu/Cu2O nanoparticles were characterized by X-ray Diffraction (XRD, Energy Dispersive X-ray Fluorescence (EDXRF, Scanning Electron Microscope (SEM, and Transmission Electron Microscope (TEM. The analysis revealed the pattern of face-centered cubic (fcc crystal structure of copper Cu metal and cubic cuprites structure for Cu2O. The SEM result showed monodispersed and agglomerated particles with two micron sizes of about 180 nm and 800 nm, respectively. The TEM result showed few single crystal particles of face-centered cubic structures with average particle size about 11-14 nm. The catalytic activity of Cu/Cu2O nanoparticles for the decomposition of hydrogen peroxide was investigated and compared with manganese oxide MnO2. The results showed that the second-order equation provides the best correlation for the catalytic decomposition of H2O2 on Cu/Cu2O. The catalytic activity of hydrogen peroxide by Cu/Cu2O is less than the catalytic activity of MnO2 due to the presence of copper metal Cu with cuprous oxide Cu2O. © 2015 BCREC UNDIP. All rights reservedReceived: 6th January 2015; Revised: 14th March 2015; Accepted: 15th March 2015How to Cite: Badawy, S.M., El-Khashab, R.A., Nayl, A.A. (2015. Synthesis, Characterization and Catalytic Activity of Cu/Cu2O Nanoparticles Prepared in Aqueous Medium. Bulletin of Chemical Reaction Engineering & Catalysis, 10 (2: 169-174. (doi:10.9767/bcrec.10.2.7984.169-174 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.7984.169-174  

  16. Glucomannan-mediated facile synthesis of gold nanoparticles for catalytic reduction of 4-nitrophenol

    Science.gov (United States)

    Gao, Zhao; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

    2014-08-01

    A facile one-pot approach for synthesis of gold nanoparticles with narrow size distribution and good stability was presented by reducing chloroauric acid with a polysaccharide, konjac glucomannan (KGM) in alkaline solution, which is green and economically viable. Here, KGM served both as reducing agent and stabilizer. The effects of KGM on the formation and stabilization of as-synthesized gold nanoparticles were studied systematically by a combination of UV-visible (UV-vis) absorption spectroscopy, transmission electron microscopy, X-ray diffraction, dynamic light scattering, and Fourier transform infrared spectroscopy. Furthermore, the gold nanoparticles exhibited a notable catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol.

  17. A Sustainable and Efficient Synthesis of Benzyl Phosphonates Using PEG/KI Catalytic System.

    Science.gov (United States)

    Disale, Shamrao; Kale, Sandip; Abraham, George; Kahandal, Sandeep; Sawarkar, Ashish N; Gawande, Manoj B

    2016-01-01

    An efficient and expedient protocol for the synthesis of benzyl phosphonates using KI/K2CO3 as a catalytic system and PEG-400 as benign solvent has been developed. The reaction proceeds smoothly at room temperature achieving excellent selectivity and yield of the corresponding products. The combination of PEG-400, KI, and K2CO3 in this reaction avoids the need of volatile/toxic organic solvents and reactive alkali metals or metal nanoparticles/hydrides. We believe that this benign combination (PEG-400 and KI) could be used for other related organic transformations. PMID:27579301

  18. Mesoporous MgO: Synthesis, physico-chemical, and catalytic properties

    Science.gov (United States)

    Maerle, A. A.; Kasyanov, I. A.; Moskovskaya, I. F.; Romanovsky, B. V.

    2016-06-01

    Mesoporous MgO was obtained via the hydrothermal synthesis using both ionogenic and non-ionogenic surfactants as structure-directing templates. The materials prepared were characterized by SEM, BET-N2, XRD, and TG-DTA techniques. MgO particles are spherical 20-μm aggregates of primary oxide particles well shaped as rectangular parallelepipeds. Magnesium oxide samples have the specific surface area of 290-400 m2/g and pore sizes of 3.3-4.1 nm. Their mesoporous structure remained unchanged after calcination up to 350°C. Catalytic activity of mesoporous MgO was studied in acetone condensation reaction.

  19. Ionic liquids as a convenient new medium for the catalytic asymmetric dihydroxylation of olefins using a recoverable and reusable osmium/ligand.

    Science.gov (United States)

    Branco, Luís C; Afonso, Carlos A M

    2004-06-25

    The use of room-temperature ionic liquids (RTILs) in the Sharpless catalytic asymmetric dihydroxylation (AD) as a cosolvent or replacement of the tert-butanol was studied in detail by screening 11 different RTILs. The AD reaction is faster in 1-n-butyl-3-methylimidazolium hexafluorophosphate [C(4)mim][PF(6)] as a cosolvent than in the conventional system of tert-butanol/H(2)O. For the range of six substrates tested, comparable or even higher yields and enantiomeric excess (ee) were found using [C(4)mim][PF(6)] or 1-n-octyl-3-methylimidazolium hexafluorophosphate [C(8)mim][PF(6)] compared to the conventional solvent system. Due to high affinity of the catalytic osmium/quiral ligand system to the ionic liquid, the use of ionic liquid/water (biphasic) or ionic liquid/water/tert-butanol (monophasic) solvent systems provides a recoverable, reusable, robust, efficient, and simple system for the AD reaction. Using 1-hexene and [C(4)mim][PF(6)] as RTIL it was possible to reuse the catalytic system for 9 cycles with only a 5% of yield reduction from the first cycle, allowing an overall yield of 87%, TON = 1566, and with similar ee. Additionally, for each cycle, after extraction of the reaction mixture with diethyl ether, the osmium content in the organic phase (containing the AD product) and in the aqueous phase was in the range of the detection limit (amount, respectively. In contrast, the ionic liquid phase retained more than 90% of the osmium content of the previous cycle. PMID:15202893

  20. Synthesis of gold nanoparticles using renewable Punica granatum juice and study of its catalytic activity

    Science.gov (United States)

    Dash, Shib Shankar; Bag, Braja Gopal

    2014-01-01

    Punica granatum juice, a delicious multivitamin drink of great medicinal significance, is rich in different types of phytochemicals, such as terpenoids, alkaloids, sterols, polyphenols, sugars, fatty acids, aromatic compounds, amino acids, tocopherols, etc. We have demonstrated the use of the juice for the synthesis of gold nanoparticles (AuNPs) at room temperature under very mild conditions. The synthesis of the AuNPs was complete in few minutes and no extra stabilizing or capping agents were necessary. The size of the nanoparticles could be controlled by varying the concentration of the fruit extract. The AuNPs were characterized by surface plasmon resonance spectroscopy, high resolution transmission electron microscopy, fourier transform infrared spectroscopy and X-ray diffraction studies. Catalytic activity of the synthesized colloidal AuNPs has also been demonstrated.

  1. Arginine-assisted synthesis and catalytic properties of single-crystalline palladium tetrapods.

    Science.gov (United States)

    Fu, Geng-Tao; Jiang, Xian; Wu, Rui; Wei, Shao-Hua; Sun, Dong-Mei; Tang, Ya-Wen; Lu, Tian-Hong; Chen, Yu

    2014-12-24

    Noble metallic nanocrystals (NMNCs) with highly branched morphologies are an exciting new class of nanomaterials because of their great potential application in catalysis, sensing, optics, and electronics originating from their unique structures. Herein, we report a facile water-based method to synthesize high-quality palladium (Pd) tetrapods with the assistance of arginine molecule, which is more economical and environmentally friendly than the previous reported carbon monoxide (CO)-assisted synthesis in the organic system. During the synthesis, arginine molecule plays an essential role in controlling the tetrapod-like morphology. The as-synthesized Pd tetrapods have a potential application in the formic acid (HCOOH)-induced reduction of highly toxic hexavalent chromium (Cr(VI)) owing to their improved catalytic performance for the HCOOH decomposition. PMID:25469763

  2. Asymmetric Synthesis Using Novel Cationic Diether-Coordinated Lewis Acid and Stereoselective Synthesis of Piperidones and 1,2-Amino Alcohols

    OpenAIRE

    Ishimaru, Kaori

    1997-01-01

    CONTENTS Chapter 1.Asymmetric Synthesis Using Novel Cationic Diether-Coordinated Lewis Acids  1-1.Introduction / p1  1-2.Cationic Lewis Acids for [4+2]Type Cycloaddition of α-Chiral Aldimines / p12  1-3.Development of Novel Cationic Lewis Acids Coordinated by a Chiral Diether Ligand / p18  1-4.Attempt to Develop Novel Lewis Acids Bearinga Monoether-Coordinated Ligand / p31  1-5.Aldol Reaction by Using the Novel Cationic Lewis Acids / p39  1-6.Synthesis of the Modified Chi...

  3. Catalytic enantioselective 1,3-dipolar cycloadditions of azomethine ylides for biology-oriented synthesis.

    Science.gov (United States)

    Narayan, Rishikesh; Potowski, Marco; Jia, Zhi-Jun; Antonchick, Andrey P; Waldmann, Herbert

    2014-04-15

    , mostly from our work, of the application of 1,3-dipolar cycloaddition reactions of azomethine ylides for the catalytic enantioselective synthesis of complex products. We successfully applied the 1,3-dipolar cycloaddition in the synthesis of spiro-compounds such as spirooxindoles, for kinetic resolution of racemic compounds in the synthesis of an iridoid inspired compound collection and in the synthesis of a nitrogen-bridged bicyclic tropane scaffold by application of 1,3-fused azomethine ylides. Furthermore, we performed the synthesis of complex molecules with eight stereocenters using tandem cycloadditions. In a programmable sequential double cycloaddition, we demonstrated the synthesis of both enantiomers of complex products by simple changes in the order of addition of chemicals. Complex products were obtained using enantioselective higher order [6 + 3] cycloaddition of azomethine ylides with fulvenes followed by Diels-Alder reaction. The bioactivity of these compound collections is also discussed. PMID:24730692

  4. Precipitation and calcination synthesis methods forming nano-sized platinum catalytic particles for methanol and hydrogen oxidation

    Science.gov (United States)

    Naidoo, S.; Naidoo, Q.; Musil, E.; Linkov, V.; Vaivars, G.

    2013-03-01

    Under varying experimental conditions of calcination and precipitation reactions, different particle sizes and levels of platinum on carbon supported (Pt/C) catalysts were obtained. Rapid precipitation following a chemical reaction ensured formation of nano-sized catalytic particles using super-saturated concentrations under controlled conditions was a significant contribution in understanding the synthesis process and how it relates to an increased number of catalytic reaction sites ultimately providing superior electrochemical (EC) activity. These conditions influenced nucleation and growth rates of the catalytic particles. The super-saturation concentrations of the reactants in the reaction vessel played a direct role in producing the desired morphology of the crystallites.

  5. Facile synthesis of magnetically separable reduced graphene oxide/magnetite/silver nanocomposites with enhanced catalytic activity.

    Science.gov (United States)

    Ji, Zhenyuan; Shen, Xiaoping; Yue, Xiaoyang; Zhou, Hu; Yang, Juan; Wang, Yuqin; Ma, Lianbo; Chen, Kangmin

    2015-12-01

    In this study, the combination of magnetite (Fe3O4) with reduced graphene oxide (RGO) generates a new hybrid substrate for the dispersion of noble metal nanoparticles. Well-dispersed silver (Ag) nanoparticles loaded on the surface of Fe3O4 modified RGO are achieved by an efficient two-step approach. Through reducing Ag(+) ions, highly dispersed Ag nanoparticles are in-situ formed on the RGO/Fe3O4 substrate. It is found that the existence of Fe3O4 nanocrystals can significantly improve the dispersity and decrease the particle size of the in-situ formed Ag nanoparticles. Magnetic study reveals that the as-prepared RGO/Fe3O4/Ag ternary nanocomposites display room-temperature superparamagnetic behavior. The catalytic properties of the RGO/Fe3O4/Ag ternary nanocomposites were evaluated with the reduction of 4-nitrophenol into 4-aminophenol as a model reaction. The as-synthesized RGO/Fe3O4/Ag ternary catalysts exhibit excellent catalytic stability and much higher catalytic activity than the corresponding RGO/Ag catalyst. Moreover, the RGO/Fe3O4/Ag catalysts can be easily magnetically separated for reuse. This study further demonstrates that nanoparticles modified graphene can act as an effective hybrid substrate for the synthesis of multi-component and multifunctional graphene-based composites. PMID:26263498

  6. Surface and catalytic properties of potassium-modified cobalt molybdenum catalysts for ammonia synthesis

    International Nuclear Information System (INIS)

    The influence of potassium addition on the structural, catalytic and surface properties of the cobalt molybdenum nitride was studied. The measurements of the catalytic activity and the specific surface area as well as the phase analysis with the use of X-ray diffraction were performed. The mixtures of Co3Mo3N and Co2Mo3N phases have been found to constitute the samples. The concentration ratio between the Co2Mo3N and Co3Mo3N phases is notably influenced by potassium admixture. The specific surface area of the catalysts changes also with the Co2Mo3N/Co3Mo3N ratio. The catalytic activity of the catalysts in the ammonia synthesis carried out at 400 deg. C and under the pressure of 10 MPa can be increased up to 2.4 times by the addition of potassium compounds. There is the optimal range of potassium concentration between 0.8 and 1.2 wt.%.

  7. Co-Cu Nanoparticles: Synthesis by Galvanic Replacement and Phase Rearrangement during Catalytic Activation.

    Science.gov (United States)

    Nafria, Raquel; Genç, Aziz; Ibáñez, Maria; Arbiol, Jordi; Ramírez de la Piscina, Pilar; Homs, Narcís; Cabot, Andreu

    2016-03-01

    The control of the phase distribution in multicomponent nanomaterials is critical to optimize their catalytic performance. In this direction, while impressive advances have been achieved in the past decade in the synthesis of multicomponent nanoparticles and nanocomposites, element rearrangement during catalyst activation has been frequently overseen. Here, we present a facile galvanic replacement-based procedure to synthesize Co@Cu nanoparticles with narrow size and composition distributions. We further characterize their phase arrangement before and after catalytic activation. When oxidized at 350 °C in air to remove organics, Co@Cu core-shell nanostructures oxidize to polycrystalline CuO-Co3O4 nanoparticles with randomly distributed CuO and Co3O4 crystallites. During a posterior reduction treatment in H2 atmosphere, Cu precipitates in a metallic core and Co migrates to the nanoparticle surface to form Cu@Co core-shell nanostructures. The catalytic behavior of such Cu@Co nanoparticles supported on mesoporous silica was further analyzed toward CO2 hydrogenation in real working conditions. PMID:26878153

  8. Monomeric Cu(Ⅱ) Complex Containing Chiral Phase-transfer Catalyst as Ligand and Its Asymmetrically Catalytic Reaction

    Institute of Scientific and Technical Information of China (English)

    QU Zhi-Rong; XIONG Ren-Gen

    2008-01-01

    The thermal treatment of CuCl2 with N-(4'-vinylbenzyl)cinchonidinitim chloride(L1)afforded a monomeric discrete homochiral copper(Ⅱ)complex N-4'-(vinylbenzyl)cinchonidinium trichlorocoprate(Ⅱ)(1).Their applications to the enantioselectively catalytic alkylation reaction of N-(diphenylmethylidene)glycine tert-butyl ester(3)show that the higher ee value observed in catalyst 1 than that in the corresponding free ligand L1 is probably due to the rigidity enhancement after the coordination of N atom of quinoline ring to the copper ion.

  9. Efficient Access to Multifunctional Trifluoromethyl Alcohols through Base-Free Catalytic Asymmetric C-C Bond Formation with Terminal Ynamides.

    Science.gov (United States)

    Cook, Andrea M; Wolf, Christian

    2016-02-01

    The asymmetric addition of terminal ynamides to trifluoromethyl ketones with a readily available chiral zinc catalyst gives CF3 -substituted tertiary propargylic alcohols in up to 99 % yield and 96 % ee. The exclusion of organozinc additives and base as well as the general synthetic utility of the products are key features of this reaction. The value of the β-hydroxy-β-trifluoromethyl ynamides is exemplified by selective transformations to chiral Z- and E-enamides, an amide, and N,O-ketene acetals. The highly regioselective hydration, stereoselective reduction, and hydroacyloxylation reactions proceed with high yields and without erosion of the ee value of the parent β-hydroxy ynamides. PMID:26806871

  10. Metal-catalyzed Asymmetric Hetero-Diels-Alder Reactions of Unactivated Dienes with Glyoxylates

    DEFF Research Database (Denmark)

    Johannsen, Mogens; Yao, Sulan; Graven, Anette

    1998-01-01

    The development of a catalytic asymmetric hetero-Diels-Alder methodology for the reaction of unactivated dienes with glyoxylates is presented. Several different asymmetric catalysts can be used, but copper-bisoxazolines and aluminium-BINOL give the highest yield, and the best chemo- and...... enantioselectivities. The reaction course is dependent on several factors such as the solvent and the anions coordinated to the catalyst. The scope of the reaction is outlined by the total synthesis of a natural occurring actinidiolide....

  11. Synthesis, characterization and catalytic activity toward methanol oxidation of electrocatalyst Pt4+-NH2-MCM-41

    International Nuclear Information System (INIS)

    Highlights: ► It was first confirmed that the Pt4+ exhibited a good electro-catalytic property for methanol oxidation. ► The Pt4+ perfectly distributed on a mesoporous molecular sieve matrix synthesis by a facile method. ► The good performance of catalyst resistance to poisoning because of a homogeneous distribution of Pt4+ and large specific surface area. - Abstract: Mesoporous material with functional group (Pt4+-NH2-MCM-41) was prepared by grafting aminopropyl group and adsorbing platinum ions on the surface of the commercial molecular sieve (MCM-41). The characterization carried out by X-ray photoelectron spectroscopy, X-ray diffraction, and N2 adsorption–desorption measurement pointed out that Pt was adsorbed on the NH2-MCM-41 surface as the oxidation state (Pt4+) and the surface area of Pt4+-NH2-MCM-41 was up to 564 m2/g. Transmission electron microscopy and elemental mapping indicated a homogeneous distribution of Pt4+ throughout all surface of the mesoporous materials. Electro-catalytic properties of methanol oxidation on the Pt4+-NH2-MCM-41 electrode were investigated with electrochemical methods. The results showed that the Pt4+-NH2-MCM-41 electrode exhibited catalytic activity in the methanol electro-oxidation with the apparent activation energy being 49.29 kJ/mol, and the control step of methanol electro-oxidation was the mass transfer process. It is first proved that platinum ions had good electro-catalytic property for methanol oxidation and provided a new idea for developing electrode materials in future.

  12. Synthesis and catalytic properties of highly branched palladium nanostructures using seeded growth

    Science.gov (United States)

    Graham, L.; Collins, G.; Holmes, J. D.; Tilley, R. D.

    2016-01-01

    In order to develop nanocatalysts with enhanced catalytic performance, it is important to be able to synthesize nanocrystals enclosed by high-index surface facets, due to their high density of low coordinated atoms at step, ledge and kink sites. Here, we report a facile seed-mediated route to the synthesis of highly branched Pd nanostructures with a combination of {113}, {115} and {220} high-index surface planes. The size of these nanostructures is readily controlled by a simple manipulation of the seed concentration. The selective use of oleylamine and oleic acid was also found to be critical to the synthesis of these structures, with Pd icosahedra enclosed by low-index {111} facets being produced when hexadecylamine was employed as capping ligand. The structure-property relationship of these nanostructures as catalysts in Suzuki-cross coupling reactions was then investigated and compared, with the high-index faceted branched Pd nanostructures found to be the most effective catalysts.In order to develop nanocatalysts with enhanced catalytic performance, it is important to be able to synthesize nanocrystals enclosed by high-index surface facets, due to their high density of low coordinated atoms at step, ledge and kink sites. Here, we report a facile seed-mediated route to the synthesis of highly branched Pd nanostructures with a combination of {113}, {115} and {220} high-index surface planes. The size of these nanostructures is readily controlled by a simple manipulation of the seed concentration. The selective use of oleylamine and oleic acid was also found to be critical to the synthesis of these structures, with Pd icosahedra enclosed by low-index {111} facets being produced when hexadecylamine was employed as capping ligand. The structure-property relationship of these nanostructures as catalysts in Suzuki-cross coupling reactions was then investigated and compared, with the high-index faceted branched Pd nanostructures found to be the most effective catalysts

  13. Influence of the synthesis parameters on the physico-chemical and catalytic properties of cerium oxide for application in the synthesis of diethyl carbonate

    International Nuclear Information System (INIS)

    Synthesis of cerium (IV) oxide by means of room temperature precipitation method was carried out. The effect of preparation variables such as synthesis time, calcination temperature and pH of the solution on resulting CeO2 properties was discussed. Moreover, the comparison of CeO2 samples prepared in a static and rotation mode of synthesis is presented. The solid catalysts were characterized by means of X-ray powder diffraction, scanning electron microscopy, transmission electron microscope, nitrogen physisorption, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy using pyridine as a probe molecule and temperature programmed desorption of CO2. Significant variations in physico-chemical properties of CeO2 by varying the preparation conditions were observed. Furthermore, the catalytic performances of CeO2 catalysts were compared in the synthesis of diethyl carbonate starting from ethanol and CO2 using butylene oxide as a dehydrating agent. The dependence of CeO2 properties on its catalytic activity is evaluated in detail. - Highlights: • Synthesis of cerium (IV) oxide by precipitation method. • Influence of synthesis time, calcination temperature, mode of stirring and solution pH on properties. • Characterization by XRD, SEM, TEM, nitrogen physisorption, XPS, FTIR. • Catalytic performance diethyl carbonate synthesis from ethanol and CO2

  14. Efficient Synthesis of Optically Active Alcohols

    Institute of Scientific and Technical Information of China (English)

    J.S. Chen; Z.R. Dong; Y.Y. Li; B.Z. Li; Y. Xing; W.Y. Shen; G. Chen; X.Q. Zhang; J. X. Gao

    2005-01-01

    @@ 1Introduction Optically active secondary alcohols are versatile building blocks for synthesis of unnatural biological active compounds and functional materials. Therefore, study on efficient synthesis of optically active alcohols is becoming an important subject in synthetic organic chemistry. Catalytic asymmetric reduction of carbonyl compounds is a practical method to create chiral alcohols. For the past decades, a large number of catalytic methods have been developed to achieve this goal.

  15. Highly enantioselective and efficient synthesis of flavanones including pinostrobin through the rhodium-catalyzed asymmetric 1,4-addition.

    Science.gov (United States)

    Korenaga, Toshinobu; Hayashi, Keigo; Akaki, Yusuke; Maenishi, Ryota; Sakai, Takashi

    2011-04-15

    An efficient synthesis of bioactive chiral flavanones (1) was achieved through the Rh-catalyzed asymmetric 1,4-addition of arylboronic acid to chromone. The reaction in toluene proceeded smoothly at room temperature in the presence of 0.5% Rh catalyst with electron-poor chiral diphosphine MeO-F(12)-BIPHEP. In this reaction, the 1,2-addition to (S)-1 frequently occurred to yield (2S,4R)-2,4-diaryl-4-chromanol as a byproduct, which could be reduced by changing the reaction solvent to CH(2)Cl(2) to deactivate the Rh catalyst (3% required). PMID:21413690

  16. Synthesis of Silver Nanoparticles Using Triticum aestivum and Its Effect on Peroxide Catalytic Activity and Toxicology

    Directory of Open Access Journals (Sweden)

    Shobha Waghmode

    2013-01-01

    Full Text Available The synthesis of stable silver nanoparticles using bioreduction method was investigated. Biological synthesis of silver nanoparticles using Triticum aestivum (khapali ghahu extract was investigated. The effect of a specific variety of plants and how it affects the growth of silver nanoparticles was investigated in our work and it was polydispersed. UV-visible spectroscopy was used to monitor the formation of silver nanoparticles within 15 minutes. The peaks in XRD pattern are in good agreement with those of face-centered-cubic form of metallic silver. Further the IR and TEM shows confirmation of nanocrystalline nature of silver nanoparticles. These nanoparticles dislodged by ultrasonication showed an absorption peak at 430 nm in UV-visible spectrum corresponding to the Plasmon resonance of silver nanoparticles. UV-visible titration experiments showed evidence that silver nanoparticles facilitate hydrogen peroxide reduction showing excellent catalytic activity at 200 μL. In this preliminary toxicology study, Earthworm toxicology we checked and is stable up to 1500 ppm concentration. The use of plant extract for silver nanoparticles synthesis offers the benefits of eco-friendliness and amenability for large-scale production.

  17. Catalytic synthesis of bamboo-like multiwall BN nanotubes via SHS-annealing process

    International Nuclear Information System (INIS)

    Bamboo-like multiwall boron nitride (BN) nanotubes were synthesized via annealing porous precursor prepared by self-propagation high temperature synthesis (SHS) method. The as-synthesized BN nanotubes were characterized by the field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD), Raman and Fourier transform infrared (FTIR) spectroscopy. These nanotubes have uniform diameters of about 60 nm and an average length of about 10 μm. Four growth models, including tip, base, based tip and base-tip growth models, are proposed based on the catalytic vapor-liquid-solid (VLS) growth mechanism for explaining the formation of the as-synthesized bamboo-like BN nanotubes. Chemical reactions and annealing mechanism are also discussed. -- Graphical Abstract: A novel and effective annealing porous precursor route to bulk synthesis of bamboo-like multiwall BN nanotubes. Four growth models of VLS growth mechanism for these nanotubes are proposed. Display Omitted Research highlights: → Bulk bamboo-like BN nanotubes were synthesized by SHS-annealing method. → Boron-containing, porous precursor played a crucial role in bulk synthesis process. → Four possible growth models were proposed to explain the formation of the bamboo-like BN nanotubes.

  18. Synthesis of ceramic catalytic system based on CuO/CeO2 for preferential oxidation reaction of CO

    International Nuclear Information System (INIS)

    The aim this is work is to develop catalysts based on CuO/CeO2 by means two different types of synthesis methods: combustion synthesis and Pechini. CuO/CeO2 catalysts were synthesized with 0.5 mol of CuO for both synthesis methods used. The catalysts were characterized by XRD with the Rietveld refinement, EDX and textural analysis by the BET method. The results show that both methods of synthesis led to the formation of catalysts with segregated phases formed on the structures of the obtained materials, such segregated phases were formed by the presence of catalytic active species CuO and these phases had different characteristics depending on the type of method synthesis used. Small differences were observed in the evaluation of textural characteristics of the catalysts developed in this work according to the synthesis method employed. (author)

  19. Asymmetric Total Synthesis of (+)- and (−)-Clusianone and (+)- and (−)Clusianone Methyl Enol Ether via ACC Alkylation and Evaluation of their Anti-HIV Activity

    Science.gov (United States)

    Garnsey, Michelle R.; Matous, James A.; Kwiek, Jesse J.; Coltart, Don M.

    2011-01-01

    The total asymmetric synthesis of (+)- and (−)-clusianone and (+)- and (−)-clusianone methyl enol ether is reported. Asymmetric induction is achieved through the use of ACC alkylation, providing the key intermediates with an er of 99:1. The four synthetic compounds were evaluated for their anti-HIV activity. Both (+)- and (−)-clusianone displayed significant anti-HIV activity. PMID:21414776

  20. Pt3Co concave nanocubes: synthesis, formation understanding, and enhanced catalytic activity toward hydrogenation of styrene.

    Science.gov (United States)

    Wang, Chenyu; Lin, Cuikun; Zhang, Lihua; Quan, Zewei; Sun, Kai; Zhao, Bo; Wang, Feng; Porter, Nathan; Wang, Yuxuan; Fang, Jiye

    2014-02-01

    We report a facile synthesis route to prepare high-quality Pt3Co nanocubes with a concave structure, and further demonstrate that these concave Pt3Co nanocubes are terminated with high-index crystal facets. The success of this preparation is highly dependent on an appropriate nucleation process with a successively anisotropic overgrowth and a preservation of the resultant high-index planes by control binding of oleyl-amine/oleic acid with a fine-tuned composition. Using a hydrogenation of styrene as a model reaction, these Pt3Co concave nanocubes as a new class of nanocatalysts with more open structure and active atomic sites located on their high-index crystallographic planes exhibit an enhanced catalytic activity in comparison with low-indexed surface terminated Pt3Co nanocubes in similar size. PMID:24382713

  1. The Difference between ZSM-5 Zeolites Manufactured from Various Synthesis Systems and Their Catalytic Performances

    Institute of Scientific and Technical Information of China (English)

    Zhao Huanyu; Liu Yunqi; Liu Chunying; Liu Chenguang

    2005-01-01

    ZSM-5 zeolites with similar Si/Al ratio were synthesized successfully using various templates [nbutylamine (BTA), tetrapropylammonium bromide (TPABr) and no template (NT)] under hydrothermal conditions. The samples were characterized by XRD, SEM, Py-IR and BET surface area measurements in order to understand the template effects and the differences between the ZSM-5 samples. The synthesis of ZSM-5 with organic templates was relatively easier than those with inorganic templates and without template.SEM results revealed that ZSM-5 synthesized with different templates had different morphologies in similar particle size. Toluene disproportionation reaction was carried out over the catalyst samples to evaluate the catalytic properties. The results have shown that large crystals which have a correspondingly small external surface showed a high para-xylene selectivity, and the amount of C9+ and C5- was much less than that obtained from zeolite with small crystals.

  2. Synthesis, characterization, and catalytic properties of stable mesoporous molecular sieve MCM-41 prepared from zeolite mordenite

    International Nuclear Information System (INIS)

    Mesoporous molecular sieves (denoted as M-MCM-41) with ordered hexagonal structure have been successfully synthesized from the assembly of precursors from preformed zeolite Mordenite with CTAB surfactant micelle in alkaline media. The samples were characterized by XRD, N2 adsorption, IR and DTG. The materials exhibit highly hydrothermal stability, as compared with conventional MCM-41. Characterization results indicate that the mesoporous walls of M-MCM-41 contain the secondary building units similar to those in microporous crystal of zeolite Mordenite. In catalytic dealkylation of C10+ aromatic hydrocarbon, M-MCM-41 shows higher activities in comparison with Mordenite and MCM-41, which would be ascribed to the combination of advantages of both MCM-41 (large pores) and Mordenite (strong acidity). Furthermore, this synthesis strategy could be used as a new general method for the preparation of hydrothermally stable mesoporous aluminosilicate materials under alkaline conditions

  3. Catalytic CVD Synthesis of Carbon Nanotubes: Towards High Yield and Low Temperature Growth

    Directory of Open Access Journals (Sweden)

    Marijana Mionić

    2010-11-01

    Full Text Available The catalytic chemical vapor deposition (CCVD is currently the most flexible and economically attractive method for the growth of carbon nanotubes. Although its principle is simple, the precisely controlled growth of carbon nanotubes remains very complex because many different parameters influence the growth process. In this article, we review our recent results obtained on the synthesis of carbon nanotubes via CCVD. We discuss the role of the catalyst and the catalyst support. Our recent results obtained from the water assisted growth and the equimolar C2H2-CO2 reaction are also discussed. Both procedures lead to significantly enhanced carbon nanotube growth. In particular, the latter allows growing carbon nanotubes on diverse substrate materials at low temperatures.

  4. Synthesis of bamboo-like carbon nanotubes by ethanol catalytic combustion technique

    Institute of Scientific and Technical Information of China (English)

    CHENG Jin; ZOU Xiao-ping; LI Fei; ZHANG Hong-dan; REN Peng-fei

    2006-01-01

    Bamboo-like carbon nanotubes were synthesized by ethanol catalytic combustion (ECC) technique with combustion method. Copper plate was employed as substrate,ethanol as carbon source,and iron chloride as catalyst precursor. The as-grown black powder was characterized by means of scanning electron microscopy,transmission electron microscopy and Raman spectroscopy. The results show that the thinner bamboo-like carbon nanotubes have a relatively good structure that the compartment layers are more regular,while the thicker carbon nanotubes have a relatively irregular bamboo-like structure:the proposed method is simple to synthesize bamboo-like carbon nanotubes and has some advantages,such as flexible synthesis conditions,simple setup,and environment-friendly.

  5. Synthesis of a nano-crystalline solid acid catalyst from fly ash and its catalytic performance

    Energy Technology Data Exchange (ETDEWEB)

    Chitralekha Khatri; Ashu Rani [Government P.G. College, Kota (India). Environmental Chemistry Laboratory

    2008-10-15

    The synthesis of nano-crystalline activated fly ash catalyst (AFAC) with crystallite size of 12 nm was carried out by chemical and thermal treatment of fly ash, a waste material generated from coal-burning power plants. Fly ash was chemically activated using sulfuric acid followed by thermal activation at 600{sup o}C. The variation of surface and physico-chemical properties of the fly ash by activation methods resulted in improved acidity and therefore, catalytic activity for acid catalyzed reactions. The AFAC was characterized by X-ray diffraction, FT-IR spectroscopy, N{sub 2}-adsorption-desorption isotherm, scanning electron microscopy, flame atomic absorption spectrophotometry and sulfur content by CHNS/O elemental analysis. It showed amorphous nature due to high silica content (81%) and possessed high BET surface area (120 m{sup 2}/g). The catalyst was found to be highly active solid acid catalyst for liquid phase esterification of salicylic acid with acetic anhydride and methanol giving acetylsalicylic acid and methyl salicylate respectively. A maximum yield of 97% with high purity of acetylsalicylic acid (aspirin) and a very high conversion 87% of salicylic acid to methyl salicylate (oil of wintergreen) was obtained with AFAC. The surface acidity and therefore, catalytic activity in AFAC was originated by increased silica content, hydroxyl content and higher surface area as compared to fly ash. The study shows that coal generated fly ash can be converted into potential solid acid catalyst for acid catalyzed reactions. Furthermore, this catalyst may replace conventional environmentally hazardous homogeneous liquid acids making an ecofriendly; solvent free, atom efficient, solid acid based catalytic process. 27 refs., 5 figs., 2 tabs.

  6. Stable Alkynyl Glycosyl Carbonates: Catalytic Anomeric Activation and Synthesis of a Tridecasaccharide Reminiscent of Mycobacterium tuberculosis Cell Wall Lipoarabinomannan.

    Science.gov (United States)

    Mishra, Bijoyananda; Neralkar, Mahesh; Hotha, Srinivas

    2016-06-27

    Oligosaccharide synthesis is still a challenging task despite the advent of modern glycosidation techniques. Herein, alkynyl glycosyl carbonates are shown to be stable glycosyl donors that can be activated catalytically by gold and silver salts at 25 °C in just 15 min to produce glycosides in excellent yields. Benzoyl glycosyl carbonate donors are solid compounds with a long shelf life. This operationally simple protocol was found to be highly efficient for the synthesis of nucleosides, amino acids, and phenolic and azido glycoconjugates. Repeated use of the carbonate glycosidation method enabled the highly convergent synthesis of tridecaarabinomannan in a rapid manner. PMID:26879797

  7. Green Synthesis of Smart Metal/Polymer Nanocomposite Particles and Their Tuneable Catalytic Activities

    Directory of Open Access Journals (Sweden)

    Noel Peter Bengzon Tan

    2016-03-01

    Full Text Available Herein we report a simple and green synthesis of smart Au and Ag@Au nanocomposite particles using poly(N-isopropylacrylamide/polyethyleneimine (PNIPAm/PEI core-shell microgels as dual reductant and templates in an aqueous system. The nanocomposite particles were synthesized through a spontaneous reduction of tetrachloroauric (III acid to gold nanoparticles at room temperature, and in situ encapsulation and stabilization of the resultant gold nanoparticles (AuNPs with amine-rich PEI shells. The preformed gold nanoparticles then acted as seed nanoparticles for further generation of Ag@Au bimetallic nanoparticles within the microgel templates at 60 °C. These nanocomposite particles were characterized by TEM, AFM, XPS, UV-vis spectroscopy, zeta-potential, and particle size analysis. The synergistic effects of the smart nanocomposite particles were studied via the reduction of p-nitrophenol to p-aminophenol. The catalytic performance of the bimetallic Ag@Au nanocomposite particles was 25-fold higher than that of the monometallic Au nanoparticles. Finally, the controllable catalytic activities of the Au@PNIPAm/PEI nanocomposite particles were demonstrated via tuning the solution pH and temperature.

  8. Synthesis and Catalytic Features of Hybrid Metal Nanoparticles Supported on Cellulose Nanofibers

    Directory of Open Access Journals (Sweden)

    Hirotaka Koga

    2011-11-01

    Full Text Available The structural and functional design of metal nanoparticles has recently allowed remarkable progress in the development of high-performance catalysts. Gold nanoparticles (AuNPs are among the most innovative catalysts, despite bulk Au metal being regarded as stable and inactive. The hybridization of metal NPs has attracted major interest in the field of advanced nanocatalysts, due to electro-mediated ligand effects. In practical terms, metal NPs need to be supported on a suitable matrix to avoid any undesirable aggregation; many researchers have reported the potential of polymer-supported AuNPs. However, the use of conventional polymer matrices make it difficult to take full advantage of the inherent properties of the metal NPs, since most of active NPs are imbedded inside the polymer support. This results in poor accessibility for the reactants. Herein, we report the topochemical synthesis of Au and palladium (Pd bimetallic NPs over the surfaces of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO-oxidized cellulose nanofibers (TOCNs, and their exceptional catalytic performance. Highly-dispersed AuPdNPs were successfully synthesized in situ on the crystal surfaces of TOCNs with a very high density of carboxylate groups. The AuPdNPs@TOCN nanocomposites exhibit excellent catalytic efficiencies in the aqueous reduction of 4-nitrophenol to 4-aminophenol, depending on the molar ratios of Au and Pd.

  9. Synthesis and Catalytic Applications of Ruthenium(0) Nanoparticles in Click Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Avvaru Praveen; Baek, Minwook; Sridhar, Chirumarry; Kumar, Begari Prem; Lee, Yongill [Changwon National Univ., Changwon (Korea, Republic of)

    2014-04-15

    Here we report a facile synthesis of ruthenium (Ru) Nanoparticles (NPs) by chemical co-precipitation method. The calcination of ruthenium hydroxide samples at 500 .deg. C under hydrogen atmosphere lead to the formation of Ru{sup 0} NPs. The size and aggregation of Ru NPs depends on the pH of the medium, and type of surfactant and its concentration. The X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope image (TEM) analyses of particles indicated the formation of Ru{sup 0} NPs, and have 10 to 20 nm sizes. As-synthesized Ru{sup 0} NPs are characterized and investigated their catalytic ability in click chemistry (azide-alkyne cycloaddition reactions), showing good results in terms of reactivity. Interestingly, small structural differences in triazines influence the catalytic activity of Ru{sup 0} nanocatalysts. Click chemistry has recently emerged to become one of the most powerful tools in drug discovery, chemical biology, proteomics, medical sciences and nanotechnology/nanomedicine. In addition, preliminary tests of recycling showed good results with neither loss of activity or significant precipitation.

  10. Synthesis and catalytic application of palladium nanoparticles supported on kaolinite-based nanohybrid materials.

    Science.gov (United States)

    Ngnie, Gaelle; Dedzo, Gustave K; Detellier, Christian

    2016-05-31

    Palladium nanoparticles (PdNPs) were deposited on the surface of the modified clay mineral, kaolinite. To improve compatibility, abundance and control of the size of the nanoparticles, kaolinite was modified by the grafting of an amino alcohol (triethanolamine (TEA)) and an ionic liquid (1-(2-hydroxyethyl)-3-methylimidazolium (ImIL)). Characterization techniques (XRD, TGA, solid state (13)C NMR and FTIR spectroscopy) confirmed the effective grafting of these compounds on the internal surface of kaolinite. After the synthesis of PdNPs onto clay particles, TEM allowed the visualization of abundant PdNPs with sizes ranging from 4 to 6 nm, uniformly distributed onto the platelets of modified kaolinite. Unmodified clay showed low abundance and random distribution of the nanoparticles. The catalysts obtained were effective for the catalytic reduction of 4-nitrophenol (4-NP), the material with TEA being the most effective. These materials have exhibited excellent performance during the Heck and particularly the Suzuki-Miyaura coupling reactions, with reaction yields up to 100%. These catalysts showed a very slight loss in activity for three consecutive catalytic cycles (less than 10% decrease of the activity compared to the first cycle). This was an evidence that the prior grafting modification of kaolinite helps in significantly improving the quality of the synthesized NPs and also promotes their strong attachment onto the clay mineral surface. PMID:27160392

  11. FACILE GREEN SYNTHESIS OF GOLD NANOPARTICLES WITH GREAT CATALYTIC ACTIVITY USING ULVA FASCIATA

    Directory of Open Access Journals (Sweden)

    V. Sugantha Kumari

    2014-03-01

    Full Text Available We report a facile, green, and high yielding approache for the synthesis and stabilization of monodisperse gold nanoparticles (AuNPs using green seaweed Ulva fasciata extract. Characterization of the obtained AuNPs was performed using UV-visible, Fourier transform infrared (FTIR, X-ray diffraction (XRD and transmission electron microscopy (TEM. UV-visible absorption spectroscopy was used to determine the yield of the gold nanoparticles. The UV-visible absorption spectrum showed a characteristic optical peak of AuNPs at 541 nm. The X-ray diffraction pattern suggested the formation and crystallinity of AuNPs. Spherical AuNPs synthesized with an average particle size of 10 ± 3 nm were confirmed by TEM. FTIR analysis supported the role of phytochemicals of Ulva fasciata extract for bioreduction and stabilization of AuNPs. Moreover, the synthesized AuNPs exhibit remarkable catalytic efficiency by using the reduction of 4-nitroaniline by potassium borohydride in aqueous solution using UV-visible absorption spectroscopy. Catalytic reduction followed pseudo-first-order kinetics with respect to 4-Nitrophenol.

  12. Synthesis, characterization and photo catalytic studies of the composites by tantalum oxide and zinc oxide nanorods

    Science.gov (United States)

    Chennakesavulu, K.; Reddy, M. Madhusudhana; Reddy, G. Ramanjaneya; Rabel, A. M.; Brijitta, J.; Vinita, V.; Sasipraba, T.; Sreeramulu, J.

    2015-07-01

    In-situ synthesis of ZnO:Ta2O5 composites in basic medium by using tantalum chloride and zinc chloride as precursors. The prepared composites were characterized by Fourier Transform Infrared spectroscopy (FTIR), confocal Raman spectroscopy, diffuse reflectance UV-Vis spectrophotometer (DRS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, N2-sorption isotherms, Thermo Gravimetric Analysis (TGA), High Resolution Transmission Electron Microscope (HRTEM), X-ray Photoelectron Spectroscopy (XPS), and Field Emission Scanning Electron Microscopy (FESEM/EDS). The composite materials were used as photocatalyst in the degradation Rhodamine-B (RhB) dye under visible light irradiation. The catalytic activity and removal percentage of the dye was determined by the spectrophotometric method. This indicates the percentage of degradation was more for the ZnO:Ta2O5 composites. The kinetic parameter obeys pseudo-first order reaction. It may be due to fixed amount the catalysts and concentration of dye solution. The catalytic activity of the recycled ZnO:Ta2O5 catalyst was compared with fresh catalyst.

  13. Synthesis and catalytic properties of microemulsion-derived cerium oxide nanoparticles

    Science.gov (United States)

    Kockrick, Emanuel; Schrage, Christian; Grigas, Anett; Geiger, Dorin; Kaskel, Stefan

    2008-07-01

    The synthesis of cerium dioxide nanoparticles using an inverse microemulsion technique and precipitation method was investigated. Cerium hydroxide nanoparticles were synthesized by adding diluted ammonia to n-heptane-surfactant-cerium nitrate system. The micelle and particle size in the range of 5-12 nm were controlled by varying the molar water to surfactant ratio and analyzed by dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM). Cerium hydroxide nanoparticles were isolated and subsequently treated at 100-600 °C to obtain nanoscale ceria. Crystallite sizes of cerium dioxide in the range of 6-16 nm were estimated by Scherrer analysis by X-ray diffraction (XRD) and HRTEM. The catalytic activity of particles annealed at 400 and 600 °C in soot combustion reactions was characterized by temperature-programmed oxidation (TPO) indicating a size-dependant activity. Crystallite sizes and catalytic stability of elevated ceria systems were tested in second combustion cycles.

  14. Synthesis, characterization and catalytic activity of carbon-silica hybrid catalyst from rice straw

    Science.gov (United States)

    Janaun, J.; Safie, N. N.; Siambun, N. J.

    2016-07-01

    The hybrid-carbon catalyst has been studied because of its promising potential to have high porosity and surface area to be used in biodiesel production. Silica has been used as the support to produce hybrid carbon catalyst due to its mesoporous structure and high surface area properties. The chemical synthesis of silica-carbon hybrid is expensive and involves more complicated preparation steps. The presence of natural silica in rice plants especially rice husk has received much attention in research because of the potential as a source for solid acid catalyst synthesis. But study on rice straw, which is available abundantly as agricultural waste is limited. In this study, rice straw undergone pyrolysis and functionalized using fuming sulphuric acid to anchor -SO3H groups. The presence of silica and the physiochemical properties of the catalyst produced were studied before and after sulphonation. The catalytic activity of hybrid carbon silica acid catalyst, (H-CSAC) in esterification of oleic acid with methanol was also studied. The results showed the presence of silica-carbon which had amorphous structure and highly porous. The carbon surface consisted of higher silica composition, had lower S element detected as compared to the surface that had high carbon content but lower silica composition. This was likely due to the fact that Si element which was bonded to oxygen was highly stable and unlikely to break the bond and react with -SO3H ions. H-CSAC conversions were 23.04 %, 35.52 % and 34.2 7% at 333.15 K, 343.15 K and 353.15 K, respectively. From this research, rice straw can be used as carbon precursor to produce hybrid carbon-silica catalyst and has shown catalytic activity in biodiesel production. Rate equation obtained is also presented.

  15. Eco-friendly green synthesis of silver nanoparticles using salmalia malabarica: synthesis, characterization, antimicrobial, and catalytic activity studies

    Science.gov (United States)

    Murali Krishna, I.; Bhagavanth Reddy, G.; Veerabhadram, G.; Madhusudhan, A.

    2015-07-01

    An economically viable and "green" process has been developed for the synthesis of silver nanoparticles (AgNPs) with an average size of 7 nm using non-toxic and renewable salmalia malabarica gum (SMG) as reducing and capping agent without using any chemical reducing agent. The effect of various parameters such as concentration of SMG and silver nitrate and reaction time for the synthesis of AgNPs was studied. The synthesized AgNPs are systematically characterized by UV/Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction and Transmission electron microscopy. The resultant SMG-capped AgNPs are highly stable and had significant antibacterial action on both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The catalytic action of the SMG-capped AgNPs to initiate the reduction of 4-nitrophenol (4-NP) in the presence of NaBH4 has also been reported. The kinetics of the reaction was found to be of pseudo-first-order with respect to the 4-NP.

  16. Asymmetric reactions in continuous flow

    Directory of Open Access Journals (Sweden)

    Xiao Yin Mak

    2009-04-01

    Full Text Available An overview of asymmetric synthesis in continuous flow and microreactors is presented in this review. Applications of homogeneous and heterogeneous asymmetric catalysis as well as biocatalysis in flow are discussed.

  17. Catalytic performance of symmetrical and unsymmetrical sulfur-containing pincer complexes: synthesis and tandem catalytic activity of the first PCS-pincer palladium complex

    OpenAIRE

    Gagliardo, M.; Selander, N.; Mehendale, N.C.; van Koten, G; Klein Gebbink, R. J. M.; Szabó, K.J.

    2008-01-01

    The synthesis and catalytic applications of a new aryl-based unsymmetrical PCS-pincer complex are reported. Preparation of the robust air- and moisture-stable PCS-pincer palladium complex 5[X] started from the symmetrical ,-dibromo-meta-xylene and involved the selective substitution of one bromide by PPh2(BH3), followed by substitution of the second bromide by SPh and subsequent introduction of the palladium. The new PCS complexes (5[X]) were employed as catalysts in two important organic tra...

  18. Photoinduced catalytic synthesis of biologically important metabolites from formaldehyde and ammonia under plausible "prebiotic" conditions

    Science.gov (United States)

    Delidovich, I. V.; Taran, O. P.; Simonov, A. N.; Matvienko, L. G.; Parmon, V. N.

    2011-08-01

    The article analyzes new and previously reported data on several catalytic and photochemical processes yielding biologically important molecules. UV-irradiation of formaldehyde aqueous solution yields acetaldehyde, glyoxal, glycolaldehyde and glyceraldehyde, which can serve as precursors of more complex biochemically relevant compounds. Photolysis of aqueous solution of acetaldehyde and ammonium nitrate results in formation of alanine and pyruvic acid. Dehydration of glyceraldehyde catalyzed by zeolite HZSM-5-17 yields pyruvaldehyde. Monosaccharides are formed in the course of the phosphate-catalyzed aldol condensation reactions of glycolaldehyde, glyceraldehyde and formaldehyde. The possibility of the direct synthesis of tetroses, keto- and aldo-pentoses from pure formaldehyde due to the combination of the photochemical production of glycolahyde and phosphate-catalyzed carbohydrate chain growth is demonstrated. Erythrulose and 3-pentulose are the main products of such combined synthesis with selectivity up to 10%. Biologically relevant aldotetroses, aldo- and ketopentoses are more resistant to the photochemical destruction owing to the stabilization in hemiacetal cyclic forms. They are formed as products of isomerization of erythrulose and 3-pentulose. The conjugation of the concerned reactions results in a plausible route to the formation of sugars, amino and organic acids from formaldehyde and ammonia under presumed 'prebiotic' conditions.

  19. Room-temperature solution synthesis of Ag nanoparticle functionalized molybdenum oxide nanowires and their catalytic applications

    International Nuclear Information System (INIS)

    A simple chemical solution route for the synthesis of large-scale high-quality Ag nanoparticle functionalized molybdenum oxide nanowire at room temperature has been developed. In the synthesis, the protonated amine was intercalated into the molybdenum bronze layers to reduce the electrostatic force of the lamellar structures, and then the Ag nanoparticle functionalized long nanowires could be easily induced by a redox reaction between a molybdenum oxide–amine intermediate and Ag+ at room temperature. The intercalation lamellar structures improved the nucleation and growth of the Ag nanoparticles, with the result that uniform Ag nanoparticles occurred on the surface of the MoO3 nanowire. In this way Ag nanoparticles with average sizes of around 6 nm, and high-purity nanowires with mean diameter of around 50 nm and with typical lengths of several tens to hundreds of micrometers were produced. The heteronanostructured nanowires were intricately and inseparably connected to each other with hydrogen bonds and/or bridge oxygen atoms and packed together, forming a paper-like porous network film. The Ag–MoO3 nanowire film performs a promoted catalytic property for the epoxidation of cis-cyclooctene, and the heteronanostructured nanowire film sensor shows excellent sensing performance to hydrogen and oxygen at room temperature. (paper)

  20. Synthesis, characterization and catalytic evaluation of zirconia-pillared bentonite for 1,3-dioxalane synthesis

    International Nuclear Information System (INIS)

    The aim of this work is to study the solids obtained by pillaring Tunisian bentonite with zirconium polycations from the hydrolysis of zirconium tetrachloride. For comparative purposes, the pillaring of Wyoming montmorillonite, a reference clay, is also studied. Variations in the dialysis number, concentration of Zr solution, pH, temperature in the synthesis procedure as well as the pillaring method, affect the structure and properties of the pillared clay obtained. It has been verified that the structure of the pillared clays strongly depends on the method of preparation and the pH Zr solution in some cases, well ordered pillared clays (with basal spacings between 15 and 18.2 A) have been obtained, while in several others noncrystalline solids yielded. Delamination of the clays seems to take place both when the intercalation solutions obtained from zirconium tetrachloride have pH > 2.8 and when they are subjected to a reflux treatment. Best results were obtained at pH = 2.8 [Zr4+] = 0.1 M, at room temperature, and when using five dialysis, the direct method. The specific total surface area and micropore volume of the solids have reached the values up to 200 m2 g-1 and 0.06 cm3 g-1, respectively. Potentiometric titration and mass titration data suggest that pillared materials produce a shift of the point zero charge toward the point zero charge of the zirconium oxide. The amount of ZrO2 fixed have varied between 6 and 30% of the weight of the pillared samples. The activity of the zirconium pillared clay for 1,3-dioxolane synthesis has been investigated. The method of intercalation has been found to be the most suitable for this reaction. (authors)

  1. Asymmetric synthesis of 3-butylphthalide using isomannide and isosorbide as chiral auxiliaries

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A new approach for asymmetric syntheses of (S) and (R)-3-n-butylphthalide (NBP) is presented. The diastereoselective addition of dibutylzinic to aromatic aldehyde 10 or 11 generated from isomannide- or isosorbide-derived chiral auxiliary afforded S-NBP or R-NBP in high optical yields.

  2. Selective Catalytic Synthesis Using the Combination of Carbon Dioxide and Hydrogen: Catalytic Chess at the Interface of Energy and Chemistry.

    Science.gov (United States)

    Klankermayer, Jürgen; Wesselbaum, Sebastian; Beydoun, Kassem; Leitner, Walter

    2016-06-20

    The present Review highlights the challenges and opportunities when using the combination CO2 /H2 as a C1 synthon in catalytic reactions and processes. The transformations are classified according to the reduction level and the bond-forming processes, covering the value chain from high volume basic chemicals to complex molecules, including biologically active substances. Whereas some of these concepts can facilitate the transition of the energy system by harvesting renewable energy into chemical products, others provide options to reduce the environmental impact of chemical production already in today's petrochemical-based industry. Interdisciplinary fundamental research from chemists and chemical engineers can make important contributions to sustainable development at the interface of the energetic and chemical value chain. The present Review invites the reader to enjoy this exciting area of "catalytic chess" and maybe even to start playing some games in her or his laboratory. PMID:27237963

  3. Shape-controlled synthesis of Pd nanocrystals and their catalytic applications.

    Science.gov (United States)

    Zhang, Hui; Jin, Mingshang; Xiong, Yujie; Lim, Byungkwon; Xia, Younan

    2013-08-20

    Palladium is a marvelous catalyst for a rich variety of reactions in industrial processes and commercial devices. Most Pd-catalyzed reactions exhibit structure sensitivity, meaning that the activity or selectivity depends on the arrangement of atoms on the surface. Previously, such reactions could only be studied in ultrahigh vacuum using Pd single crystals cut with a specific crystallographic plane. However, these model catalysts are far different from real catalytic systems owing to the absence of atoms at corners and edges and the extremely small specific surface areas for the model systems. Indeed, enhancing the performance of a Pd-based catalyst, in part to reduce the amount needed of this precious and rare metal for a given reaction, requires the use of Pd with the highest possible specific surface area. Recent advances in nanocrystal synthesis are offering a great opportunity to investigate and quantify the structural sensitivity of catalysts based on Pd and other metals. For a structure-sensitive reaction, the catalytic properties of Pd nanocrystals are strongly dependent on both the size and shape. The shape plays a more significant role in controlling activity and selectivity, because the shape controls not only the facets but also the proportions of surface atoms at corners, edges, and planes, which affect the outcomes of possible reactions. We expect catalysts based on Pd nanocrystals with optimized shapes to meet the increasing demands of industrial applications at reduced loadings and costs. In this Account, we discuss recent advances in the synthesis of Pd nanocrystals with controlled shapes and their resulting performance as catalysts for a large number of reactions. First, we review various synthetic strategies based on oxidative etching, surface capping, and kinetic control that have been used to direct the shapes of nanocrystals. When crystal growth is under thermodynamic control, the capping agent plays a pivotal role in determining the shape of

  4. Novel techniques for the synthesis of three-way catalytic converter support materials

    Science.gov (United States)

    Anyaba, Prince Nwabueze

    Current automobiles use catalytic converters, consisting of noble metals on an oxide support, to convert noxious engine exhaust pollutants into less harmful species. The development of mesoporous oxide supports with optimal pore geometries could enable these devises to decrease in size and weight and significantly reduce the metal loadings required to achieve optimal performance. Thus, in this work, I investigated a wide range of techniques for the synthesis of mesoporous oxides to determine if they could be adapted to ceria-zirconia-yttria mixed oxide (CZY) systems, which are the industry standard for the optimal oxide support for catalytic converter applications. Additionally, I compared and critically evaluated the catalytic performance of the CZY mixed oxides, which were synthesized from the various templating techniques. The catalytic performance test was broken up into two: catalyst activity test which was determined based on the light-off temperatures at which 50% conversion of the reacting species have been converted; and resistance to surface area loss under accelerated aging at heating rate of 20°C/min form 700 to 1000°C, with the final temperature being held fixed for 4 h. To date, the most cost effective methods for preparing mesoporous materials are via techniques that employ templates or structure directing agents. These templates can be divided into two groups: endo-templates (i.e., soft templates, such as surfactants, dendrimers, and block copolymers) and exo-templates (i.e., hard templates, such as porous carbons and resins). The soft templating techniques generally involve both sol-gel and templating methods, while the hard templates required no sol-gel chemistry to achieve the desired templating effect. The precursors for ceria, zirconia, and yttria used were cerium (III) nitrate hexahydrate, zirconyl nitrate, and yttrium nitrate hexahydrate, respectively. The mesoporous CZY materials that were synthesized had surface area values that were

  5. CuO-CeO2 binary oxide nanoplates: Synthesis, characterization, and catalytic performance for benzene oxidation

    International Nuclear Information System (INIS)

    This work reports the first synthesis of CuO-CeO2 binary oxides with a plate-like morphology by a solvothermal method. The as-prepared CuO-CeO2 nanoplates calcined at 400 oC were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectrum, and tested for catalytic oxidation of dilute benzene in air. Various structural characterizations showed that large amounts of copper species were exposed on the CuO-CeO2 nanoplate surface. The effect of the synthesis conditions on the structure of the product, as well as the growth process of the nanoplates, has been studied and discussed. The CuO-CeO2 nanoplates exhibited an excellent catalytic activity for benzene oxidation despite its relatively low surface area and could catalyze the complete oxidation of benzene at a temperature as low as 240 oC.

  6. Asymmetric Inducing Synthesis of Optically Active Tetrahedral Cluster Containing SMCoW Core

    Institute of Scientific and Technical Information of China (English)

    ZHAO,Quan-Yi(赵全义); ZHANG,Yu-Hua(张玉华); HU,Bin(胡斌); ZHANG,Wei-Qiang(张伟强); ZHU,Bao-Hua(朱保华); YIN,Yuan-Qi(殷元骐); XIA,Chun-Gu(夏春谷)

    2004-01-01

    The chiral clusters (μ3-S)MCoW(CO)8[η5-CsH4C(O)OCH3] [M=Ru (2), Fe (3)] were synthesized by asymmetric induction of N-benzylcinchonium chloride as phase-transfer catalyst (PTC). The most suitable amount of PTC is 70 mol%. Cluster 3 was determined by single crystal X-ray diffraction analysis. The best ee of the chiral cluster is over 20%.

  7. Asymmetric Synthesis and Absolute Configuration Assignment of a New Type of Bedaquiline Analogue

    OpenAIRE

    Chang-Jiang Qiao; Xiao-Kui Wang; Fei Xie; Wu Zhong; Song Li

    2015-01-01

    Bedaquiline is the first FDA-approved new chemical entity to fight multidrug-resistant tuberculosis in the last forty years. Our group replaced the quinoline ring with a naphthalene ring, leading to a new type of triarylbutanol skeleton. An asymmetric synthetic route was established for our bedaquiline analogues, and the goal of assigning their absolute configurations was achieved by comparison of experimental and calculated electronic circular dichroism spectra, and was confirmed by the comb...

  8. Synthesis of phosphine ligands with helical chirality for applications in asymmetric catalysis

    Czech Academy of Sciences Publication Activity Database

    Andronova, Angelina; Stará, Irena G.; Starý, Ivo

    Praha : -, 2009. s. 90-90. ISBN 978-80-02-02160-5. [ESOC 2009. European Symposium on Organic Chemistry /16./. 12.07.2009-16.07.2009, Praha] R&D Projects: GA MŠk LC512; GA ČR GA203/09/1766; GA ČR GA203/07/1664 Institutional research plan: CEZ:AV0Z40550506 Keywords : helicene * asymmetric catalysis * phosphites Subject RIV: CC - Organic Chemistry

  9. 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.

  10. Spiro-fused carbohydrate oxazoline ligands: Synthesis and application as enantio-discrimination agents in asymmetric allylic alkylation.

    Science.gov (United States)

    Kraft, Jochen; Golkowski, Martin; Ziegler, Thomas

    2016-01-01

    In the present work, we describe a convenient synthesis of spiro-fused D-fructo- and D-psico-configurated oxazoline ligands and their application in asymmetric catalysis. The ligands were synthesized from readily available 3,4,5-tri-O-benzyl-1,2-O-isopropylidene-β-D-fructopyranose and 3,4,5-tri-O-benzyl-1,2-O-isopropylidene-β-D-psicopyranose, respectively. The latter compounds were partially deprotected under acidic conditions followed by condensation with thiocyanic acid to give an anomeric mixture of the corresponding 1,3-oxazolidine-2-thiones. The anomeric 1,3-oxazolidine-2-thiones were separated after successive benzylation, fully characterized and subjected to palladium catalyzed Suzuki-Miyaura coupling with 2-pyridineboronic acid N-phenyldiethanolamine ester to give the corresponding 2-pyridyl spiro-oxazoline (PyOx) ligands. The spiro-oxazoline ligands showed high asymmetric induction (up to 93% ee) when applied as chiral ligands in palladium-catalyzed allylic alkylation of 1,3-diphenylallyl acetate with dimethyl malonate. The D-fructo-PyOx ligand provided mainly the (R)-enantiomer while the D-psico-configurated ligand gave the (S)-enantiomer with a lower enantiomeric excess. PMID:26877819

  11. Asymmetric synthesis of crambescin A-C carboxylic acids and their inhibitory activity on voltage-gated sodium channels.

    Science.gov (United States)

    Nakazaki, Atsuo; Nakane, Yoshiki; Ishikawa, Yuki; Yotsu-Yamashita, Mari; Nishikawa, Toshio

    2016-06-21

    Synthesis of both enantiomers of crambescin B carboxylic acid is described. A cis-enyne starting material was epoxidized under the conditions of Katsuki asymmetric epoxidation to give 95% ee of the epoxide, which was transformed to crambescin B carboxylic acid via bromocation-triggered cascade cyclization as the key step. Enantiomerically pure crambescin A and C carboxylic acids were also synthesized from the product of the cascade reaction. Structure-activity relationship (SAR) studies against voltage-gated sodium channel (VGSC) inhibition using those synthetic compounds revealed that the natural enantiomer of crambescin B carboxylic acid was most active and comparable to tetrodotoxin, and the unalkylated cyclic guanidinium structure is indispensible, while the carboxylate moiety is not important. The absolute stereochemistry of crambescin A was determined by a comparison of the methyl ester derived from natural crambescin A with that derived from the stereochemically defined crambescin A carboxylic acid synthesized in this study. PMID:27215973

  12. Synthesis ZrO2-Montmorillonite and Application as Catalyst in Catalytic Cracking of Heavy Fraction of Crude Oil

    Directory of Open Access Journals (Sweden)

    Is Fatimah

    2010-10-01

    Full Text Available Research on synthesis and characterization of ZrO2-Montmorillonit and its application as catalyst in heavy fraction of crude oil (HFCO conversion has been investigated. Synthesis of catalyst was done by pillarization of ZrO2 into silicate interlayer of montmorillonite structure. The success in synthesis is shown by XRD and BET surface area measurement in that basal spacing d001 was increase after pillarization. Activity test of material was showed that ZrO2 dispersion affected catalytic activity in liquid production and the activity was increased asn increasing temperature in the range of 473K-673K. Composition of liquid product indicated that ZrO2-Montmorillonit tend to produce kerosene related to metal oxide distribution in synthesis. © 2008 BCREC UNDIP. All rights reserved.[Received: 3 June 2008, Accepted: 15 July 2008][How to Cite: I. Fatimah, K. Wijaya, K. H. Setyawan. (2008. Synthesis ZrO2-Montmorillonite and Application as Catalyst in Catalytic Cracking of Heavy Fraction of Crude Oil. Bulletin of Chemical Reaction Engineering and Catalysis, 3(1-3: 9-13.  doi:10.9767/bcrec.3.1-3.7118.9-13][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.3.1-3.7118.9-13 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/7118

  13. Synthesis ZrO2-Montmorillonite and Application as Catalyst in Catalytic Cracking of Heavy Fraction of Crude Oil

    Directory of Open Access Journals (Sweden)

    Khoirul Himmi Setyawan

    2008-04-01

    Full Text Available Research on synthesis and characterization of ZrO2-Montmorillonit and its application as catalyst in heavyfraction of crude oil (HFCO conversion has been investigated. Synthesis of catalyst was done by pillarizationof ZrO2 into silicate interlayer of montmorillonite structure. The success in synthesis is shown by XRDand BET surface area measurement in that basal spacing d001 was increase after pillarization. Activitytest of material was showed that ZrO2 dispersion affected catalytic activity in liquid production and the activitywas increased asn increasing temperature in the range of 473K-673K. Composition of liquid productindicated that ZrO2-Montmorillonit tend to produce kerosene related to metal oxide distribution in synthesis. © 2008 BCREC UNDIP. All rights reserved.[Received: 3 June 2008, Accepted: 15 July 2008][How to Cite: I. Fatimah, K. Wijaya, K. H. Setyawan. (2008. Synthesis ZrO2-Montmorillonite and Application as Catalyst in Catalytic Cracking of Heavy Fraction of Crude Oil. Bulletin of Chemical Reaction Engineering and Catalysis, 3(1-3: 9-13. doi:10.9767/bcrec.3.1-3.17.9-13

  14. Selectivity, Compatibility, Downstream Functionalization, and Silver Effect in the Gold and Palladium Dual-Catalytic Synthesis of Lactones

    OpenAIRE

    Al-Amin, Mohammad; Johnson, Joel S.; Blum, Suzanne A.

    2014-01-01

    The chemo- and regioselectivity and functional group compatibility in gold and palladium cooperatively catalyzed cross-coupling reactions were determined in the synthesis of lactones; the selectivity in the gold and palladium dual-metal catalysis system was distinct from that available for the same class of substrates in systems with only gold catalysis or only palladium catalysis rather than dual catalysis. The dual-catalytic rearrangement reaction selectively promoted oxidative addition at ...

  15. Catalytic Z-Selective Cross-Metathesis in Complex Molecule Synthesis: A Convergent Stereoselective Route to Disorazole C1

    OpenAIRE

    Speed, Alexander W. H.; Mann, Tyler J.; O’Brien, Robert V.; Schrock, Richard R.; Hoveyda, Amir H.

    2014-01-01

    A convergent diastereo- and enantioselective total synthesis of anticancer and antifungal macrocyclic natural product disorazole C1 is reported. The central feature of the successful route is the application of catalytic Z-selective cross-metathesis (CM). Specifically, we illustrate that catalyst-controlled stereoselective CM can be performed to afford structurally complex Z-alkenyl–B(pin) as well as Z-alkenyl iodide compounds reliably, efficiently, and with high selectivity (pin = pinacolato...

  16. Optimization on electrochemical synthesis of HKUST-1 as candidate catalytic material for Green diesel production

    Science.gov (United States)

    Lestari, W. W.; Nugraha, R. E.; Winarni, I. D.; Adreane, M.; Rahmawati, F.

    2016-04-01

    In the effort to support the discovery of new renewable energy sources in Indonesia, biofuel is one of promising options. The conversion of vegetable oil into ready-biofuel, especially green diesel, needs several steps, one of which is a hydrogenation or hydro-deoxygenation reaction. In this case, the catalyst plays a very important role regarding to its activity and selectivity, and Metal-Organic Frameworks (MOFs) becoming a new generation of heterogeneous catalyst in this area. In this research, a preliminary study to optimize electrochemical synthesis of the catalytic material based on MOFs, namely HKUST-1 [Cu3(BTC)2], has been conducted. Some electrochemical reaction parameters were tested, for example by modifying the electrochemical synthetic conditions, i.e. by performing variation of voltages (12, 13, 14, and 15 Volt), temperatures (RT, 40, 60, and 80 °C) and solvents (ethanol, water, methanol and dimethyl-formamide (DMF)). Material characterization was carried out by XRD, SEM, FTIR, DTA/TG and SAA. The results showed that the optimum synthetic conditions of HKUST-1 are performed at room temperature in a solvent combination of water: ethanol (1: 1) and a voltage of 15 Volt for 2 hours. The XRD-analysis revealed that the resulted peaks are identical to the simulated powder pattern generated from single crystal data and comparable to the peaks of solvothermal method. However, the porosity of the resulting material through electrochemical method is still in the range of micro-pore according to IUPAC and 50% smaller than the porosity resulted from solvothermal synthesis. The corresponding compounds are thermally stable until 300 °C according to TG/DTA.

  17. Nicotinamide adenine dinucleotide assisted shape-controlled synthesis of catalytically active raspberry-like gold nanostructures

    International Nuclear Information System (INIS)

    Graphical abstract: A facile method was developed for the synthesis of raspberry-like Au nanostructure and it was used as an electrocatalyst for the oxidation of methanol and reduction of oxygen. - Highlights: • Raspberry-like gold nanostructures have been synthesized. • Nicotinamide adenine dinucleotide plays an important role in the synthesis. • Raspberry-like Au nanostructure has an excellent electrocatalytic activity in methanol oxidation and oxygen reduction. - Abstract: We describe the shape-controlled growth of raspberry-like gold (Au) nanostructures and their application in the electrochemical oxidation of methanol and reduction of oxygen. Nicotinamide adenine dinucleotide (NAD+) plays a vital role in the growth of raspberry-like Au nanostructures. The preferential adsorption of NAD+ onto the (011) facets of Au favors the growth of raspberry-like morphology. In the absence of NAD+, icosahedral Au nanostructures were obtained. The raspberry-like Au nanostructures have been characterized by UV-visible spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and electrochemical measurements. The FESEM image shows that the raspberry-like morphology has an average size of 170 nm. The spectral profile shows a broad band between 650 and 795 nm. Compared to Au nanoseeds and icosahedral Au nanostructures that were grown in the absence of NAD+, the raspberry-like morphology has excellent catalytic activity towards the electrochemical oxidation of methanol and reduction of oxygen. On the raspberry-like nanoparticle-based electrode, the oxidation of methanol was observed at 0.35 V in alkaline pH, and the reduction of oxygen was observed at -0.06 and -0.4 V in 0.1 M PBS. The electrochemical reduction of oxygen occurs in two steps: (i) reduction of oxygen to H2O2 and (ii) further reduction of electrogenerated H2O2 to water. The electrochemical performance of the raspberry-like nanostructure-based electrode is highly stable

  18. Efficient Catalytic Activity BiFeO3 Nanoparticles Prepared by Novel Microwave-Assisted Synthesis.

    Science.gov (United States)

    Zou, Jing; Gong, Wanyun; Ma, Jinai; Li, Lu; Jiang, Jizhou

    2015-02-01

    A novel microwave-assisted sol-gel method was applied to the synthesis of the single-phase perovskite bismuth ferrite nanoparticles (BFO NPs) with the mean diameter ca. 73.7 nm. The morphology was characterized by scanning electron microscope (SEM). The X-ray diffraction (XRD) revealed the rhombohedral phase with R3c space group. The weak ferromagnetic behavior at room temperature was affirmed by the vibrating sample magnetometer (VSM). According to the UV-vis diffuse reflectance spectrum (UV-DSR), the band gap energy of BFO NPs was determined to be 2.18 eV. The electrochemical activity was evaluated by BFO NPs-chitosan-glassy carbon electrode (BFO-CS-GCE) sensor for detection of p-nitrophenol contaminants. The material showed an efficient oxidation catalytic activity by degrading methylene blue (MB). It was found that the degradation efficiency of 10 mg L-1 MB at pH 6.0 was above 90.9% after ultrasound- and microwave-combined-assisted (US-MW) irradiation for 15 min with BFO NPs as catalyst and H202 as oxidant. A possible reaction mechanism of degradation of MB was also proposed. PMID:26353647

  19. Catechin-capped gold nanoparticles: green synthesis, characterization, and catalytic activity toward 4-nitrophenol reduction

    Science.gov (United States)

    Choi, Yoonho; Choi, Myung-Jin; Cha, Song-Hyun; Kim, Yeong Shik; Cho, Seonho; Park, Youmie

    2014-03-01

    An eco-friendly approach is described for the green synthesis of gold nanoparticles using catechin as a reducing and capping agent. The reaction occurred at room temperature within 1 h without the use of any external energy and an excellent yield (99%) was obtained, as determined by inductively coupled plasma mass spectrometry. Various shapes of gold nanoparticles with an estimated diameter of 16.6 nm were green-synthesized. Notably, the capping of freshly synthesized gold nanoparticles by catechin was clearly visualized with the aid of microscopic techniques, including high-resolution transmission electron microscopy, atomic force microscopy, and field emission scanning electron microscopy. Strong peaks in the X-ray diffraction pattern of the as-prepared gold nanoparticles confirmed their crystalline nature. The catalytic activity of the as-prepared gold nanoparticles was observed in the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. The results suggest that the newly prepared gold nanoparticles have potential uses in catalysis.

  20. Electrochemical synthesis of NiFe2O4 nanoparticles: Characterization and their catalytic applications

    International Nuclear Information System (INIS)

    Highlights: ► Nickel ferrite nanoparticles were synthesized by new electrochemical method. ► Stoichometric nanoparticles with 20 nm of size can be prepared with this method. ► Nickel ferrites nanoparticles were used as catalysts in the direct oxidation of glucose at pH 7. - Abstract: In this work a new route for preparation of nickel ferrites nanoparticles has been developed. The synthesis is carried out in an electrochemical cell using three electrodes, a sheet of iron was employed as cathode and two sheets of iron and nickel were used as sacrificial anodes. The obtained nanoparticles were washed several times with distilled water, separated magnetically and dried under vacuum with constant temperature for 12 h. The characterization of the nanoparticles was carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Inductively coupled plasma mass spectrometry (ICP–MS). Magnetic measurements were carried out using a vibrating sample magnetometer (VSM). To evaluate the catalytical properties of these nanoparticles against the oxidation of glucose a graphite paste electrode (GPE) was made. The proportions of the nanoparticles in GPE were 5, 10, 20 and 50% in weight. The electrode shows promising properties for its use as catalyst in the glucose oxidation.

  1. Synthesis and characterization of Polyindole and its catalytic performance study as a heterogeneous catalyst

    Indian Academy of Sciences (India)

    Prakash Chhattise; Kalpana Handore; Amit Horne; Kakasaheb Mohite; Atul Chaskar; Sabrina Dallavalle; Vasant Chabukswar

    2016-03-01

    The catalytic performance study of polyindole as a heterogeneous catalyst is reported for the synthesis of 3,3'-arylmethylene-bis-1H-Indole derivatives using various substituted aldehydes and indole under reflux reaction condition with good to excellent yield. Polyindole was synthesized by chemical oxidative polymerization using citric acid as a dopant. The synthesized polymer was well characterized by various spectroscopic techniques like FT-IR, XRD, FESEM, etc. The XRD pattern confirms the partially crystalline nature of polyindole. The FESEM images of polyindole revealed the formation of irregularly shaped particulate nature with size in the range of 0.2 to 6 micron. In FT-IR spectrum, the major peak at 3400 cm-1 indicates N-H stretching and at 1564−1624 cm-1 indicates C-C stretching of benzenoid ring of indole. The presence of peak at 3400 cm-1 indicates that the polymerization does not occur at nitrogen. The present protocol has certain advantages like recyclability, low loading of the catalyst, low-cost and efficient use of polyindole as a heterogeneous catalyst.

  2. Incorporation of catalytic dehydrogenation into Fischer-Tropsch synthesis to lower carbon dioxide emissions

    Energy Technology Data Exchange (ETDEWEB)

    Huffman, Gerald P

    2012-09-18

    A method for producing liquid fuels includes the steps of gasifying a starting material selected from a group consisting of coal, biomass, carbon nanotubes and mixtures thereof to produce a syngas, subjecting that syngas to Fischer-Tropsch synthesis (FTS) to produce a hyrdrocarbon product stream, separating that hydrocarbon product stream into C1-C4 hydrocarbons and C5+ hydrocarbons to be used as liquid fuels and subjecting the C1-C4 hydrocarbons to catalytic dehydrogenation (CDH) to produce hydrogen and carbon nanotubes. The hydrogen produced by CDH is recycled to be mixed with the syngas incident to the FTS reactor in order to raise the hydrogen to carbon monoxide ratio of the syngas to values of 2 or higher, which is required to produce liquid hydrocarbon fuels. This is accomplished with little or no production of carbon dioxide, a greenhouse gas. The carbon is captured in the form of a potentially valuable by-product, multi-walled carbon nanotubes (MWNT), while huge emissions of carbon dioxide are avoided and very large quantities of water employed for the water-gas shift in traditional FTS systems are saved.

  3. Synthesis, spectral and catalytic dehydrogenation studies of ruthenium complexes containing NO bidentate ligands

    Science.gov (United States)

    Shoair, A. F.; El-Bindary, A. A.

    2014-10-01

    The synthesis and characterization of ruthenium mononuclear complexes containing NO bidentate ligands are reported. The complexes cis-[RuII(bpy)2L](PF6)n (1a-c), [RuIIICl(L)2(H2O)] (2a-b) and [RuIIICl2(L)2]Cl (2c) were prepared by the reaction of cis-[RuIICl2(bpy)2]·2H2O (bpy = 2,2";-bipyridine) and/or RuCl3·nH2O with the Ligands: 2-aminophenol (2-aph), 8-hydroxyquinoline (8-hq) and 4-aminoantipyrine (4-apy). These complexes were characterized by elemental analysis, spectroscopic (IR, UV-Vis, 1H NMR, ESR) and magnetic susceptibility measurements. The ligand field parameters, Δo (splitting parameter), B (Racah parameter of interelectronic repulsion), and β (nephelauxetic ratio) were calculated. The redox properties were also investigated electrochemically by cyclic voltammetry. The complexes cis-[RuII(bpy)2(8-hq)](PF6)2 (1b) and [RuIIICl(8-hq)2(H2O)] (2b) have been investigated in conjunction with N-methylmorpholine-N-oxide (NMO) as co-oxidant for the catalytic dehydrogenation of benzyl amine, p-methyl benzylamine and p-nitrobenzylamine to their respective nitriles.

  4. Facile synthesis of pentacle gold-copper alloy nanocrystals and their plasmonic and catalytic properties

    Science.gov (United States)

    He, Rong; Wang, You-Cheng; Wang, Xiaoyong; Wang, Zhantong; Liu, Gang; Zhou, Wei; Wen, Longping; Li, Qunxiang; Wang, Xiaoping; Chen, Xiaoyuan; Zeng, Jie; Hou, J. G.

    2014-07-01

    The combination of gold and copper is a good way to pull down the cost of gold and ameliorate the instability of copper. Through shape control, the synergy of these two metals can be better exploited. Here, we report an aqueous phase route to the synthesis of pentacle gold-copper alloy nanocrystals with fivefold twinning, the size of which can be tuned in the range from 45 to 200 nm. The growth is found to start from a decahedral core, followed by protrusion of branches along twinning planes. Pentacle products display strong localized surface plasmon resonance peaks in the near-infrared region. Under irradiation by an 808-nm laser, 70-nm pentacle nanocrystals exhibit a notable photothermal effect to kill 4T1 murine breast tumours established on BALB/c mice. In addition, 70-nm pentacle nanocrystals show better catalytic activity than conventional citrate-coated 5-nm Au nanoparticles towards the reduction of p-nitrophenol to p-aminophenol by sodium borohydride.

  5. Synthesis, characterization and catalytic performance of nanosized iron-cobalt catalysts for light olefins production

    Institute of Scientific and Technical Information of China (English)

    Mostafa Feyzi; Asadollah Hassankhani

    2011-01-01

    Nanosized Fe-Co catalysts were prepared by co-precipitation method and studied for the conversion of synthesis gas to light olefins.In particular,the effects of a range of preparation variables such as Co/Fe molar ratios of the precipitation solution,pH value of precipitate,temperature of precipitation,promoters and loading of optimum promoter on the structure and catalytic performance are investigated.The optimal nano catalyst for light olefins (C2-C4) production was obtained overthe catalyst with Co/Fe molar ratio of 3/1 which promoted with 2 wt% K.The results show that the best operational conditions were GHSV =2200 h-1 (H2/CO =2/1) at 260 ℃ under atmospheric pressure.Characterization of catalysts were carried out using X-ray diffraction (XRD),thermal gravimetric analysis (TGA),differential scanning calorimetry (DSC),scanning electron microscopy (SEM),transmission electron microscopy (TEM) and N2 physisorption measurements such as BrunauerEmmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods.

  6. Modular solid-phase synthesis, catalytic application and efficient recycling of supported phosphine-phosphite ligand libraries.

    Science.gov (United States)

    Heutz, Frank J L; Kamer, Paul C J

    2016-02-01

    In spite of decades of research in the field of homogeneous asymmetric catalysis the discovery of new high performance catalysts still relies heavily on trial-and-error. There is still a lack of efficient combinatorial methods which enable the synthesis and screening of vast ligand libraries, especially for bidentate phosphorus ligands. Here we present a highly modular solid-phase synthetic approach which provides facile access to libraries of phosphine-phosphite ligands in quantitative yield requiring only minimal work-up. The obtained library of supported phosphine-phosphites was successfully applied in rhodium catalyzed asymmetric hydrogenation obtaining high enantioselectivities up to 98%. Also, these polymer supported ligands could be successfully recycled under batch conditions exhibiting only a small decline of activity and no loss of selectivity. PMID:26486695

  7. Asymmetric Synthesis and Absolute Configuration Assignment of a New Type of Bedaquiline Analogue

    Directory of Open Access Journals (Sweden)

    Chang-Jiang Qiao

    2015-12-01

    Full Text Available Bedaquiline is the first FDA-approved new chemical entity to fight multidrug-resistant tuberculosis in the last forty years. Our group replaced the quinoline ring with a naphthalene ring, leading to a new type of triarylbutanol skeleton. An asymmetric synthetic route was established for our bedaquiline analogues, and the goal of assigning their absolute configurations was achieved by comparison of experimental and calculated electronic circular dichroism spectra, and was confirmed by the combined use of circular dichroism and NMR spectroscopy.

  8. Asymmetric Synthesis and Absolute Configuration Assignment of a New Type of Bedaquiline Analogue.

    Science.gov (United States)

    Qiao, Chang-Jiang; Wang, Xiao-Kui; Xie, Fei; Zhong, Wu; Li, Song

    2015-01-01

    Bedaquiline is the first FDA-approved new chemical entity to fight multidrug-resistant tuberculosis in the last forty years. Our group replaced the quinoline ring with a naphthalene ring, leading to a new type of triarylbutanol skeleton. An asymmetric synthetic route was established for our bedaquiline analogues, and the goal of assigning their absolute configurations was achieved by comparison of experimental and calculated electronic circular dichroism spectra, and was confirmed by the combined use of circular dichroism and NMR spectroscopy. PMID:26690407

  9. Flexible and Asymmetric Ligand in Constructing Coordinated Complexes: Synthesis, Crystal Structures and Fluorescent Characterization

    Directory of Open Access Journals (Sweden)

    Jianhua Lin

    2010-12-01

    Full Text Available Flexible and asymmetric ligand L [L = 1-((pyridin-3-ylmethyl-1H-benzotriazole], is used as a basic backbone to construct complicated metal-organic frameworks. Two new polymers, namely, [Ag2(L2(NO32]n (1 and [Ag(L(ClO4]n (2, were synthesized and characterized by X-ray structure analysis and fluorescent spectroscopy. The complex 1 gives an “S” type double helical conformation, whereas complex 2 exhibits a 1D zigzag configuration. Different anions affect the silver coordination geometry and crystal packing topology.

  10. Green synthesis of gold nanoparticles using Trigonella foenum-graecum and its size-dependent catalytic activity

    Science.gov (United States)

    Aswathy Aromal, S.; Philip, Daizy

    2012-11-01

    The development of new synthesis methods for monodispersed nanocrystals using cheap and nontoxic chemicals, environmentally benign solvents and renewable materials remains a challenge to the scientific community. Most of the current methods involve known protocols which may be potentially harmful to either environment or human health. Recent research has been focused on green synthesis methods to produce new nanomaterials, ecofriendly and safer with sustainable commercial viability. The present work reports the green synthesis of gold nanoparticles using the aqueous extract of fenugreek (Trigonella foenum-graecum) as reducing and protecting agent. The pathway is based on the reduction of AuCl4- by the extract of fenugreek. This method is simple, efficient, economic and nontoxic. Gold nanoparticles having different sizes in the range from 15 to 25 nm could be obtained by controlling the synthesis parameters. The nanoparticles have been characterized by UV-Visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. The high crystallinity of nanoparticles is evident from clear lattice fringes in the HRTEM images, bright circular spots in the SAED pattern and peaks in the XRD pattern. FTIR spectrum indicates the presence of different functional groups present in the biomolecule capping the nanoparticles. The synthesized gold nanoparticles show good catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol by excess NaBH4. The catalytic activity is found to be size-dependent, the smaller nanoparticles showing faster activity.

  11. Stereoselective Synthesis of Highly Functionalized Cyclopropanes. Application to the Asymmetric Synthesis of (1S,2S)-2,3-Methanoamino Acids.

    Science.gov (United States)

    Dorizon, Philippe; Su, Guifa; Ludvig, Gitte; Nikitina, Lilyia; Paugam, Renée; Ollivier, Jean; Salaün, Jacques

    1999-06-25

    One-pot palladium(0)-catalyzed alkylation and S(N)(') cyclization of 1,4-dichlorobut-2-ene 1 by the anion of alpha-substituted carbonitriles 2a-d can provide highly functionalized cyclopropanes (E)-4a-d, diastereoselectivity, (de 88-100%). Several attempts to achieve the asymmetric synthesis of the 1-amino-2-ethenylcyclopropanecarbonitrile (E)-9, by means of this new procedure, i.e., using chiral palladium ligands, chiral aminoacetonitriles (-)- and (+)-12 (from 1-hydroxypinanone) or chiral allyl chlorides (4S)-20b-d and (4R)-20e (from (2S) ethyl lactate) have pointed up the reversibility of the palladium-catalyzed cyclization step, responsible for the low enantioselectivity observed (ee 88%) and provided the enantiomerically enriched 1-amino-2-propenylcyclopropanecarbonitrile (E)-22 (ee > 83%) suitable precursor of (1S,2S)-2,3-methanoamino acids. PMID:11674544

  12. Asymmetric AgPd-AuNR heterostructure with enhanced photothermal performance and SERS activity

    Science.gov (United States)

    Zhang, Han; Liu, Zeke; Kang, Xiaolin; Guo, Jun; Ma, Wanli; Cheng, Si

    2016-01-01

    Most as-reported nanostructures through galvanic replacement reactions are still symmetric hollow structures, until now. Asymmetric structures fabricated through a galvanic replacement reaction have been rarely reported. However, asymmetric heterostructures can generally lead to new intriguing properties through asymmetric synergistic coupling. Here, we report a simple synthesis of an asymmetric one-ended AgPd bimetal on Au nanorods (AuNR) by combining a galvanic replacement reaction with an Ostwald ripening process. The morphological evolution from a nanodumbbell to a dandelion structure is thoroughly investigated. The unique asymmetric AgPd-AuNR heterostructures possess the required plasmonic performance and avoid strong damping caused by the poor plasmonic metal Pd, resulting in a superior photothermal heating performance and enhanced SERS sensitivity for in situ monitoring of a catalytic reaction compared with the symmetric counterparts.Most as-reported nanostructures through galvanic replacement reactions are still symmetric hollow structures, until now. Asymmetric structures fabricated through a galvanic replacement reaction have been rarely reported. However, asymmetric heterostructures can generally lead to new intriguing properties through asymmetric synergistic coupling. Here, we report a simple synthesis of an asymmetric one-ended AgPd bimetal on Au nanorods (AuNR) by combining a galvanic replacement reaction with an Ostwald ripening process. The morphological evolution from a nanodumbbell to a dandelion structure is thoroughly investigated. The unique asymmetric AgPd-AuNR heterostructures possess the required plasmonic performance and avoid strong damping caused by the poor plasmonic metal Pd, resulting in a superior photothermal heating performance and enhanced SERS sensitivity for in situ monitoring of a catalytic reaction compared with the symmetric counterparts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07333b

  13. Synthesis and biological evaluation of asymmetric gramicidin S analogues containing modified D-phenylalanine residues

    NARCIS (Netherlands)

    van der Knaap, Matthijs; Engels, Eefje; Busscher, Henk J.; Otero, Jose M.; Llamas-Saiz, Antonio L.; van Raaij, Mark J.; Mars-Groenendijk, Roos H.; Noort, Daan; van der Marel, Gijsbert A.; Overkleeft, Herman S.; Overhand, Mark

    2009-01-01

    The synthesis of new analogues of the cationic antimicrobial peptide gramicidin S, having a modified D-phenylalanine residue, their antibacterial properties against several Gram positive and negative strains, as well as their hemolytic activity is reported. (C) 2009 Elsevier Ltd. All rights reserved

  14. Synthesis and biological evaluation of asymmetric gramicidin S analogues containing modified d-phenylalanine residues

    NARCIS (Netherlands)

    Knaap, M. van der; Engels, E.; Busscher, H.J.; Otero, J.M.; Llamas-Saiz, A.L.; Raaij, M.J. van; Mars-Groenendijk, R.H.; Noort, D.; Marel, G.A. van der; Overkleeft, H.S.; Overhand, M.

    2009-01-01

    The synthesis of new analogues of the cationic antimicrobial peptide gramicidin S, having a modified d-phenylalanine residue, their antibacterial properties against several Gram positive and negative strains, as well as their hemolytic activity is reported. © 2009 Elsevier Ltd. All rights reserved.

  15. Synthesis, Characterization and Properties of Asymmetric Methide Anion Based Ionic Liquids Containing Nitrile Groups

    Institute of Scientific and Technical Information of China (English)

    ZOU Ting; LU Liang; LIU Xiu-Li; ZHANG Zhan; WANG Li-Bing; FU Xian-Lei; GAO Guo-Hua; KOU Yuan; HE Ming-Yuan

    2008-01-01

    A series of asymmetric methide anion based ionic liquids containing nitrile groups have been synthesized for the first time using the method of ion-exchange between sodium/potassium methide and various quaternary bro-mide/chloride salts of trimethylamine, triethylamine, tributylamine, N-methylpyrrolidine, and N-methylimidazole. All of the functionalised ionic liquids were characterized by IR, 1H, 13C NMR, MS and elemental analysis. The de-composition temperature of the ionic liquids measured via TGA ranged from 219 to 339 ℃. The functionalised ionic liquid, [Bmim][C(CN)2COCH3], was used as a ligand for Suzuki coupling reaction. The yields of the coupling reaction increased 10%-15% by the addition of the functionalised ionic liquid, [Bmim] [C(CN)2COCH3].

  16. Large Scale Synthesis of NiCo Layered Double Hydroxides for Superior Asymmetric Electrochemical Capacitor

    Science.gov (United States)

    Li, Ruchun; Hu, Zhaoxia; Shao, Xiaofeng; Cheng, Pengpeng; Li, Shoushou; Yu, Wendan; Lin, Worong; Yuan, Dingsheng

    2016-01-01

    We report a new environmentally-friendly synthetic strategy for large-scale preparation of 16 nm-ultrathin NiCo based layered double hydroxides (LDH). The Ni50Co50-LDH electrode exhibited excellent specific capacitance of 1537 F g-1 at 0.5 A g-1 and 1181 F g-1 even at current density as high as 10 A g-1, which 50% cobalt doped enhances the electrical conductivity and porous and ultrathin structure is helpful with electrolyte diffusion to improve the material utilization. An asymmetric ultracapacitor was assembled with the N-doped graphitic ordered mesoporous carbon as negative electrode and the NiCo LDH as positive electrode. The device achieves a high energy density of 33.7 Wh kg-1 (at power density of 551 W kg-1) with a 1.5 V operating voltage.

  17. Synthesis and characterization of polystyrene coated iron oxide nanoparticles and asymmetric assemblies by phase inversion

    KAUST Repository

    Xie, Yihui

    2014-09-02

    Films with a gradient concentration of magnetic iron oxide nanoparticles are reported, based on a phase inversion membrane process. Nanoparticles with ∼13 nm diameter were prepared by coprecipitation in aqueous solution and stabilized by oleic acid. They were further functionalized by ATRP leading to grafted polystyrene brush. The final nanoparticles of 33 nm diameter were characterized by TGA, FTIR spectroscopy, GPC, transmission electron microscopy, and dynanmic light scattering. Asymmetric porous nanoparticle assemblies were then prepared by solution casting and immersion in water. The nanocomposite film production with functionalized nanoparticles is fast and technically scalable. The morphologies of films were characterized by scanning electron microscopy and atomic force microscopy, demonstrating the presence of sponge-like structures and finger-like cavities when 50 and 13 wt % casting solutions were, respectively, used. The magnetic properties were evaluated using vibrating sample magnetometer.

  18. Rapid catalytic processes in reforming of methane and successive synthesis of methanol and its derivatives

    Science.gov (United States)

    Inui, Tomoyuki

    1997-11-01

    In order to obtain high quality fuels and basic raw materials for petrochemical industries, novel catalysts which enable the realization of new synthetic routes have been investigated. First, a highly active Rh-modified Ni-based composite catalyst, NiCe 2O 3PtRh, supported on a ceramic fiber in a plate shape was developed, which reformed methane into the syngas having an appropriate ratio of H2/CO. Furthermore, more combustible ethane or propane was added into the reaction gas and its catalytic combustion was allowed to occur on the same catalyst. The combustion heat compensated the reforming heat resulting in an extraordinarily high space-time yield of hydrogen, as high as 10,000 mol/1·h, even under the condition of a very short contact time, 5 ms, and a very low furnace temperature at around 400°C. Next, a highly active catalyst for methanol synthesis from CO 2-rich or CO-rich syngases was developed. A Cu-based CuZnCrAlGa mixed oxide catalyst was prepared by the uniform gelation method and it was mixed with Pd supported on χ-alumina. The composite catalyst exhibited a much higher activity than the conventional catalyst prepared by the precipitation method and a space-time yield of methanol of 1,300 and 6,730 g/l·h was amounted, respectively, from CO 2-rich and CO-rich syngases under 80 atm and at 270°C. Finally, the products obtained as mentioned above were introduced into the reactor, which was connected in series and the methanol was totally converted into hydrocarbons. In the case of a HGa-silicate catalyst, gasoline was obtained at as high a value as 1,860 g/l·h in space-time yield, and in the case of SAPO-34, ethylene and propylene were obtained with an equivalent selectivity.

  19. Synthesis of asymmetric supramolecular compounds using a Ni(0) catalysed homo-coupling approach

    NARCIS (Netherlands)

    Cassidy, Lynda; Horn, Sabine; Cleary, Laura; Halpin, Yvonne; Browne, Wesley R.; Vos, Johannes G.

    2009-01-01

    The synthesis and characterisation of a series of dinuclear ruthenium and osmium polypyridyl metal complexes based on the bridging ligands [5-(5'-bipyridin-2',2 ''-yl)-3-(pyridin-2-yl)]-1,2,4-triazole (Hpytr-bipy), 2,2 ''-bis(pyridin-2 '' yl)-5,5 ''-bis(pyridin-3 ''-yl) (bipy-bipy) and 5,5'-bis(pyri

  20. Large-Scale Synthesis of Palladium Concave Nanocubes with High-Index Facets for Sustainable Enhanced Catalytic Performance

    Science.gov (United States)

    Xie, Xiaobin; Gao, Guanhui; Pan, Zhengyin; Wang, Tingjun; Meng, Xiaoqing; Cai, Lintao

    2015-02-01

    The catalytic activity of palladium (Pd) nanostructures highly relies on their size and morphology, especially enclosed with high-index facets, which provide more active sites so as to enhance their catalytic performance comparing with their low-index facet counterparts. Herein, Pd concave nanocubes enclosed with {730} facets by a one-pot scalable liquid method, with various high-index facets are synthesized via tuning reduction kinetics. Due to their high-index facets, the Pd concave nanocubes exhibit much higher electrocatalytic activity and stability for methanol oxidation than the Pd nanocubes enclosed by {100} facets and commercial Pd/C. Furthermore, we scale up synthesis of Pd concave nanocubes by expanding the volume of all species to fifty times with high-yield production.

  1. Facile Synthesis of Fe-Doped Titanate Nano tubes with Enhanced Photo catalytic Activity for Castor Oil Oxidation

    International Nuclear Information System (INIS)

    Iron-doped titanate nano tubes were synthesized by hydrothermal method, and the photo catalytic activity was greatly enhanced by iron doping. Followed by the discovery of carbon nano tubes, synthesis of one-dimensional (1D) nano materials has attracted great interest because of their exceptional electrical and mechanical properties [1-4]. Some inorganic 1D nano materials including ZnO, VOx, and TiO2 have been synthesized in recent years [5-8]. Among these materials, titanic compound nanotubes have stimulated particular interest. Titanic nano crystals have been extensively studied in photo catalytic or photoelectrochemical systems and so forth [9-12], and fabrication of tubular structures offers an effective approach to adjust their properties, which are crucial in practical applications. For example, the photo catalytic activity of TiO2 could be enhanced by the tubular structures because of their large specific surface, which leads to a higher potential of applications in environmental purification and generation of hydrogen gas and so forth [13]. Recently, particular interest is devoted to obtain H2Ti3O7-type nano tubes synthesized by hydrothermal method [14-16], and these nano tubes show excellent ion-exchange ability and photo catalytic activities and may be applied to photo catalysis, photoluminescence, and dye-sensitized solar cells [3]. However, their structures are still not well understood. The photo catalytic property is originated from the charge carriers produced by the excitation process on the particle surface, and the photo catalytic efficiency is determined by the transfer rate and recombination rate of carriers [17]. However, the carriers are usually unstable and easy to recombine. To improve the photo catalytic efficiency, the transfer rate must be enhanced and recombination rate should be reduced. Introducing other elements especially the transition metal ions into the matrix has been proved to be an effective method to improve the photo catalytic

  2. Synthesis, Annealing and Performance of Pd-Au Asymmetric Composite Membranes for Hydrogen Purification

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Yi Hua [Worcester Polytechnic Institute; Chen, Chao-Huang [Worcester Polytechnic Institute; Catalano, Jacopo [Worcester Polytechnic Institute; Guazzone, Federico [Worcester Polytechnic Institute; Payzant, E Andrew [ORNL

    2013-01-01

    Composite asymmetric Pd-Au membranes, based on porous Inconel and Hastelloy tubular supports, were prepared by means of electroless deposition and galvanic displacement techniques and tested, before and after Au deposition, in pure H2 atmosphere. The final membranes, with Au average bulk composition up to 16.7 wt%, were 9 15 m thick and showed, for the entire duration of characterization, H2/He ideal selectivity in excess of 900. The annealing of the as-prepared membranes was conducted through the coating and diffusion mechanism in He and H2 atmospheres at 500 C. The annealing conditions were chosen after non-isothermal and isothermal HT-XRD studies on coupons synthetized with similar preparation methods. After the formation of the Pd-Au layer, the membranes showed steady flux and a stable Au gradient on the membrane top layer. Comparisons between permeance for Pd/Au and pure Pd membranes indicated that the membranes with an Au average bulk composition of 4.5 and 5.4 wt% had an enhancement, up to 20%, of the H2 permeability in the temperature range 250 450 C with respect to pure Pd membranes. On the other hand, the membrane having the highest Au composition, 16.7 wt%, even though characterized by a lower H2 permeability (77% of pure Pd) had a rather high surface Au composition (approximately 46 wt%), which might provide good H2S poisoning tolerance.

  3. An Environmentally Benign System for Synthesis of β-Hydroxylketones: L-Histidine Asymmetrically Catalyzed Direct Aldol Reactions in Aqueous Micelle and Water-like Media

    Institute of Scientific and Technical Information of China (English)

    PENG Yi-Yuan; PENG Shu-Jun; DING Qiu-Ping; WANG Qi; CHENG Jin-Pei

    2007-01-01

    The first histidine catalyzed direct aldol reactions of ketones with nitrobenzaldehydes in water and in poly(ethylene glycol) (PEG) were reported. It reveals that histidine is a good aldol catalyst for synthesis of β-hydroxylketones in water and in PEG, giving good to excellent yields of the respective products. Better enantioand regioselectivity were achieved using low molecular weight PEG as the media. The results show that histidine and PEG-200 or -300 may constitute a promising environmentally benign system for asymmetric synthesis of β-hydroxylketones.

  4. The absolute configuration of (+)-oxopropaline D by theoretical calculation of specific rotation and asymmetric synthesis.

    Science.gov (United States)

    Kuwada, Takeshi; Fukui, Miyako; Hata, Toshiyuki; Choshi, Tominari; Nobuhiro, Junko; Ono, Yukio; Hibino, Satoshi

    2003-01-01

    The specific optical rotations of (R)-oxopropaline D calculated by two ab initio MO methods were +52+/-31 degrees and +61+/-29 degrees, respectively, and (+)-oxopropaline D (3) was presumed to have an R-configuration. On the basis of this theoretical result, the reaction of 1-litio-beta-carboline with (R)-glyceraldehyde acetonide followed by oxidation with MnO(2) gave (R)-oxopropaline D acetonide (4a), which was consistent with the previously synthesized (+)-oxopropaline D acetonide (4) in all respects. From the results of theoretical calculations and the experimental synthesis, we determined that natural (+)-oxopropaline D (3) has an R-configuration. PMID:12520122

  5. Concise and Straightforward Asymmetric Synthesis of a Cyclic Natural Hydroxy-Amino Acid

    Directory of Open Access Journals (Sweden)

    Mario J. Simirgiotis

    2014-11-01

    Full Text Available An enantioselective total synthesis of the natural amino acid (2S,4R,5R-4,5-di-hydroxy-pipecolic acid starting from D-glucoheptono-1, 4-lactone is presented. The best sequence employed as a key step the intramolecular nucleophilic displacement by an amino function of a 6-O-p-toluene-sulphonyl derivative of a methyl D-arabino-hexonate and involved only 12 steps with an overall yield of 19%. The structures of the compounds synthesized were elucidated on the basis of comprehensive spectroscopic (NMR and MS and computational analysis.

  6. Trienamine catalyzed asymmetric synthesis and biological investigation of a cytochalasin B-inspired compound collection.

    Science.gov (United States)

    Sellstedt, Magnus; Schwalfenberg, Melanie; Ziegler, Slava; Antonchick, Andrey P; Waldmann, Herbert

    2016-01-01

    Due to their enhanced metabolic needs many cancers need a sufficient supply of glucose, and novel inhibitors of glucose import are in high demand. Cytochalasin B (CB) is a potent natural glucose import inhibitor which also impairs the actin cytoskeleton leading to undesired toxicity. With a view to identifying selective glucose import inhibitors we have developed an enantioselective trienamine catalyzed synthesis of a CB-inspired compound collection. Biological analysis revealed that indeed actin impairment can be distinguished from glucose import inhibition and led to the identification of the first selective glucose import inhibitor based on the basic structural architecture of cytochalasin B. PMID:26606903

  7. Synthesis of chiral lactams via asymmetric hydrogenation of α,β-unsaturated nitriles.

    Science.gov (United States)

    Kong, Duanyang; Li, Meina; Zi, Guofu; Hou, Guohua

    2016-04-26

    A highly efficient Rh-catalyzed enantioselective hydrogenation of α,β-unsaturated nitriles containing ester/amide groups has been developed. Under mild conditions, with a complex of rhodium and (S,S)-f-spiroPhos as the catalyst, a variety of α,β-unsaturated nitriles bearing an ester or amide group were successfully hydrogenated to the corresponding chiral nitriles with excellent enantioselectivities (up to 99.7% ee) and high turnover numbers (TON = 10 000). Furthermore, this catalyst system was also successfully applied to the synthesis of important chiral pharmacophore fragments, lactams, Paroxetine and amino acids. PMID:27056402

  8. Synthesis of asymmetric supramolecular compounds using a Ni(0) catalysed homo-coupling approach

    OpenAIRE

    Cassidy, Lynda; Horn, Sabine; Cleary, Laura; Halpin, Yvonne; Browne, Wesley R.; Vos, Johannes G.

    2009-01-01

    The synthesis and characterisation of a series of dinuclear ruthenium and osmium polypyridyl metal complexes based on the bridging ligands [5-(5'-bipyridin-2',2 ''-yl)-3-(pyridin-2-yl)]-1,2,4-triazole (Hpytr-bipy), 2,2 ''-bis(pyridin-2 '' yl)-5,5 ''-bis(pyridin-3 ''-yl) (bipy-bipy) and 5,5'-bis(pyridin-2 ''-yl)-3,3'-bis(1,2,4-triazole) (Hpytr-Hpytr) are reported. The dinuclear complexes have been synthesised via a Ni(0) catalysed cross-coupling reaction from brominated precursors. With this a...

  9. Asymmetric synthesis of quaternary aryl amino acid derivatives via a three-component aryne coupling reaction

    Directory of Open Access Journals (Sweden)

    Elizabeth P. Jones

    2011-11-01

    Full Text Available A method was developed for the synthesis of α-alkyl, α-aryl-bislactim ethers in good to excellent yields and high diastereoselectivities, consisting of a facile one-pot procedure in which the aryl group is introduced by means of a nucleophilic addition to benzyne and the alkyl group by alkylation of a resultant benzylic anion. Hydrolysis of the sterically less hindered adducts gave the corresponding quaternary amino acids with no racemization, whereas hydrolytic ring opening gave the corresponding valine dipeptides from bulkier bislactims.

  10. Rawal's catalyst as an effective stimulant for the highly asymmetric Michael addition of β-keto esters to functionally rich nitro-olefins.

    Science.gov (United States)

    Suresh Kumar, A; Prabhakar Reddy, T; Madhavachary, R; Ramachary, Dhevalapally B

    2016-06-15

    A general approach to asymmetric synthesis of highly substituted dihydroquinolines was achieved through neighboring ortho-amino group engaged sequential Michael/amination/dehydration reactions on (E)-2-(2-nitrovinyl)anilines with cyclic and acyclic β-keto esters in the presence of a catalytic amount of Rawal's quinidine-NH-benzyl squaramide followed by TFA. PMID:26611712

  11. 咪唑类离子液体及其催化有机不对称反应%Imidazolium ionic liquids and catalytic asymmetric reactions of organic

    Institute of Scientific and Technical Information of China (English)

    姜红波

    2011-01-01

    离子液体作为一种新型绿色溶剂,具有许多独特的物理化学性质,近年来逐渐被人们所认知,并发现可用在许多重要领域.本文简单介绍离子液体及其特点,重点介绍在咪唑类离子液体中典型的不对称加氢反应、不对称Michael加成反应、不对称Aldol反应、不对称烯丙基反应和不对称氟化反应.%As a new type of green solvents, ionic liquids has many unique physical and chemical properties.It has been perceived and found in many important areas available in recent years.This article briefly describes the types and characteristics of ionic liquids, focusing on the typical asymmetric hydrogenation reaction, asymmetric Michael addition reaction, asymmetric Aldol reaction, asymmetric allylation reaction and asymmetric fluorination reaction in imidazolium ionic liquids.

  12. Synthesis of 1-alkyl triazolium triflate room temperature ionic liquids and their catalytic studies in multi-component Biginelli reaction

    Indian Academy of Sciences (India)

    Sankaranarayanan Nagarajan; Tanveer M Shaikh; Elango Kandasamy

    2015-09-01

    Synthesis of three Brønsted acid-based ionic liquids, namely, 1-ethyl-1,2,4-triazolium triflate (1a), 1-propyl-1,2,4-triazolium triflate (1b) and 1-butyl-1,2,4-triazolium triflate (1c), is described. These ionic liquids have been employed as catalysts for convenient and high-yielding one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones and 3,4-dihydropyrimidin-2(1H)-thiones, which are Biginelli reaction products. Advantages of the methodology are operational convenience, short reaction times, avoidance of chromatographic purification and non-production of toxic waste. Further, the catalysts are easily recovered and reused without any noticeable diminution in their catalytic activity.

  13. Modularly designed transition metal PNP and PCP pincer complexes based on aminophosphines: synthesis and catalytic applications.

    Science.gov (United States)

    Benito-Garagorri, David; Kirchner, Karl

    2008-02-01

    Transition metal complexes are indispensable tools for any synthetic chemist. Ideally, any metal-mediated process should be fast, clean, efficient, and selective and take place in a catalytic manner. These criteria are especially important considering that many of the transition metals employed in catalysis are rare and expensive. One of the ways of modifying and controlling the properties of transition metal complexes is the use of appropriate ligand systems, such as pincer ligands. Usually consisting of a central aromatic backbone tethered to two two-electron donor groups by different spacers, this class of tridentate ligands have found numerous applications in various areas of chemistry, including catalysis, due to their combination of stability, activity, and variability. As we focused on pincer ligands featuring phosphines as donor groups, the lack of a general method for the preparation of both neutral (PNP) and anionic (PCP) pincer ligands using similar precursor compounds as well as the difficulty of introducing chirality into the structure of pincer ligands prompted us to investigate the use of amines as spacers between the aromatic ring and the phosphines. By introduction of aminophosphine and phosphoramidite moieties into their structure, the synthesis of both PNP and PCP ligands can be achieved via condensation reactions between aromatic diamines and electrophilic chlorophosphines (or chlorophosphites). Moreover, chiral pincer complexes can be easily obtained by using building blocks obtained from the chiral pool. Thus, we have developed a modular synthetic strategy with which the steric, electronic, and stereochemical properties of the ligands can be varied systematically. With the ligands in hand, we studied their reactivity towards different transition metal precursors, such as molybdenum, ruthenium, iron, nickel, palladium, and platinum. This has resulted in the preparation of a range of new pincer complexes, including various iron complexes, as

  14. Synthesis, structural characterization, and catalytic properties of tungsten-exchanged H-ZSM5

    International Nuclear Information System (INIS)

    W-exchanged H-ZSM5 was prepared by sublimation of WCl6 at 673 K followed by hydrolysis of exchanged WClx species at 523 K. D2 exchange with residual OH groups showed that each W initially replaced about two zeolitic protons for W/Al ratios of 0.29 and 0.44, consistent with the formation of (WO2)2+ containing W6+ species bridging two cation exchange sites. As temperatures reached973 K during D2-OH exchange, these species reduced to (WO2)+ with the concurrent formation of one OD group. CH4 conversion turnover rates (per W) and C2-C1 2 selectivities are very similar to those observed on a Mo/H-ZSM5 sample with similar cation exchange level. As in the case of Mo/H-ZSM5, WOx/H-ZSM5 precursors are initially inactive in CH4 reactions, but they activate during induction with the concurrent evolution of CO, H2O, and an excess amount of H2. The reduction and carburization processes occurring during CH4 reactions and the structure of the exchanged WOx precursors was probed using in situ X-ray absorption spectroscopy (XAS). XAS studies confirmed the isolated initial nature of the exchanged WOx precursors after hydrolysis and dehydration and the formation of WCx clusters 0.6 nm in diameter during CH4 reactions at 973 K. The structural and catalytic resemblance between W- and Mo-exchanged H-ZSM5 is not unexpected, in view of chemical similarities between oxides or carbides of Mo and W. The synthesis of exchanged WOx precursors and their subsequent carburization during CH4 reactions, however, are more difficult than the corresponding processes for the MoOx counterparts. This may account for previous reports of lower CH4 reaction rates and aromatics selectivities on W/H-ZSM5 compared with those observed on Mo/H-ZSM5 and with those reported here for rigorously exchanged W/H-ZSM5

  15. Synthesis, structural characterization, and catalytic properties of tungsten-exchanged H-ZSM5

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Weiping; Meitzner, George D.; Marler, David O.; Iglesia, Enrique

    2001-01-18

    W-exchanged H-ZSM5 was prepared by sublimation of WCl6 at 673 K followed by hydrolysis of exchanged WClx species at 523 K. D2 exchange with residual OH groups showed that each W initially replaced about two zeolitic protons for W/Al ratios of 0.29 and 0.44, consistent with the formation of (WO2)2+ containing W6+ species bridging two cation exchange sites. As temperatures reached973 K during D2-OH exchange, these species reduced to (WO2)+ with the concurrent formation of one OD group. CH4 conversion turnover rates (per W) and C2-C1 2 selectivities are very similar to those observed on a Mo/H-ZSM5 sample with similar cation exchange level. As in the case of Mo/H-ZSM5, WOx/H-ZSM5 precursors are initially inactive in CH4 reactions, but they activate during induction with the concurrent evolution of CO, H2O, and an excess amount of H2. The reduction and carburization processes occurring during CH4 reactions and the structure of the exchanged WOx precursors was probed using in situ X-ray absorption spectroscopy (XAS). XAS studies confirmed the isolated initial nature of the exchanged WOx precursors after hydrolysis and dehydration and the formation of WCx clusters 0.6 nm in diameter during CH4 reactions at 973 K. The structural and catalytic resemblance between W- and Mo-exchanged H-ZSM5 is not unexpected, in view of chemical similarities between oxides or carbides of Mo and W. The synthesis of exchanged WOx precursors and their subsequent carburization during CH4 reactions, however, are more difficult than the corresponding processes for the MoOx counterparts. This may account for previous reports of lower CH4 reaction rates and aromatics selectivities on W/H-ZSM5 compared with those observed on Mo/H-ZSM5 and with those reported here for rigorously exchanged W/H-ZSM5.

  16. Process Considerations for the Asymmetric Synthesis of Chiral Amines using ω-Transaminase

    DEFF Research Database (Denmark)

    Lima Afonso Neto, Watson

    improve its stability and allow recycling and easy separation; (ii) the use of controlled release of substrate (fed-batch) or in situ substrate supply – (ISSS) to decrease substrate inhibition and deal with the substrate low solubility; and (iii) the use of in situ product (ISPR) and co-product removal...... (IScPR) to respectively alleviate product inhibition and shift the reaction equilibrium. From an academic point of view, more important than the implementation of these technologies to a specific example, is the development of a general methodology that can be later applied in other cases. Hence, this......) the selection of suitable polymeric resins for product removal. The work has been performed in collaboration with c-LEcta GmbH (Leipzig, Germany) and DSM Innovative Synthesis (Geleen, The Netherlands) who supplied the enzymes for the case study, making possible the successful demonstration of the...

  17. Self-assembly of Ag-TiO2 Nanoparticles:Synthesis, Characterization and Catalytic Application

    Institute of Scientific and Technical Information of China (English)

    WANG Xin; LIU Xiaoheng; WANG Xinyun

    2012-01-01

    The formation of Ag clusters on titanium oxide (TiO2) nanoparticles was achieved by selfassembly process and calcination.The obtained nanoparticles were characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM),and ultraviolet visible spectroscopy (UV-Vis),and conventional techniques (XRD,TEM and UV-Vis) were used to identify Ag particles on the TiO2 surfaces.The results show that Ag-TiO2 particles can be applied to improve catalytic activity of the epoxidation of styrene oxides.Styrene oxide is the main product of catalytic reaction with H2O2 as the oxidant by using Ag-TiO2 nanoparticles as catalysts.High catalytic activitity of styrene oxide can be obtainable at 80 ℃.The reaction temperature,reaction time,the molar ratio of H2O2/styrene and solvent affect greatly the catalytic epoxidation of styrene.

  18. Direct Synthesis, Characterization and Catalytic Performance of Iron-Containing SBA-15 for Phenol Degradation

    Institute of Scientific and Technical Information of China (English)

    XIE Huan-ling; XU Wen-guo

    2008-01-01

    An iron-containing SBA-15(Fe-SBA-15) has been synthesized via one-pot hydrothermal method under weak acidic conditions. A series of characterizations show nanocomposite materials of iron particles supported over mesostructured materials. The catalytic activity of these iron-containing SBA-15 materials has been tested for the heterogeneous Fenton degradation of phenolic aqueous solutions. The catalytic performance has been monitored in terms of phenol conversion, whereas the catalytic stability was evaluated by catalyst recycle. The influence of concentration of hydrogen peroxide, catalyst loading, catalyst prepared with different Fe/Si molar ratios in the gel and pH values of the solution on phenol conversion has been studied. Achieving a good catalytic performance accompanied with a noteworthy stability, Fe-SBA-15 materials prepared by this method are shown as the successful catalyst for degradation of phenolic aqueous solutions by Fenton process.

  19. In Situ Synthesis of Bimetallic Hybrid Nanocatalysts on a Paper-Structured Matrix for Catalytic Applications

    OpenAIRE

    Hirotaka Koga; Takuya Kitaoka; Yuuka Umemura

    2011-01-01

    Bimetallic nanoparticles have attracted significant attention as their electrochemical and catalytic properties being superior to those of the individual component nanoparticles. In this study, gold-silver hybrid nanoparticles (AuAgNPs) with an Aucore-Agshell nanostructure were successfully synthesized on zinc oxide (ZnO) whiskers. The as-prepared nanocatalyst, denoted AuAgNPs@ZnO whisker, exhibits an excellent catalytic efficiency in the aqueous reduction of 4-nitrophenol to 4-aminophenol; t...

  20. Synthesis, Characterization and catalytic activity of triorganotin(IV) carboxylates for the production of biodiesel from rocket seed oil

    International Nuclear Information System (INIS)

    Organotin(IV) carboxylates have a wide range of industrial applications such as antifouling paints, PVC stabilization, ion carries in electrochemical membranes and homogeneous catalysts. The catalytic application of organotin carboxylates are in the field of silicone curing, polyurethane formation and esterification. Only a limited literature is available regarding the use of organotin carboxylates in the transesterification of vegetable oil to produce biodiesel . The present study deals with the synthesis of some new triorganotin(IV) carboxylates for their subsequent use as catalyst for transesterification of rocket seed oil to produce biodiesel. The three new triorganotin(IV) i.e. (Me/sub 3/SnL) (1),(Bu/sub 3/Snl) (2) and (Ph/sub 3/SnL) (3), were synthesized by refluxing sodium salt of ligand (NaL), where L=O/sub 2/C(CH/sub 3/)C=CHC/sub 6/H/sub 4/F with trimethyl, tributyl and triphenyl tin(IV) chlorides, respectively for 10 hrs. The synthesized compounds were characterized by instrumental techniques like FT-IR and NMR (1H, 13C). The catalytic activity of these compounds was assessed for transesterification of triglycerides in rocket seed oil to produce biodiesel. All the tested compounds showed good catalytic activity in the order 1> 2 > 3. (author)

  1. Efficient Synthesis of Chiral Trisubstituted 1,2-Allenyl Ketones by Catalytic Asymmetric Conjugate Addition of Malonic Esters to Enynes.

    Science.gov (United States)

    Yao, Qian; Liao, Yuting; Lin, Lili; Lin, Xiaobin; Ji, Jie; Liu, Xiaohua; Feng, Xiaoming

    2016-01-01

    An N,N'-dioxide/scandium(III) complex catalyzed, highly efficient conjugate addition of malonic esters to enynes is described. A range of trisubstituted 1,2-allenyl ketones were obtained in high yields (up to 99 %) with good d.r. (up to 95/5) and excellent ee values (97 %-99 %). Moreover, the products could be easily transformed into chiral furan and 5-hydroxypyrazoline derivatives, both of which are important skeletons of many biologically active compounds and pharmacologicals. PMID:26694204

  2. The effect of CNTs on structures and catalytic properties of AuPd clusters for H2O2 synthesis.

    Science.gov (United States)

    Yang, Hua-feng; Xie, Peng-yang; Yu, Hui-you; Li, Xiao-nian; Wang, Jian-guo

    2012-12-28

    The structures and catalytic properties of AuPd clusters supported on carbon nanotubes (CNTs) for H(2)O(2) synthesis have been investigated by means of density functional theory calculations. Firstly, the structures of AuPd clusters are strongly influenced by CNTs, in which the bottom layers are mainly composed of Pd and the top layers are a mix of Au and Pd due to the stronger binding of Pd than Au on CNTs. Especially, it is found that O(2) adsorption on the Pd/CNTs interfacial sites is much weaker than that on the only Pd sites, which is in contrast to transition metal oxide (for example TiO(2), Al(2)O(3), CeO(2)) supported metal clusters. Furthermore, Pd ensembles on the interfacial sites have far superior catalytic properties for H(2)O(2) formation than those away from CNT supports due to the changes in electronic structures caused by the CNTs. Therefore, our study provides a physical insight into the enhanced role of carbon supports in H(2)O(2) synthesis over supported AuPd catalysts. PMID:23032860

  3. Aqueous Phase Synthesis of ZIF-8 Membrane with Controllable Location on an Asymmetrically Porous Polymer Substrate.

    Science.gov (United States)

    Shamsaei, Ezzatollah; Lin, Xiaocheng; Low, Ze-Xian; Abbasi, Zahra; Hu, Yaoxin; Liu, Jefferson Zhe; Wang, Huanting

    2016-03-01

    In this study, we have demonstrated a simple, scalable, and environmentally friendly route for controllable fabrication of continuous, well-intergrown ZIF-8 on a flexible polymer substrate via contra-diffusion method in conjunction with chemical vapor modification of the polymer surface. The combined chemical vapor modification and contra-diffusion method resulted in controlled formation of a thin, defect-free, and robust ZIF-8 layer on one side of the support in aqueous solution at room temperature. The ZIF-8 membrane exhibited propylene permeance of 1.50 × 10(-8) mol m(-2) s(-1) Pa(-1) and excellent selective permeation properties; after post heat-treatment, the membrane showed ideal selectivities of C3H6/C3H8 and H2/C3H8 as high as 27.8 and 2259, respectively. The new synthesis approach holds promise for further development of the fabrication of high-quality polymer-supported ZIF membranes for practical separation applications. PMID:26886288

  4. Asymmetric chemoenzymatic synthesis of miconazole and econazole enantiomers. The importance of chirality in their biological evaluation.

    Science.gov (United States)

    Mangas-Sánchez, Juan; Busto, Eduardo; Gotor-Fernández, Vicente; Malpartida, Francisco; Gotor, Vicente

    2011-04-01

    A simple and novel chemoenzymatic route has been applied for the first time in the synthesis of miconazole and econazole single enantiomers. Lipases and oxidoreductases have been tested in stereoselective processes; the best results were attained with oxidoreductases for the introduction of chirality in an adequate intermediate. The behaviors of a series of ketones and racemic alcohols in bioreductions and acetylation procedures, respectively, have been investigated; the best results were found with alcohol dehydrogenases A and T, which allowed the production of (R)-2-chloro-1-(2,4-dichlorophenyl)ethanol in enantiopure form under very mild reaction conditions. Final chemical modifications have been performed in order to isolate the target fungicides miconazole and econazole both as racemates and as single enantiomers. Biological evaluation of the racemates and single enantiomers has shown remarkable differences against the growth of several microorganisms; while (R)-miconazole seemed to account for most of the biological activity of racemic miconazole on all the strains tested, both enantiomers of econazole showed considerable biological activities. In this manner, (R)-econazole showed higher values against Candida krusei , while higher values were observed for (S)-econazole against Cryptococcus neoformans, Penicillium chrysogenum, and Aspergillus niger. PMID:21384803

  5. Asymmetric Roadmap to Diverse Polycyclic Benzopyrans via Phosphine-Catalyzed Enantioselective [4 + 2]-Annulation Reaction.

    Science.gov (United States)

    Danda, Adithi; Kesava-Reddy, Naredla; Golz, Christopher; Strohmann, Carsten; Kumar, Kamal

    2016-06-01

    The catalytic addition of the amino acid derived bifunctional N-acylaminophosphine to an α-substituted allene ester generated a zwitterionic dipole that engaged the vinylogous ester function of 3-cyano-chromones in a [4 + 2] annulation reaction to deliver tetrahydroxanthones embodying three consecutive chiral centers in high yields and with excellent enantioselectivities. The established asymmetric synthesis further paves the way to two different classes of complex, sp(3)-rich tetracyclic benzopyrans via efficient cascade reactions. PMID:27187586

  6. Synthesis of silver nanoparticles: Effects of anionic ligands on formation and catalytic activity

    International Nuclear Information System (INIS)

    We report a facile method to synthesize water soluble Ag nanoparticles (NPs) using various anionic complexing ligands as reducing as well as stabilizing agents. The formation of the particles depends on the initial molar ratio of ligands to silver nitrate. Also, the alkaline condition of preparative solution is found to be necessary for the formation of Ag NPs. It has been important to mention here that the temperature of the reaction mixture plays an important factor on the rate of formation of the particles. The particles were characterized by UV–vis spectroscopy, transmission electron microscopy, dynamic light scattering and X-ray diffraction techniques. The formed particles were found to be stable for more than a month. Zeta potential measurements suggest that the negative potential created by the adsorbed complexing ligands contribute to the stability of the Ag NPs suspensions. The effect of the ligands on the formation, stability and catalytic activity of the Ag NPs was evaluated. The obtained Ag NPs exhibit a good catalytic activity toward reduction of o-nitroaniline. The results reveal that the presence of more coordination sites in the ligands affects the catalytic activity of the particles. - Highlights: • Formation of Ag nanoparticles using anionic ligands as reducing agents and stabilizers. • Number of –COOH groups in the ligands affect the formation of particles. • The formed nanoparticles show good catalytic activity. • Number of –COOH groups in the ligands affect the catalytic activity of the particles

  7. Thicker is better? Synthesis and evaluation of well-defined polymer brushes with controllable catalytic loadings.

    Science.gov (United States)

    Fernandes, Antony E; Dirani, Ali; d'Haese, Cécile; Deumer, Gladys; Guo, Weiming; Hensenne, Peter; Nahra, Fady; Laloyaux, Xavier; Haufroid, Vincent; Nysten, Bernard; Riant, Olivier; Jonas, Alain M

    2012-12-01

    Polymer brushes (PBs) have been used as supports for the immobilization of palladium complexes on silicon surfaces. The polymers were grown by surface-initiated atom-transfer radical polymerization (SI-ATRP) and postdecorated with dipyridylamine (dpa) ligands. The pendant dpa units were in turn complexed with [Pd(OAc)(2)] to afford hybrid catalytic surfaces. A series of catalytic samples of various thicknesses (ca. 20-160 nm) and associated palladium loadings (ca. 10-45 nmol  cm(-2)) were obtained by adjusting the SI-ATRP reaction time and characterized by ellipsometry, X-ray reflectivity, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS revealed a near-linear relationship between thickness of the polymer brush and palladium content, which confirmed the robustness of the preparation and postmodification sequence presented herein, rendering possible the creation of functional architectures with predefined catalytic potential. The activities of the catalytic PBs were determined by systematically exploring a full range of substrate-to-catalyst ratios in a model palladium(0)-catalyzed reaction. Quantitative transformations were observed for loadings down to 0.03 mol % and a maximum turnover number (TON) of around 3500 was established for the system. Comparison of the catalytic performances evidenced a singular influence of the thickness on conversions and TONs. The limited recyclability of the hairy catalysts has been attributed to palladium leaching. PMID:23032959

  8. Asymmetric Synthesis of Spirocyclic 2-Benzopyrans for Positron Emission Tomography of σ1 Receptors in the Brain

    Directory of Open Access Journals (Sweden)

    Katharina Holl

    2014-01-01

    Full Text Available Sharpless asymmetric dihydroxylation of styrene derivative 6 afforded chiral triols (R-7 and (S-7, which were cyclized with tosyl chloride in the presence of Bu2SnO to provide 2-benzopyrans (R-4 and (S-4 with high regioselectivity. The additional hydroxy moiety in the 4-position was exploited for the introduction of various substituents. Williamson ether synthesis and replacement of the Boc protective group with a benzyl moiety led to potent σ1 ligands with high σ1/σ2-selectivity. With exception of the ethoxy derivative 16, the (R-configured enantiomers represent eutomers with eudismic ratios of up to 29 for the ester (R-18. The methyl ether (R-15 represents the most potent σ1 ligand of this series of compounds, with a Ki value of 1.2 nM and an eudismic ratio of 7. Tosylate (R-21 was used as precursor for the radiosynthesis of [18F]-(R-20, which was available by nucleophilic substitution with K[18F]F K222 carbonate complex. The radiochemical yield of [18F]-(R-20 was 18%–20%, the radiochemical purity greater than 97% and the specific radioactivity 175–300 GBq/µmol. Although radiometabolites were detected in plasma, urine and liver samples, radiometabolites were not found in brain samples. After 30 min, the uptake of the radiotracer in the brain was 3.4% of injected dose per gram of tissue and could be reduced by coadministration of the σ1 antagonist haloperidol. [18F]-(R-20 was able to label those regions of the brain, which were reported to have high density of σ1 receptors.

  9. Synthesis of Functionalized Iron Oxide Nanoparticle with Amino Pyridine Moiety and Studies on Their Catalytic Behavior

    OpenAIRE

    Girija, D.; Naik, Halehatty S. Bhojya; Kumar, B. Vinay; Sudhamani, C. N.

    2011-01-01

    Aim: The main objective of this paper is to study the synthesis of functionalized iron oxide nanoparticle and its reactivity towards chromene synthesis Study design: Functionalized iron oxide nanoparticle study. Place and duration of study: Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta, between December 2009 and July 2010. Methodology: This paper describes synthesis of stable functionalized iron oxide nanoparticles ...

  10. Dealloying-based facile synthesis and highly catalytic properties of Au core/porous shell nanoparticles

    Science.gov (United States)

    Kim, Minho; Ko, Sung Min; Nam, Jwa-Min

    2016-06-01

    Porous nanostructures exhibit excellent catalytic properties due to high surface-to-volume ratio, good surface reactivity and various structural features, but controlling the distribution, size, shape and density of pores and structural features of these particles is highly challenging. Herein, we report a tunable dealloying-based facile synthetic strategy to form highly porous Au core/porous shell nanoparticles (CPS NPs) in high yield by selectively dissolving Ag atoms from Au/Au-Ag core/alloy shell NPs. The CPS NPs exhibit a very short induction time, high conversion rate constant, low activation energy and high turnover frequency due to their catalytically active porous shells containing networked thin ligaments, surface defects, ultra-high porosity and photothermal properties. The CPS NPs are more catalytic Au NPs than other reported Au nanostructures, and the strategy and results open avenues in porous nanostructures and nanocatalysts.Porous nanostructures exhibit excellent catalytic properties due to high surface-to-volume ratio, good surface reactivity and various structural features, but controlling the distribution, size, shape and density of pores and structural features of these particles is highly challenging. Herein, we report a tunable dealloying-based facile synthetic strategy to form highly porous Au core/porous shell nanoparticles (CPS NPs) in high yield by selectively dissolving Ag atoms from Au/Au-Ag core/alloy shell NPs. The CPS NPs exhibit a very short induction time, high conversion rate constant, low activation energy and high turnover frequency due to their catalytically active porous shells containing networked thin ligaments, surface defects, ultra-high porosity and photothermal properties. The CPS NPs are more catalytic Au NPs than other reported Au nanostructures, and the strategy and results open avenues in porous nanostructures and nanocatalysts. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01321j

  11. Incorporation of catalytic dehydrogenation into Fischer-Tropsch synthesis of liquid fuels from coal to minimize carbon dioxide emissions

    Energy Technology Data Exchange (ETDEWEB)

    Gerald P. Huffman [University of Kentucky, Lexington, KY (United States). Consortium for Fossil Fuel Science and Department of Chemical & Materials Engineering

    2011-08-15

    Synthesis gas (syngas) produced from coal typically has hydrogen to carbon monoxide ratios in the range of approximately 0.7-1.1, depending on the gasification method. In order to produce liquid fuels from this syngas by Fischer-Tropsch synthesis (FTS), these ratios must be raised to 2.0 or higher. If this is accomplished by the water-gas shift reaction, the traditional method, large emissions of carbon dioxide are produced. In this paper, it is shown that catalytic dehydrogenation (CDH) of the gaseous C1-C4 products of FT synthesis and recycling of the resulting hydrogen to the syngas feed-stream can increase the H{sub 2}/CO ratio to the desired values with little or no production of carbon dioxide. All carbon from the CDH reaction is in the form of a potentially valuable by-product, multi-walled carbon nanotubes (MWCNT). The amounts of hydrogen and MWCNT produced, carbon dioxide emissions avoided, and water saved are calculated for a 50,000 bbl/day FTS-CDH plant and it is demonstrated that the energy balance for the process is favorable. Methods of utilizing the large quantity of MWCNT produced are discussed. 50 refs., 6 figs., 3 tabs.

  12. Synthesis and catalytic properties of cobalt- and molybdenum-containing mesoporous MCM-41 molecular sieves

    OpenAIRE

    Ayyappan, S.; Ulagappan, N

    1996-01-01

    Mesoporous MCM-41 type silicas containing molybdenum and cobalt have been prepared with pore sizes in the range 30-38 Angstrom and 54-59 Angstrom. Catalytic properties of these materials have been examined with respect to the oxidation of cyclooctene and aniline.

  13. Synthesis of concave gold nanocuboids with high-index facets and their enhanced catalytic activity.

    Science.gov (United States)

    Li, Lidong; Peng, Yi; Yue, Yonghai; Hu, Ye; Liang, Xiu; Yin, Penggang; Guo, Lin

    2015-07-25

    Novel concave gold nanocuboids bounded by 24 high-index {611} facets are synthesized using the seed-mediated growth method via an overgrowth mechanism. The as-synthesized products demonstrated greatly enhanced catalytic activity for the electro-oxidation of glucose and the reduction of 4-nitrothiophenol (4-NTP) under a laser. PMID:26097908

  14. Synthesis and catalytic activity of histidine-based NHC ruthenium complexes

    OpenAIRE

    Monney, Angèle; Venkatachalam, Galmari; Albrecht, Martin

    2011-01-01

    Main-chain C,N-protected histidine has been successfully alkylated at both side-chain nitrogens. The corresponding histidinium salt was metallated with ruthenium(II) by a transmetalation procedure, thus providing histidine-derived NHC ruthenium complexes. These bio-inspired comsxsxsplexes show appreciable activity in the catalytic transfer hydrogenation of ketones. peer-reviewed

  15. Synthesis, Crystal Structure and Catalytic Behavior of 1-Ethyl-3-benyl-imidazolyl Tetranuclear N-Heterocyclic Carbene Silver Bromide

    Institute of Scientific and Technical Information of China (English)

    WANG Zhi-Guo; SU Zhi-Xian; BIAN Qing-Quan; LIU Si-Man; LIU Ting

    2012-01-01

    The title complex [Ag(carbene)2]2[Ag2Br4] has been synthesized by the reaction of Ag2O with 1-ethyl-3-benyl-imidazolium bromide in DMSO at room temperature, and characterized by elemental analysis, 1H NMR and single-crystal X-ray diffraction analysis. It crystallizes in triclinic, space group P with a = 10.1597(10), b =11.0646(11), c = 13.0245(14) , α = 102.230(2), β = 90.606, γ = 113.9250(10)o, V = 1300.3(2) 3, Mr = 748.06, Z = 2, Dc = 1.911 g/cm3, μ(MoKα) = 4.60 mm-1 and F(000) = 728. The structure was refined to R = 0.0316 and wR = 0.0835 for 3744 observed reflections with I 〉 2σ(I). The title compound crystallizes as a centrosymmetric tetranuclear compound. One half of the molecule comprises the asymmetric unit of the structure. The Ag(1) atom is nearly linear or T-shaped when the Ag(1)-Ag(2) interaction is taken into consideration, which is bi-coordinated by two carbene carbon atoms. The Ag(2) atom adopts tetrahedral geometry. The catalytic behavior of the title complex has been investigated, and the results indicate it has a highly catalytic activation for L-lactide polymerization.

  16. Hydrothermal synthesis of an ortho-metallated Co(III) complex anchored by a carboxylate group with a selective oxidation catalytic property.

    Science.gov (United States)

    Zhang, Shi-Yuan; Shi, Wei; Ma, Jian-Gong; Zhang, Yu-Qi; Zhang, Zhen-Jie; Cheng, Peng

    2013-03-28

    An air-stable and water-tolerant ortho-metallated complex [Co(tfb)(bpy)(2)](NO(3))·3H(2)O was obtained via hydrothermal synthesis. The mechanism for the formation of Co-C bond was studied using both DFT calculations and experimental analysis. This highly stable complex exhibits good catalytic performance for the selective oxidation of cyclohexane. PMID:23348750

  17. Synthesis and Catalytic Hydrogen Transfer Reaction of Ruthenium(II) Complex

    Energy Technology Data Exchange (ETDEWEB)

    Son, Jung Ik; Kim, Aram; Noh, Hui Bog; Lee, Hyun Ju; Shim, Yoon Bo; Park, Kang Hyun [Pusan National University, Busan (Korea, Republic of)

    2012-01-15

    The ruthenium(II) complex [Ru(bpy){sub 2}-(PhenTPy)] was synthesized, and used for the transfer hydrogenation of ketones and the desired products were obtained in good yield. Based on the presented results, transition-metal complexes can be used as catalysts for a wide range of organic transformations. The relationship between the electro-reduction current density and temperature are being examined in this laboratory. Attempts to improve the catalytic activity and determine the transfer hydrogenation mechanism are currently in progress. The catalytic hydrogenation of a ketone is a basic and critical process for making many types of alcohols used as the final products and precursors in the pharmaceutical, agrochemical, flavor, fragrance, materials, and fine chemicals industries. The catalytic hydrogenation process developed by Noyori is a very attractive process. Formic acid and 2-propanol have been used extensively as hydrogenation sources. The advantage of using 2-propanol as a hydrogen source is that the only side product will be acetone, which can be removed easily during the workup process. Hydrogen transfer (HT) catalysis, which generates alcohols through the reduction of ketones, is an attractive protocol that is used widely. Ruthenium(II) complexes are the most useful catalysts for the hydrogen transfer (HT) of ketones. In this method, a highly active catalytic system employs a transition metal as a catalyst to synthesize alcohols, and is a replacement for the hydrogen-using hydrogenation process. The most active system is based on Ru, Rh and Ir, which includes a nitrogen ligand that facilitates the formation of a catalytically active hydride and phosphorus.

  18. Synthesis and Catalytic Hydrogen Transfer Reaction of Ruthenium(II) Complex

    International Nuclear Information System (INIS)

    The ruthenium(II) complex [Ru(bpy)2-(PhenTPy)] was synthesized, and used for the transfer hydrogenation of ketones and the desired products were obtained in good yield. Based on the presented results, transition-metal complexes can be used as catalysts for a wide range of organic transformations. The relationship between the electro-reduction current density and temperature are being examined in this laboratory. Attempts to improve the catalytic activity and determine the transfer hydrogenation mechanism are currently in progress. The catalytic hydrogenation of a ketone is a basic and critical process for making many types of alcohols used as the final products and precursors in the pharmaceutical, agrochemical, flavor, fragrance, materials, and fine chemicals industries. The catalytic hydrogenation process developed by Noyori is a very attractive process. Formic acid and 2-propanol have been used extensively as hydrogenation sources. The advantage of using 2-propanol as a hydrogen source is that the only side product will be acetone, which can be removed easily during the workup process. Hydrogen transfer (HT) catalysis, which generates alcohols through the reduction of ketones, is an attractive protocol that is used widely. Ruthenium(II) complexes are the most useful catalysts for the hydrogen transfer (HT) of ketones. In this method, a highly active catalytic system employs a transition metal as a catalyst to synthesize alcohols, and is a replacement for the hydrogen-using hydrogenation process. The most active system is based on Ru, Rh and Ir, which includes a nitrogen ligand that facilitates the formation of a catalytically active hydride and phosphorus

  19. L-Tartaric Acid as a New Chiral Auxiliary for Asymmetric Synthesis of Piperazinones, Morpholinones, Dihydroquinoxalinones and Dihydrobenzoxazinones

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yelim; Park, Kon Ji; Park, Yong Sun [Konkuk Univ., Seoul (Korea, Republic of)

    2012-11-15

    We have reported the dynamic resolution of α-bromo esters in nucleophilic substitution using L-tartaric acid derivatives as a new effective chiral auxiliary. In the substitutions with ethylenediamine and 2-aminoethanol nucleophiles, spontaneous cyclization can provide a convenient procedure for asymmetric syntheses of 3-substituted piperazin-2-ones and morpholin-2-ones. In addition, the substitutions with arylamine nucleophiles such as 1,2-diaminobenzene and 2-aminophenol can provide an efficient method for asymmetric syntheses of dihydroquinoxalinones and dihydrobenzoxazinones. The simple protocol with mild condition suggests further applications to asymmetric syntheses of various heterocyclic compounds.

  20. Environmentally benign synthesis of amides and ureas via catalytic dehydrogenation coupling of volatile alcohols and amines in a Pd-Ag membrane reactor

    KAUST Repository

    Chen, Tao

    2016-05-31

    In this study, we report the direct synthesis of amides and ureas via the catalytic dehydrogenation of volatile alcohols and amines using the Milstein catalyst in a Pd-Ag/ceramic membrane reactor. A series of amides and ureas, which could not be synthesized in an open system by catalytic dehydrogenation coupling, were obtained in moderate to high yields via catalytic dehydrogenation of volatile alcohols and amines. This process could be monitored by the hydrogen produced. Compared to the traditional method of condensation, this catalytic system avoids the stoichiometric pre-activation or in situ activation of reagents, and is a much cleaner process with high atom economy. This methodology, only possible by employing the Pd-Ag/ceramic membrane reactor, not only provides a new environmentally benign synthetic approach of amides and ureas, but is also a potential method for hydrogen storage.

  1. Poly (ethylene oxide)-block-poly (n-butyl acrylate)-blockpoly (acrylic acid) triblock terpolymers with highly asymmetric hydrophilic blocks: synthesis and aqueous solution properties

    OpenAIRE

    Petrov, P; Yoncheva, K. (Krassimira); Mokreva, P. (Pavlina); Konstantinov, S.; J M Irache; Müller, A.H.E. (Axel H.E.)

    2013-01-01

    The synthesis and aggregation behaviour in aqueous media of novel amphiphilic poly(ethylene oxide)- block-poly(n-butyl acrylate)-block-poly(acrylic acid) (PEO–PnBA–PAA) triblock terpolymers were studied. Terpolymers composed of two highly asymmetric hydrophilic PEO (113 monomer units) and PAA (10–17 units) blocks, and a longer soft hydrophobic PnBA block (163 or 223 units) were synthesized by atom transfer radical polymerisation (ATRP) of n-butyl acrylate and tert-butyl acrylate ...

  2. Enantioselective synthesis of aziridines using asymmetric transfer hydrogenation as a precursor for chiral derivatives used as bonding agent for rocket solid propellants

    Directory of Open Access Journals (Sweden)

    Aparecida M. Kawamoto

    2002-11-01

    Full Text Available A rapid, expedient and enantioselective method for the synthesis of beta-hydroxy amines and monosubstituted aziridines in up to 99% e.e., via asymmetric transfer hydrogenation of a-amino ketones and cyclisation through treatment with tosyl chloride and base, is described. (1R,2R-N-(para-toluenesulfonyl-1,2-ethylenediamine with formic acid has been utilised as a ligand for the Ruthenium (II catalysed enantioselective transfer hydrogenation of the ketones.The chiral 2-methyl aziridine, which is a potentially more efficient bonding agent for Rocket Solid Propellant has been successfully achieved.

  3. Abroma augusta Linn bark extract-mediated green synthesis of gold nanoparticles and its application in catalytic reduction

    Science.gov (United States)

    Das, Subhajit; Bag, Braja Gopal; Basu, Ranadhir

    2014-11-01

    The bark extract of Abroma augusta Linn is rich in medicinally important phytochemicals including antioxidants and polyphenols. First one step green synthesis of gold nanoparticles (AuNPs) has been described utilizing the bark extract of Abroma augusta L. and chloroauric acid under very mild reaction conditions. The phytochemicals present in the bark extract acted both as a reducing as well as a stabilizing agent, and no additional stabilizing and capping agents were needed. Detailed characterizations of the stabilized AuNPs were carried out by surface plasmon resonance spectroscopy, high resolution transmission electron microscopy, and X-ray diffraction studies. The catalytic activity of the freshly synthesized gold nanoparticles has been demonstrated for the sodium borohydride reduction of 4-nitrophenol to 4-aminophenol, and the kinetics of the reduction reaction have been studied spectrophotometrically.

  4. Synthesis and Catalytic Performance of Ni/SiO2 for Hydrogenation of 2-Methylfuran to 2-Methyltetrahydrofuran

    Directory of Open Access Journals (Sweden)

    Fu Ding

    2015-01-01

    Full Text Available A series of Ni/SiO2 catalysts with different Ni content were prepared by sol-gel method for application in the synthesis of 2-methyltetrahydrofuran (2-MTHF by hydrogenation of 2-methylfuran (2-MF. The catalyst structure was investigated by X-ray diffraction (XRD, transmission electron microscopy (TEM, X-ray photoelectron spectroscopy (XPS, and temperature programmed reduction (TPR. It is found that structures and catalytic performance of the catalysts were highly affected by the Ni content. The catalyst with a 25% Ni content had an appropriate size of the Ni species and larger BET surface area and produced a higher 2-MF conversion with enhanced selectivity in 2-MTHF.

  5. A facile route to controlled synthesis of Co3O4 nanoparticles and their environmental catalytic properties

    International Nuclear Information System (INIS)

    Using ammonia and Co(CH3COO)2·4H2O as starting materials, a facile and surfactant-free route to controlled synthesis of Co3O4 nanoparticles was proposed. Co3O4 nanoparticles with average sizes of 3.5, 6, 11, 19 and 70 nm were obtained through adjusting the ethanol amount in the solvent (the ratio of ethanol to water) or the concentration of raw materials. In this process, the presence of enough O2 was crucial for the formation of pure Co3O4 phase. The environmental catalytic properties of as-obtained Co3O4 nanoparticles were investigated. The results indicated their remarkable catalysis for ozonation degradation of phenol, which denoted a promising application as catalyst in waste-water treatment

  6. Catalytic properties of crystalline titanium silicalites. 1. Synthesis and characterization of titanium-rich zeolites with MFI structure

    Energy Technology Data Exchange (ETDEWEB)

    Thangaraj, A.; Kumar, R.; Mirajkar, S.P.; Ratnasamy, P. (National Chemical Lab., Pune (India))

    1991-07-01

    Crystalline titanium silicalites with the MFI structure and high titanium content (Si/Ti{double bond}10) have been prepared using improved synthesis procedures. The monoclinic lattice symmetry of silicalite-1 changes to orthorhombic on introduction of titanium. The titanium silicalites retain their orthorhombic symmetry even after calcination in air. On progressive incorporation of titanium, (1) the unit cell dimensions and volume (from XRD) increase linearly, (2) the crystal size decreases progressively, (3) the intensity of the framework IR band at 960 cm{sup {minus}1} increases, (4) a band around 47,000 c{sup {minus}1} appears in the electronic spectra due to charge transfer transitions involving Ti(IV) sites, (5) the hydrophilicity of the zeolite (from water adsorptions measurements) increases, (6) the adsorption capacity for cyclohexane increases, (7) the {sup 29}Si MAS NMR lines exhibit progressive broadening, and finally (8) the catalytic activity in the hydroxylation of phenol to catechol and hydroquinone also increases markedly. Based on these observations, it is concluded that a significant fraction of titanium in these samples is situated in framework positions. The catalytic properties of these well-defined titanium-modified zeolites will be described in more detail in the subsequent parts of this series.

  7. Mesoporous titania-alumina mixed oxide: A preliminary study on synthesis and application in selective catalytic reduction of NOx

    International Nuclear Information System (INIS)

    Titania-alumina mixed oxide was synthesized hydrothermally using tetrapropylammonium hydroxide (TPAOH) as the template. The dried, calcined and palladium loaded samples were characterized for particle morphology, weight loss, nitrogen adsorption/desorption at liquid nitrogen temperature, texture and metal dispersion. The Pd loaded material was tested for NO reduction in a fixed bed catalytic reactor using a simulated gas mixture closely resembling lean burn engine exhaust. Scanning electron microscopy of the dried and calcined samples revealed a well developed tubular fibrous network of titania-alumina. Thermogravimetry (TG) of the dried sample indicated about 16% weight loss due to decomposition of an oxy-hydroxide structure of the material, mostly boehmite, which was confirmed by X-ray diffraction (XRD) measurements. The boehmite phase changed to poorly crystalline γ-alumina upon calcination where as titania remained as anatase. BET specific surface area, adsorption-desorption isotherms and BJH pore size distributions indicated formation of a mesoporous structure. The surface area of the dried material increased when calcined at 600 deg. C but the pore size distribution patterns for the dried, calcined and palladium dispersed materials remained unchanged. These observations along with TG and XRD analyses suggest that a thermo-resistant, mesoporous, high surface area, crystalline titania-alumina framework can be prepared using the hydrothermal synthesis route. A peak NOx conversion of 75% with the palladium dispersed catalyst indicates high catalytic activity, possibly due to high dispersion of Pd confirmed by CO chemisorption studies

  8. Hierarchical ZnO microspheres built by sheet-like network: Large-scale synthesis and structurally enhanced catalytic performances

    International Nuclear Information System (INIS)

    Highlights: ► Hierarchical ZnO microspheres were prepared through a facile precursor procedure in the absence of self-assembled templates, organic additives, or matrices. ► The building blocks of microspheres, sheet-like ZnO networks, are porous mesocrystal terminated with (0 1 −1 0) crystal planes. ► The hierarchical ZnO microsphere catalyst exhibits structure-induced enhancement of catalytic performance and a strong durability. - Abstract: Large-scale novel hierarchical ZnO microspheres were fabricated by a facile precursor procedure in the absence of self-assembled templates, organic additives, or matrices. A field emission scanning electron microscopy (FESEM) image reveals that the ZnO microspheres with diameter of 5–18 μm are built by sheet-like ZnO networks with average thickness of 40 nm and length of several microns. High resolution transmission electron microscopy (HRTEM) image indicates that the building blocks, sheet-like ZnO networks, are porous mesocrystal terminated with {0 1 −1 0} crystal planes. A potential application of the ZnO microspheres as a catalyst in the synthesis of 5-substituted 1H-tetrazoles was investigated. It was found that the hierarchical ZnO microsphere catalyst exhibits structure-induced enhancement of catalytic performance and a strong durability.

  9. The concise synthesis of chiral tfb ligands and their application to the rhodium-catalyzed asymmetric arylation of aldehydes

    OpenAIRE

    Nishimura, Takahiro; Kumamoto, Hana; Nagaosa, Makoto; Hayashi, Tamio

    2009-01-01

    New C2-symmetric tetrafluorobenzobarrelene ligands were prepared and applied successfully to the rhodium-catalyzed asymmetric addition of arylboronic acids to aromatic aldehydes giving chiral diarylmethanols in high yield with high enantioselectivity.

  10. Synthesis of Silver Nanoparticles Using Triticum aestivum and Its Effect on Peroxide Catalytic Activity and Toxicology

    OpenAIRE

    Sharada Dagade; Pooja Chavan; Shobha Waghmode; Vidya Kalyankar

    2013-01-01

    The synthesis of stable silver nanoparticles using bioreduction method was investigated. Biological synthesis of silver nanoparticles using Triticum aestivum (khapali ghahu) extract was investigated. The effect of a specific variety of plants and how it affects the growth of silver nanoparticles was investigated in our work and it was polydispersed. UV-visible spectroscopy was used to monitor the formation of silver nanoparticles within 15 minutes. The peaks in XRD pattern are in good agreeme...

  11. Catalytic Enantioselective 1,3-Dipolar Cycloadditions of Azomethine Ylides for Biology-Oriented Synthesis

    OpenAIRE

    Narayan, Rishikesh; Potowski, Marco; Jia, Zhi-Jun; Antonchick, Andrey P.; Waldmann, Herbert

    2014-01-01

    Conspectus Cycloaddition reactions are among the most powerful methods for the synthesis of complex compounds. In particular, the development and application of the 1,3-dipolar cycloaddition, an important member of this reaction class, has grown immensely due to its powerful ability to efficiently build various five-membered heterocycles. Azomethine ylides are commonly used as dipoles for the synthesis of the pyrrolidine scaffold, which is an important motif in natural products, pharmaceutica...

  12. Synthesis and Application of Chiral Spiro Cp Ligands in Rhodium-Catalyzed Asymmetric Oxidative Coupling of Biaryl Compounds with Alkenes.

    Science.gov (United States)

    Zheng, Jun; Cui, Wen-Jun; Zheng, Chao; You, Shu-Li

    2016-04-27

    The vastly increasing application of chiral Cp ligands in asymmetric catalysis results in growing demand for novel chiral Cp ligands. Herein, we report a new class of chiral Cp ligands based on 1,1'-spirobiindane, a privileged scaffold for chiral ligands and catalysts. The corresponding Rh complexes are shown to be excellent catalysts in asymmetric oxidative coupling reactions, providing axially chiral biaryls in 19-97% yields with up to 98:2 er. PMID:27070297

  13. Catalytic Chemical Vapor Deposition Synthesis of Carbon Aerogels of High-Surface Area and Porosity

    Directory of Open Access Journals (Sweden)

    Armando Peña

    2012-01-01

    Full Text Available In this work carbon aerogels were synthesized by catalytic chemical vapor deposition method (CCVD. Ferrocene were employed as a source both of catalytic material (Fe and of carbon. Gaseous hydrogen and argon were used as reductant and carrier gas, respectively. The products of reaction were collected over alumina. The morphology and textural properties of the soot produced in the reaction chamber were investigated using Scanning Electron Microscopy, High-Resolution Transmission Electron Microscopy, X-ray photoelectron spectroscopy, and N2 physisorption (BET and BHJ methods. After the evaluation of the porous structure of the synthesized products, 780 ± 20 m2/g of SBET and 0.55 ± 0.02 cm3/g of VBJH were found. The presence of iron carbide and the partial oxidation of carbon nanostructures were revealed by XPS.

  14. Facile Synthesis of Au Nanoparticles Embedded in an Ultrathin Hollow Graphene Nanoshell with Robust Catalytic Performance.

    Science.gov (United States)

    Liu, Hongyang; Wang, Jia; Feng, Zhenbao; Lin, Yangming; Zhang, Liyun; Su, Dangsheng

    2015-10-01

    Au nanoparticles (NPs) uniformly embedded into an ultrathin hollow graphene nanoshell (Au@HGN) are synthesized using a facile template-based procedure. The obtained Au@HGN catalyst exhibits robust and stable catalytic performance in the reduction of 4-nitrophenol to 4-aminophenol, compared with that of traditional Au/TiO2 and previously reported Au- and Ag-based catalysts. PMID:26280245

  15. Synthesis of chitosan supported palladium nanoparticles and its catalytic activity towards 2-nitrophenol reduction

    Science.gov (United States)

    Dhanavel, S.; Nivethaa, E. A. K.; Esther, G.; Narayanan, V.; Stephen, A.

    2016-05-01

    Chitosan supported Palladium nanoparticles were synthesized by a simple cost effective chemical reduction method using NaBH4. The prepared nanocomposite was characterized by X-Ray diffraction analysis, FESEM and Energy dispersive spectroscopy analysis of X-rays (EDAX). The catalytic performance of the nanocomposite was evaluated on the reduction of 2-Nitrophenol to the 2-Amino phenol with rate constant 1.08 × 10-3 S-1 by NaBH4 using Spectrophotometer.

  16. Synthesis and catalytic activities of porphyrin-based PCP pincer complexes.

    OpenAIRE

    Fujimoto, Keisuke; Yoneda, Tomoki; Yorimitsu, Hideki; Osuka, Atsuhiro

    2013-01-01

    2,18-Bis(diphenylphosphino)porphyrins undergo peripheral cyclometalation with group 10 transition-metal salts to afford the corresponding porphyrin-based PCP pincer complexes. The porphyrinic plane and the PCP-pincer unit are apparently coplanar, with small strain. The catalytic activities of the porphyrin-based pincer complexes at the periphery were investigated in the allylation of benzaldehyde with allylstannane and in the 1,4-reduction of chalcone to discover the electronic interplay betw...

  17. Green synthesis and synergistic catalytic effect ofAg/reduced graphene oxide nanocomposite

    Science.gov (United States)

    Hsu, Kai-Chih; Chen, Dong-Hwang

    2014-09-01

    A nanocomposite of silver nanoparticles and reduced graphene oxide (Ag/rGO) has been developed as a catalyst for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with sodium borohydride, owing to the larger specific surface area and synergistic effect of rGO. A facile and rapid microwave-assisted green route has been used for the uniform deposition of Ag nanoparticles and the reduction of graphene oxide simultaneously with l-arginine as the reducing agent. The resulting Ag/rGO nanocomposite contained about 51 wt% of Ag, and the Ag nanoparticles deposited on the surface of rGO had a mean diameter of 8.6 ± 3.5 nm. Also, the Ag/rGO nanocomposite exhibited excellent catalytic activity and stability toward the reduction of 4-NP to 4-AP with sodium borohydride. The reduction reaction obeyed the pseudo-first-order kinetics. The rate constants increased not only with the increase of temperature and catalyst amount but also with the increase of initial 4-NP concentration, revealing that the support rGO could enhance the catalytic activity via a synergistic effect. A mechanism for the catalytic reduction of 4-NP with NaBH4 by Ag/rGO nanocomposite via both the liquid-phase and solid-phase routes has been suggested.

  18. Supercritical CO{sub 2} mediated synthesis and catalytic activity of graphene/Pd nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Lulu [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of); Nguyen, Van Hoa [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of); Department of Chemistry, Nha Trang University, 2 Nguyen Dinh Chieu, Nha Trang (Viet Nam); Shim, Jae-Jin, E-mail: jjshim@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeoungbuk 712-749 (Korea, Republic of)

    2015-11-15

    Highlights: • RGO/Pd composite was efficiently prepared via a facile method in supercritical CO{sub 2}. • Graphene sheets were coated uniformly with Pd nanoparticles with a size of ∼8 nm. • Composites exhibited excellent catalytic activity in the Suzuki reaction even after 10 cycles. - Abstract: Graphene sheets were decorated with palladium nanoparticles using a facile and efficient method in supercritical CO{sub 2}. The nanoparticles were formed on the graphene sheets by the simple hydrogen reduction of palladium(II) hexafluoroacetylacetonate precursor in supercritical CO{sub 2}. The product was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Highly dispersed nanoparticles with various sizes and shapes adhered well to the graphene sheets. The composites showed high catalytic activities for the Suzuki reaction under aqueous and aerobic conditions within 5 min. The effects of the different Pd precursor loadings on the catalytic activities of the composites were also examined.

  19. Ordered hexagonal mesoporous aluminosilicates with low Si/Al ratio: synthesis, characterization, and catalytic application.

    Science.gov (United States)

    Liu, Aifeng; Che, Hongwei; Liu, Chuanzhi; Fu, Quanrong; Jiang, Ruijiao; Wang, Cheng; Wang, Liang

    2014-06-01

    Ordered hexagonal mesoporous aluminosilicates with lower Si/Al ratio below 5 have been successfully synthesized via the co-assembly of preformed aluminosilicate precursors with Gemini surfactant [C12H25N+(CH3)2(CH2)6N+(CH3)2C12H25] x 2Br(-) as the template. Powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, N2 adsorption-desorption isotherm measurements, Fourier transform infrared spectroscopy, 27Al nuclear magnetic resonance, thermogravimetric analysis, and temperature-programmed desorption of cyclohexylamine are employed to characterize the resulting samples. The phenol alkylation reaction is carried out to evaluate their catalytic performances. These studies indicate that the sample with a low Si/Al ratio of 3 still retains a highly ordered hexagonal mesoporous structure. And it also possesses the highest acidity of 0.96 mmol among the samples with lower Si/Al ratios below 5 due to its higher specific surface area together with more content of tetrahedrally coordinated Al in the framework. The catalytic tests confirm that the acidity of the samples plays a key role in determining their catalytic performances. PMID:24738433

  20. Reduced graphene oxide supported platinum nanocubes composites: one-pot hydrothermal synthesis and enhanced catalytic activity

    International Nuclear Information System (INIS)

    Reduced graphene oxide (rGO) supported platinum nanocubes (Pt-NCs) composites (Pt-NCs/rGO) were synthesized successfully by a water-based co-chemical reduction method, in which polyallylamine hydrochloride acted as a multi-functional molecule for the functionalization of graphene oxide, anchorage of PtII precursor, and control of Pt crystal facets. The morphology, structure, composition, and catalytic property of Pt-NCs/rGO composites were characterized in detail by various spectroscopic techniques. Transmission electron microscopy images showed well-defined Pt-NCs with an average size of 9 nm uniformly distributed on the rGO surface. The as-prepared Pt-NCs/rGO composites had excellent colloidal stability in the aqueous solution, and exhibited superior catalytic activity towards the hydrogenation reduction of nitro groups compared to commercial Pt black. The improved catalytic activity originated from the abundant exposed Pt{100} facets of Pt-NCs, excellent dispersion of Pt-NCs on the rGO surface, and synergistic effect between Pt-NCs and rGO. (paper)

  1. Multicatalyst system in asymmetric catalysis

    CERN Document Server

    Zhou, Jian

    2014-01-01

    This book introduces multi-catalyst systems by describing their mechanism and advantages in asymmetric catalysis.  Helps organic chemists perform more efficient catalysis with step-by-step methods  Overviews new concepts and progress for greener and economic catalytic reactions  Covers topics of interest in asymmetric catalysis including bifunctional catalysis, cooperative catalysis, multimetallic catalysis, and novel tandem reactions   Has applications for pharmaceuticals, agrochemicals, materials, and flavour and fragrance

  2. Extracellular synthesis of mycogenic silver nanoparticles by Cylindrocladium floridanum and its homogeneous catalytic degradation of 4-nitrophenol

    Science.gov (United States)

    Narayanan, Kannan Badri; Park, Hyun Ho; Sakthivel, Natarajan

    2013-12-01

    Green synthesis of extracellular mycogenic silver nanoparticles using the fungus, Cylindrocladium floridanum is reported. The synthesized mycogenic silver nanoparticles were characterized using UV-Vis absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. The nanoparticles exhibit fcc structure with Bragg's reflections of (1 1 1), (2 0 0), (2 2 0) and (3 1 1) was evidenced by XRD pattern, high-resolution TEM lattice fringes and circular rings in selected-area electron diffraction (SAED) pattern. The morphology of nanoparticles was roughly spherical in shape with an average size of ca. 25 nm. From FTIR spectrum, it was found that the biomolecules with amide I and II band were involved in the stabilization of nanoparticles. These mycogenic silver nanoparticles exhibited the homogeneous catalytic potential in the reduction of pollutant, 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride, which followed a pseudo-first-order kinetic model. Thus, the synthesis of metal nanoparticles using sustainable microbial approach opens up possibilities in the usage of mycogenic metal nanoparticles as catalysts in various chemical reactions.

  3. Dextrin-mediated synthesis of Ag NPs for colorimetric assays of Cu(2+) ion and Au NPs for catalytic activity.

    Science.gov (United States)

    Bankura, Kalipada; Rana, Dipak; Mollick, Md Masud Rahaman; Pattanayak, Sutanuka; Bhowmick, Biplab; Saha, Nayan Ranjan; Roy, Indranil; Midya, Tarapada; Barman, Gadadhar; Chattopadhyay, Dipankar

    2015-09-01

    A facile one-pot approach for rapid synthesis of silver and gold nanoparticles (Ag NPs and Au NPs) with narrow size distribution and good stability was described by reducing silver nitrate and chloroauric acid with polysaccharide dextrin. Here, dextrin was used as both a reducing and stabilizing agent for synthesis of NPs. The as-synthesized Ag NPs and Au NPs were characterized by UV-visible absorption spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The Ag NPs and Au NPs exhibited an absorption maxima at 404 and 547 nm respectively. TEM images showed NPs in the range of 8-28 nm. The crystallinity of the NPs was measured by XRD analysis. Furthermore, the as-prepared Ag NPs revealed colorimetric sensor property for detection of Cu(2+) ions based on changes in absorbance resulting from metal ion-induced aggregation of NPs or direct deposition of metal ions onto NPs. The as-prepared Au NPs exhibited a notable catalytic activity toward the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4. PMID:26143120

  4. Synthesis,characterization and catalytic properties of mesoporous MCM-48 containing zeolite secondary building units

    Institute of Scientific and Technical Information of China (English)

    LI Qiang; DOU Tao; ZHANG Ying; LI Yuping; WANG Shan; SUN Famin

    2007-01-01

    Mesoporous aluminosilicate MCM-48 containing zeolite secondary building units in the pore wall has been synthesized in alkaline media with a two-step procedure.The aluminosilicate precursors comprising zeolite secondary building units were first synthesized by carefully controlling reaction conditions and then were assembled using cotemplates of geminisurfactant [C18H37N(CH3)2(CH2)3-N(CH3)2C18H37]2+ (18-3-18) and triethanolamine (TEA).X-ray Diffraction (XRD) patterns of the as-made samples indicated that highly ordered mesostmctured MCM-48 was formed.Transmission Electron Microscopy (TEM) images further verified the formation of MCM-48 with uniform cubic pore channel system having the pore opening diameter of about 25 A.Compared with the conventionally synthesized MCM-48,the as-synthesized MCM-48 sample showed an adsorption band at 520-600 cm-1 in its FT-IR spectrum,which was assigned to five-membered ring vibration from zeolite structure.This suggested the presence of zeolite building units in the pore wall.N2 adsorption data showed that the material had a much higher specific surface area (1 200 m2/g)than the conventional MCM-48(1 100 m2/g).Finally,the catalytic performance of the as-made MCM-48 was evaluated by hydrogenation dealkylation reaction of heavy aromatic hydrocarbons.Catalytic results showed that the as-made MCM-48 catalyst exhibited higher conversion than the conventional MCM-48 catalyst.The as-made mesostructured MCM-48 may have a potential catalytic application in the conversion of bulky molecules.

  5. The Enhanced Catalytic Activities of Asymmetric Au-Ni Nanoparticle Decorated Halloysite-Based Nanocomposite for the Degradation of Organic Dyes

    Science.gov (United States)

    Jia, Lei; Zhou, Tao; Xu, Jun; Li, Xiaohui; Dong, Kun; Huang, Jiancui; Xu, Zhouqing

    2016-02-01

    Janus particles (JPs) are unique among the nano-/microobjects because they provide asymmetry and can thus impart drastically different chemical or physical properties. In this work, we have fabricated the magnetic halloysite nanotube (HNT)-based HNTs@Fe3O4 nanocomposite (NCs) and then anchored the Janus Au-Ni or isotropic Au nanoparticles (NPs) to the surface of external wall of sulfydryl modified magnetic nanotubes. The characterization by physical methods authenticates the successful fabrication of two different magnetic HNTs@Fe3O4@Au and HNTs@Fe3O4@Au-Ni NCs. The catalytic activity and recyclability of the two NCs have been evaluated considering the degradation of Congo red (CR) and 4-nitrophenol (4-NP) using sodium borohydride as a model reaction. The results reveal that the symmetric Au NPs participated NCs display low activity in the degradation of the above organic dyes. However, a detailed kinetic study demonstrates that the employ of bimetallic Janus Au-Ni NPs in the NCs indicates enhanced catalytic activity, owing to the structurally specific nature. Furthermore, the magnetic functional NCs reported here can be used as recyclable catalyst which can be recovered simply by magnet.

  6. The Enhanced Catalytic Activities of Asymmetric Au-Ni Nanoparticle Decorated Halloysite-Based Nanocomposite for the Degradation of Organic Dyes.

    Science.gov (United States)

    Jia, Lei; Zhou, Tao; Xu, Jun; Li, Xiaohui; Dong, Kun; Huang, Jiancui; Xu, Zhouqing

    2016-12-01

    Janus particles (JPs) are unique among the nano-/microobjects because they provide asymmetry and can thus impart drastically different chemical or physical properties. In this work, we have fabricated the magnetic halloysite nanotube (HNT)-based HNTs@Fe3O4 nanocomposite (NCs) and then anchored the Janus Au-Ni or isotropic Au nanoparticles (NPs) to the surface of external wall of sulfydryl modified magnetic nanotubes. The characterization by physical methods authenticates the successful fabrication of two different magnetic HNTs@Fe3O4@Au and HNTs@Fe3O4@Au-Ni NCs. The catalytic activity and recyclability of the two NCs have been evaluated considering the degradation of Congo red (CR) and 4-nitrophenol (4-NP) using sodium borohydride as a model reaction. The results reveal that the symmetric Au NPs participated NCs display low activity in the degradation of the above organic dyes. However, a detailed kinetic study demonstrates that the employ of bimetallic Janus Au-Ni NPs in the NCs indicates enhanced catalytic activity, owing to the structurally specific nature. Furthermore, the magnetic functional NCs reported here can be used as recyclable catalyst which can be recovered simply by magnet. PMID:26852228

  7. Synthesis of mesoporous silica hollow nanospheres with multiple gold cores and catalytic activity.

    Science.gov (United States)

    Chen, Junchen; Xue, Zhaoteng; Feng, Shanshan; Tu, Bo; Zhao, Dongyuan

    2014-09-01

    The core-shell Au@resorcinol-formaldehyde (RF) nanospheres with multiple cores have been successfully synthesized by a modified Stöber method. After coating mesoporous silica and the calcination, the Au@meso-SiO2 hollow nanospheres with multiple gold cores can be obtained, which have a high surface area (∼537 m(2)/g) and uniform pore size (∼2.5 nm). The Au@meso-SiO2 hollow nanospheres can be used as a catalyst for the reduction of 4-nitrophenol by NaBH4 into 4-aminophenol, and exhibit excellent catalytic performance. PMID:24935190

  8. Synthesis and Catalytic Performance of Graphene Modified CuO-ZnO- for Hydrogenation to Methanol

    OpenAIRE

    Zheng-juan Liu; Xing-jiang Tang; Shan Xu; Xiao-lai Wang

    2014-01-01

    CuO-ZnO-Al2O3 and graphene nanosheet (GNS) were synthesized by coprecipitation route and reduction of exfoliated graphite oxides method, respectively. GNS modified CuO-ZnO-Al2O3 nanocomposites were synthesized by high energy ball milling method. The structure, morphology, and character of the synthesized materials were studied by BET, XRD, TEM, and H2-TPR. It was found that by high energy ball milling method the CuO-ZnO-Al2O3 nanoparticles were uniformly dispersed on GNS surfaces. The catalyt...

  9. Switching the enantioselectivity in catalytic [4 + 1] cycloadditions by changing the metal center: principles of inverting the stereochemical preference of an asymmetric catalysis revealed by DFT calculations.

    Science.gov (United States)

    Mazumder, Shivnath; Crandell, Douglas W; Lord, Richard L; Baik, Mu-Hyun

    2014-07-01

    The mechanisms of the asymmetric [4 + 1] carbocyclization of vinylallenes with carbon monoxide catalyzed by Pt(0) and Rh(I) carrying the chiral support ligand (R,R)-Me-DuPHOS (Me-DuPHOS = 1,2-bis(2,5-dimethylphosphorano)benzene) were studied using density functional theoretical models. Previously, it was observed that the (R)-stereoisomer of the 5-substituted 2-alkylidene-3-cyclopentenone products was obtained with Pt(0), but the (S)-enantiomer was formed when Rh(I) metal was used to promote the reaction. Our calculations suggest that the rate-determining step in both cases consists of a C-C coupling between the vinyl end of the vinylallene substrate and carbon monoxide that is accompanied by charge transfer from the metal center to the organic substrate. The reason that the two metals give different enantiomer products lies in the very different geometries of the metal centers in the transition state. The platinum center adopts a square-planar geometry throughout the C-C coupling reaction, which forces the carbonyl to migrate from the metastable, pseudoaxial position into the equatorial plane. During this migration, the carbonyl encounters the spatial constraints caused by the asymmetric DuPHOS ligand, while the vinylallene fragment is pushed away from the metal center. Thus, regardless of the steric demands of the organic substrate, the transition state that places the vinyl in a position that allows the CO to move into the sterically less crowded side of the molecule is preferred. Rh, on the other hand, maintains a square-pyramidal geometry throughout the reaction, keeping the CO ligand at the axial coordination site. The C-C coupling is accomplished by pulling the vinylallene substate closer to the metal and, as a result, the transition state that causes the least amount of steric clashes between the substrate and the DuPHOS ligand is favored, which affords the (S)-enantiomeric product. PMID:24842228

  10. Hydrophilic pyrazine-based phosphane ligands: synthesis and application in asymmetric hydride transfer and H2-hydrogenation of acetophenone

    NARCIS (Netherlands)

    Nikishkin, N.; Huskens, J.; Verboom, W.

    2013-01-01

    Pyrazine-based hydrophilic phosphanes are useful ligands for the ruthenium- and rhodium-catalyzed hydrogenations of acetophenone under hydride transfer and dihydrogen conditions. The effect of alcohol additives on the catalytic, enantioselective aqueous hydrogenation of acetophenone is examined with

  11. A Case of Remote Asymmetric Induction in the Peptide-Catalyzed Desymmetrization of a Bis(phenol)

    OpenAIRE

    Lewis, Chad A.; Gustafson, Jeffrey L.; Chiu, Anna; Balsells, Jaume; Pollard, David; Murry, Jerry; Reamer, Robert A.; Hansen, Karl B.; Miller, Scott J.

    2008-01-01

    We report a catalytic approach to the synthesis of a key intermediate on the synthetic route to a pharmaceutical drug candidate in single enantiomer form. In particular, we illustrate the discovery process employed to arrive at a powerful, peptide-based asymmetric acylation catalyst. The substrate this catalyst modifies represents a remarkable case of desymmetrization, wherein the enantiotopic groups are separated by nearly a full nanometer, and the distance between the reactive site and the ...

  12. MICROWAVE-ASSISTED SHAPE-CONTROLLED BULK SYNTHESIS OF NOBLE NANOCRYSTALS AND THEIR CATALYTIC PROPERTIES

    Science.gov (United States)

    Bulk and shape-controlled synthesis of gold (Au) nanostructures with various shapes such as prisms, cubes and hexagons is described that occurs via microwave-assisted spontaneous reduction of noble metal salts using an aqueous solution of α-D-glucose, sucrose and maltose. The exp...

  13. Catalytic Conia-ene and related reactions.

    Science.gov (United States)

    Hack, Daniel; Blümel, Marcus; Chauhan, Pankaj; Philipps, Arne R; Enders, Dieter

    2015-10-01

    Since its initial inception, the Conia-ene reaction, known as the intramolecular addition of enols to alkynes or alkenes, has experienced a tremendous development and appealing catalytic protocols have emerged. This review fathoms the underlying mechanistic principles rationalizing how substrate design, substrate activation, and the nature of the catalyst work hand in hand for the efficient synthesis of carbocycles and heterocycles at mild reaction conditions. Nowadays, Conia-ene reactions can be found as part of tandem reactions, and the road for asymmetric versions has already been paved. Based on their broad applicability, Conia-ene reactions have turned into a highly appreciated synthetic tool with impressive examples in natural product synthesis reported in recent years. PMID:26031492

  14. One-pot, one-step, catalytic synthesis of 2,5-diformylfuran from fructose

    Science.gov (United States)

    Tao, Furong; Cui, Yuezhi; Yang, Pengfei; Gong, Yinghua

    2014-07-01

    MIL-101, a chromium-based metal-organic framework, is known for its very large pore size, large surface area and good stability. However, application of this material in catalysis is still limited. In this paper, a simple and practical catalytic method for the preparation 2,5-diformylfuran (DFF) directly from fructose was investigated. 5% Pd-V(3: 2)@MIL-101 was evaluated as a potential and effective catalyst for the direct oxidation of fructose. The amount of the catalyst, reaction time and temperature had a large effect on the reaction. At the optimized reaction conditions, when the reaction was conducted at 140°C for 600 min, 1 atm oxygen pressure, the yield of DFF reached 34%, fructose conversion was up to 100%. In our system, the main side products were 5-formyl-2-furancarboxylic acid (FFCA) and 2,5-furandicarboxylic acid (FDCA), which are the products of deep oxidation of DFF. This simple and effective catalytic system may be valuable to facilitate energy-efficient conversion of fructose into biofuels and platform chemicals.

  15. Synthesis and utilization of catalytically cracked cashew nut shell liquid in a diesel engine

    KAUST Repository

    Vedharaj, S.

    2015-09-30

    In this study, CNSL (Cashew nut shell liquid), an economically viable feedstock among the other contemporary resources, has been considered as an appropriate source of alternate fuel. Herein, CNSL was extracted from cashew nut outer shell, a waste product, through a unique approach of steam treatment process followed by mechanical crushing technique. In contrast to the past studies that have attempted to use unprocessed CNSL directly as substitute for diesel, this study has resorted to use processed CNSL by cracking it using zeolite catalyst. Thus, both the extraction of CNSL from cashew nut outer shell and processing of it through catalytic cracking process to help synthesize CC-CNSL (catalytically cracked CNSL) are different, which underscores the significance of the current work. In wake of adopting such distinct methodologies with fuel characterization, the properties of CC-CNSL such as viscosity and calorific value were figured out to be improved. Subsequently, CC-CNSL20 (20% CC-CNSL and 80% diesel) was tested at different fuel injection pressure such as 200 bar, 235 bar, 270 bar and 300 bar so as to optimize its use in a single cylinder diesel engine. From the engine experimental study, CC-CNSL20 was found to evince better engine performance than diesel and the composite emissions of CO (carbon monoxide), HC (hydrocarbon), NOX (oxides of nitrogen) and smoke, computed based on ISO 8178 D2 standard test cycle, were found to be better than diesel and incompliance with the legislative norms for genset.

  16. Facile synthesis of pristine graphene-palladium nanocomposites with extraordinary catalytic activities using swollen liquid crystals.

    Science.gov (United States)

    Vats, T; Dutt, S; Kumar, R; Siril, P F

    2016-01-01

    Amazing conductivity, perfect honeycomb sp(2) arrangement and the high theoretical surface area make pristine graphene as one of the best materials suited for application as catalyst supports. Unfortunately, the low reactivity of the material makes the formation of nanocomposite with inorganic materials difficult. Here we report an easy approach to synthesize nanocomposites of pristine graphene with palladium (Pd-G) using swollen liquid crystals (SLCs) as a soft template. The SLC template gives the control to deposit very small Pd particles of uniform size on G as well as RGO. The synthesized nanocomposite (Pd-G) exhibited exceptionally better catalytic activity compared with Pd-RGO nanocomposite in the hydrogenation of nitrophenols and microwave assisted C-C coupling reactions. The catalytic activity of Pd-G nanocomposite during nitrophenol reduction reaction was sixteen times higher than Pd nanoparticles and more than double than Pd-RGO nanocomposite. The exceptionally high activity of pristine graphene supported catalysts in the organic reactions is explained on the basis of its better pi interacting property compared to partially reduced RGO. The Pd-G nanocomposite showed exceptional stability under the reaction conditions as it could be recycled upto a minimum of 15 cycles for the C-C coupling reactions without any loss in activity. PMID:27619321

  17. Synthesis and catalytic activity of metallo-organic complexes bearing 5-amino 2-ethylpyridine -2-carboximidate

    Indian Academy of Sciences (India)

    LUO MEI; XU JIA; ZHANG JING CHENG

    2016-06-01

    A series of copper, cobalt, nickel and manganese complexes were synthesized and characterized. Reaction of 5-amino-2-cyanopyridine with $ MCl_{2}$·x$H_{2}O$ (M: $Cu^{2+}$, $Co^{2+}$, $Ni^{2+}$, $Mn^{2+})$ in anhydrous ethanol resulted in the formation of four complexes $[NH_{2}EtPyCuCl_{2}(CH_{3}OH)].H_{2}O 1$, $[(NH_{2}EtPyHCl)_{3}Co]$$(Cl)_{3}.3H_{2}O 2$, $[(NH_{2}EtPy)_{2}$ 2$(H_{2}O)Ni]$ $(Cl_{2})$ 3, and $[(NH_{2}EtPy)_{2}$ 2$(H_{2}O)$ Mn]$(Cl_{2})$ 4 $[NH_{2} EtPy=5-amino-oethylpyridine-2-carboximidate], respectively. The structures of these compounds were determined by X-raydiffraction, NMR and IR spectroscopy, and elemental analysis. Each complex was then used as a catalyst in the Henry reaction, and its catalytic activity was determined by 1H NMR. Good catalytic effects were achieved (69–87%).

  18. Exergy analysis of thermochemical ethanol production via biomass gasification and catalytic synthesis

    International Nuclear Information System (INIS)

    In this paper an exergy analysis of thermochemical ethanol production from biomass is presented. This process combines a steam-blown indirect biomass gasification of woody feedstock, with a subsequent conversion of produced syngas into ethanol. The production process involves several process sections, including biomass drying and gasification, syngas cleaning, reforming, conditioning, and compression, ethanol synthesis, separation of synthesis products, and heat recovery. The process is simulated with a computer model using the flow-sheeting software Aspen Plus. The exergy analysis is performed for various ethanol catalysts, including Rh-based and MoS2-based (target) catalysts as well as for various gasification temperatures. The exergetic efficiency is 43.5% for Rh-based and 44.4% for MoS2-based (target) catalyst, when ethanol is considered as the only exergetic output. In case when by-products of ethanol synthesis are considered as the additional output the exergetic efficiency for Rh-based catalyst increases to 58.9% and 65.8% for MoS2-based (target) catalyst. The largest exergy losses occur in biomass gasifier and ethanol synthesis reactor. The exergetic efficiency for both ethanol catalysts increases with decreasing gasification temperature. -- Highlights: ► Thermochemical ethanol production from biomass via biomass gasification and ethanol synthesis has been modeled. ► Exergy analysis is performed for various process conditions and ethanol catalysts. ► Exergetic efficiencies biomass-to-ethanol range from 43.5% for Rh-based catalyst to 44.4% for MoS2-based catalyst. ► The largest exergy losses take place in the biomass gasification. ► Exergy losses in gasification can be reduced at lower gasification temperatures.

  19. Mimusops elengi bark extract mediated green synthesis of gold nanoparticles and study of its catalytic activity

    Science.gov (United States)

    Majumdar, Rakhi; Bag, Braja Gopal; Ghosh, Pooja

    2016-04-01

    The bark extract of Mimusops elengi is rich in different types of plant secondary metabolites such as flavonoids, tannins, triterpenoids and saponins. The present study shows the usefulness of the bark extract of Mimusops elengi for the green synthesis of gold nanoparticles in water at room temperature under very mild conditions. The synthesis of the gold nanoparticles was complete within a few minutes without any extra stabilizing or capping agents and the polyphenols present in the bark extract acted as both reducing as well as stabilizing agents. The synthesized colloidal gold nanoparticles were characterized by HRTEM, surface plasmon resonance spectroscopy and X-ray diffraction studies. The synthesized gold nanoparticles have been used as an efficient catalyst for the reduction of 3-nitrophenol and 4-nitrophenol to their corresponding aminophenols in water at room temperature.

  20. Atom-economic catalytic amide synthesis from amines and carboxylic acids activated in situ with acetylenes

    Science.gov (United States)

    Krause, Thilo; Baader, Sabrina; Erb, Benjamin; Gooßen, Lukas J.

    2016-01-01

    Amide bond-forming reactions are of tremendous significance in synthetic chemistry. Methodological research has, in the past, focused on efficiency and selectivity, and these have reached impressive levels. However, the unacceptable amounts of waste produced have led the ACS GCI Roundtable to label ‘amide bond formation avoiding poor atom economy' as the most pressing target for sustainable synthetic method development. In response to this acute demand, we herein disclose an efficient one-pot amide coupling protocol that is based on simple alkynes as coupling reagents: in the presence of a dichloro[(2,6,10-dodecatriene)-1,12-diyl]ruthenium catalyst, carboxylate salts of primary or secondary amines react with acetylene or ethoxyacetylene to vinyl ester intermediates, which undergo aminolysis to give the corresponding amides along only with volatile acetaldehyde or ethyl acetate, respectively. The new amide synthesis is broadly applicable to the synthesis of structurally diverse amides, including dipeptides. PMID:27282773

  1. Atom-economic catalytic amide synthesis from amines and carboxylic acids activated in situ with acetylenes.

    Science.gov (United States)

    Krause, Thilo; Baader, Sabrina; Erb, Benjamin; Gooßen, Lukas J

    2016-01-01

    Amide bond-forming reactions are of tremendous significance in synthetic chemistry. Methodological research has, in the past, focused on efficiency and selectivity, and these have reached impressive levels. However, the unacceptable amounts of waste produced have led the ACS GCI Roundtable to label 'amide bond formation avoiding poor atom economy' as the most pressing target for sustainable synthetic method development. In response to this acute demand, we herein disclose an efficient one-pot amide coupling protocol that is based on simple alkynes as coupling reagents: in the presence of a dichloro[(2,6,10-dodecatriene)-1,12-diyl]ruthenium catalyst, carboxylate salts of primary or secondary amines react with acetylene or ethoxyacetylene to vinyl ester intermediates, which undergo aminolysis to give the corresponding amides along only with volatile acetaldehyde or ethyl acetate, respectively. The new amide synthesis is broadly applicable to the synthesis of structurally diverse amides, including dipeptides. PMID:27282773

  2. Glucomannan-mediated facile synthesis of gold nanoparticles for catalytic reduction of 4-nitrophenol

    OpenAIRE

    Gao, Zhao; Su, Rongxin; Huang, Renliang; Qi, Wei; He, Zhimin

    2014-01-01

    A facile one-pot approach for synthesis of gold nanoparticles with narrow size distribution and good stability was presented by reducing chloroauric acid with a polysaccharide, konjac glucomannan (KGM) in alkaline solution, which is green and economically viable. Here, KGM served both as reducing agent and stabilizer. The effects of KGM on the formation and stabilization of as-synthesized gold nanoparticles were studied systematically by a combination of UV-visible (UV-vis) absorption spectro...

  3. Template-directed synthesis of nets based upon octahemioctahedral cages that encapsulate catalytically active metalloporphyrins

    KAUST Repository

    Zhang, ZhenJie

    2012-01-18

    meso-Tetra(N-methyl-4-pyridyl)porphine tetratosylate (TMPyP) templates the synthesis of six new metal-organic materials by the reaction of benzene-1,3,5-tricarboxylate with transition metals, five of which exhibit HKUST-1 or tbo topology (M = Fe, Mn, Co, Ni, Mg). The resulting materials, porph@MOMs, selectively encapsulate the corresponding metalloporphyrins in octahemioctahedral cages and can serve as size-selective heterogeneous catalysts for oxidation of olefins. © 2011 American Chemical Society.

  4. Synthesis of α-Amidoketones from Vinyl Esters via a Catalytic/Thermal Cascade Reaction.

    Science.gov (United States)

    Holthusen, Katharina; Leitner, Walter; Franciò, Giancarlo

    2016-06-01

    A straightforward, modular, and atom-efficient method is reported for the synthesis of α-amidoketones from vinyl esters via a cascade reaction including hydroformylation, condensation with a primary amine, and a rearrangement step giving water as the only byproduct. The reaction sequence can be performed in one pot or as a three-step procedure. The synthetic applicability is demonstrated by the preparation of different α-amidoketones in moderate to good yields. PMID:27196947

  5. Green Synthesis of Smart Metal/Polymer Nanocomposite Particles and Their Tuneable Catalytic Activities

    OpenAIRE

    Noel Peter Bengzon Tan; Cheng Hao Lee; Pei Li

    2016-01-01

    Herein we report a simple and green synthesis of smart Au and Ag@Au nanocomposite particles using poly(N-isopropylacrylamide)/polyethyleneimine (PNIPAm/PEI) core-shell microgels as dual reductant and templates in an aqueous system. The nanocomposite particles were synthesized through a spontaneous reduction of tetrachloroauric (III) acid to gold nanoparticles at room temperature, and in situ encapsulation and stabilization of the resultant gold nanoparticles (AuNPs) with amine-rich PEI shells...

  6. Ruthenium(II) hydrazone Schiff base complexes: Synthesis, spectral study and catalytic applications

    Science.gov (United States)

    Manikandan, R.; Viswanathamurthi, P.; Muthukumar, M.

    2011-12-01

    Ruthenium(II) hydrazone Schiff base complexes of the type [RuCl(CO)(B)(L)] (were B = PPh 3, AsPh 3 or Py; L = hydrazone Schiff base ligands) were synthesized from the reactions of hydrazone Schiff base ligand (obtained from isonicotinoylhydrazide and different hydroxy aldehydes) with [RuHCl(CO)(EPh 3) 2(B)] (where E = P or As; B = PPh 3, AsPh 3 or Py) in 1:1 molar ratio. All the new complexes have been characterized by analytical and spectral (FT-IR, electronic, 1H, 13C and 31P NMR) data. They have been tentatively assigned an octahedral structure. The synthesized complexes have exhibited catalytic activity for oxidation of benzyl alcohol to benzaldehyde and cyclohexanol to cyclohexanone in the presence of N-methyl morpholine N-oxide (NMO) as co-oxidant. They were also found to catalyze the transfer hydrogenation of aliphatic and aromatic ketones to alcohols in KOH/Isopropanol.

  7. Synthesis, Structure and Catalytic Activity Comparison of Tris- and Tetracoordinated Lanthanide Amides

    Institute of Scientific and Technical Information of China (English)

    XIE,Mei-Hua(谢美华); LIU,Xin-Yuan(刘心元); WANG,Shao-Wu(王绍武); LIU,Li(刘莉); WU,Yong-Yong(吴勇勇); YANG,Gao-Sheng(杨高升); ZHOU,Shuang-Liu(周双六); SHENG,En-Hong(盛恩宏); HUANG,Zi-Xiang(黄子祥)

    2004-01-01

    Tetracoordinated lanthanide amides [(Me3Si)2N]3Ln (μ-Cl)Li(THF)3 (Ln=La (1), Pr (2)) were synthesized by the reaction of anhydrous lanthanide(Ⅲ) chlorides LnCl3 (Ln=La, Pr) with 3 equiv. of lithium bis(trimethylsilyl)amide (Me3Si)2NLi in THF, followed by recrystallization from toluene. Sublimation of 1 and 2 afforded the triscoordinate lanthanide amides [(Me3Si)2N]3Ln (Ln =La, Pr). The crystal structure of 2 was determined by X-ray diffraction analysis. The catalytic activity studies show that the tetracoordinate amides can be used as single-component MMA (methyl methacrylate) polymerization catalysts, while the triscoordinate amides showed poor activity on MMA polymerization under the same conditions.

  8. Facile synthesis and catalytic properties of silver colloidal nanoparticles stabilized by SDBS

    Indian Academy of Sciences (India)

    Wen Wang; Yinmin Song; Quansheng Liu; Keli Yang

    2014-06-01

    A facile method was explored to prepare stable silver colloidal nanoparticles (AgCNPs) in water. Sodium dodecyl benzene sulfonate (SDBS) was used as the stabilizing agent, without addition of any co-surfactant. The reaction was rapid and the product prepared at different conditions was measured by transmission electron microscopy (TEM) and UV-Vis spectroscopy. The results showed that AgCNPs stabilized by SDBS was stable in water with narrow size distribution (1-5 nm). The amount of surfactant has great influence on the products. When the molar ratio of Ag+ to SDBS increased to 1 : 4, AgCNPs can be obtained with high dispersion (2-3 nm), which has high catalytic activity on reduction of 4-nitrobenzoic acid to 4-aminobenzoic acid.

  9. Room Temperature Synthesis and Catalytic Properties of Surfactant-Modified Ag Nanoparticles

    Directory of Open Access Journals (Sweden)

    Weihua Li

    2012-01-01

    Full Text Available Well-dispersed Ag nanoparticles with size of 20–30 nm were synthesized in water at room temperature with a self-made novel imidazoline Gemini surfactant quaternary ammonium salt of di (2-heptadecyl-1-formyl aminoethyl imidazoline hexanediamine. Transmission electron microscopy, X-ray powder diffraction, ultraviolet-visible absorption spectra, and Fourier transform infrared ray were used to characterize the Ag nanoparticles. Results showed that the micellized aggregation of imidazoline Gemini surfactant in water, the growth of Ag initial particles, and the interaction (adsorption and coordination between surfactant and Ag+/Ag nanoparticles took place simultaneously to form the well-dispersed Ag nanoparticles. Catalytic results show that the surface-modified Ag product was an active metal catalyst for methyl orange reduction reaction due to the effective adsorption between Ag nanoparticles and methyl orange molecules, which was of promising application in environmental protection.

  10. Nickel(II) complexes containing thiosemicarbazone and triphenylphosphine: Synthesis, spectroscopy, crystallography and catalytic activity

    Science.gov (United States)

    Priyarega, S.; Kalaivani, P.; Prabhakaran, R.; Hashimoto, T.; Endo, A.; Natarajan, K.

    2011-09-01

    Four new Ni(II) complexes of the general formula [Ni(PPh 3)(L)] (L = dibasic tridentate ligand derived from 4-diethylamino-salicylaldehyde and thiosemicarbazide or 4-N-substituted thiosemicarbazide) have been reported. The new complexes have been synthesized and characterized by analytical and spectroscopic (IR, electronic, 1H NMR and 31P NMR) techniques. Molecular structure of one of the complexes has been determined by X-ray crystallography. The complex, [Ni(PPh 3)(L4)] (H 2L4 = thiosemicarbazone prepared from 4-diethylamino-salicylaldehyde and 4-phenylthiosemicarbazide) crystallized in monoclinic space group with two molecules per unit cell and has the dimensions of a = 13.232(6) Å, b = 10.181(5) Å, c = 13.574(7) Å, α = 90°, β = 98.483(2)° and γ = 90°. Catalytic activity of the complexes has been explored for aryl-aryl coupling reaction.

  11. Green synthesis of gold nanoparticles using aspartame and their catalytic activity for p-nitrophenol reduction

    Science.gov (United States)

    Wu, Shufen; Yan, Songjing; Qi, Wei; Huang, Renliang; Cui, Jing; Su, Rongxin; He, Zhimin

    2015-05-01

    We demonstrated a facile and environmental-friendly approach to form gold nanoparticles through the reduction of HAuCl4 by aspartame. The single-crystalline structure was illustrated by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FTIR) results indicated that aspartame played a pivotal role in the reduction and stabilization of the gold crystals. The crystals were stabilized through the successive hydrogen-bonding network constructed between the water and aspartame molecules. Additionally, gold nanoparticles synthesized through aspartame were shown to have good catalytic activity for the reduction of p-nitrophenol to p-aminophenol in the presence of NaBH4.

  12. Synthesis, characterization, scale-up and catalytic behaviour of Co3O4 nanoparticles

    Indian Academy of Sciences (India)

    Manpreet Singh; N K Ralhan; Sukhdeep Singh

    2015-04-01

    Highly uniform cobalt oxide (Co3O4) nanoparticles were synthesized via thermal decomposition of cobalt hydroxy carbonates with particle size around 16 ± 1 nm. The process gives reproducible results in batches of 1–5 kg. The particles show good catalytic activity for the oxidation of oxalic acid and benzaldehyde under mild temperature conditions. The characterization was performed by X-ray diffractometry (XRD), Transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectrum and Nuclear magnetic resonance (NMR). The XRD measurements show cubic spinel phase and Debye–Scherrer relation was used to measure average particle size. The convenience of the production of catalyst can be exploited for its large-scale production and use in laboratories, R&Ds and industries.

  13. Solvothermal synthesis of Fe-MOF-74 and its catalytic properties in phenol hydroxylation.

    Science.gov (United States)

    Bhattacharjee, Samiran; Choi, Jung-Sik; Yang, Seung-Tae; Choi, Sang Beom; Kim, Jaheon; Ahn, Wha-Seung

    2010-01-01

    A Fe-containing metal-organic framework, Fe-MOF-74, was solvothermally synthesized using FeCl2.4H2O and 2,5-di-hydroxy-1,4-benzenedicarboxylic acid. Characterization was conducted by XRD, BET surface area measurement, FT-IR spectroscopy, TGA, and elemental analysis, which confirmed successful preparation of Fe-MOF-74 having an identical framework structure to that reported for MOF-74. Fe-MOF-74 was found to be an effective heterogeneous catalyst for the hydroxylation of phenol using H2O2 as an oxidant; 60% phenol conversion was achieved at 20 degrees C in water with 68 and 32% selectivity to catechol and hydroquinone, respectively. The effect of temperature, phenol/H2O2 mole ratio, catalyst quantity, and solvent on catalytic performance was discussed, and a reaction mechanism is proposed based upon the experimental results. PMID:20352823

  14. Post-synthesis, characterization and catalytic properties of fluorine-planted MWW-type titanosilicate.

    Science.gov (United States)

    Fang, Xiangqing; Wang, Qiang; Zheng, Anmin; Liu, Yueming; Lin, Longfei; Wu, Haihong; Deng, Feng; He, Mingyuan; Wu, Peng

    2013-04-14

    F-Ti-MWW was post-synthesized by implanting fluorine species into a Ti-MWW framework through an acid treatment process in the presence of ammonium fluoride. The effects of NH4F addition amount, acid treatment temperature and precursor Ti content were investigated on the incorporation of F species, the zeolite structure and the coordination sites of Ti. Fluorine-implanting improved the surface hydrophobicity of the zeolite and altered the electropositivity nearby the tetrahedral Ti sites through forming the SiO3/2F and SiO4/2F(-) units. The negative effect of SiO4/2F(-) units in F-Ti-MWW was eliminated selectively by convenient anion-exchange with various alkali chlorides. F-Ti-MWW containing the SiO3/2F units possessed better catalytic activity and reusability, and a longer catalyst lifetime than conventional Ti-MWW. PMID:23440001

  15. Pyrolysis-GCMS Analysis of Solid Organic Products from Catalytic Fischer-Tropsch Synthesis Experiments

    Science.gov (United States)

    Locke, Darren R.; Yazzie, Cyriah A.; Burton, Aaron S.; Niles, Paul B.; Johnson, Natasha M.

    2015-01-01

    Abiotic synthesis of complex organic compounds in the early solar nebula that formed our solar system is hypothesized to occur via a Fischer-Tropsch type (FTT) synthesis involving the reaction of hydrogen and carbon monoxide gases over metal and metal oxide catalysts. In general, at low temperatures (less than 200 C), FTT synthesis is expected to form abundant alkane compounds while at higher temperatures (greater than 200 C) it is expected to product lesser amounts of n-alkanes and greater amounts of alkene, alcohol, and polycyclic aromatic hydrocarbons (PAHs). Experiments utilizing a closed-gas circulation system to study the effects of FTT reaction temperature, catalysts, and number of experimental cycles on the resulting solid insoluble organic products are being performed in the laboratory at NASA Goddard Space Flight Center. These experiments aim to determine whether or not FTT reactions on grain surfaces in the protosolar nebula could be the source of the insoluble organic matter observed in meteorites. The resulting solid organic products are being analyzed at NASA Johnson Space Center by pyrolysis gas chromatography mass spectrometry (PY-GCMS). PY-GCMS yields the types and distribution of organic compounds released from the insoluble organic matter generated from the FTT reactions. Previously, exploratory work utilizing PY-GCMS to characterize the deposited organic materials from these reactions has been reported. Presented here are new organic analyses using magnetite catalyst to produce solid insoluble organic FTT products with varying reaction temperatures and number of experimental cycles.

  16. Synthesis of Novel Derivatives of (R)-Cysteine and Their Application in Asymmetric Reduction of Prochiral Ketones

    Institute of Scientific and Technical Information of China (English)

    WANG Hui; PEI Wei-wei; YE Wei-ping

    2005-01-01

    Novel chiral β-amino alcohols containing sulfide or sulfonyl groups were synthesized from (R)-cysteine. Their chiral induction in the asymmetric borane reduction of prochiral ketones was investigated. Optically active secondary alcohols with moderate or high e.e. values were obtained, and the causes of different enantioselectivities between these two sulfur-containing chiral β-amino alcohols were researched.

  17. Synthesis, characterization, and catalytic application of ordered mesoporous carbon–niobium oxide composites

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Juan-Li; Gao, Shuang; Liu, Chun-Ling; Liu, Zhao-Tie; Dong, Wen-Sheng, E-mail: wsdong@snnu.edu.cn

    2014-11-15

    Graphical abstract: The ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process. - Highlights: • Ordered mesoporous carbon–niobium oxide composites were synthesized. • The content of Nb{sub 2}O{sub 5} in the composites could be tuned from 38 to 75%. • Niobium species were highly dispersed in amorphous carbon framework walls. • The composites exhibited good catalytic performance in the dehydration of fructose. - Abstract: Ordered mesoporous carbon–niobium oxide composites have been synthesized by a multi-component co-assembly method associated with a carbonization process using phenolic resol as carbon source, niobium chloride as precursor and amphiphilic triblock copolymer Pluronic F127 as template. The resulting materials were characterized using a combination of techniques including differential scanning calorimetry–thermogravimetric analysis, N{sub 2} physical adsorption, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results show that with increasing the content of Nb{sub 2}O{sub 5} from 38 to 75% the specific surface area decreases from 306.4 to 124.5 m{sup 2} g{sup −1}, while the ordered mesoporous structure is remained. Niobium species is well dispersed in the amorphous carbon framework. The mesoporous carbon–niobium oxide composites exhibit high catalytic activity in the dehydration of fructose to 5-hydroxymethylfurfural. A 100% conversion of fructose and a 76.5% selectivity of 5-hydroxymethylfurfural were obtained over the carbon–niobium oxide composite containing 75% Nb{sub 2}O{sub 5} under the investigated reaction conditions.

  18. Size-controlled synthesis of monodisperse nickel nanoparticles and investigation of their magnetic and catalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Yuan; Jia, Rongrong; Zhao, Jinchong; Liang, Jilei; Liu, Yunqi, E-mail: liuyq@upc.edu.cn; Liu, Chenguang

    2014-10-15

    Graphical abstract: - Highlights: • Monodisperse nickel nanoparticles (NPs) with different size were synthesized via the thermal decomposition approach. • The size of nickel NPs can easily be controlled by changing synthetic conditions. • The possible growth mechanism of nickel NPs was proposed. • The as-synthesized nickel NPs exhibited superparamagnetism characteristics at room temperature, and the saturation magnetization increased significantly with increasing size of the nickel NPs. • The dehydrogenation reaction of cyclohexane on nickel NPs was structure sensitive reaction. - Abstract: Monodisperse nickel nanoparticles (NPs) with different size were synthesized via the thermal decomposition approach using nickel acetylacetonate as precursors and trioctylphosphine as surfactant in oleylamine. The structure and morphology of as-synthesized nickel NPs were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and selected area electron diffraction (SAED). The surface states of as-synthesized nickel NPs were characterized by Fourier transform infrared (FT-IR) spectra. The textural properties of as-synthesized nickel NPs were characterized by N{sub 2} adsorption–desorption. The size of as-synthesized nickel NPs was found to be easily controlled by changing synthetic conditions, including P:Ni precursor ratio, reaction temperature, reaction time and oleylamine quantity, and the possible growth mechanism of nickel NPs was proposed. In addition, the magnetic measurements showed that the as-synthesized nickel NPs exhibited superparamagnetism characteristics at room temperature, and the saturation magnetization increased significantly with the increase in nickel NPs’ size. Finally, the size-dependent catalytic properties of nickel NPs for cyclohexane dehydrogenation reaction were studied. The results demonstrated that the catalytic activity can be enhanced by decreasing the size of NPs, which indicated that the dehydrogenation

  19. Synthesis, characterization of nickel aluminate nanoparticles by microwave combustion method and their catalytic properties

    International Nuclear Information System (INIS)

    Highlights: • Simple route for the preparation of nickel aluminate. • NiAl2O4 microwave absorbent was invented by a simple method. • High specific surface area was obtained at low temperature. • Evaluation of magnetic, optical and catalytic properties. - Abstract: Microwave combustion method (MCM) is a direct method to synthesize NiAl2O4 nanoparticles and for the first time we report the using of Sesame (Sesame indicum L.) plant extract in the present study. Solutions of metal nitrates and plant extract as a gelling agent are subsequently combusted using microwave. The structure and morphology of NiAl2O4 nanoparticles are investigated by X-ray diffraction (XRD), Fourier transforms infrared spectra (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), high resolution transmission electron microscopy (HR-TEM), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy, Brunauer–Emmett–Teller (BET) analysis and vibrating sample magnetometer (VSM). XRD pattern confirmed the formation of cubic phase NiAl2O4. The formation of NiAl2O4 is also confirmed by FT-IR. The formation of NiAl2O4 nanoparticles is confirmed by HR-SEM and HR-TEM. Furthermore, the microwave combustion leads to the formation of fine particles with uniform morphology. The magnetic properties of the synthesized NiAl2O4 nano and microstructures were investigated by vibrating sample magnetometer (VSM) and their hysteresis loops were obtained at room temperature. Further, NiAl2O4 prepared by MCM using Sesame (S. indicum L.) plant extract is tested for the catalytic activity toward the oxidation of benzyl alcohol

  20. Facile synthesis of two-dimensional graphene/SnO2/Pt ternary hybrid nanomaterials and their catalytic properties

    Science.gov (United States)

    Zhu, Chengzhou; Wang, Ping; Wang, Li; Han, Lei; Dong, Shaojun

    2011-10-01

    In this paper, we reported a simple, aqueous-phase route to the synthesis of two-dimensional graphene/SnO2 composite nanosheets (GSCN) hybrid nanostructures consisting of 5 nm Pt nanoparticles supported on the both sides of GSCN. Functional two-dimensional GSCN were obtained through the reduction of graphene oxide (GO) using SnCl2 in the presence of polyelectrolyte poly(diallyldimethylammonium chloride) (PDDA). The main advantages of this preparation are that the reduction of GO, the formation of SnO2 and the functionalization of GSCN were achieved simultaneously through one-pot reaction. GSCN/Pt ternary hybrid nanomaterials were generated by in situ reduction of negatively charged PtCl62- precursors adsorbed on the positively charged surface of GSCN through electrostatic attraction. The as-synthesized GSCN/Pt ternary hybrid nanomaterials exhibited high cycle stabilization during the catalytic reduction of p-nitrophenol into p-aminophenol by NaBH4. Additionally, our approach is expected to extend to other hybrid nanomaterials. We believe that the obtained GSCN/Pt ternary hybrid nanomaterials have great potential for applications in other field, such as electrochemical energy storage, sensors, and so on.In this paper, we reported a simple, aqueous-phase route to the synthesis of two-dimensional graphene/SnO2 composite nanosheets (GSCN) hybrid nanostructures consisting of 5 nm Pt nanoparticles supported on the both sides of GSCN. Functional two-dimensional GSCN were obtained through the reduction of graphene oxide (GO) using SnCl2 in the presence of polyelectrolyte poly(diallyldimethylammonium chloride) (PDDA). The main advantages of this preparation are that the reduction of GO, the formation of SnO2 and the functionalization of GSCN were achieved simultaneously through one-pot reaction. GSCN/Pt ternary hybrid nanomaterials were generated by in situ reduction of negatively charged PtCl62- precursors adsorbed on the positively charged surface of GSCN through

  1. Catalytic formal [2+2+1] synthesis of pyrroles from alkynes and diazenes via TiII/TiIV redox catalysis

    Science.gov (United States)

    Gilbert, Zachary W.; Hue, Ryan J.; Tonks, Ian A.

    2016-01-01

    Pyrroles are structurally important heterocycles. However, the synthesis of polysubstituted pyrroles is often challenging. Here, we report a multicomponent, Ti-catalysed formal [2+2+1] reaction of alkynes and diazenes for the oxidative synthesis of penta- and trisubstituted pyrroles: a nitrenoid analogue to classical Pauson-Khand-type syntheses of cyclopentenones. Given the scarcity of early transition-metal redox catalysis, preliminary mechanistic studies are presented. Initial stoichiometric and kinetic studies indicate that the mechanism of this reaction proceeds through a formally TiII/TiIV redox catalytic cycle, in which an azatitanacyclobutene intermediate, resulting from [2+2] alkyne + Ti imido coupling, undergoes a second alkyne insertion followed by reductive elimination to yield pyrrole and a TiII species. The key component for catalytic turnover is the reoxidation of the TiII species to a TiIV imido via the disproportionation of an η2-diazene-TiII complex.

  2. Iridium ultrasmall nanoparticles, worm-like chain nanowires, and porous nanodendrites: One-pot solvothermal synthesis and catalytic CO oxidation activity

    Science.gov (United States)

    Zhang, Tao; Li, Shuai-Chen; Zhu, Wei; Ke, Jun; Yu, Jing-Wen; Zhang, Zhi-Ping; Dai, Lin-Xiu; Gu, Jun; Zhang, Ya-Wen

    2016-06-01

    We report a facile one-pot solvothermal synthesis of monodisperse iridium (Ir) ultrasmall (1.5-2.5 nm in diameter) nanoparticles (NPs), worm-like chain nanowires (NWs), and porous nanodendrites (NDs), for which CO oxidation reaction has been employed as a probe reaction to investigate the effects of nanoparticle size and surface-capping organics on the catalytic activities. Time-dependent experiments revealed that an oriented attachment mechanism induced by the strong adsorption of halide anions (Br- and I-) on specific facet of Ir nanoclusters or by decreasing the reduction rate of Ir precursors with changing their concentrations during the synthesis was responsible for the formation of Ir NWs and NDs. Annealing tests indicated that an O2-H2 atmosphere treatment turned out to be an effective measure to clean up the surface-capping organics of Ir NPs supported on commercial SiO2. Catalytic CO oxidation reaction illustrated that a significant improvement in the catalytic activity of CO oxidation reaction was achieved together with the changing of activation energies after such atmosphere treatment for the supported catalysts of the ultrasmall Ir NPs. It is noteworthy that this enhancement in catalytic activity could be ascribed to the changes in the surface status (including populations of Ir species in metallic and oxidized states, removal of surface capping organics, the variety of active sites, and total effective active site number) for the supported nanocatalysts during the atmosphere treatment.

  3. A Biomimetic Strategy to Access the Silybins: Total Synthesis of (−)-Isosilybin A

    OpenAIRE

    McDonald, Benjamin R.; Nibbs, Antoinette E.; Scheidt, Karl A.

    2014-01-01

    We report the first asymmetric, total synthesis of (−)-isosilybin A. A late-stage catalytic biomimetic cyclization of a highly functionalized chalcone is employed to form the characteristic benzopyranone ring. A robust and flexible approach to this chalcone provides an entry to the preparation of the entire isomeric family of silybin natural products.

  4. Catechin-capped gold nanoparticles: green synthesis, characterization, and catalytic activity toward 4-nitrophenol reduction

    OpenAIRE

    Choi, Yoonho; Choi, Myung-Jin; Cha, Song-Hyun; Kim, Yeong Shik; Cho, Seonho; Park, Youmie

    2014-01-01

    An eco-friendly approach is described for the green synthesis of gold nanoparticles using catechin as a reducing and capping agent. The reaction occurred at room temperature within 1 h without the use of any external energy and an excellent yield (99%) was obtained, as determined by inductively coupled plasma mass spectrometry. Various shapes of gold nanoparticles with an estimated diameter of 16.6 nm were green-synthesized. Notably, the capping of freshly synthesized gold nanoparticles by ca...

  5. Kinetically controlled synthesis of Au102(SPh)44 nanoclusters and catalytic application

    Science.gov (United States)

    Chen, Yongdong; Wang, Jin; Liu, Chao; Li, Zhimin; Li, Gao

    2016-05-01

    We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent thiophenol ligands, evidenced by the analyses of UV-vis and MALDI mass spectrometry. Finally, the TiO2-supported Au102(SPh)44 nanocluster catalyst is investigated in the selective oxidation of sulfides into sulfoxides by the PhIO oxidant and gives rise to high catalytic activity (e.g., 80-99% conversion of R-S-R' sulfides with 96-99% selectivity for R-S(&z.dbd;O)-R' sulfoxides). The Au102(SPh)44/TiO2 catalyst also shows excellent recyclability in the sulfoxidation process.We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent

  6. Gold nanostars: Benzyldimethylammonium chloride-assisted synthesis, plasmon tuning, SERS and catalytic activity.

    Science.gov (United States)

    Ndokoye, Pancras; Li, Xinyong; Zhao, Qidong; Li, Tingting; Tade, Moses O; Liu, Shaomin

    2016-01-15

    Fabrication of Au nanostars (AuNSs) can expand the application range of Au nanoparticles because of their high electron density and localized surface plasmon resonance (LSPR) on branches. Exploiting this potential requires further refinement of length of the branches and radius of their tips. To this end, we successfully synthesized AuNSs with uniform and sharply-pointed branches by combining benzyldimethylammonium chloride (BDAC) and cetyltrimethylammonium bromide (CTAB) at low BDAC/CTAB ratios. Once mixed with CTAB, BDAC lowers the critical micelle concentration (CMC) for quick formation of the micelles, which provides favorable growth templates for AuNSs formation. Besides, BDAC increases the concentration of Cl(-), which favors Ag(+) in adsorbing on Au facets. This feature is crucial for the yield boosting and synergic shape control of AuNSs regardless of types of Au seeds used. Use of less amounts of seeds as the center of nucleation benefited sharper and longer growth of the branches. AuNSs exhibited excellent enhancement of surface-enhanced Raman scattering (SERS) intensities as the result of high electron density localized at the tips; however, the enhancement degree varied in accordance with the size of branches. In addition, AuNSs showed high catalytic performance toward the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Efficient catalysis over AuNSs originates from their corners, stepped surfaces and high electron density at the tips. PMID:26476203

  7. Facile and Green Synthesis of Palladium Nanoparticles-Graphene-Carbon Nanotube Material with High Catalytic Activity

    Science.gov (United States)

    Sun, Tai; Zhang, Zheye; Xiao, Junwu; Chen, Chen; Xiao, Fei; Wang, Shuai; Liu, Yunqi

    2013-08-01

    We report a facile and green method to synthesize a new type of catalyst by coating Pd nanoparticles (NPs) on reduced graphene oxide (rGO)-carbon nanotube (CNT) nanocomposite. An rGO-CNT nanocomposite with three-dimensional microstructures was obtained by hydrothermal treatment of an aqueous dispersion of graphene oxide (GO) and CNTs. After the rGO-CNT composites have been dipped in K2PdCl4 solution, the spontaneous redox reaction between the GO-CNT and PdCl42- led to the formation of nanohybrid materials consisting rGO-CNT decorated with 4 nm Pd NPs, which exhibited excellent and stable catalytic activity: the reduction of 4-nitrophenol to 4-aminophenol using NaBH4 as a catalyst was completed in only 20 s at room temperature, even when the Pd content of the catalyst was 1.12 wt%. This method does not require rigorous conditions or toxic agents and thus is a rapid, efficient, and green approach to the fabrication of highly active catalysts.

  8. Ruthenium (II) complexes containing quinone based ligands: synthesis, characterization and catalytic applications

    International Nuclear Information System (INIS)

    A series of ruthenium (II) complexes containing ONS and ONO donor ligands of general formula (RuX(CO)(B)(L)) (X = H or Cl; B = PPh3, AsPh3 or Py; L = mono negative tridentate ligand) were synthesized from the reactions of tridentate ligand with (RuHX(CO)(EPh3)2(B)) (X = H or Cl; E = P or As; B = PPh3, AsPh3 or Py) in 1:1 molar ratio. All the new complexes have been characterized by analytical and spectral (FT-IR, electronic, 1H, 13C and 31PNMR) data. They have been tentatively assigned an octahedral structure. The synthesized complexes have exhibited catalytic activity for oxidation of benzyl alcohol to benzaldehyde and cyclohexanol to cyclohexanone in the presence of N-methyl morpholine N-oxide (NMO) as co-oxidant. They were also found to catalyze the transfer hydrogenation of aliphatic and aromatic ketones to alcohols in KOH/lsopropanol. (author)

  9. Ruthenium(II) chalconate complexes: Synthesis, characterization, catalytic, and biological studies

    Science.gov (United States)

    Muthukumar, M.; Viswanathamurthi, P.

    2009-10-01

    A series of new hexa-coordinated ruthenium(II) carbonyl complexes of the type [RuCl(CO)(EPh 3)(B)(L)] (E = P or As; B = PPh 3, AsPh 3 or Py; L = 2'-hydroxychalcones) have been prepared by reacting [RuHCl(CO)(EPh 3) 2(B)] (E = P or As; B = PPh 3, AsPh 3 or Py) with 2'-hydroxychalcones in benzene under reflux. The new complexes have been characterized by analytical and spectral (IR, electronic, 1H, 31P and 13C NMR) data. Based on the above data, an octahedral structure has been assigned for all the complexes. The new complexes exhibit catalytic activity for the oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N-methylmorpholine- N-oxide (NMO) as co-oxidant and also found efficient catalyst in the transfer hydrogenation of ketones. The antifungal properties of the complexes have also been examined and compared with standard Bavistin.

  10. Microwave-assisted facile green synthesis of silver nanoparticles and spectroscopic investigation of the catalytic activity

    Indian Academy of Sciences (India)

    Siby Joseph; Beena Mathew

    2015-06-01

    Silver nanoparticles have been successfully synthesized in aqueous medium by a green, rapid and costefficient synthetic approach based on microwave irradiation. In this study, iota-carrageenan (I-carrageenan) is used both as reducing and stabilizing agent. The formation of nanoparticles is determined using UV–vis, Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray (EDX) and high-resolution-transmission electron microscopic (HR-TEM) analysis. Transmission electron microscopic (TEM) images show that the nanoparticles are of spherical shape with an average diameter of 18.2 nm. I-carrageenan-stabilized silver nanoparticles show outstanding catalytic activity for the reduction of 4-nitrophenol in the presence of NaBH4 in aqueous medium. The reaction follows pseudo-first-order kinetics and the reaction rate increases with the increase in amount of the catalyst. The study of the temperature dependence of reaction rate gives activation energy of 42.81 kJ mol−1. The synthesized silver nanoparticles are anticipated to be a promising material for pollution abatement.

  11. Synthesis and bio-catalytic activity of isostructural cobalt(III)-phenanthroline complexes

    Indian Academy of Sciences (India)

    Dhananjay Dey; Arnab Basu Roy; Anandan Ranjani; Loganathan Gayathri; Saravanan Chandraleka; Dharumadurai Dhanasekaran; Mohammad Abdulkader Akbarsha; Chung-Yu Shen; Hui-Lien Tsai; Milan Maji; Niranjan Kole; Bhaskar Biswas

    2015-04-01

    We have synthesized two isostructural mononuclear cobalt(III) complexes [1]NO3·3H2O and [1]NO3·CH3CO2H·H2O {[1]+ = [Co(1,10-phenanthroline)2Cl2]+} and characterized by single crystal X-ray structural analyses. Mass spectral studies of the complexes indicate both the compounds to produce identical cationic species viz., [Co(phen)2Cl2]+ in methanol solution. [1]+ has been evaluated as model system for the catechol oxidase enzyme by using 3,5-di-tert-butylcatechol (3,5-DTBC) as the substrate in methanol medium, which revealed that the cationic complex efficiently inhibits catalytic activity with kcat value 9.65 × 102 h−1. [1]+ cleaved pBR 322 DNA without addition of an activating agent. Further, the anti-cancer activity of [1]+ on human hepatocarcinoma cell line (HepG2) has been examined. The induction of apoptosis induced in the cell line was assessed base on the changes in cell morphology, which showed the efficacy of [1]+ to induce apoptosis in 53% of cells during 24 h treatment. Interestingly, the observed IC50 values reveal that [1]+ brings about conformational change on DNA strongly and exhibits remarkable cytotoxicity.

  12. Catalytic pyrogenation synthesis of C/Ni composite nanoparticles: controllable carbon structures and high permittivities

    Energy Technology Data Exchange (ETDEWEB)

    Lu, B; Huang, H; Dong, X L; Lei, J P, E-mail: dongxl@dlut.edu.c [School of Materials Science and Engineering, Dalian University of Technology, Dalian, Liaoning 116024 (China)

    2010-03-17

    Catalytic pyrogenation of methane gas in the presence of Ni nanoparticles was employed to synthesize C/Ni composite nanoparticles at various reaction temperatures. The Ni nanoparticles prepared by the arc-discharge method served as a catalyst to decompose the hydrocarbon molecules and also provided isolated templates for the formation of carbon nanocapsules at 400 and 500 {sup 0}C or multi-walled carbon nanotubes at 600 and 650 {sup 0}C. The generation and growth mechanism of the carbon shells are discussed on the basis of structure evolution. By dispersing the nanoparticles homogeneously into a paraffin matrix, the electromagnetic parameters of the nanoparticles have been investigated in the frequency range 2-18 GHz. The samples exhibit high permittivities varying with the microstructures of the nanoparticles. The relationship between the dielectric properties and diverse carbon structures is indicated. The high permittivities of the nanoparticles are attributed to the better conductivity of the carbon shells and the charge polarizations at the defects or interfaces between metal cores and carbon shells.

  13. Hydrothermal synthesis, structure, and catalytic properties of UO2Sb2O4

    International Nuclear Information System (INIS)

    A new uranyl antimonite, UO2Sb2O4 (1), has been prepared from the hydrothermal reaction of UO3 with Sb2O3 and KCl. The structure of 1 consists of neutral two-dimensional ∞2[UO2Sb2O4] layers. The U(VI) centers are ligated by two trans oxo ligands and four square pyramidal antimonite anions. In addition, the U(VI) also forms long contacts with two additional oxygen atoms that are distorted by 12.7(2) degree sign out of the equatorial plane perpendicular to the uranyl unit. These long interactions are significant owing to evidence supplied by bond valence sum calculations. The two-dimensional layers found in 1 are built from one-dimensional chains formed from edge-sharing UO6 octahedra that run along the b-axis, and are linked together by [Sb2O4]2- chains. A flow microreactor system has been used to study the catalytic activity of 1, and these results show that it can be used as a catalyst in the conversion of propene and O2 to acrolein. Crystallographic data: 1, monoclinic, space group C2/m, a=13.490(2) A, b=4.0034(6) A, c=5.1419(8) A, β=104.165(3) deg., Z=2, MoKα, λ=0.71073, R(F)=1.74% for 30 parameters with 365 reflections with I>2σ(I)

  14. Yucca-derived synthesis of gold nanomaterial and their catalytic potential

    Science.gov (United States)

    Krishnamurthy, Sneha; Esterle, Andrea; Sharma, Nilesh C.; Sahi, Shivendra V.

    2014-11-01

    AuNPs ranging in 20 to 300 nm size were synthesized at a room temperature using Yucca filamentosa leaf extract. Diverse nanomaterial morphologies were obtained by varying the extract concentration, reaction pH, and temperature. While low volumes of extract (0.25 and 0.5 mL) induced the formation of microscale Au sheets with edge length greater than 1 μm, high volumes yielded spherical particles ranging from 20 to 200 nm. Varying pH of the solution significantly influenced the particle shape with the production of largely spherical particles at pH 5 to 6 and truncated triangles at pH 2. Separation of multidimensional nanostructures was achieved using a novel method of sucrose density gradient centrifugation. The catalytic function of Yucca-derived AuNPs was demonstrated by degradation of a wastewater dye: methylene blue using spectrophotometric measurements over time. Treatment with Au nanosheets and spheres demonstrated methylene blue degradation approximately 100% greater than the activity in control at 60 min.

  15. Synthesis, characterization, and catalytic properties of micro-mesoporous, amorphous titanosilicate catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Keshavaraja, A.; Ramaswamy, V.; Soni, H.S. [National Chemical Laboaratory, Pune (India)] [and others

    1995-12-01

    Titanosilicates, synthesized under ambient conditions in the absence of nitrogenated organic bases, exhibit (i) an amorphous nature (XRD, electron diffraction, TEM); (ii) a bimodal, narrow pore size distribution with pore widths around 0.8 and 3.6 nm, respectively, and surface areas of about 500-700 m{sup 2}g{sup -1} (BET); (iii) absorption bands at 960 cm{sup -1} (IR) and 220 nm (UV), respectively; (iv) a radial electron density distribution pattern indicating the presence of isolated TiO{sub 4} units in a silica matrix; and (v) catalytic activity and selectivity comparable to crystalline TS-1 (MFI) in the oxidation (with aqueous H{sub 2}O{sub 2}) of benzene, toluene, and phenol. Unlike other solid catalysts known so far, these amorphous titanosilicates provide a higher yield of catechol than hydroquinone in the oxidation of phenol. In contrast to TS-1 or TS-2 (MEL), the oxyfunctionalization of the side chain in toluene is more predominant than the aromatic ring hydroxylation indicating a radical mechanism of oxidation. 29 refs., 12 figs., 5 tabs.

  16. Kinetically controlled synthesis of Au102(SPh)44 nanoclusters and catalytic application.

    Science.gov (United States)

    Chen, Yongdong; Wang, Jin; Liu, Chao; Li, Zhimin; Li, Gao

    2016-05-21

    We here explore a kinetically controlled synthetic protocol for preparing solvent-solvable Au102(SPh)44 nanoclusters which are isolated from polydispersed gold nanoclusters by solvent extraction and size exclusion chromatography (SEC). The as-obtained Au102(SPh)44 nanoclusters are determined by matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry, in conjunction with UV-vis spectroscopy and thermogravimetric analysis (TGA). However, Au99(SPh)42, instead of Au102(SPh)44, is yielded when the polydispersed gold nanoclusters are etched in the presence of excess thiophenol under thermal conditions (e.g., 80 °C). Interestingly, the Au102(SPh)44 nanoclusters also can convert to Au99(SPh)42 with equivalent thiophenol ligands, evidenced by the analyses of UV-vis and MALDI mass spectrometry. Finally, the TiO2-supported Au102(SPh)44 nanocluster catalyst is investigated in the selective oxidation of sulfides into sulfoxides by the PhIO oxidant and gives rise to high catalytic activity (e.g., 80-99% conversion of R-S-R' sulfides with 96-99% selectivity for R-S([double bond, length as m-dash]O)-R' sulfoxides). The Au102(SPh)44/TiO2 catalyst also shows excellent recyclability in the sulfoxidation process. PMID:26758553

  17. Synthesis, characterization, and catalytic activity in Suzuki coupling and catalase-like reactions of new chitosan supported Pd catalyst.

    Science.gov (United States)

    Baran, Talat; Inanan, Tülden; Menteş, Ayfer

    2016-07-10

    The aim of this study is to analyze the synthesis of a new chitosan supported Pd catalyst and examination of its catalytic activity in: Pd catalyst was synthesized using chitosan as a biomaterial and characterized with FTIR, TG/DTG, XRD, (1)H NMR, (13)C NMR, SEM-EDAX, ICP-OES, Uv-vis spectroscopies, and magnetic moment, along with molar conductivity analysis. Biomaterial supported Pd catalyst indicated high activity and long life time as well as excellent turnover number (TON) and turnover frequency (TOF) values in Suzuki reaction. Biomaterial supported Pd catalyst catalyzed H2O2 decomposition reaction with considerable high activity using comparatively small loading catalyst (10mg). Redox potential of biomaterial supported Pd catalyst was still high without negligible loss (13% decrease) after 10 cycles in reusability tests. As a consequence, eco-friendly biomaterial supported Pd catalyst has superior properties such as high thermal stability, long life time, easy removal from reaction mixture and durability to air, moisture and high temperature. PMID:27106147

  18. Synthesis, characterization and catalytic activity of two novel cis - dioxovanadium(V) complexes: [VO2(L)] and [VO2(HLox)

    International Nuclear Information System (INIS)

    Two novel complexes, [VO2(L)] (1) and [VO2(HLox)] (2), were synthesized and characterized by IV, UV-Vis and NMR spectroscopy, cyclic voltammetry, elemental analysis and X-ray diffraction. The synthesis of a new ligand, H2Lox, is also described. Complexes 1 and 2 were obtained by the reaction of [VO(acac)2] with the ligands HL and H2Lox, respectively. Alternatively, 2 was also obtained by the reaction of HL with [VO(acac)2] in the presence of hydroxylamine, and by the reaction of 1 with hydroxylamine. Crystallographic data show that complexes 1 and 2 have similar molecular structures, in which the cis-dioxovanadium(V) center is coordinated to L- or HLox-, respectively, in a distorted octahedral environment. The catalytic activity of these compounds towards cyclohexane oxidation was evaluated using H2O2 and t-BuOOH as oxidants. Both complexes presented > 70% selectivity for cyclohexylhydroperoxide formation. B3LYP/6.31G(d) calculations were used to confirm the geometry and to help assign the electronic spectra. (author)

  19. Electrochemical synthesis of NiFe{sub 2}O{sub 4} nanoparticles: Characterization and their catalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Galindo, R. [Chemistry Department, Universidad de Guanajuato, Cerro de la Venada S/N, Pueblito de Rocha, C.P. 36040 Guanajuato Gto. (Mexico); Department of Physical Chemistry Applied, Universidad Autonoma de Madrid, Cantoblanco S/N, C.P 28049 Madrid (Spain); Mazario, E. [Department of Physical Chemistry Applied, Universidad Autonoma de Madrid, Cantoblanco S/N, C.P 28049 Madrid (Spain); Gutierrez, S. [Chemistry Department, Universidad de Guanajuato, Cerro de la Venada S/N, Pueblito de Rocha, C.P. 36040 Guanajuato Gto. (Mexico); Morales, M.P. [Materials Science Institute of Madrid, Sor Juana Ines de la Cruz 3, Cantoblanco, 28049 Madrid (Spain); Herrasti, P., E-mail: pilar.herrasti@uam.es [Department of Physical Chemistry Applied, Universidad Autonoma de Madrid, Cantoblanco S/N, C.P 28049 Madrid (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Nickel ferrite nanoparticles were synthesized by new electrochemical method. Black-Right-Pointing-Pointer Stoichometric nanoparticles with 20 nm of size can be prepared with this method. Black-Right-Pointing-Pointer Nickel ferrites nanoparticles were used as catalysts in the direct oxidation of glucose at pH 7. - Abstract: In this work a new route for preparation of nickel ferrites nanoparticles has been developed. The synthesis is carried out in an electrochemical cell using three electrodes, a sheet of iron was employed as cathode and two sheets of iron and nickel were used as sacrificial anodes. The obtained nanoparticles were washed several times with distilled water, separated magnetically and dried under vacuum with constant temperature for 12 h. The characterization of the nanoparticles was carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), and Inductively coupled plasma mass spectrometry (ICP-MS). Magnetic measurements were carried out using a vibrating sample magnetometer (VSM). To evaluate the catalytical properties of these nanoparticles against the oxidation of glucose a graphite paste electrode (GPE) was made. The proportions of the nanoparticles in GPE were 5, 10, 20 and 50% in weight. The electrode shows promising properties for its use as catalyst in the glucose oxidation.

  20. Synthesis of high purity single-walled carbon nanotubes from ethanol by catalytic gas flow CVD reactions

    International Nuclear Information System (INIS)

    Highly pure single-walled carbon nanotubes (SWNTs) with their contents >96% of the total products were achieved by chemical vapour deposition gas flow reactions using ethanol as the carbon source. The high purity SWNTs were formed under critically controlled synthesis conditions and by applying a high hydrogen flow, under which the non-catalytic condensation of carbon was completely suppressed. Purification of the products in acid at ambient conditions readily yielded over 99% pure SWNT products, as the only impurities left in the products were iron particles of clean surface. Therefore, the present study demonstrates the full potential of the CVD gas flow reactions in continuous production of high quality SWNTs. Comparable syntheses were conducted using other alcohols in place of ethanol and it was found that high alkyl alcohols like isopropanol and hexanol produced more amorphous carbon while methanol produced no carbon. The high yield growth of SWNTs was attributed greatly to the reaction chemistry of ethanol and the 'right' amount of hydrogen in the system, as discussed

  1. Green synthesis of silver nanoparticles using Terminalia cuneata and its catalytic action in reduction of direct yellow-12 dye

    Science.gov (United States)

    Edison, Thomas Nesakumar Jebakumar Immanuel; Lee, Yong Rok; Sethuraman, Mathur Gopalakrishnan

    2016-05-01

    Facile green synthesis of silver nanoparticles (AgNPs) using aqueous bark extract of Terminalia cuneata has been reported in this article. The effects of concentration of the extract, reaction time and pH were studied by UV-Vis spectroscopy. Appearance of yellow color with λmax around ~ 420 nm suggested the formation of AgNPs. The stable AgNPs were further characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), dynamic light scattering (DLS) with zeta potential and high resolution transmission electron microscopy (HR-TEM) with energy dispersive X-ray spectroscopy (EDS) analysis. The synthesized AgNPs were in the size range of 25-50 nm with a distorted spherical shape identified from HR-TEM analysis. The catalytic activity of AgNPs on the reduction of direct yellow-12 using NaBH4 was analyzed using a UV-Vis spectrophotometer. This study showed the efficacy of biogenic AgNPs in catalyzing the reduction of direct yellow-12.

  2. Crystallography of Magnetite Plaquettes and their Significance as Asymmetric Catalysts for the Synthesis of Chiral Organics in Carbonaceous Chondrites

    Science.gov (United States)

    Chan, Q. H. S.; Zolensky, M. E.

    2015-01-01

    We have previously observed the magnetite plaquettes in carbonaceous chondrites using scanning electron microscope (SEM) imaging, examined the crystal orientation of the polished surfaces of magnetite plaquettes in CI Orgueil using electron backscattered diffraction (EBSD) analysis, and concluded that these magnetite plaquettes are likely naturally asymmetric materials. In this study, we expanded our EBSD observation to other magnetite plaquettes in Orgueil, and further examined the internal structure of these remarkable crystals with the use of X-ray computed microtomography.

  3. 手性辅剂樟脑磺内酰胺在不对称合成中的应用%Application of Chial Camphorsultam in Asymmetric Synthesis

    Institute of Scientific and Technical Information of China (English)

    曹秀芳; 刘盛华

    2011-01-01

    综述了手性辅剂樟脑磺内酰胺在不对称共轭加成反应、不对称Diels-Alder反应、不对称1,3-偶极环加成反应、不对称羰基化合物的a-烷基化反应、不对称羟醛缩合反应及胺化反应中的应用研究进展.%This review summarizes some application progress of camphorsultam as chiral auxiliary in asymmetric synthesis including conjugate addition, Diels-Alder reaction, 1,3-dipolar cycloaddition, α-alkylation of ketone, aldol condensation and amination reaction etc.

  4. Synthesis characterization and catalytic action of hexagonal gold nanoparticles using essential oils extracted from Anacardium occidentale

    Science.gov (United States)

    Sheny, D. S.; Mathew, Joseph; Philip, Daizy

    2012-11-01

    A new phytochemical method for the synthesis of gold nanoparticles is reported. The essential oils extracted from the fresh leaves of Anacardium occidentale are used for the reduction of auric acid to Au nanoparticles (NPs). The formation and morphology of synthesized NPs are investigated with the help of UV-visible, TEM and FTIR spectroscopy. The NPs synthesized at room temperature are mono-dispersed and hexagonal in shape with an average size of 36 nm while those prepared at higher temperature are composed of a mixture of anisotropic particles. The UV-visible absorption spectra of these anisotropic NPs show asymmetry in the longer wavelength side. The quantity of oil is an important criterion modulating the shape of NPs. Possible biochemical mechanism leading to the formation of NPs is studied using FTIR spectroscopy. The potential of synthesized Au NPs as catalyst is explored for the hydrogenation of p-nitro phenol to p-amino phenol at room temperature.

  5. Self-assembled catalytic DNA nanostructures for synthesis of para-directed polyaniline.

    Science.gov (United States)

    Wang, Zhen-Gang; Zhan, Pengfei; Ding, Baoquan

    2013-02-26

    Templated synthesis has been considered as an efficient approach to produce polyaniline (PANI) nanostructures. The features of DNA molecules enable a DNA template to be an intriguing template for fabrication of emeraldine PANI. In this work, we assembled HRP-mimicking DNAzyme with different artificial DNA nanostructures, aiming to manipulate the molecular structures and morphologies of PANI nanostructures through the controlled DNA self-assembly. UV-vis absorption spectra were used to investigate the molecular structures of PANI and monitor kinetic growth of PANI. It was found that PANI was well-doped at neutral pH and the redox behaviors of the resultant PANI were dependent on the charge density of the template, which was controlled by the template configurations. CD spectra indicated that the PANI threaded tightly around the helical DNA backbone, resulting in the right handedness of PANI. These reveal the formation of the emeraldine form of PANI that was doped by the DNA. The morphologies of the resultant PANI were studied by AFM and SEM. It was concluded from the imaging and spectroscopic kinetic results that PANI grew preferably from the DNAzyme sites and then expanded over the template to form 1D PANI nanostructures. The strategy of the DNAzyme-DNA template assembly brings several advantages in the synthesis of para-coupling PANI, including the region-selective growth of PANI, facilitating the formation of a para-coupling structure and facile regulation. We believe this study contributes significantly to the fabrication of doped PANI nanopatterns with controlled complexity, and the development of DNA nanotechnology. PMID:23272944

  6. Bis(imidazolin-2-iminato) rare earth metal complexes: synthesis, structural characterization, and catalytic application.

    Science.gov (United States)

    Trambitas, Alexandra G; Melcher, Daniel; Hartenstein, Larissa; Roesky, Peter W; Daniliuc, Constantin; Jones, Peter G; Tamm, Matthias

    2012-06-18

    Reaction of anhydrous rare earth metal halides MCl(3) with 2 equiv of 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-imine (Im(Dipp)NH) and 2 equiv of trimethylsilylmethyl lithium (Me(3)SiCH(2)Li) in THF furnished the complexes [(Im(Dipp)N)(2)MCl(THF)(n)] (M = Sc, Y, Lu). The molecular structures of all three compounds were established by single-crystal X-ray diffraction analyses. The coordination spheres around the pentacoordinate metal atoms are best described as trigonal bipyramids. Reaction of YbI(2) with 2 equiv of LiCH(2)SiMe(3) and 2 equiv of the imino ligand Im(Dipp)NH in tetrahydrofuran did not result in a divalent complex, but instead the Yb(III) complex [(Im(Dipp)N)(2)YbI(THF)(2)] was obtained and structurally characterized. Treatment of [(Im(Dipp)N)(2)MCl(THF)(n)] with 1 equiv of LiCH(2)SiMe(3) resulted in the formation of [(Im(Dipp)N)(2)M(CH(2)SiMe(3))(THF)(n)]. The coordination arrangement of these compounds in the solid state at the metal atoms is similar to that found for the starting materials, although the introduction of the neosilyl ligand induces a significantly greater distortion from the ideal trigonal-bipyramidal geometry. [(Im(Dipp)N)(2)Y(CH(2)SiMe(3))(THF)(2)] was used as precatalyst in the intramolecular hydroamination/cyclization reaction of various terminal aminoalkenes and of one aminoalkyne. The complex showed high catalytic activity and selectivity. A comparison with the previously reported dialkyl yttrium complex [(Im(Dipp)N)Y(CH(2)SiMe(3))(2)(THF)(3)] showed no clear tendency in terms of activity. PMID:22662762

  7. Design and synthesis of ruthenium(II) OCO pincer type NHC complexes and their catalytic role towards the synthesis of amides

    Indian Academy of Sciences (India)

    Muthukumaran Nirmala; Periasamy Viswanathamurthi

    2016-01-01

    The present contribution describes the synthesis and characterization of a family of robust ruthenium complexes, supported by a tridentate pincer ligand of the type bis-phenolate--heterocyclic carbene [Bu(OCO)2−] (NHC). Ruthenium(II) complexes (1-3) bearing bis-phenolate--heterocyclic carbene ligand were synthesized in good yields by the reaction of imidazolinium proligand (HL) with metal precursors [RuHCl(CO)(EPh3)2(B)] (E = P or As; B = PPh3, AsPh3 or Py) by transmetalation from the corresponding silver carbene complex. All the Ru(II)-NHC complexes have been characterized by elemental analyses, spectroscopic methods as well as ESI mass spectrometry. Based on the spectral results, an octahedral geometry was assigned for all the complexes. The tridentate nature of the Bu(OCO)2− ligand as well as some level of steric protection provided by the Bu groups may rationalize the excellent stability of the Ru-Ccarbene bond in the present systems. Moreover, for the explorations of catalytic potential of the synthesized compounds, all the three [Ru-NHC] complexes (1-3) were tested as catalysts for amidation of alcohols with amines. Notably, the complex 1 was found to be very efficient and versatile catalyst towards amidation of a wide range of alcohols with amines.

  8. Synthesis, characterization and catalytic activity of indium substituted nanocrystalline Mobil Five (MFI) zeolite

    International Nuclear Information System (INIS)

    Highlights: • In situ modification of the MFI zeolite by incorporation of indium. • The samples were characterized by XRD, FTIR, TGA, UV–vis (DRS), SAA, EDX and SEM. • The incorporation of indium was confirmed by XRD, FT-IR, UV–vis (DRS), EDX and TGA. • Hydroxylation of phenol reaction was studied on the synthesized catalysts. - Abstract: A series of indium doped Mobil Five (MFI) zeolite were synthesized hydrothermally with silicon to aluminium and indium molar ratio of 100 and with aluminium to indium molar ratios of 1:1, 2:1 and 3:1. The MFI zeolite phase was identified by XRD and FT-IR analysis. In XRD analysis the prominent peaks were observed at 2θ values of around 6.5° and 23° with a few additional shoulder peaks in case of all the indium incorporated samples suggesting formation of pure phase of the MFI zeolite. All the samples under the present investigation were found to exhibit high crystallinity (∼92%). The crystallite sizes of the samples were found to vary from about 49 to 55 nm. IR results confirmed the formation of MFI zeolite in all cases showing distinct absorbance bands near 1080, 790, 540, 450 and 990 cm−1. TG analysis of In-MFI zeolites showed mass losses in three different steps which are attributed to the loss due to adsorbed water molecules and the two types TPA+ cations. Further, the UV–vis (DRS) studies reflected the position of the indium metal in the zeolite framework. Surface area analysis of the synthesized samples was carried out to characterize the synthesized samples The analysis showed that the specific surface area ranged from ∼357 to ∼361 m2 g−1 and the pore volume of the synthesized samples ranged from 0.177 to 0.182 cm3 g−1. The scanning electron microscopy studies showed the structure of the samples to be rectangular and twinned rectangular shaped. The EDX analysis was carried out for confirmation of Si, Al and In in zeolite frame work. The catalytic activities of the synthesized samples were

  9. Synthesis, characterization and catalytic activity of indium substituted nanocrystalline Mobil Five (MFI) zeolite

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Kishor Kr. [Department of Chemistry, ADP College, Nagaon, Assam 782002 (India); Nandi, Mithun [Department of Chemistry, Gauhati University, Guwahati, Assam 781014 (India); Talukdar, Anup K., E-mail: anup_t@sify.com [Department of Chemistry, Gauhati University, Guwahati, Assam 781014 (India)

    2015-06-15

    Highlights: • In situ modification of the MFI zeolite by incorporation of indium. • The samples were characterized by XRD, FTIR, TGA, UV–vis (DRS), SAA, EDX and SEM. • The incorporation of indium was confirmed by XRD, FT-IR, UV–vis (DRS), EDX and TGA. • Hydroxylation of phenol reaction was studied on the synthesized catalysts. - Abstract: A series of indium doped Mobil Five (MFI) zeolite were synthesized hydrothermally with silicon to aluminium and indium molar ratio of 100 and with aluminium to indium molar ratios of 1:1, 2:1 and 3:1. The MFI zeolite phase was identified by XRD and FT-IR analysis. In XRD analysis the prominent peaks were observed at 2θ values of around 6.5° and 23° with a few additional shoulder peaks in case of all the indium incorporated samples suggesting formation of pure phase of the MFI zeolite. All the samples under the present investigation were found to exhibit high crystallinity (∼92%). The crystallite sizes of the samples were found to vary from about 49 to 55 nm. IR results confirmed the formation of MFI zeolite in all cases showing distinct absorbance bands near 1080, 790, 540, 450 and 990 cm{sup −1}. TG analysis of In-MFI zeolites showed mass losses in three different steps which are attributed to the loss due to adsorbed water molecules and the two types TPA{sup +} cations. Further, the UV–vis (DRS) studies reflected the position of the indium metal in the zeolite framework. Surface area analysis of the synthesized samples was carried out to characterize the synthesized samples The analysis showed that the specific surface area ranged from ∼357 to ∼361 m{sup 2} g{sup −1} and the pore volume of the synthesized samples ranged from 0.177 to 0.182 cm{sup 3} g{sup −1}. The scanning electron microscopy studies showed the structure of the samples to be rectangular and twinned rectangular shaped. The EDX analysis was carried out for confirmation of Si, Al and In in zeolite frame work. The catalytic activities of

  10. Catalytic performance of cerium iron complex oxides for partial oxidation of methane to synthesis gas

    Institute of Scientific and Technical Information of China (English)

    LI Kongzhai; WANG Hua; WEI Yonggang; LIU Mingchun

    2008-01-01

    The cerium iron complex oxides oxygen carder was prepared by the co-precipitation method. The reactions between methane and lattice oxygen from the complex oxides were investigated in a fixed micro-reactor system. The reduced oxygen carrier could be re-oxidized by air and its initial state could be restored. The characterizations of the oxygen carriers were studied using XRD, O2-TPD, and H2-TPR. The results showed that the bulk lattice oxygen of CeO2-Fe2O3 was found to be suitable for the partial oxidation of methane to synthesis gas. There were two kinds of oxygen species on the oxygen carder: the stronger oxygen species that was responsible for the complete oxidation of methane, and the weaker oxygen species (bulk lattice oxygen) that was responsible for the selective oxidation of methane to CO and H2 at a higher temperature. Then, the lost bulk lattice oxygen could be selectively supplemented by air re-oxidation at an appropriate reaction con-dition. CeFeO3 appeared on the oxygen carrier after 10 successive redox cycles, however, it was not bad for the selectivity of CO and H2.

  11. A general strategy for the catalytic, highly enantio- and diastereoselective synthesis of indolizidine-based alkaloids.

    Science.gov (United States)

    Abels, Falko; Lindemann, Chris; Schneider, Christoph

    2014-02-10

    Sixteen indolizidine-based alkaloids (IBAs) that were isolated as poison constituents of the skin of frogs were synthesized in a highly flexible and stereoselective manner. As a key step, a three-component, organocatalytic, highly enantio- and diastereoselective vinylogous Mukaiyama-Mannich reaction was employed furnishing optically highly enriched butyrolactams as central intermediates on a multigram scale. The attached six-membered ring was constructed through cyclization of the pendant enoate moiety onto the pyrrolidine ring. The absolute configuration of the bridgehead chiral center and the adjacent 8-position was established in the initial vinylogous Mannich reaction, whereas the 3- and 5-substituents were introduced through organometallic addition at a late stage of the synthesis with full stereochemical control from the substrate. With this strategy, simple as well as even more complex alkaloids were accessible in good overall yields as single stereoisomers. These syntheses also served to establish the absolute and relative configuration of those IBAs that had never been synthesized before. PMID:24436076

  12. Hydrothermal synthesis of leucite nanoparticles using anionic surfactant: Structural evaluation and catalytic properties

    Science.gov (United States)

    Farrukh, Muhammad Akhyar; Naseem, Fizza; Imtiaz, Ayesha; Khaleeq-ur-Rahman, Muhammad; Martins, Tatiana Duque; Zia, Khalid Mahmood

    2016-06-01

    Surfactant-assisted synthesis of leucite (KAlSi2O6) nanoparticles was carried out by a hydrothermal method using an anionic surfactant at variable temperatures and surfactant concentrations. The newly synthesized leucite nanoparticles were characterized by FTIR, TGA, XRD, FESEM, and TEM. These nanoparticles have a wide and direct band gap at their smallest particle size ( E g = 3.30 eV), showing a significant quantum confinement effect. Samples of leucite were prepared at 180°C with different SDS concentrations 0.006, 0.007, 0.008, 0.009, and 0.01 M and were used to degrade methylene blue under ultraviolet radiations. These samples degraded methylene blue to 18.5, 31.7, 45.81, 31.61, 30.1%, respectively. The most effective catalyst is the one which was synthesized at 200°C and the CMC value of the surfactant (sodium dodecyl sulfate) having the percentage degradation of 49.1%.

  13. Radiation-induced synthesis of Fe-doped TiO2: Characterization and catalytic properties

    International Nuclear Information System (INIS)

    Fe-doped TiO2 catalyst was prepared by wet impregnation, using TiO2 P25 Degussa as a precursor and Fe(NO3)3 as a dopant, followed by irradiation with an electron beam or γ-rays. Surface properties of Fe/TiO2 samples were examined by BET, XRD, ToF-SIMS, and TPR methods. The photocatalytic activity towards destruction of the anionic surfactant, sodium dodecylbenzenesulfonate (SDBS), in aqueous solutions was higher for the irradiated Fe/TiO2 catalysts than for bare TiO2 P25 or that calcined at 500 °C. The results show that irradiated catalysts exhibit a more uniform texture with high dispersion of iron species. An enhancement of the activity of irradiated Fe/TiO2 systems can be attributed to the synergetic effects of small crystallite size and homogenous distribution of iron species including FeTiO3 phase. - Highlights: ► Radiation-induced synthesis of iron-doped titania. ► Fe(NO3)3 as promoter of TiO2 P25 Degussa. ► Decomposition of dodecylbenzenesulfonate in aqueous solutions. ► Higher photocatalytic activity of irradiated Fe/TiO2 catalysts than that of calcined at 500 °C.

  14. Amine-Catalyzed Asymmetric (3 + 3) Annulations of β'-Acetoxy Allenoates: Enantioselective Synthesis of 4H-Pyrans.

    Science.gov (United States)

    Ni, Chunjie; Tong, Xiaofeng

    2016-06-29

    The asymmetric (3 + 3) annulations of β'-acetoxy allenoates with either 3-oxo-nitriles or pyrazolones have been realized by using 6'-deoxy-6'-[(l)-N,N-(2,2'-oxidiethyl)-valine amido]quinine (6h) as the catalyst. The three functions of catalyst 6h, including Lewis base (quinuclidine N), H-bond donor (amide NH), and Brønsted base (morpholine N), cooperatively take crucial roles on the chemo- and enantioselectivity, allowing for the construction of 4H-pyran and 4H-pyrano[2,3-c]pyrazole in high yields and enantioselectivity. PMID:27310820

  15. Green synthesis of CuO nanoparticles by aqueous extract of Gundelia tournefortii and evaluation of their catalytic activity for the synthesis of N-monosubstituted ureas and reduction of 4-nitrophenol.

    Science.gov (United States)

    Nasrollahzadeh, Mahmoud; Maham, Mehdi; Sajadi, S Mohammad

    2015-10-01

    A facile, efficient and environmentally-friendly protocol has been developed for the green synthesis of CuO nanoparticles (NPs) by aqueous extract of Gundelia tournefortii as a mild, renewable and non-toxic reducing agent. CuO NPs were characterized by SEM, TEM, XRD, EDS, FT-IR and UV-vis spectroscopy. More importantly, the green synthesized CuO NPs presented excellent catalytic activity for reduction of 4-nitrophenol and synthesis of N-monosubstituted ureas via hydration of cyanamides with the aid of acetaldoxime as an effective water surrogate in ethanol as a green solvent. The catalyst was easily separated and the recovered catalyst was reused many times without any significant loss of the catalytic activity. PMID:26073846

  16. Ni–Mo and Co–Mo alloy nanoparticles for catalytic chemical vapor deposition synthesis of carbon nanotubes

    International Nuclear Information System (INIS)

    Highlights: • Thermal decomposition of the ε-Keggin-type polyoxomolybdate clusters Mo12O28(μ2-OH)12{Ni(H2O)3}4 and Mo12O28(μ2-OH)12{Co(H2O)3}4 produces NiMoO4 and CoMoO4 phases. • The NiMoO4 and CoMoO4 phases are converted in alloys with a metal ratio of 1:1. • The Ni–Mo and Co–Mo alloy nanoparticles catalyze a CCVD growth of carbon nanotubes. - Abstract: Here, we show for the first time a catalytic chemical vapor deposition (CCVD) synthesis of carbon nanotubes (CNTs) using polyoxomolybdate clusters Mo12O28(μ2-OH)12{Ni(H2O)3}4 and Mo12O28(μ2-OH)12{Co(H2O)3}4 as a source of catalyst nanoparticles. X-ray diffraction analyses indicated that the products of thermal decomposition of the clusters contain NiMoO4 and CoMoO4 phases, which are converted into Ni–Mo and Co–Mo alloys at 900 °C in hydrogen environment. High-resolution transmission electron microscopy in combination with energy-dispersive X-ray spectroscopy confirmed the CNT growth from bimetallic nanoparticles. Synergism between two metals in an alloy resulted in large-scale production of non-bundled few-walled CNTs with narrow diameter distribution and high quality

  17. Synthesis, characterization of double perovskite Ca2MSbO6 (M = Dy, Fe, Cr, Al) materials via sol–gel auto-combustion and their catalytic properties

    International Nuclear Information System (INIS)

    Double perovskite-type oxide Ca2MSbO6 materials, where M = Dy, Fe, Cr, and Al, were prepared by using the sol–gel auto-combustion method. The role of different B-site cations on their synthesis, structures, morphologies and catalytic properties was investigated. The progress of double-perovskite type structure formation and the disappearance of the organic phases were monitored by infrared absorption spectroscopy (FTIR). Double perovskite oxide structures were evaluated using X-ray diffraction (XRD), while the microstructure of obtained compounds was studied using scanning electron microscopy (SEM). Also, BET surface areas were measured at the liquid nitrogen temperature by nitrogen adsorption. Catalytic properties of the obtained compounds were evaluated by test reaction of hydrogen peroxide decomposition. - Highlights: • Ca2MSbO6 double perovskites were obtained by sol–gel auto-combustion method. • Ca2MSbO6 (M = Dy, Fe, Cr and Al) as catalysts in H2O2 decomposition • Strong relationship between particles' shape, BET area and catalytic performance • Ca2FeSbO6 spherical grains show superior catalytic activity

  18. Synthesis and characterization of ZnO-Al2 O3 oxides as energetic electro-catalytic material for glucose fuel cell

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    One of the thrust areas of research is to find an alternative fuel to meet the increasing demand for energy. Glucose is a good source of alternative fuel for clean energy and is easily available in abundance from both naturally occurring plants and industrial processes. Electrochemical oxidation of glucose in fuel cell requires high electro-catalytic surface of the electrode to produce the clean electrical energy with minimum energy losses in the cell. Pt and Pt based alloys exhibit high electro-catalytic properties but they are expensive. For energy synthesis at economically cheap price, non Pt based inexpensive high electro catalytic material is required. Electro synthesized ZnO-Al2 O3 composite is found to exhibit high electro-catalytic properties for glucose oxidation. The Cyclic Voltammetry and Chronoamperometry curves reflect that the material is very much comparable to Pt as far as the maximum current and the steady state current delivered from the glucose oxidation are concerned. XRD image confirms the mixed oxide composite. SEM images morphology show increased 3D surface areas at higher magnification. This attributed high current delivered from electrochemical oxidation of glucose on this electrode surface.

  19. In situ and ex situ electron microscopy and X-ray diffraction characterization of the evolution of a catalytic system - from synthesis to deactivation

    DEFF Research Database (Denmark)

    Gardini, Diego

    . In the last years, heterogeneous catalysis has also acquired a major role in the growing field of green chemistry, where minimization of waste products and increased synthesis efficiency are of utmost importance. The catalytic properties of a material system are strongly connected to its overall...... the understanding of the structural properties and mechanisms at the origin of catalytic activity. This thesis presents the potential and uniqueness of ex situ and in situ transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques in the characterization of several supported...... combination of high resolution TEM (HRTEM) and electron energy loss spectroscopy (EELS) revealed the degradation of the supported carbide particles probably due to the formation of volatile molybdenum hydroxide species. The activity of silver nanoparticles as catalyst for soot oxidation was studied in...

  20. One-pot synthesis of hierarchical FeZSM-5 zeolites from natural aluminosilicates for selective catalytic reduction of NO by NH3

    Science.gov (United States)

    Yue, Yuanyuan; Liu, Haiyan; Yuan, Pei; Yu, Chengzhong; Bao, Xiaojun

    2015-03-01

    Iron-modified ZSM-5 zeolites (FeZSM-5s) have been considered to be a promising catalyst system to reduce nitrogen oxide emissions, one of the most important global environmental issues, but their synthesis faces enormous economic and environmental challenges. Herein we report a cheap and green strategy to fabricate hierarchical FeZSM-5 zeolites from natural aluminosilicate minerals via a nanoscale depolymerization-reorganization method. Our strategy is featured by neither using any aluminum-, silicon-, or iron-containing inorganic chemical nor involving any mesoscale template and any post-synthetic modification. Compared with the conventional FeZSM-5 synthesized from inorganic chemicals with the similar Fe content, the resulting hierarchical FeZSM-5 with highly-dispersed iron species showed superior catalytic activity in the selective catalytic reduction of NO by NH3.

  1. Acylation, Diastereoselective Alkylation, and Cleavage of an Oxazolidinone Chiral Auxiliary: A Multistep Asymmetric Synthesis Experiment for Advanced Undergraduates

    Science.gov (United States)

    Smith, Thomas E.; Richardson, David P.; Truran, George A.; Belecki, Katherine; Onishi, Megumi

    2008-01-01

    An introduction to the concepts and experimental techniques of diastereoselective synthesis using a chiral auxiliary is described. The 4-benzyl-2-oxazolidinone chiral auxiliary developed by Evans is acylated with propionic anhydride under mild conditions using DMAP as an acyl transfer catalyst. Deprotonation with NaN(TMS)[subscript 2] at -78…

  2. N-Methylphthalimide-substituted benzimidazolium salts and PEPPSI Pd–NHC complexes: synthesis, characterization and catalytic activity in carbon–carbon bond-forming reactions

    Science.gov (United States)

    Gök, Yetkin; İlhan, İlhan Özer

    2016-01-01

    Summary A series of novel benzimidazolium salts (1–4) and their pyridine enhanced precatalyst preparation stabilization and initiation (PEPPSI) themed palladium N-heterocyclic carbene complexes [PdCl2(NHC)(Py)] (5–8), where NHC = 1-(N-methylphthalimide)-3-alkylbenzimidazolin-2-ylidene and Py = 3-chloropyridine, were synthesized and characterized by means of 1H and 13C{1H} NMR, UV–vis (for 5–8), ESI-FTICR-MS (for 2, 4, 6–8) and FTIR spectroscopic methods and elemental analysis. The synthesized compounds were tested in Suzuki–Miyaura cross-coupling (for 1–8) and arylation (for 5–8) reactions. As catalysts, they demonstrated a highly efficient route for the formation of asymmetric biaryl compounds even though they were used in very low loading. For example, all compounds displayed good catalytic activity for the C–C bond formation of 4-tert-butylphenylboronic acid with 4-chlorotoluene. PMID:26877810

  3. Design, Synthesis and Antitumor Activity of Asymmetric Bis(s-triazole Schiff-base)s Bearing Functionalized Side-Chain

    Institute of Scientific and Technical Information of China (English)

    HU,Guo-Oiang; HOU,Li-Li; XIE,Song-Oiang; HUANG,Wen-Long

    2008-01-01

    1-Amino-2-pyrid-3-yl-5-(2-benzoylethylthio)-s-triazole (1) was condensed with 1-amino-3-mercapto-5-[(un)substituted phenyl]-s-triazoles and subsequently substituted with chloroacetic acid to afford bis-s-triazole sulfanylacetic acid mono-Schiff bases (3a-3e),which were condensed with 9-formylanthracene to produce asymmetric bis(s-triazole Schiff base) sulfanylacetic acids (4a-4e).The structures of new synthesized compounds were characterized by elemental analysis and spectral data,and their in vitro antitumor activity against L1210,CHO and HL60 cell lines was evaluted via the respective IC50 values by methylthiazole trazolium (MTT) assay.

  4. 1,6- and 1,7-Regioisomers of Asymmetric and Symmetric Perylene Bisimides: Synthesis, Characterization and Optical Properties

    Directory of Open Access Journals (Sweden)

    Hsing-Yang Tsai

    2013-12-01

    Full Text Available The 1,6- and 1,7-regioisomers of dinitro- (1,6-A and 1,7-A and diamino-substituted perylene bisimides (1,6-B and 1,7-B, and 1-amino-6-nitro- and 1-amino-7-nitroperylene bisimides (1,6-C and 1,7-C were synthesized. The 1,6-A and 1,7-A regioisomers were successfully separated by high performance liquid chromatography and characterized by 500 MHz 1H-NMR spectroscopy, and subsequently, their reduction which afforded the corresponding diaminoperylene bisimides 1,6-B and 1,7-B, respectively. On the other hand, the monoreduction of 1,6-A and 1,7-A, giving the asymmetric 1-amino-6-nitro (1,6-C and 1-amino-7-nitroperylene bisimides (1,7-C, respectively, can be performed by shortening the reaction time from 6 h to 1 h. This is the first time the asymmetric 1,6-disubstituted perylene bisimide 1,6-C is obtained in pure form. The photophysical properties of 1,6-A and 1,7-A were found to be almost the same. However, the regioisomers 1,6-C and 1,7-C, as well as 1,6-B and 1,7-B, exhibit significant differences in their optical characteristics. Time-dependent density functional theory calculations performed on these dyes are reported in order to rationalize their electronic structure and absorption spectra.

  5. Synthesis of lathanum or La-B doped KIT-6 mesoporous materials and their application in the catalytic oxidation of styrene

    Institute of Scientific and Technical Information of China (English)

    詹望成; 郭杨龙; 王艳芹; 郭耘; 卢冠忠

    2010-01-01

    La-doped and La-B-doped KIT-6 mesoporous materials were prepared by direct hydrothermal synthesis with pH-adjusting method and characterized by X-ray diffractometer(XRD),nitrogen sorption,FT-IR,UV-Vis,X-ray photoelectron spectroscopy(XPS) and ICP-AES.The catalytic performance for the oxidation of styrene by hydrogen peroxide,tert-butyl hydroperoxide or oxygen was investigated.The results showed that the introduction of heteroatoms did not destroy the mesostructure of KIT-6 with cubic Ia3d space group.La or ...

  6. NaY zeolites modified by La~(3+) and Ba~(2+): the effect of synthesis details on surface structure and catalytic performance for lactic acid to acrylic acid

    Institute of Scientific and Technical Information of China (English)

    闫婕; 余定华; 李恒; 孙鹏; 黄和

    2010-01-01

    Modified NaY zeolites have been widely studied and the modification metal element is normally single, while few researches have been conducted on NaY zeolites modified by two kinds of metals. In our study, a series of La3+ and Ba2+ modified NaY zeolites were synthesized through different impregnation procedures. Lactic acid dehydration to acrylic acid was selected as a probe reaction to test the catalytic performance of these zeolites synthesized. The effects of synthesis details on their pore structures an...

  7. One-pot multiple reactions: asymmetric synthesis of 2,6-cis-disubstituted piperidine alkaloids from chiral aziridine.

    Science.gov (United States)

    Yadav, Nagendra Nath; Choi, Jihye; Ha, Hyun-Joon

    2016-07-01

    A divergent, new, and highly stereoselective synthesis of cis-2,6-disubstituted piperidine natural products including isosolenopsins, deoxocassine, and spectaline was achieved from chiral aziridine decorated with appropriate alkyl chains for isosolenopsins or alkynyl groups for deoxocassine and spectaline at C2. The characteristic feature of this synthesis is one-pot sequential reactions under atmospheric hydrogen including the reduction of alkyne (for deoxocassine and spectaline), reductive ring-opening of aziridine, debenzylation, and intramolecular reductive amination in high yields. The prerequisite aziridines were elaborated from commercially available (2S)-hydroxymethylaziridine through oxidation, Wittig olefination, and the Grignard reaction for isosolenopsins or substrate-controlled lithium alkynylate addition for deoxocassine and spectaline. PMID:27189444

  8. Role of Carboxylate ligands in the Synthesis of AuNPs: Size Control, Molecular Interaction and Catalytic Activity

    KAUST Repository

    Aljohani, Hind Abdullah

    2016-05-22

    low temperature. The structure of the citrate layer on the AuNP surface may be a key factor in gaining a more detailed understanding of nanoparticle formation and stabilization. This can be affecting the catalytic activity. These thoughts invited us to systematically examine the role of sodium citrate as a stabilizer of gold nanoparticles, which is the main theme of this thesis. This research is focused on three main objectives, controlling the size of the gold nanoparticles based on citrate (and other carboxylate ligands Trisodium citrate dihydrate, Isocitric Acid, Citric acid, Trimesic acid, Succinic Acid, Phthalic acid, Disodium glutarate, Tartaric Acid, Sodium acetate, Acetic Acid and Formic Acid by varying the concentration of Gold/sodium citrate, investigating the interaction of the citrate layer on the AuNP surface, and testing the activity of the Au/TiO2 catalysts for the oxidation of carbon monoxide. This thesis will be divided into five chapters. In Chapter 1, a general literature study on the various applications and methods of synthesis of Au nanoparticles is described. Then we present the main synthetic pathways of Au nanoparticles we selected. A part of the bibliographic study was given to the use of Au nanoparticles in catalysis. In Chapter 2, we give a brief description of the different experimental procedures and characterization techniques utilized over the course of the present work. The study of the size control and the interaction between gold nanoparticles and the stabilizer (carboxylate groups) was achieved by using various characterization techniques such as UV-visible spectroscopy, Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Nuclear Magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). In Chapter 3, we discuss the synthesis and size control of Au nanoparticles by following the growth of these nanoparticles by UV-Visible spectroscopy and TEM. We

  9. Synthesis of LaNiO3 perovskite by the modified proteic gel method and study of catalytic properties in the syngas production

    International Nuclear Information System (INIS)

    This work describes a study on the synthesis of LaNiO3 perovskites via the modified proteic gel method, varying collagen content and on the catalytic activity of LaNiO3 and LaNiO3/Al2O3 in the syngas (CO + H2) production. X-ray diffraction patterns revealed the formation of perovskite structure in all samples prepared by proteic gel synthesis method, varying collagen content and after calcination at 700 deg C for 2 h. LaNiO3/Al2O3 catalyst prepared by the impregnation method showed diffraction peaks due to the perovskite structure and to the support (Al2O3). This catalyst presented: specific surface of 46.1 m2 g-1, two reduction peaks in the temperature programmed reduction (TPR) profile and 46% of methane conversion (by the partial oxidation of methane using oxygen) after 18 h of reaction. (author)

  10. Green synthesis of the Cu/ZnO nanoparticles mediated by Euphorbia prolifera leaf extract and investigation of their catalytic activity.

    Science.gov (United States)

    Momeni, Seyedeh Samaneh; Nasrollahzadeh, Mahmoud; Rustaiyan, Abdolhossein

    2016-06-15

    A green synthesis process was developed for the preparation of the Cu/ZnO nanoparticles (NPs) using Euphorbia prolifera leaf extract as a mild, renewable and non-toxic reducing agent and efficient stabilizer without using dangerous, hazardous and toxic materials. The approach of biosynthesis appears to be cost efficient eco-friendly and easy alternative to conventional methods of the Cu/ZnO NPs synthesis. The Cu/ZnO NPs were characterized by FESEM, EDS, elemental mapping, TEM and XRD. TEM micrograph has shown the formation of Cu NPs with the size in the range of 5-17nm. In addition, the synthesized Cu/ZnO NPs presented excellent catalytic activity for the degradation of Methylene blue (MB) and Congo red (CR) in the presence of NaBH4 in water at room temperature. PMID:27038280

  11. Enhanced metal loading in SBA-15-type catalysts facilitated by salt addition. Synthesis, characterization and catalytic epoxide alcoholysis activity of molybdenum incorporated porous silica

    Energy Technology Data Exchange (ETDEWEB)

    Budhi, Sridhar [Iowa State Univ., Ames, IA (United States); Colorado School of Mines, Golden, CO (United States); Peeraphatdit, Chorthip [Iowa State Univ., Ames, IA (United States); Pylypenko, Svitlana [Colorado School of Mines, Golden, CO (United States); Nguyen, Vy H.T. [Iowa State Univ., Ames, IA (United States); Ames Lab., Ames, IA (United States); Smith, Emily A. [Iowa State Univ., Ames, IA (United States); Ames Lab., Ames, IA (United States); Trewyn, Brian G. [Iowa State Univ., Ames, IA (United States); Colorado School of Mines, Golden, CO (United States)

    2014-02-07

    We report a novel method to increase the metal loading in SBA-15 silica matrix via direct synthesis. It was demonstrated through the synthesis and characterization of a series of molybdenum containing SBA-15 mesoporous silica catalysts prepared with and without diammonium hydrogen phosphate (DHP) as an additive. Catalysts prepared with DHP show a 2–3 times increase in incorporation of molybdenum in the silica matrix and pore size enlargement. The synthesized catalysts were characterized using nitrogen sorption, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma–optical emission spectroscopy (ICP–OES). The catalytic activity of catalysts prepared with DHP for alcoholysis of epoxides was superior than the catalyst prepared without DHP. Alcoholysis of epoxides was demonstrated for a range of alcohols and epoxides under ambient conditions in as little as 30 min with high selectivity.

  12. Synthesis, crystallization mechanism, and catalytic properties of titanium-rich TS-1 free of extraframework titanium species.

    Science.gov (United States)

    Fan, Weibin; Duan, Ren-Guan; Yokoi, Toshiyuki; Wu, Peng; Kubota, Yoshihiro; Tatsumi, Takashi

    2008-08-01

    A new route to the synthesis of TS-1 has been developed using (NH4)2CO3 as a crystallization-mediating agent. In this way, the framework Ti content can be significantly increased without forming extraframework Ti species. The prepared catalyst had a Si/Ti ratio as low as 34 in contrast to the ratio of 58 achieved with the methods A and B established by the Enichem group (Clerici, M. G.; Bellussi, G.; Romano, U. J. Catal. 1991, 129, 159) and Thangaraj and Sivasanker (Thangaraj, A.; Sivasanker, S. J. Chem. Soc., Chem. Commun. 1992, 123), respectively. The material contained less defect sites than the samples synthesized by the other two methods. As a result, it showed much higher activity for the oxidation of various organic substrates, such as linear alkanes/alkenes and alcohols, styrene, and benzene. The crystallization mechanism of TS-1 in the presence of (NH4)2CO3 was studied by following the whole crystallization process with X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetry/differential thermal analysis (TG/DTA), inductively coupled plasma atomic emission spectrometry (ICP), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-vis spectroscopy, and (29)Si MAS (magic-angle spinning) NMR spectroscopy techniques. It was shown that the presence of (NH4)2CO3 not only drastically lowered down pH, slowing down the crystallization process and making the incorporation of Ti into the framework match well with nucleation and crystal growth, but also modified the crystallization mechanism. It seems that the solid-phase transformation mechanism predominated in the crystallization process initiated by dissociation, reorganization, and recoalescence of the solidified gel although a small amount of nongelatinated Ti shifted to the solid during the crystal growth period. In contrast, a typical homogeneous nucleation mechanism occurred in the method A system. Thus, although in

  13. Synthesis of Highly Porous Poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) Asymmetric Membranes

    KAUST Repository

    Xie, Yihui

    2016-03-24

    For the first time, self-assembly and non-solvent induced phase separation was applied to polysulfone-based linear block copolymers, reaching mechanical stability much higher than other block copolymers membranes used in this method, which were mainly based on polystyrene blocks. Poly(tert-butyl acrylate)-b-polysulfone-b-poly(tert-butyl acrylate) (PtBA30k-b-PSU14k-b-PtBA30k) with a low polydispersity of 1.4 was synthesized by combining step-growth condensation and RAFT polymerization. Various advanced electron microscopies revealed that PtBA30k-b-PSU14k-b-PtBA30k assembles into worm-like cylindrical micelles in DMAc and adopts a “flower-like” arrangement with the PSU central block forming the shell. Computational modeling described the mechanism of micelle formation and morphological transition. Asymmetric nanostructured membranes were obtained with a highly porous interconnected skin layer and a sublayer with finger-like macrovoids. Ultrafiltration tests confirmed a water permeance of 555 L m-2 h-1 bar-1 with molecular weight cut-off of 28 kg/mol. PtBA segments on the membrane surface were then hydrolyzed and complexed with metals, leading to cross-linking and enhancement of antibacterial capability.

  14. Synthesis, characterization and thermal study of some transition metal complexes of an asymmetrical tetradentate Schiff base ligand

    Directory of Open Access Journals (Sweden)

    ACHUT S. MUNDE

    2010-03-01

    Full Text Available Complexes of Cu(II, Ni(II, Co(II, Mn(II and Fe(III with an asymmetric tetradentate Schiff base ligand derived from dehydroacetic acid, 4-methyl-o-phenylenediamine and salicylic aldehyde were synthesized and characterized by elemental analysis, conductometry, magnetic susceptibility, UV–Vis, IR, 1H-NMR spectroscopy, X-ray diffraction analysis of powdered samples and thermal analysis, and screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as a dibasic tetadentate ligand towards the central metal ion with an ONNO donor atoms sequence. From the microanalytical data, the stoichiometry of the complexes 1:1 (metal:ligand was found. The physico-chemical data suggested square planar geometry for the Cu(II and Ni(II complexes and octahedral geometry for the Co(II, Mn(II and Fe(III complexes. The thermal behaviour (TGA/DTA of the complexes was studied and kinetic parameters were determined by Horowitz–Metzger and Coats–Redfern methods. The powder X-ray diffraction data suggested a monoclinic crystal system for the Co(II, Mn(II and Fe(III complexes. The ligand and their metal complexes were screened for antibacterial activity against Staphylococcus aureus and Escherichia coli and fungicidal activity against Aspergillus niger and Trichoderma viride.

  15. 1: Mass asymmetric fission barriers for 98Mo; 2: Synthesis and characterization of actinide-specific chelating

    International Nuclear Information System (INIS)

    Excitation functions have been measured for complex fragment emission from the compound nucleus 98Mo, produced by the reaction of 86Kr with 12C. Mass asymmetric fission barriers have been obtained by fitting the excitation functions with a transition state formalism. The extracted barriers are ∼ 5.7 MeV higher, on average, than the calculations of the Rotating Finite Range Model (RFRM). These data clearly show an isospin dependence of the conditional barriers when compared with the extracted barriers from 90Mo and 94Mo. Eleven different liquid/liquid extractants were synthesized based upon the chelating moieties 3,2-HOPO and 3,4-HOPO; additionally, two liquid/liquid extractants based upon the 1,2-HOPO chelating moiety were obtained for extraction studies. The Pu(IV) extractions, quite surprisingly, yielded results that were very different from the Fe(III) extractions. The first trend remained the same: the 1,2-HOPOs were the best extractants, followed closely by the 3,2-HOPOs, followed by the 3,4-HOPOs; but in these Pu(IV) extractions the 3,4-HOPOs performed much better than in the Fe(III) extractions. 129 refs

  16. 1: Mass asymmetric fission barriers for {sup 98}Mo; 2: Synthesis and characterization of actinide-specific chelating agents

    Energy Technology Data Exchange (ETDEWEB)

    Veeck, A.C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Livermore National Lab., CA (United States). Glenn T. Seaborg Inst. for Transactinium Science]|[Lawrence Berkeley National Lab., CA (United States). Nuclear Science Div.

    1996-08-01

    Excitation functions have been measured for complex fragment emission from the compound nucleus {sup 98}Mo, produced by the reaction of {sup 86}Kr with {sup 12}C. Mass asymmetric fission barriers have been obtained by fitting the excitation functions with a transition state formalism. The extracted barriers are {approximately} 5.7 MeV higher, on average, than the calculations of the Rotating Finite Range Model (RFRM). These data clearly show an isospin dependence of the conditional barriers when compared with the extracted barriers from {sup 90}Mo and {sup 94}Mo. Eleven different liquid/liquid extractants were synthesized based upon the chelating moieties 3,2-HOPO and 3,4-HOPO; additionally, two liquid/liquid extractants based upon the 1,2-HOPO chelating moiety were obtained for extraction studies. The Pu(IV) extractions, quite surprisingly, yielded results that were very different from the Fe(III) extractions. The first trend remained the same: the 1,2-HOPOs were the best extractants, followed closely by the 3,2-HOPOs, followed by the 3,4-HOPOs; but in these Pu(IV) extractions the 3,4-HOPOs performed much better than in the Fe(III) extractions. 129 refs.

  17. Catalytic Asymmetric Umpolung Reactions of Imines

    OpenAIRE

    Wu, Yongwei; Hu, Lin; Li, Zhe; Deng, Li

    2015-01-01

    Imines, carbon-nitrogen double bonds, are fundamentally important functional groups in organic chemistry. This is largely due to the fact that imines act as electrophiles in C–C bond forming reactions towards carbon nucleophiles, thereby serving one of the most widely used precursors for the formation of amines in both synthetic and biosynthetic settings. 1–5 If the carbon atom of the imine could be rendered electron-rich, the imine could react as a nucleophile instead of as an electrophile. ...

  18. Direct asymmetric vinylogous aldol reaction of allyl ketones with isatins: Divergent synthesis of 3-hydroxy-2-oxindole derivatives

    KAUST Repository

    Zhu, Bo

    2013-05-03

    6 in 1: The highly enantioselective title reaction is mediated by a bifunctional catalyst and leads to E-configured vinylogous aldol products (see scheme). These products are used as common intermediates in the synthesis of six biologically active 3-hydroxy-2-oxindole derivatives (e.g., CPC-1). Computational studies indicated that the observed stereoselectivity is a result of favorable secondary π-π* and H-bonding interactions in the transition state. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Asymmetric synthesis of a functionalized tricyclo[6.2.0.02,6]decane ring system present in kelsoene and poduran

    Indian Academy of Sciences (India)

    Amrita Ghosh; Subrata Ghosh

    2014-11-01

    Synthesis of a functionalized tricyclo[6.2.0.02,6]decane derivative in enantiomerically pure form, the core structure present in the natural products kelsoene and poduran, is described. The key steps involve a stereocontrolled copper (I)-catalyzed intramolecular [2+2] photocycloaddition of a 1, 6-diene prepared from D-mannitol to form a substituted bicyclo[3.2.0]heptane derivative and a ring closing olefin metathesis involving the vicinal substituents on the five-membered ring of the bicyclo[3.2.0]heptane derivative.

  20. Synthesis of transparent ZnO/PMMA nanocomposite films through free-radical copolymerization of asymmetric zinc methacrylate acetate and in-situ thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Lin [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Li Fan, E-mail: lfan@ncu.edu.cn [Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Chen Yiwang, E-mail: ywchen@ncu.edu.cn [Department of Chemistry, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China); Wang Xiaofeng [Institute of Polymers, Nanchang University, 999 Xuefu Avenue, Nanchang 330031 (China)

    2011-08-15

    In this paper, a new and simple approach for in-situ preparation of transparent ZnO/poly(metyl methacrylate) (ZnO/PMMA) nanocomposite films was developed. Poly(methyl methacrylate)-co-poly(zinc methacrylate acetate) (PMMA-co-PZnMAAc) copolymer was synthesized via free-radical polymerization between methyl methacrylate (MMA) and zinc methacrylate acetate (ZnMAAc), where asymmetric ZnMAAc with only one terminal double bond (C=C) was applied to act as the precursor for ZnO nanocrystals and could avoid cross-link. Subsequently, transparent ZnO/PMMA nanocomposite films were obtained by in-situ thermal decomposition. Scanning electron microscope (SEM) image revealed that ZnO nanocrystals were homogeneously dispersed in PMMA matrix. With thermal decomposition time increasing, the absorption intensity in UV region and photoluminescence intensity of ZnO/PMMA nanocomposite films enhanced. However, the optical properties diminished when the thermal decomposition temperature increased. The TGA measurement displayed ZnO/PMMA nanocomposite films prepared by the in-situ synthesis method possessed better thermal stability compared with those prepared by the physical blending method and pristine PMMA films. - Highlights: > ZnO/PMMA hybrid films were prepared via free-radical polymerization and in-situ thermal decomposition. > ZnO NCs are homogeneously dispersed in the PMMA matrix and these films have good optical properties. > Thermal stability of these films is improved compared with those of physically blending ones.

  1. Characterization of 12-molybdophosphoric acid supported on mesoporous silica MCM-41 and its catalytic performance in the synthesis of hydroquinone diacetate

    International Nuclear Information System (INIS)

    12-molybdophosphoric acid (PMA) was supported on mesoporous molecular sieves MCM-41 by impregnation of 12-molybdophosphoric acid followed by calcination. The nanochannels of MCM-41 provide a large surface area for the solid state dispersion of 12-molybdophosphoric acid. The samples have been characterized by N2 adsorption–desorption at −196 °C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and FT-IR measurements. The acidity and catalytic activity have been, respectively, examined by nonaqueous titration of n-butylamine in acetonitrile and synthesis of hydroquinone diacetate. The results showed that ordered hexagonal pore structure was observed in the synthesized MCM-41. Also the results indicate that PMA are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles while PMA retains its Keggin structure. On the other hand, with increasing the introduced PMA amount, the specific surface area decreases, and the mesoporous ordering of the samples become poor. Both the surface acidity and the catalytic activity sharply increase with the modification of MCM-41 by PMA but decrease by increasing the calcination temperature. The sample with 55 wt% PMA/MCM-41 calcined at 350 °C shows the highest acidity and catalytic activity.

  2. Characterization of 12-molybdophosphoric acid supported on mesoporous silica MCM-41 and its catalytic performance in the synthesis of hydroquinone diacetate

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Awad I., E-mail: awahmed@mans.edu.eg [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Samra, S.E.; El-Hakam, S.A. [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt); Khder, A.S. [Faculty of Applied Science, Umm Al Qura University, Makkah (Saudi Arabia); El-Shenawy, H.Z.; El-Yazeed, W.S. Abo [Chemistry Department, Faculty of Science, Mansoura University, Mansoura (Egypt)

    2013-10-01

    12-molybdophosphoric acid (PMA) was supported on mesoporous molecular sieves MCM-41 by impregnation of 12-molybdophosphoric acid followed by calcination. The nanochannels of MCM-41 provide a large surface area for the solid state dispersion of 12-molybdophosphoric acid. The samples have been characterized by N{sub 2} adsorption–desorption at −196 °C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and FT-IR measurements. The acidity and catalytic activity have been, respectively, examined by nonaqueous titration of n-butylamine in acetonitrile and synthesis of hydroquinone diacetate. The results showed that ordered hexagonal pore structure was observed in the synthesized MCM-41. Also the results indicate that PMA are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles while PMA retains its Keggin structure. On the other hand, with increasing the introduced PMA amount, the specific surface area decreases, and the mesoporous ordering of the samples become poor. Both the surface acidity and the catalytic activity sharply increase with the modification of MCM-41 by PMA but decrease by increasing the calcination temperature. The sample with 55 wt% PMA/MCM-41 calcined at 350 °C shows the highest acidity and catalytic activity.

  3. Characterization of 12-molybdophosphoric acid supported on mesoporous silica MCM-41 and its catalytic performance in the synthesis of hydroquinone diacetate

    Science.gov (United States)

    Ahmed, Awad I.; Samra, S. E.; El-Hakam, S. A.; Khder, A. S.; El-Shenawy, H. Z.; El-Yazeed, W. S. Abo

    2013-10-01

    12-molybdophosphoric acid (PMA) was supported on mesoporous molecular sieves MCM-41 by impregnation of 12-molybdophosphoric acid followed by calcination. The nanochannels of MCM-41 provide a large surface area for the solid state dispersion of 12-molybdophosphoric acid. The samples have been characterized by N2 adsorption-desorption at -196 °C, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and FT-IR measurements. The acidity and catalytic activity have been, respectively, examined by nonaqueous titration of n-butylamine in acetonitrile and synthesis of hydroquinone diacetate. The results showed that ordered hexagonal pore structure was observed in the synthesized MCM-41. Also the results indicate that PMA are highly dispersed on mesoporous silica MCM-41 spherical nanoparticles while PMA retains its Keggin structure. On the other hand, with increasing the introduced PMA amount, the specific surface area decreases, and the mesoporous ordering of the samples become poor. Both the surface acidity and the catalytic activity sharply increase with the modification of MCM-41 by PMA but decrease by increasing the calcination temperature. The sample with 55 wt% PMA/MCM-41 calcined at 350 °C shows the highest acidity and catalytic activity.

  4. An asymmetric pericyclic cascade approach to oxindoles

    OpenAIRE

    Richmond, Edward

    2014-01-01

    The research in this thesis describes an asymmetric pericyclic cascade approach to the synthesis of a range of enantioenriched oxindoles using enantiopure oxazolidine derived nitrones and disubstituted ketenes. Chapter 1 aims to place this work in the context of the literature, describing other commonly employed or state-of-the-art asymmetric approaches to oxindoles and related compounds. Examples of where these approaches have been used successfully in the total synthesis of related indol...

  5. Synthesis and Catalytic Performance of Graphene Modified CuO-ZnO-Al2O3 for CO2 Hydrogenation to Methanol

    Directory of Open Access Journals (Sweden)

    Zheng-juan Liu

    2014-01-01

    Full Text Available CuO-ZnO-Al2O3 and graphene nanosheet (GNS were synthesized by coprecipitation route and reduction of exfoliated graphite oxides method, respectively. GNS modified CuO-ZnO-Al2O3 nanocomposites were synthesized by high energy ball milling method. The structure, morphology, and character of the synthesized materials were studied by BET, XRD, TEM, and H2-TPR. It was found that by high energy ball milling method the CuO-ZnO-Al2O3 nanoparticles were uniformly dispersed on GNS surfaces. The catalytic performance for the methanol synthesis from CO2 hydrogenation was also tested. It was shown experimentally that appropriate incorporation of GNS into the CuO-ZnO-Al2O3 could significantly increase the catalyst activity for methanol synthesis. The 10 wt.% GNS modified CuO-ZnO-Al2O3 catalyst gave a methanol space time yield (STY of 92.5% higher than that on the CuO-ZnO-Al2O3 catalyst without GNS. The improved catalytic performance was attributed to the excellent promotion of GNS to dispersion of CuO and ZnO particles.

  6. Synthesis, structural characterization and selectively catalytic properties of metal-organic frameworks with nano-sized channels: A modular design strategy

    International Nuclear Information System (INIS)

    Modular design method for designing and synthesizing microporous metal-organic frameworks (MOFs) with selective catalytical activity was described. MOFs with both nano-sized channels and potential catalytic activities could be obtained through self-assembly of a framework unit and a catalyst unit. By selecting hexaaquo metal complexes and the ligand BTC (BTC=1,3,5-benzenetricarboxylate) as framework-building blocks and using the metal complex [M(phen)2(H2O)2]2+ (phen=1,10-phenanthroline) as a catalyst unit, a series of supramolecular MOFs 1-7 with three-dimensional nano-sized channels, i.e. [M1(H2O)6].[M2(phen)2(H2O)2]2.2(BTC).xH2O (M1, M2=Co(II), Ni(II), Cu(II), Zn(II), or Mn(II), phen=1,10-phenanthroline, BTC=1,3,5-benzenetricarboxylate, x=22-24), were synthesized through self-assembly, and their structures were characterized by IR, elemental analysis, and single-crystal X-ray diffraction. These supramolecular microporous MOFs showed significant size and shape selectivity in the catalyzed oxidation of phenols, which is due to catalytic reactions taking place in the channels of the framework. Design strategy, synthesis, and self-assembly mechanism for the construction of these porous MOFs were discussed. - Grapical abstract: A modular design strategy has been developed to synthesize microporous metal-organic frameworks with potential catalytic activity by self-assembly of the framework-building blocks and the catalyst unit

  7. SYNTHESIS OF POLYMER-STABILIZED PLATINUM/RUTHENIUM BIMETALLIC COLLOIDS AND THEIR CATALYTIC PROPERTIES FOR SELECTIVE HYDROGENATION OF CROTONALDEHYDE

    Institute of Scientific and Technical Information of China (English)

    Wei-xia Tu; Han-fan Liu

    2005-01-01

    Polymer-stabilized platinum/ruthenium bimetallic colloids (Pt/Ru) were synthesized by polyol reduction with microwave irradiation and characterized by TEM and XPS. The colloidal nanoparticles have small and narrow size distributions. Catalytic performance of the Pt/Ru colloidal catalysts was investigated on the selective hydrogenation of crontonaldehyde (CRAL). A suitable amount of the added metal ions and base can improve the selectivity of CRAL to crotylalcohol (CROL) remarkably. The catalytic activity and the selectivity are dependent on the compositions of bimetallic colloids. Thereinto, PVP-stabilized 9Pt/1Ru colloid with a molar ratio of metals Pt:Ru = 9:1 shows the highest catalytic selectivity 77.3% to CROL at 333 K under 4.0 MPa of hydrogen.

  8. A novel green synthesis and characterization of Ag NPs with its ultra-rapid catalytic reduction of methyl green dye

    International Nuclear Information System (INIS)

    Ampicillin derived silver nanoparticles were synthesized in an aqueous medium. Particle size and shape were determined by Transmission electron microscopy which showed the monodispersed morphology. The Fourier transform infrared spectra were represented the interaction of Ampicillin with surface of Ampicillin derived silver nanoparticles. X-ray powder diffraction study gave crystalline nature of the Ampicillin derived silver nanoparticles which exhibited exceptional catalytic activity for the reduction of Methylene Green dye. However, complete reduction of dye was accomplished by Ampicillin derived silver nanoparticles within 4 min only. The catalytic performance of these nanoparticles was adsorbed on glass. They were recovered easily from reaction medium and reused with enhanced catalytic potential. Based upon these results it has been concluded that Ampicillin derived silver nanoparticles are novel, rapid and highly economical alternative for environmental safety against pollution by dyes and extendable for control of other reducible contaminants as well.

  9. Synthesis, characterization of bimetallic V-Fe-SBA-15 and its catalytic performance in the hydroxylation of phenol.

    Science.gov (United States)

    Gao, Fei; Zhang, Yanhua; Wang, Chunling; Wu, Cheng; Kong, Yan; Zhao, Bin; Dong, Lin; Chen, Yi

    2007-12-01

    A series of V-Fe incorporated-SBA-15 has been synthesized by adjustment of the pH value of the gel mixtures and characterized by using XRD, N2-adsorption, ICP, FT-IR, Raman, and UV-vis techniques. Results indicated that all samples exhibited typical hexagonal arrangement of mesoporous structure with high surface areas and the heteroatoms were probably incorporated into the framework of SBA-15. Catalytic performances of the obtained materials were evaluated in the hydroxylation of phenol with H2O2, and the catalytic results revealed that the selectivity for catechol (CAT) and hydroquinone (HQ) could be controlled by adjusting the contents of V and Fe in the samples, and an appropriate n(V)/n(Fe) mol ratio in SBA-15 could approach the optimal catalytic performance. PMID:18283835

  10. Experimental and numerical investigation of the catalytic partial oxidation of methane to synthesis gas for power generation applications[Dissertation 17183

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, A.

    2007-07-01

    The present work addresses the catalytic partial oxidation (CPO) of methane to synthesis gas, with particular emphasis on power generation applications. A combined experimental and numerical investigation of methane partial oxidation to synthesis gas (H{sub 2}, CO) over rhodium-based catalysts has been carried out at pressures of up to 10 bar. The reactivity of the produced hydrogen and the suitably-low light-off temperatures of the CPO reactor, greatly facilitate operation of power generation gas turbines with reduced NO{sub x} emissions, stable operation with low calorific value fuels, and new combustion strategies for efficient CO{sub 2} capture. Those strategies utilize CPO of methane with oxygen (separated from air) and large exhaust gas recycle (H{sub 2}O and CO{sub 2}). An optically accessible catalytic channel-flow reactor was used to carry out Raman spectroscopy of major gas-phase species and laser induced fluorescence (LIF) of formaldehyde, in order to gain fundamental information on the catalytic and gas-phase chemical pathways. Transverse concentration profiles measured by the spontaneous Raman scattering technique determined the catalytic reactivity, while the LIF provided flame shapes and anchoring positions that, in turn, characterized the gaseous reactivity. Comparison between measurements and 2-D CFD computations, led to the validation of detailed catalytic and gas-phase reaction mechanisms. Experiments in a subscale gas-turbine honeycomb catalytic reactor have shown that the foregoing reaction mechanisms were also appropriate under gas-turbine relevant conditions with short reactant residence times. The light-off behavior of the subscale honeycomb reactor was reproduced by transient 2-D CFD computations. Ignition and extinction in CPO was studied. It was shown that, despite the chemical impact of the H{sub 2}O diluent during the transient catalytic ignition event, the light-off times themselves were largely unaffected by the exhaust gas dilution

  11. Discovery and application of new bacterial strains for asymmetric synthesis of L-tert-butyl leucine in high enantioselectivity.

    Science.gov (United States)

    Jin, Jian-Zhong; Chang, Dong-Liang; Zhang, Jie

    2011-06-01

    Discovery of new bacterial strains with fast identification in a miniaturized system was performed for the synthesis of optically active L-tert-butyl leucine. With tert-butyl leucine amide as nitrogen source, one bacterial strain with high conversion and high enantioselectivity was discovered among 120 isolated microorganisms from local soils and identified as Mycobacterium sp. JX009. Glucose and ammonium chloride were examined as the good carbon source and nitrogen source for the cells' growth separately. The cells grew better at 30 °C and at pH 7.5 with higher activity of 2,650 U/l in comparison with other conditions. Cells' stability was improved by immobilization on synthetic resin 0730 without pretreatment. Tert-butyl leucine amide (30 mM) was successfully hydrolyzed by immobilized cells and examined as the highest chemical concentration that cells could endure. After six reaction cycles, the immobilized cells retained 90% activity with production of L-tert-butyl leucine in 98% ee. The results firstly reported the application of new bacterial strain in the hydrolysis of tert-butyl leucine amide to produce optically active L-tert-butyl leucine in an efficient way with investigation in detail. PMID:21153891

  12. Synthesis of novel carbon/silica composites based strong acid catalyst and its catalytic activities for acetalization

    Indian Academy of Sciences (India)

    Yueqing Lu; Xuezheng Liang; Chenze Qi

    2012-06-01

    Novel solid acid based on carbon/silica composites are synthesized through one-pot hydrothermal carbonization of hydroxyethylsulfonic acid, sucrose and tetraethyl orthosilicate (TEOS). The novel solid acid owned the acidity of 2.0 mmol/g, much higher than that of the traditional solid acids such as Nafion and Amberlyst-15 (0.8 mmol/g). The catalytic activities of the solid acid are investigated through acetalization. The results showed that the novel solid acid was very efficient for the reactions. The high acidity and catalytic activities made the novel carbon/silica composites based solid acid hold great potential for the green chemical processes.

  13. The Multiple Facets of Iodine(III) Compounds in an Unprecedented Catalytic Auto-amination for Chiral Amine Synthesis.

    Science.gov (United States)

    Buendia, Julien; Grelier, Gwendal; Darses, Benjamin; Jarvis, Amanda G; Taran, Frédéric; Dauban, Philippe

    2016-06-20

    Iodine(III) reagents are used in catalytic one-pot reactions, first as both oxidants and substrates, then as cross-coupling partners, to afford chiral polyfunctionalized amines. The strategy relies on an initial catalytic auto C(sp(3) )-H amination of the iodine(III) oxidant, which delivers an amine-derived iodine(I) product that is subsequently used in palladium-catalyzed cross-couplings to afford a variety of useful building blocks with high yields and excellent stereoselectivities. This study demonstrates the concept of self-amination of the hypervalent iodine reagents, which increases the value of the aryl moiety. PMID:27158802

  14. Reducing-Agent-Free Instant Synthesis of Carbon-Supported Pd Catalysts in a Green Leidenfrost Droplet Reactor and Catalytic Activity in Formic Acid Dehydrogenation

    Science.gov (United States)

    Lee, Dong-Wook; Jin, Min-Ho; Lee, Young-Joo; Park, Ju-Hyoung; Lee, Chun-Boo; Park, Jong-Soo

    2016-05-01

    The development of green synthesis methods for supported noble metal catalysts remains important challenges to improve their sustainability. Here we first synthesized carbon-supported Pd catalysts in a green Leidenfrost droplet reactor without reducing agents, high-temperature calcination and reduction procedures. When the aqueous solution containing Pd nitrate precursor, carbon support, and water is dripped on a hot plate, vapor layer is formed between a solution droplet and hot surface, which allow the solution droplet to be levitated on the hot surface (Leidenfrost phenomena). Subsequently, Pd nanoparticles can be prepared without reducing agents in a weakly basic droplet reactor created by the Leidenfrost phenomena, and then the as-prepared Pd nanoparticles are loaded on carbon supports during boiling down the droplet on hot surface. Compared to conventional incipient wetness and chemical synthetic methods, the Leidenfrost droplet reactor does not need energy-consuming, time-consuming, and environmentally unfriendly procedures, which leads to much shorter synthesis time, lower carbon dioxide emission, and more ecofriendly process in comparison with conventional synthesis methods. Moreover, the catalysts synthesized in the Leidenfrost droplet reactor provided much better catalytic activity for room-temperature formic acid decomposition than those prepared by the incipient wetness method.

  15. Design and Synthesis of Chiral Zn2+ Complexes Mimicking Natural Aldolases for Catalytic C–C Bond Forming Reactions in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Susumu Itoh

    2014-01-01

    Full Text Available Extending carbon frameworks via a series of C–C bond forming reactions is essential for the synthesis of natural products, pharmaceutically active compounds, active agrochemical ingredients, and a variety of functional materials. The application of stereoselective C–C bond forming reactions to the one-pot synthesis of biorelevant compounds is now emerging as a challenging and powerful strategy for improving the efficiency of a chemical reaction, in which some of the reactants are subjected to successive chemical reactions in just one reactor. However, organic reactions are generally conducted in organic solvents, as many organic molecules, reagents, and intermediates are not stable or soluble in water. In contrast, enzymatic reactions in living systems proceed in aqueous solvents, as most of enzymes generally function only within a narrow range of temperature and pH and are not so stable in less polar organic environments, which makes it difficult to conduct chemoenzymatic reactions in organic solvents. In this review, we describe the design and synthesis of chiral metal complexes with Zn2+ ions as a catalytic factor that mimic aldolases in stereoselective C–C bond forming reactions, especially for enantioselective aldol reactions. Their application to chemoenzymatic reactions in aqueous solution is also presented.

  16. Synthesis of porous NiFe2O4 microparticles and its catalytic properties for methane combustion

    International Nuclear Information System (INIS)

    Highlights: → Microporous NiFe2O4 spinel particles with uniform size of 1-2 μm was prepared by oxalic acid co-precipitation method. → The NiFe2O4 exhibits a good catalytic activity for methane combustion with the methane light-off temperature below 350 deg. C. → The excellent catalytic activity may be attributed to the surface oxygen vacancies arising from the peculiar inverse spinel structure with Oh site occupied by Fe2+ and Ni2+. - Abstract: In this paper, we report the obtention of agglomerate porous NiFe2O4 microparticles type-spinel with uniform size of 1-2 μm by the oxalic acid co-precipitation method. The structure, morphology and surface of microparticles as-synthesized were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), respectively. Fixed bed reactor test confirmed that the NiFe2O4 microparticles exhibit a good catalytic activity for methane combustion with the methane light-off temperature below 350 deg. C. XPS spectrum revealed that the excellent catalytic activity may be attributed to the surface oxygen vacancies arising from the peculiar inverse spinel structure with octahedral (Oh) site occupied by Fe2+ and Ni2+ cations.

  17. A green surfactant-assisted synthesis of hierarchical TS-1 zeolites with excellent catalytic properties for oxidative desulfurization.

    Science.gov (United States)

    Du, Shuting; Li, Fen; Sun, Qiming; Wang, Ning; Jia, Mingjun; Yu, Jihong

    2016-02-25

    Hierarchical TS-1 zeolites with uniform intracrystalline mesopores have been successfully synthesized through the hydrothermal method by using the green and cheap surfactant Triton X-100 as the mesoporous template. The resultant materials exhibit remarkably enhanced catalytic activity in oxidative desulfurization reactions compared to the conventional TS-1 zeolite. PMID:26881277

  18. Designed copper-amine complex as an efficient template for one-pot synthesis of Cu-SSZ-13 zeolite with excellent activity for selective catalytic reduction of NOx by NH3.

    Science.gov (United States)

    Ren, Limin; Zhu, Longfeng; Yang, Chengguang; Chen, Yanmei; Sun, Qi; Zhang, Haiyan; Li, Caijin; Nawaz, Faisal; Meng, Xiangju; Xiao, Feng-Shou

    2011-09-21

    Low-cost copper-amine complex was rationally designed to be a novel template for one-pot synthesis of Cu-SSZ-13 zeolites. Proper confirmation and appropriate size make this complex fit well with CHA cages as an efficient template. The products exhibit superior catalytic performance on NH(3)-SCR reaction. PMID:21625721

  19. Characterization and catalytic performance of CeO2-Co/SiO2 catalyst for Fischer-Tropsch synthesis using nitrogen-diluted synthesis gas over a laboratory scale fixed-bed reactor

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Dai; Changchun Yu

    2008-01-01

    The surface species of CO hydrogenation on CeO2-Co/SiO2 catalyst were investigated using the techniques of temperature programmed reaction and transient response method. The results indicated that the formation of H2O and CO2 was the competitive reaction for the surface oxygen species, CH4 was produced via the hydrogenation of carbon species step by step, and C2 products were formed by the polymerization of surface-active carbon species (-CH2-). Hydrogen assisted the dissociation of CO. The hydrogenation of surface carbon species was the rate-limiting step in the hydrogenation of CO over CeO2-Co/SiO2 catalyst. The investigation of total pressure, gas hourly space velocity (GHSV), and product distribution using nitrogen-rich synthesis gas as feedstock over a laboratory scale fixed-bed reactor indicated that total pressure and GHSV had a significant effect on the catalytic performance of CeO2-Co/SiO2 catalyst. The removal of heat and control of the reaction temperature were extremely critical steps, which required lower GHSV and appropriate CO conversion to avoid the deactivation of the catalyst. The feedstock of nitrogen-rich synthesis gas was favorable to increase the conversion of CO, but there was a shift of product distribution toward the light hydrocarbon. The nitrogen-rich synthesis gas was feasible for F-T synthesis for the utilization of remote natural gas.

  20. In situ catalytic synthesis of high-graphitized carbon-coated LiFePO4 nanoplates for superior Li-ion battery cathodes.

    Science.gov (United States)

    Ma, Zhipeng; Fan, Yuqian; Shao, Guangjie; Wang, Guiling; Song, Jianjun; Liu, Tingting

    2015-02-01

    The low electronic conductivity and one-dimensional diffusion channel along the b axis for Li ions are two major obstacles to achieving high power density of LiFePO4 material. Coating carbon with excellent conductivity on the tailored LiFePO4 nanoparticles therefore plays an important role for efficient charge and mass transport within this material. We report here the in situ catalytic synthesis of high-graphitized carbon-coated LiFePO4 nanoplates with highly oriented (010) facets by introducing ferrocene as a catalyst during thermal treatment. The as-obtained material exhibits superior performances for Li-ion batteries at high rate (100 C) and low temperature (-20 °C), mainly because of fast electron transport through the graphitic carbon layer and efficient Li(+)-ion diffusion through the thin nanoplates. PMID:25584530

  1. Solvothermal synthesis of octahedral NiFe2O4 nanocrystals and catalytic properties for the reduction of some aromatic nitrocompounds

    International Nuclear Information System (INIS)

    In this paper, we report the successful synthesis of octahedral NiFe2O4 nanocrystals with room-temperature ferrimagnetism via a mixed solvothermal process at 170 °C for 15 h, using Fe(NO3)3 and NiCl2 as starting reactants. The phase and morphology of the as-prepared product is characterized by means of powder X-ray diffraction, energy dispersive spectrometry, selected area electron diffraction (SAED), (high resolution) transmission electron microscopy, and scanning electron microscopy. Experiments showed that the as-prepared octahedral NiFe2O4 nanocrystals owned strong catalytic activity for the reduction of some aromatic nitro-compounds such as 4-nitrophenol, 2-nitroaniline, 4-nitroaniline, and 2,4-dinitrophenol. Under the presence of 9 mg NiFe2O4 nanocrystals, the rate constants of the reductive reactions were in turn 3.16 × 10−2 min−1 for 4-nitrophenol, 4.28 × 10−2 min−1 for 2-nitroaniline, 6.79 × 10−2 min−1 for 4-nitroaniline, and 3.26 × 10−2 min−1 for 2,4-dinitrophenol. Moreover, the present catalyst could be conveniently recycled due to its magnetism. After ten cycles, its catalytic efficiency did not obviously decrease. - Highlights: • Octahedral NiFe2O4 nanocrystals were successfully prepared by an emulsion-solvothermal route. • NiFe2O4 nanocrystals with the room-temperature magnetism could be used as a recyclable catalyst. • NiFe2O4 nanocrystals showed strong catalytic activity for the reduction of 4-NP in NaBH4 solution

  2. Solvothermal synthesis of octahedral NiFe{sub 2}O{sub 4} nanocrystals and catalytic properties for the reduction of some aromatic nitrocompounds

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Hangsong [College of Chemistry and Materials Science, Key Laboratory of Functional Molecular Solids of Ministry of Education, Anhui Laboratory of Molecule-Based Materials, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, 1 Beijing Eastern Road, Wuhu 241000 (China); Ni, Yonghong, E-mail: niyh@mail.ahnu.edu.cn [College of Chemistry and Materials Science, Key Laboratory of Functional Molecular Solids of Ministry of Education, Anhui Laboratory of Molecule-Based Materials, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, 1 Beijing Eastern Road, Wuhu 241000 (China); Xiang, Nannan [College of Chemistry and Materials Science, Key Laboratory of Functional Molecular Solids of Ministry of Education, Anhui Laboratory of Molecule-Based Materials, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, 1 Beijing Eastern Road, Wuhu 241000 (China); Ma, Xiang [Center of Modern Analyses, Nanjing University, Nanjing 210093 (China); Wan, Fengying [Library of Anhui Normal University, 1 Beijing Eastern Road, Wuhu 241000 (China)

    2015-05-05

    In this paper, we report the successful synthesis of octahedral NiFe{sub 2}O{sub 4} nanocrystals with room-temperature ferrimagnetism via a mixed solvothermal process at 170 °C for 15 h, using Fe(NO{sub 3}){sub 3} and NiCl{sub 2} as starting reactants. The phase and morphology of the as-prepared product is characterized by means of powder X-ray diffraction, energy dispersive spectrometry, selected area electron diffraction (SAED), (high resolution) transmission electron microscopy, and scanning electron microscopy. Experiments showed that the as-prepared octahedral NiFe{sub 2}O{sub 4} nanocrystals owned strong catalytic activity for the reduction of some aromatic nitro-compounds such as 4-nitrophenol, 2-nitroaniline, 4-nitroaniline, and 2,4-dinitrophenol. Under the presence of 9 mg NiFe{sub 2}O{sub 4} nanocrystals, the rate constants of the reductive reactions were in turn 3.16 × 10{sup −2} min{sup −1} for 4-nitrophenol, 4.28 × 10{sup −2} min{sup −1} for 2-nitroaniline, 6.79 × 10{sup −2} min{sup −1} for 4-nitroaniline, and 3.26 × 10{sup −2} min{sup −1} for 2,4-dinitrophenol. Moreover, the present catalyst could be conveniently recycled due to its magnetism. After ten cycles, its catalytic efficiency did not obviously decrease. - Highlights: • Octahedral NiFe{sub 2}O{sub 4} nanocrystals were successfully prepared by an emulsion-solvothermal route. • NiFe{sub 2}O{sub 4} nanocrystals with the room-temperature magnetism could be used as a recyclable catalyst. • NiFe{sub 2}O{sub 4} nanocrystals showed strong catalytic activity for the reduction of 4-NP in NaBH{sub 4} solution.

  3. Synthesis of dendritic iridium nanostructures based on the oriented attachment mechanism and their enhanced CO and ammonia catalytic activities

    Science.gov (United States)

    Wang, Chao; Xiao, Guanjun; Sui, Yongming; Yang, Xinyi; Liu, Gang; Jia, Mingjun; Han, Wei; Liu, Bingbing; Zou, Bo

    2014-11-01

    Branched iridium nanodendrites (Ir NDs) have been synthesized by a simple method based on the oriented attachment mechanism. Transmission electron microscopy images reveal the temporal growth process from small particles to NDs. Precursor concentrations and reaction temperatures have a limited effect on the morphology of Ir NDs. Metal oxide and hydroxide-supported Ir NDs exhibit enhanced activity for catalytic CO oxidation. Particularly, the Fe(OH)x-supported Ir NDs catalyst with a 4 wt% Ir loading show superior CO oxidation catalytic activity with a full conversion of CO at 120 °C. Furthermore, compared with Ir NPs and commercial Ir black, Ir NDs exhibit higher activity and stability for ammonia oxidation. The specific activity and mass activity of Ir NDs for ammonia oxidation are 1.7 and 7 times higher than that of Ir NPs. The improved catalytic activities of Ir NDs are attributed not only to their large specific surface area, but also to their considerably high index facets and rich edge and corner atoms. Hence, the obtained Ir NDs provide a promising alternative for direct ammonia fuel cells and proton-exchange membrane fuel cells.Branched iridium nanodendrites (Ir NDs) have been synthesized by a simple method based on the oriented attachment mechanism. Transmission electron microscopy images reveal the temporal growth process from small particles to NDs. Precursor concentrations and reaction temperatures have a limited effect on the morphology of Ir NDs. Metal oxide and hydroxide-supported Ir NDs exhibit enhanced activity for catalytic CO oxidation. Particularly, the Fe(OH)x-supported Ir NDs catalyst with a 4 wt% Ir loading show superior CO oxidation catalytic activity with a full conversion of CO at 120 °C. Furthermore, compared with Ir NPs and commercial Ir black, Ir NDs exhibit higher activity and stability for ammonia oxidation. The specific activity and mass activity of Ir NDs for ammonia oxidation are 1.7 and 7 times higher than that of Ir NPs. The

  4. One-pot synthesis of reduced graphene oxide supported PtCuy catalysts with enhanced electro-catalytic activity for the methanol oxidation reaction

    International Nuclear Information System (INIS)

    The outstanding performance PtCuy (y = 1,2,3) alloy nanoparticles supported on reduced graphene oxide (rGO) have been synthesized by a facile, efficient, one-pot hydrothermal synthesis approach. The as-prepared PtCuy/rGO catalysts are comprehensively characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy. Cyclic voltammetry, CO-stripping voltammetry and chronoamperometry results reveal that the PtCuy/rGO catalysts have higher electro-catalytic activity, more negative onset oxidative potential, more excellent tolerance ability for CO poisoning and enhanced stability for the electro-oxidation of methanol compared to pure Pt/rGO. As far as the as-made PtCuy/rGO catalysts are concerned, the PtCu2/rGO exhibits the highest electro-catalytic activity. The mechanism of the promoting effect of Cu on Pt is explained based on the electronic modification effect. The nature of interfacial interactions between the Pt-Cu active metal phase and the rGO supporting materials is crucial to achieving high performance

  5. Azadirachta indica plant-assisted green synthesis of Mn3O4 nanoparticles: Excellent thermal catalytic performance and chemical sensing behavior.

    Science.gov (United States)

    Sharma, Jitendra Kumar; Srivastava, Pratibha; Ameen, Sadia; Akhtar, M Shaheer; Singh, Gurdip; Yadava, Sudha

    2016-06-15

    The leaf extract of Azadirachta indica (Neem) plant was utilized as reducing agent for the green synthesis of Mn3O4 nanoparticles (NPs). The crystalline analysis demonstrated the typical tetragonal hausmannite crystal structure of Mn3O4, which confirmed the formation of Mn3O4 NPs without the existence of other oxides. Green synthesized Mn3O4 NPs were applied for the catalytic thermal decomposition of ammonium perchlorate (AP) and as working electrode for fabricating the chemical sensor. The excellent catalytic effect for the thermal decomposition of AP was observed by decreasing the decomposition temperature by 175°C with single decomposing step. The fabricated chemical sensor based on green synthesized Mn3O4 NPs displayed high, reliable and reproducible sensitivity of ∼569.2μAmM(-1)cm(-2) with reasonable limit of detection (LOD) of ∼22.1μM and the response time of ∼10s toward the detection of 2-butanone chemical. A relatively good linearity in the ranging from ∼20 to 160μM was detected for Mn3O4 NPs electrode based 2-butanone chemical sensor. PMID:27038784

  6. Large-scale synthesis of hierarchical-structured weissite (Cu2−xTe) flake arrays and their catalytic properties

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Large-scale Cu2−xTe flake arrays grown on copper foam were synthesized. • They possess superior catalytic efficiency on methylene blue with the assistance of H2O2. • The effects of preparing conditions on the growth of Cu2−xTe flake arrays were investigated. - Abstract: Large-scale weissite (Cu2−xTe) flake arrays with three-dimensional (3D) hierarchical structure have been successfully fabricated via a facile one-step solution-phase strategy through the reaction of tellurium powder and copper foam. At the end of the reaction Cu2−xTe flakes were distributed evenly on the surface of a porous solid copper substrate. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis showed the abundance of flakes grown on the 3D porous copper architecture, while X-ray diffraction (XRD) and energy-dispersive X-ray spectra (EDS) were used to determine the crystal structure and phase composition of these products. A series of experiments discovered that the size and morphology of the products could be affected by some reactive parameters including the reaction time, synthesis temperature and volume ratio of absolute ethanol/deionized water. Catalysis experiments using the in situ synthesized of Cu2−xTe flakes to catalyze the degradation of methylene blue (MB) demonstrated the strong catalytic ability of these flakes

  7. Preparation of highly ordered mesoporous AlSBA-15-SO 3H hybrid material for the catalytic synthesis of chalcone under solvent-free condition

    Science.gov (United States)

    Li, Wei; Xu, Kejin; Xu, Leilei; Hu, Jianglei; Ma, Fengyan; Guo, Yihang

    2010-03-01

    Single-step preparation of SBA-15 materials functionalized with both propylsulfonic acid groups and aluminum species (AlSBA-15-SO 3H) was carried out by hydrothermal treatment of a mixture of aluminum isopropoxide, 3-mercaptopropyltriethoxysilane, tetraethoxysilane, and triblock copolymer surfactant. At Si/Al molar ratio of 11-96, the materials exhibited well-ordered hexagonally arranged mesopores with pore diameter of ca. 9 nm, BET surface area of 546.9-666.0 m 2 g -1, and pore volume of 0.82-1.03 cm 3 g -1. As-prepared AlSBA-15-SO 3H was successfully used in the Claisen-Schmidt condensation reaction of benzaldehyde with acetophenone to produce chalcone under solvent-free condition, and the influence of the reaction parameters including temperatures, molar ratios of BZD to APN, and aluminum loadings were considered during the chalcone synthesis procedure. It showed that AlSBA-15-SO 3H exhibited significantly high catalytic activity and selectivity, outperforming the reference catalysts such as sulfuric acid, ZSM-5, and acidic MCM-49. In addition, the catalytic stability and regeneration of AlSBA-15-SO 3H was studied.

  8. Synthesis and characterization of type silicoaluminophosphates catalytic support; Sintese e caracterizacao de suportes cataliticos do tipo silicoaluminofosfatico

    Energy Technology Data Exchange (ETDEWEB)

    Leite, C.E.T.; Carvalho, M.W.N.C.; Pereira, K.R.O., E-mail: carlosedisio@hotmail.co [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Unidade Academica de Engenharia Quimica. Lab. de Catalise, Adsorcao e Biocombustiveis

    2010-07-01

    The refining processes, the catalytic hydrocracking is the future of diesel oil in Brazil and the first units are already scheduled to be inaugurated. Among the catalysts used in this process, silicoaluminophosphates (SAPO's) have considerable potential for use as they have been effective in the isomerization of n-alkanes, the isomerization of olefins and alkylation of aromatics. Because of this, the objective is to develop catalysts that will be used in hydrocracking reactions. The media like SAPO-5 were synthesized with different ratios silicon/aluminum, which is used as a catalytic support and have the function of crack organic molecules, since it has acidic character. The materials were characterized by techniques: X-ray diffraction, chemical analysis and textural by BET. After summarizing the media found that they had agreements with the crystalline phases presented in the literature.(author)

  9. Catalytic synthesis of 2-methylpyrazine over Cr-promoted copper based catalyst via a cyclo-dehydrogenation reaction route

    Indian Academy of Sciences (India)

    Fangli Jing; Yuanyuan Zhang; Shizhong Luo; Wei Chu; Hui Zhang; Xinyu Shi

    2010-07-01

    The cyclo-dehydrogenation of ethylene diamine and propylene glycol to 2-methylpyrazine was performed under the atmospheric conditions at 380°C. The Cr-promoted Cu-Zn/Al2O3 catalysts were prepared by impregnation method and characterized by ICP-AES, N2 adsorption/desorption, XRD, XPS, N2O chemisorption, TPR and NH3-TPD techniques. The amorphous chromium species existing in Cu-Zn-Cr/Al2O3 catalyst enhanced the dispersion of active component Cu, promoted the reduction of catalyst. Furthermore, the catalytic performance was significantly improved. The acidity of the catalyst played an important role in increasing the 2-MP selectivity. To optimize the reaction parameters, influences of different chromium content, reaction temperature, liquid hourly space velocity (LHSV), reactants molar ratio and time on stream on the product pattern were studied. The results demonstrated that addition of chromium promoter revealed satisfying catalytic activity, stability and selectivity of 2-methylpyrazine.

  10. Synthesis and Characterization of Metal Complexes to be Employed in the Catalytic Depolymerization of Lignin Model Compounds

    Energy Technology Data Exchange (ETDEWEB)

    Chmely, S. C.; Kim, S.; Beckham, G. T.

    2012-01-01

    Lignin is an earth-abundant biopolymer that is grossly underutilized as a value stream in current biomass conversion technologies because there exist no economic and technically feasible routes for lignin depolymerization and upgrading to fuels and chemicals. The development of new mild and selective catalytic routes to depolymerize this recalcitrant biopolymer is required to more effectively utilize lignin. To that end, our group aims to synthesize and characterize a collection of organometallic catalysts to promote atom-economical catalytic lignin deconstruction. These catalysts have been screened against dimeric lignin model compounds in order to gain mechanistic insights into their modes of action. In addition, experimental efforts have been coupled with quantum mechanical calculations to elucidate solution behavior of the catalysts as well as the mechanisms of lignin depolymerization. Detailed synthetic procedures, as well as spectroscopic and crystallographic characterization and DFT calculations will be presented.

  11. In situ synthesis, characterization, and catalytic performance of tungstophosphoric acid encapsulated into the framework of mesoporous silica pillared clay.

    Science.gov (United States)

    Li, Baoshan; Liu, Zhenxing; Han, Chunying; Ma, Wei; Zhao, Songjie

    2012-07-01

    Mesoporous silica pillared clay (SPC) incorporated with tungstophosphoric acid (HPW) has been synthesized via in situ introducing P and W source in the acidic suspension of the clay interlayer template during the formation of the silica pillared clay. The samples were characterized by XRD, XRF, FT-IR, TG-DTA, N(2) adsorption-desorption, and SEM techniques. The results showed that the HPW formed by in situ method has been effectively introduced into the framework of mesoporous silica pillared clay and its Keggin structure remained perfectly after formation of the materials. In addition, samples with similar HPW loadings were also prepared by impregnation method using SPC as the support. HPW in the incorporated samples was better dispersed into the silica pillared clay than in the impregnated samples. The results of catalytic tests indicated that the encapsulated materials demonstrated better catalytic performance than the impregnated samples in oxidative desulfurization (ODS) of dibenzothiophene (DBT). PMID:22513168

  12. Synthesis of CNTs/CuO and its catalytic performance on the thermal decomposition of ammonium perchlorate

    Directory of Open Access Journals (Sweden)

    Ping Cui

    2016-05-01

    Full Text Available Copper oxide (CuO nanoparticles were successfully deposited on carbon nanotubes’ (CNTs surface via complex-precipitation method, the nanocomposite was characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, X-ray powder diffraction (XRD, Raman spectroscopy, Fourier transform infrared (FT-IR and Brunauer–Emmett–Teller (BET. The catalytic performance of CNTs/CuO on ammonium perchlorate (AP decomposition was analyzed by differential thermal analyzer (DTA, the DTA results showed its excellent catalytic effect on AP decomposition, as 8 wt.% CNTs/CuO was added in AP, the second exothermic peak temperature decreased by 158 °C. Such composite may be a promising candidate for catalyzing the AP thermal decomposition.

  13. Facile synthesis of iron phosphide Fe{sub 2}P nanoparticle and its catalytic performance in thiophene hydrodesulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Xiang, E-mail: huangxianghd@gmail.com; Dong, Qing; Huang, He; Yue, Li; Zhu, Zhibin; Dai, Jinhui [Ocean University of China, Institute of Materials Science and Engineering (China)

    2014-12-15

    Nanosized iron phosphide (Fe{sub 2}P) was successfully synthesized under mild solvothermal conditions with environmental-friendly raw materials. The key synthetic parameters including the molar ratios of Fe/P in initial mixture, the solvothermal treatment temperature, and duration were systematically investigated, and the samples were characterized using X-ray diffraction, energy dispersive spectroscopy, and transmission electron microscopy. These measurements indicated that the nanoparticles are pure Fe{sub 2}P with an average particle size of about 20 nm. Furthermore, the catalytic performance of the as-synthesized Fe{sub 2}P/ZSM-5 in thiophene hydrodesulfurization was tested. The results showed that the desulfurization efficiency of thiophene can reach up to 88 % after 3 h with a stable catalytic activity during the whole examination process.

  14. Concise Asymmetric Synthesis and Pharmacological Characterization of All Stereoisomers of Glutamate Transporter Inhibitor TFB-TBOA and Synthesis of EAAT Photoaffinity Probes.

    Science.gov (United States)

    Leuenberger, Michele; Ritler, Andreas; Simonin, Alexandre; Hediger, Matthias A; Lochner, Martin

    2016-05-18

    Glutamate is the major excitatory neurotransmitter in the mammalian brain. Its rapid clearance after the release into the synaptic cleft is vital in order to avoid toxic effects and is ensured by several transmembrane transport proteins, so-called excitatory amino acid transporters (EAATs). Impairment of glutamate removal has been linked to several neurodegenerative diseases and EAATs have therefore received increased attention as therapeutic targets. O-Benzylated l-threo-β-hydroxyaspartate derivatives have been developed previously as highly potent inhibitors of EAATs with TFB-TBOA ((2S,3S)-2-amino-3-((3-(4-(trifluoromethyl)benzamido)benzyl)oxy)succinic acid) standing out as low-nanomolar inhibitor. We report the stereoselective synthesis of all four stereoisomers of TFB-TBOA in less than a fifth of synthetic steps than the published route. For the first time, the inhibitory activity and isoform selectivity of these TFB-TBOA enantio- and diastereomers were assessed on human glutamate transporters EAAT1-3. Furthermore, we synthesized potent photoaffinity probes based on TFB-TBOA using our novel synthetic strategy. PMID:26918289

  15. Shape-controlled synthesis of Sn-doped CuO nanoparticles for catalytic degradation of Rhodamine B.

    Science.gov (United States)

    Vomáčka, Petr; Štengl, Václav; Henych, Jiří; Kormunda, Martin

    2016-11-01

    The uniform Sn-doped CuO nanoparticles were synthesized by a simple solution method at a low temperature. The prepared samples were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), electron microscopy techniques (HRSEM, HRTEM, SAED, STEM and EDS elemental mapping), atomic force microscopy (AFM), UV/Vis spectroscopy, nitrogen physisorption (BET) and by evaluation of the catalytic activity on the degradation of Rhodamine B. The tin doping had a considerable influence on the morphology of CuO. The gradual narrowing of the particles morphology in the crystallographic [010] direction was observed with increasing the dopant concentration. The plate-like, rectangularsquare and rod-like CuO nanoparticles were obtained. The mechanism of a crystal growth of CuO associated with doping is proposed. The tin doping also affected the structural and optical properties of CuO. Increasing the amount of a dopant led to a red-shift of a band gap from 1.33 to 1.18eV. The incorporation of tin into the structure of copper oxide was confirmed by XRD and distribution of tin mapped by EDS analysis. The good catalytic properties of the as-prepared doped material were demonstrated by the enhanced catalytic removal of Rhodamine B in the presence of H2O2. The undoped CuO nanosheets reached only 24% efficiency in the removal of Rhodamine B within two hours. The best result exhibited CuO_050Sn sample containing 4at.% of tin and the degradation of Rhodamine B reached 99% within the same time. We have demonstrated a simple, scalable process for the preparation of catalytically very active Sn-doped CuO nanoparticles with varying properties. PMID:27450889

  16. Organocatalytic Asymmetric Michael Additions%有机催化不对称Michael加成反应

    Institute of Scientific and Technical Information of China (English)

    李宁; 郗国宏; 吴秋华; 刘伟华; 马晶军; 王春

    2009-01-01

    有机催化的不对称合成反应是目前研究最为活跃的领域之一.不对称Michael加成反应是合成众多重要的手性合成子和药物中间体的有效手段.目前报道的催化Michael加成反应的有机催化剂主要有脯氨酸及其衍生物、手性咪唑啉酮、手性(硫)脲、金鸡纳碱衍生物等.对各类有机催化剂在有机催化不对称Michael加成反应中的应用,以及不对称诱导反应的机理、催化剂分子结构及反应条件对其催化活性和不对称诱导作用的影响进行了评述.%Organocatalytic asymmetric reaction is an increasingly active area in organic synthesis. The asymmetric Michael addition provides a rapid access to versatile important chiral building blocks and intermediates for the synthesis of bioactive agrochemicals and pharmaceutical compounds. The reported organocatalysts for asymmetric Michael additions include proline and its derivatives, chiral imidazolidinone derivatives, chiral (thio) urea, cinchona alkaloids and so on. The applications of various organocatalysts to asymmetric Michael additions are reviewed in this paper. The reaction mechanism, catalytic activity and the asymmetric induction influenced by the structure of organocatalysts and the reaction condition are also discussed.

  17. Synthesis, spectroscopic and catalytic properties of some new boron hybrid molecule derivatives by BF2 and BPh2 chelation

    Science.gov (United States)

    Kilic, Ahmet; Alcay, Ferhat; Aydemir, Murat; Durgun, Mustafa; Keles, Armagan; Baysal, Akın

    2015-05-01

    A new series of Schiff base ligands (L1-L3) and their corresponding fluorine/phenyl boron hybrid complexes [LnBF2] and [LnBPh2] (n = 1, 2 or 3) have been synthesized and well characterized by both analytical and spectroscopic methods. The Schiff base ligands and their corresponding fluorine/phenyl boron hybrid complexes have been characterized by NMR (1H, 13C and 19F), FT-IR, UV-Vis, LC-MS, and fluorescence spectroscopy as well as melting point and elemental analysis. The fluorescence efficiencies of phenyl chelate complexes are greatly red-shifted compared to those of the fluorine chelate analogs based on the same ligands, presumably due to the large steric hindrance and hard π → π∗ transition of the diphenyl boron chelation, which can effectively prevent molecular aggregation. The boron hybrid complexes were applied to the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the presence of 2-propanol as the hydrogen source. The catalytic studies showed that boron hybrid complexes are good catalytic precursors for transfer hydrogenation of aromatic ketones in 0.1 M iso-PrOH solution. Also, we have found that both steric and electronic factors have a significant impact on the catalytic properties of this class of molecules.

  18. Catalytic aziridination of electron-deficient olefins with an N-chloro-N-sodio carbamate and application of this novel method to asymmetric synthesis.

    Science.gov (United States)

    Minakata, Satoshi; Murakami, Yuta; Tsuruoka, Ryoji; Kitanaka, Shinsuke; Komatsu, Mitsuo

    2008-12-21

    A new method for the aziridination of electron-deficient olefins using an N-chloro-N-sodio carbamate is described; the reaction was promoted by phase-transfer catalysis (solid-liquid) and afforded aziridines from alpha,beta-unsaturated ketones, esters, sulfones and amides. PMID:19048156

  19. Catalytic Asymmetric Synthesis of Both Enantiomers of 4‑Substituted 1,4-Dihydropyridines with the Use of Bifunctional Thiourea-Ammonium Salts Bearing Different Counterions

    Directory of Open Access Journals (Sweden)

    Kohzo Yoshida

    2010-11-01

    Full Text Available Organoammonium salts composed of a Brønsted acid and an anilinothiourea promoted the Michael addition of β-keto esters and α,β-unsaturated aldehydes in the presence of primary amines to give functionalized 1,4-dihydropyridines enantioselectively. With the use of the different Brønsted acids such as DFA and HBF4 with the same bifunctional thiourea, both enantiomers of 4-substituted 1,4-dihydropyridine were synthesized from the same starting materials.

  20. A new oxidovanadium(IV) Schiff base complex containing asymmetric tetradentate ONN′O′ Schiff base ligand: synthesis, characterization, crystal structure determination, thermal study and catalytic activity

    Czech Academy of Sciences Publication Activity Database

    Grivani, G.; Ghavami, A.; Eigner, Václav; Dušek, Michal; Khalaji, A.D.

    2015-01-01

    Roč. 26, č. 6 (2015), s. 779-784. ISSN 1001-8417 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : oxidovanadium(IV) * Schiff base * crystal structure * nanoparticle * epoxidation Subject RIV: CC - Organic Chemistry Impact factor: 1.587, year: 2014

  1. Efficient Synthesis of Chiral Trisubstituted 1,2‐Allenyl Ketones by Catalytic Asymmetric Conjugate Addition of Malonic Esters to Enynes

    Science.gov (United States)

    Yao, Qian; Liao, Yuting; Lin, Lili; Lin, Xiaobin; Ji, Jie

    2015-01-01

    Abstract An N,N′‐dioxide/scandium(III) complex catalyzed, highly efficient conjugate addition of malonic esters to enynes is described. A range of trisubstituted 1,2‐allenyl ketones were obtained in high yields (up to 99 %) with good d.r. (up to 95/5) and excellent ee values (97 %–99 %). Moreover, the products could be easily transformed into chiral furan and 5‐hydroxypyrazoline derivatives, both of which are important skeletons of many biologically active compounds and pharmacologicals. PMID:26694204

  2. Asymmetric collider

    International Nuclear Information System (INIS)

    The study of CP violation in beauty decay is one of the key challenges facing high energy physics. Much work has not yielded a definitive answer how this study might best be performed. However, one clear conclusion is that new accelerator facilities are needed. Proposals include experiments at asymmetric electron-positron colliders and in fixed-target and collider modes at LHC and SSC. Fixed-target and collider experiments at existing accelerators, while they might succeed in a first observation of the effect, will not be adequate to study it thoroughly. Giomataris has emphasized the potential of a new approach to the study of beauty CP violation: the asymmetric proton collider. Such a collider might be realized by the construction of a small storage ring intersecting an existing or soon-to-exist large synchrotron, or by arranging collisions between a large synchrotron and its injector. An experiment at such a collider can combine the advantages of fixed-target-like spectrometer geometry, facilitating triggering, particle identification and the instrumentation of a large acceptance, while the increased √s can provide a factor > 100 increase in beauty-production cross section compared to Tevatron or HERA fixed-target. Beams crossing at a non-zero angle can provide a small interaction region, permitting a first-level decay-vertex trigger to be implemented. To achieve large √s with a large Lorentz boost and high luminosity, the most favorable venue is the high-energy booster (HEB) at the SSC Laboratory, though the CERN SPS and Fermilab Tevatron are also worth considering

  3. The synthesis and characterisation of MDMA derived from a catalytic oxidation of material isolated from black pepper reveals potential route specific impurities.

    Science.gov (United States)

    Plummer, Christopher M; Breadon, Thomas W; Pearson, James R; Jones, Oliver A H

    2016-05-01

    This work examines the chemical synthesis of 3,4-methylenedioxy-N-methylamphetamine (MDMA) from piperonal prepared via a catalytic ruthenium tetroxide oxidation of piperine extracted from black pepper. A variety of oxidation conditions were experimented with including different solvent systems and co-oxidants. A sample of prepared piperonal was successfully converted into MDMA via 3,4-methylenedioxyphenyl-2-nitropropene (MDP2NP) and 3,4-methylenedioxyphenyl-2-propanone (MDP2P) and the impurities within each product characterised by GC-MS to give a contaminant profile of the synthetic pathway. Interestingly, it was discovered that a chlorinated analogue of piperonal (6-chloropiperonal) was created during the oxidation process by an as yet unknown mechanism. This impurity reacted alongside piperonal to give chlorinated analogues of each precursor, ultimately yielding 2-chloro-4,5-methylenedioxymethamphetamine (6-Cl-MDMA) as an impurity within the MDMA sample. The methodology developed is a simple way to synthesise a substantial amount of precursor material with easy to obtain reagents. The results also show that chlorinated MDMA analogues, previously thought to be deliberately included adulterants, may in fact be route specific impurities with potential application in determining the origin and synthesis method of seized illicit drugs. PMID:27162021

  4. Synthesis of LaNiO{sub 3} perovskite by the modified proteic gel method and study of catalytic properties in the syngas production

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Jose C.; Mesquita, Maria E.; Pedrosa, Anne M. Garrido, E-mail: annemgp@ufs.br, E-mail: annemgp@yahoo.com [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Departamento de Quimica e Engenharia Quimica; Souza, Marcelo J.B. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Departamento de Engenharia Quimica; Ruiz, Juan A.C. [Centro de Tecnologias do Gas e Energias Renovaveis (CTGAS-ER), Natal, RN (Brazil). Laboratorio de Processamento do Gas; Melo, Dulce M.A. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Centro de Ciencias Exatas e da Terra. Depaertamento de Quimica

    2012-10-15

    This work describes a study on the synthesis of LaNiO{sub 3} perovskites via the modified proteic gel method, varying collagen content and on the catalytic activity of LaNiO{sub 3} and LaNiO{sub 3}/Al{sub 2}O{sub 3} in the syngas (CO + H{sub 2}) production. X-ray diffraction patterns revealed the formation of perovskite structure in all samples prepared by proteic gel synthesis method, varying collagen content and after calcination at 700 deg C for 2 h. LaNiO{sub 3}/Al{sub 2}O{sub 3} catalyst prepared by the impregnation method showed diffraction peaks due to the perovskite structure and to the support (Al{sub 2}O{sub 3}). This catalyst presented: specific surface of 46.1 m{sup 2} g{sup -1}, two reduction peaks in the temperature programmed reduction (TPR) profile and 46% of methane conversion (by the partial oxidation of methane using oxygen) after 18 h of reaction. (author)

  5. Composite polymer/oxide hollow fiber contactors: versatile and scalable flow reactors for heterogeneous catalytic reactions in organic synthesis.

    Science.gov (United States)

    Moschetta, Eric G; Negretti, Solymar; Chepiga, Kathryn M; Brunelli, Nicholas A; Labreche, Ying; Feng, Yan; Rezaei, Fateme; Lively, Ryan P; Koros, William J; Davies, Huw M L; Jones, Christopher W

    2015-05-26

    Flexible composite polymer/oxide hollow fibers are used as flow reactors for heterogeneously catalyzed reactions in organic synthesis. The fiber synthesis allows for a variety of supported catalysts to be embedded in the walls of the fibers, thus leading to a diverse set of reactions that can be catalyzed in flow. Additionally, the fiber synthesis is scalable (e.g. several reactor beds containing many fibers in a module may be used) and thus they could potentially be used for the large-scale production of organic compounds. Incorporating heterogeneous catalysts in the walls of the fibers presents an alternative to a traditional packed-bed reactor and avoids large pressure drops, which is a crucial challenge when employing microreactors. PMID:25865826

  6. Catalytic Synthesis of α-Aminonitriles Using Nano Copper Ferrite CuFe2O4 under Green Conditions

    OpenAIRE

    Ali Gharib; Nader Noroozi Pesyan; Leila Vojdani Fard; Mina Roshani

    2014-01-01

    Copper ferrite nanomaterial CuFe2O4 as reusable heterogeneous initiator in the synthesis of α-aminonitriles. The nanocatalyst is easily recovered and its reusability is recorded. Synthesis of α-aminonitriles derivatives by one-pot reaction of different aldehydes with amines and trimethylsilyl cyanides has been developed using nano copper ferrite CuFe2O4 catalyst under room temperature and green solvent (water as solvent) conditions. α-aminonitriles are important in preparing a wide variety of...

  7. Binuclear ruthenium(III) bis(thiosemicarbazone) complexes: Synthesis, spectral, electrochemical studies and catalytic oxidation of alcohol

    Science.gov (United States)

    Mohamed Subarkhan, M.; Ramesh, R.

    2015-03-01

    A new series of binuclear ruthenium(III) thiosemicarbazone complexes of general formula [(EPh3)2(X)2Ru-L-Ru(X)2(EPh3)2] (where E = P or As; X = Cl or Br; L = NS chelating bis(thiosemicarbazone ligands) has been synthesized and characterized by analytical and spectral (FT-IR, UV-Vis and EPR). IR spectra show that the thiosemicarbazones behave as monoanionic bidentate ligands coordinating through the azomethine nitrogen and thiolate sulphur. The electronic spectra of the complexes indicate that the presence of d-d and intense LMCT transitions in the visible region. The complexes are paramagnetic (low spin d5) in nature and all the complexes show rhombic distortion around the ruthenium ion with three different 'g' values (gx ≠ gy ≠ gz) at 77 K. All the complexes are redox active and exhibit an irreversible metal centered redox processes (RuIII-RuIII/RuIV-RuIV; RuIII-RuIII/RuII-RuII) within the potential range of 0.38-0.86 V and -0.39 to -0.66 V respectively, versus Ag/AgCl. Further, the catalytic efficiency of one of the complexes [Ru2Cl2(AsPh3)4(L1)] (4) has been investigated in the case of oxidation of primary and secondary alcohols into their corresponding aldehydes and ketones in the presence of N-methylmorpholine-N-oxide(NMO) as co-oxidant. The formation of high valent RuVdbnd O species is proposed as catalytic intermediate for the catalytic cycle.

  8. Synthesis, characterization and catalytic activity of Au nanoparticles supported on PANI/α-Fe2O3 composite carriers

    International Nuclear Information System (INIS)

    A novel nanocomposite composed of gold nanoparticles, polyaniline (PANI) and hematite (α-Fe2O3) with core–shell structure has been successfully synthesized through a three-step process. Firstly, α-Fe2O3 cores were prepared by the forced hydrolysis of FeCl3. And then, aniline was polymerized in the suspension of α-Fe2O3. Finally, a surface reduction–oxidation was carried out between composite carriers and chloroauric acid to obtain the three-component nanocomposites. The morphology, crystalline structure and optical properties of the nanocomposites were measured by using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectrometer and Ultraviolet–visible (UV–vis) spectrophotometer. The results showed that the surface of α-Fe2O3 cores was coated by PANI to form core–shell structure, and Au nanoparticles were deposited on the outer surface of PANI. The average sizes of immobilized Au were 5.6 and 8.1 nm respectively. In the degradation of Rhodamine B in the presence of NaBH4, the as-prepared nanocomposites exhibit an excellent catalytic activity, and the conversion rate of Rhodamine B reached 100% in 7.5 min. -- Graphical abstract: A three-component nanocomposite with Au nanoparticles deposited on PANI/α-Fe2O3 composite carriers was synthesized for the first time, which showed an excellent catalytic activity in the reduction of Rhodamine B. Highlights: ► Three-component nanocomposites of gold, polyaniline and hematite were synthesized. ► The nanocomposites were with typical core–shell structure. ► The nanocomposites present excellent catalytic activity. ► Catalyzed by nanocomposites, 100% of RhB could be hydrogenated in 7.5 min.

  9. Green synthesis of Pd/CuO nanoparticles by Theobroma cacao L. seeds extract and their catalytic performance for the reduction of 4-nitrophenol and phosphine-free Heck coupling reaction under aerobic conditions.

    Science.gov (United States)

    Nasrollahzadeh, Mahmoud; Sajadi, S Mohammad; Rostami-Vartooni, Akbar; Bagherzadeh, Mojtaba

    2015-06-15

    We report the green synthesis of palladium/CuO nanoparticles (Pd/CuO NPs) using Theobroma cacao L. seeds extract and their catalytic activity for the reduction of 4-nitrophenol and Heck coupling reaction under aerobic conditions. The catalyst was characterized using the powder XRD, TEM, EDS, UV-vis and FT-IR. This method has the advantages of high yields, elimination of surfactant, ligand and homogeneous catalysts, simple methodology and easy work up. The catalyst can be recovered from the reaction mixture and reused several times without any significant loss of catalytic activity. PMID:25721860

  10. Synthesis, spectral, characterization, catalytic and biological studies of new RuII N2O Schiff base complexes

    International Nuclear Information System (INIS)

    Complexes of the type (RuCl(CO)(B)(L)) (B = PPh3, AsPh3, py or pip; L monobasic tridentate Schiff base) have been synthesized by the reaction of equimolar amounts of (RuHCl(CO)(EPh3)2(B)) and Schiff bases in benzene. The resulting complexes have been characterized by analytical and spectral (IR, electronic, NMR) data. An octahedral structure has been assigned to all these complexes. The new complexes have been exhibit catalytic activity for the oxidation of benzyl alcohol and cyclohexanol in the presence of N-methylmorpholine-N-oxide as co-oxidant. (author)

  11. Synthesis of carbon nanotubes by catalytic pyrolysis method with Feitknecht compound as precursor of NiZnAl catalyst

    Institute of Scientific and Technical Information of China (English)

    Yan Xiaoqi; Liu Quanrun; Zhang Songlin; Zhang Kun; Chen Jiuling; Li Yongdan

    2004-01-01

    Carbon nanotubes are synthesized by catalytic pyrolysis method with a kind of new type catalyst--nickel-zinc-alumina catalyst prepared from Feitknecht compound. Tubular carbon nanotubes, bamboo-shaped carbon naotubes, herringbone carbon nanotubues and branched carbon nanotubes are all found formed at moderate temperature. It is important for the formation of quasi-liquid state of the metal nanoparticles at the tip of carbon naotubes during the growth of carbon nanotubes to lead to different kinds of carbon nanotubes. It is likely that the addition of zinc make the activity of nickel catalyst after calcinations and reduction changed strangely.

  12. Near-Monodisperse Ni-Cu Bimetallic Nanocrystals of Variable Composition: Controlled Synthesis and Catalytic Activity for H2 Generation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yawen; Huang, Wenyu; Habas, Susan E.; Kuhn, John N.; Grass, Michael E.; Yamada, Yusuke; Yang, Peidong; Somorjai, Gabor A.

    2008-07-22

    Near-monodisperse Ni{sub 1-x}Cu{sub x} (x = 0.2-0.8) bimetallic nanocrystals were synthesized by a one-pot thermolysis approach in oleylamine/1-octadecene, using metal acetylacetonates as precursors. The nanocrystals form large-area 2D superlattices, and display a catalytic synergistic effect in the hydrolysis of NaBH{sub 4} to generate H{sub 2} at x = 0.5 in a strongly basic medium. The Ni{sub 0.5}Cu{sub 0.5} nanocrystals show the lowest activation energy, and also exhibit the highest H{sub 2} generation rate at 298 K.

  13. Catalytic addition methods for the synthesis of functionalized diazoacetoacetates and application to the construction of highly substituted cyclobutanones.

    Science.gov (United States)

    Doyle, Michael P; Kundu, Kousik; Russell, Albert E

    2005-11-10

    [reaction: see text] Methyl 3-(trialkylsilanyloxy)-2-diazo-3-butenoate undergoes Lewis acid-catalyzed Mukaiyama aldol addition with aromatic and aliphatic aldehydes in the presence of low catalytic amounts of Lewis acids in nearly quantitative yields. Scandium(III) triflate is the preferred catalyst and, notably, addition proceeds without decomposition of the diazo moiety. Diazoacetoacetate products from reactions with aromatic aldehydes undergo rhodium(II)-catalyzed ring closure to cyclobutanones with high diastereocontrol. Examples of complimentary Mannich-type addition reactions with imines are reported. PMID:16268530

  14. Synthesis of small silver nanoparticles under light radiation by fungus Penicillium oxalicum and its application for the catalytic reduction of methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Du, Liangwei, E-mail: dulily9@163.com [State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); College of Chemistry and Chemical Engineering, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); Xu, Qiuhong; Huang, Meiying [State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); College of Chemistry and Chemical Engineering, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); Xian, Liang [State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); Feng, Jia-Xun, E-mail: jiaxunfeng@sohu.com [State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China)

    2015-06-15

    At present, green and efficient synthetic strategies have been gaining great interest for the synthesis of metal nanoparticles. In this study, the synthesis of extracellular silver nanoparticles (AgNPs) under light radiation was described using the cell filtrate of Penicillium oxalicum 1–208. The pH effect of the cell filtrate on nanosynthesis was investigated by visual observation, ultraviolet–visible absorption spectroscopy, dynamic light scattering and zeta potential. The results showed that the pH of the cell filtrate affected the time of nanosynthesis, and the size, size distribution and stability of the synthesized nanoparticles. The AgNPs synthesized at pH 8.0 and 12.0 were further characterized by X-ray diffraction, selected area electron diffraction, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The synthesized AgNPs were spherical in shape, crystalline in nature and preferentially oriented in (111) plane. Small AgNPs with an average particle size of about 4 nm were successfully synthesized at pH 12.0 and well dispersed in solution without obvious aggregation. Furthermore, the AgNPs synthesized at pH 8.0 were used as catalyst and exhibited excellent catalytic activity for the reduction of methylene blue in the presence of NaBH{sub 4} at ambient temperature. - Highlights: • Extracellular silver nanoparticles were synthesized using Penicillium oxalicum assisted by simulated sunlight. • The pH of the cell filtrate affected the synthesis of silver nanoparticles. • The silver nanoparticles were more stable in weakly alkaline and alkaline solutions. • Small silver nanoparticles with good dispersibility and stability were rapidly synthesized at pH 12.0. • The reduction of methylene blue was instantly completed with silver nanoparticles synthesized at pH 8.0 used as catalyst.

  15. Synthesis of small silver nanoparticles under light radiation by fungus Penicillium oxalicum and its application for the catalytic reduction of methylene blue

    International Nuclear Information System (INIS)

    At present, green and efficient synthetic strategies have been gaining great interest for the synthesis of metal nanoparticles. In this study, the synthesis of extracellular silver nanoparticles (AgNPs) under light radiation was described using the cell filtrate of Penicillium oxalicum 1–208. The pH effect of the cell filtrate on nanosynthesis was investigated by visual observation, ultraviolet–visible absorption spectroscopy, dynamic light scattering and zeta potential. The results showed that the pH of the cell filtrate affected the time of nanosynthesis, and the size, size distribution and stability of the synthesized nanoparticles. The AgNPs synthesized at pH 8.0 and 12.0 were further characterized by X-ray diffraction, selected area electron diffraction, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The synthesized AgNPs were spherical in shape, crystalline in nature and preferentially oriented in (111) plane. Small AgNPs with an average particle size of about 4 nm were successfully synthesized at pH 12.0 and well dispersed in solution without obvious aggregation. Furthermore, the AgNPs synthesized at pH 8.0 were used as catalyst and exhibited excellent catalytic activity for the reduction of methylene blue in the presence of NaBH4 at ambient temperature. - Highlights: • Extracellular silver nanoparticles were synthesized using Penicillium oxalicum assisted by simulated sunlight. • The pH of the cell filtrate affected the synthesis of silver nanoparticles. • The silver nanoparticles were more stable in weakly alkaline and alkaline solutions. • Small silver nanoparticles with good dispersibility and stability were rapidly synthesized at pH 12.0. • The reduction of methylene blue was instantly completed with silver nanoparticles synthesized at pH 8.0 used as catalyst

  16. Pd-Modified Cu–Zn Catalysts for Methanol Synthesis from CO2/H2 Mixtures : Catalytic Structures and Performance

    NARCIS (Netherlands)

    Fierro, J.L.G.; López Granados, M.; Melián-Cabrera, I.

    2002-01-01

    The effect of palladium incorporation on the performance of a CuO–ZnO catalyst for methanol synthesis by hydrogenation of carbon dioxide is studied. Three different catalysts are prepared: the reference CuO-ZnO (CZ), and two Pd-based CuO–ZnO catalysts, PCZ-CP and PCZ-SP, which are prepared by co-pre

  17. Bio-inspired green synthesis of Fe3O4 magnetic nanoparticles using watermelon rinds and their catalytic activity

    Science.gov (United States)

    Prasad, Ch.; Gangadhara, S.; Venkateswarlu, P.

    2016-08-01

    Novel and bio-inspired magnetic nanoparticles were synthesized using watermelon rinds (WR) which are nontoxic and biodegradable. Watermelon rind extract was used as a solvent and capping and reducing agent in the synthesis. The Fe3o4 MNPs were characterized by using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer techniques (VSM). XRD studies revealed a high degree of crystalline and monophasic Fe nanoparticles of face-centered cubic stricture. FTIR analysis proved that particles are reduced and stabilized in solution by the capping agent that is likely to be proteins secreted by the biomass. The present process in an excellent candidate for the synthesis of iron nanoparticles that is simple, easy to execute, pollutant free and inexpensive. A practical and convenient method for the synthesis of highly stable and small-sized iron nanoparticles with a narrow distribution from 2 to 20 nm is reported. Also, the MNPs present in higher saturation magnetization (Ms) of 14.2 emu/g demonstrate tremendous magnetic response behavior. However, the synthesized iron nanoparticles were used as a catalyst for the preparation of biologically interesting 2-oxo-1,2,3,4-tetrahydropyrimidine derivatives in high yields. These results exhibited that the synthesized Fe3O4 MNPs could be used as a catalyst in organic synthesis.

  18. Asymmetric synthesis of (-)-renieramycin T.

    Science.gov (United States)

    Jia, Junhao; Chen, Ruijiao; Liu, Hao; Li, Xiong; Jia, Yuanliang; Chen, Xiaochuan

    2016-08-14

    (-)-Renieramycin T, an interesting tetrahydroisoquinolinequinone alkaloid with a novel renieramycin-ecteinascidin mixed framework, is synthesized from the known phenol 16 in 22 steps with 6.2% overall yield. In the convergent route, the key cyclocondensation between the isoquinoline moiety 27 and trisubstituted phenylalaninol 14 is achieved with good selectivity to furnish bistetrahydroisoquinoline 29, which permits a rapid construction of the pentacyclic framework having a fully substituted aromatic A ring. PMID:27405490

  19. A Simple and Fast Aqueous-Phase Synthesis of Ultra-Highly Concentrated Silver Nanoparticles and Their Catalytic Properties.

    Science.gov (United States)

    Shahzad, Aasim; Chung, Minsub; Yu, Taekyung; Kim, Woo-Sik

    2015-11-01

    A simple and fast synthetic route to ultra-highly concentrated silver nanoparticles with long-term stability by reducing AgNO3 with ascorbic acid in the presence of polyethyleneimine (PEI) as a stabilizer in an aqueous phase is reported. The concentration of silver precursor was as high as 2000 mm (200 g of Ag nanoparticle per liter of water) and the reaction time was less than 10 min. The resulting silver nanoparticles show long-term stability after two months of storage at room temperature without any signs of particle aggregation or precipitation in an aqueous phase. The successful ligand exchange of PEI-stabilized silver nanoparticles to polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) without particle aggregation is also demonstrated. In addition, the catalytic activities of silver nanoparticles stabilized by various stabilizers prepared by the ligand exchange method was investigated. The PEI-stabilized silver nanoparticles exhibited a higher stability than those of PEG- and PVP-stabilized silver nanoparticles in the diffusion-controlled catalytic reduction of 4-nitrophenol to 4-aminophenol by NaBH4 . PMID:26324024

  20. Simple synthesis of Al2O3 sphere composite from hybrid process with improved thermal stability for catalytic applications

    International Nuclear Information System (INIS)

    Aluminium oxide spheres were synthesized by the hybrid process applying the biopolymer chitosan. After the calcination process the porous spheres were characterized by Chemical elemental analysis (XRF), X-ray diffraction (XRD), Scanning electron microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDS), N2 adsorption–desorption isotherms, infrared spectroscopy (IR), and CO2 temperature programmed desorption (CO2-TPD). The effect of thermal treatment on surface properties of the oxide spheres was also evaluated by the catalytic ethanol dehydration reaction. The hybrid method produced interesting results related to the thermal stability against sintering process and consequently low decreases of surface area. The hybrid spheres calcination at 900 and 1200 °C produced a metastable phases of alumina with a high surface area, and nanometric crystallites. Additionally, the spheres of mixed silica-alumina synthesized by this method reveal the formation of porous spheres with highly acidic OH groups, which was suggested by the catalytic performance. - Highlights: • Al and Si/Al oxide spheres with promising properties are synthesized by hybrid method. • Al2O3 spheres show high thermal stability and resistance the loss surface area. • The SiO2 addition plays an important role in the structure and porosity of the spheres. • Al2O3 and SiO2/Al2O3 spheres presented a good activity to conversion ethanol. • The activity is related to the surface area and density of OH groups on surface

  1. Synthesis of p-Hydroxybenzaldehyde by Liquid-phase Catalytic Oxidation of p-Cresol over PVDF Modified Cobalt Pyrophosphate

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-bo; WANG De-qiang; MIAO Zhen-zhen; PAN Xi-qiang; ZHANG Zhen-dong; YANG Xiang-guang

    2013-01-01

    The influence of the wettability of a catalyst on the performance of the liquid phase oxidation of p-cresol was investigated.It was found that the surface hydrophobicity of a catalyst,which can be changed by modification with various loadings of polyvinylidene fluoride(PVDF),has a promotion effect on the catalytic performance.At the same time,the reaction parameters such as oxygen pressure,molar ratio of NaOH to p-cresol,reaction temperature and time on the catalytic performance in the liquid-phase oxidation of p-cresol were optimized.As a result,10%(mass fraction) PVDF modified cobalt pyrophosphate gave the highest conversion of 94.2% of p-cresol with a selectivity of 94.4% for p-hydroxybenzaldehyde at 348 K and a molar ratio of 4:1 of NaOH/p-cresol and an oxygen pressure of 1.0 MPa for 3 h.

  2. Facile synthesis of TiN decorated graphene and its enhanced catalytic effects on dehydrogenation performance of magnesium hydride.

    Science.gov (United States)

    Wang, Ying; Li, Li; An, Cuihua; Wang, Yijing; Chen, Chengcheng; Jiao, Lifang; Yuan, Huatang

    2014-06-21

    TiN@rGO nanohybrids were successfully synthesized by a simple "urea glass" technique. Experimental results demonstrated that TiN nanocrystals, with an average particle size of 20 nm, were uniformly anchored onto highly reduced graphene nanosheets. The as-synthesized TiN@rGO nanohybrids showed a porous planar-like structure, which had a large surface area of 177 m(2) g(-1). More importantly, the as-prepared TiN@rGO hybrids showed enhanced catalytic effects on the dehydrogenation of MgH2. The dehydrogenation thermodynamics and kinetics of the MgH2-TiN@rGO composites were systematically investigated and some significant improvements were confirmed. It was found that the 10 wt% TiN@rGO doped MgH2 sample started to release hydrogen at about 167 °C, and roughly 6.0 wt% hydrogen was released within 18 min when isothermally heated to 300 °C. In contrast, the onset dehydrogenation temperature of the pure MgH2 sample was about 307 °C, and only 3.5 wt% hydrogen was released even after 120 min of heating under identical conditions. In addition, the catalytic mechanism of TiN@rGO on the dehydrogenation of MgH2 was discussed using the Johnson-Mehl-Avrami (JMA) model and X-ray diffraction equipment. PMID:24817573

  3. Calcium-Mediated Catalytic Synthesis of 1-(Diorganylamino)-1,4-diphenyl-4-(diphenylphosphanyl)buta-1,3-dienes.

    Science.gov (United States)

    Younis, Fadi M; Krieck, Sven; Al-Shboul, Tareq M A; Görls, Helmar; Westerhausen, Matthias

    2016-05-01

    The hydroamination of diphenylbutadiyne with 1 equiv of the secondary amines HNRR' (R/R' = Ph/Ph, Ph/Me, and pTol/Me) in the presence of catalytic amounts of the tetrakis(amino)calciate K2[Ca{N(H)Dipp}4] (Dipp = 2,6-diisopropylphenyl) yields the corresponding 1-(diorganylamino)-1,4-diphenylbut-1-ene-3-ynes as a mixture of E/Z isomers. These tertiary alkenylamines react with diphenylphosphane to form RR'N-C(Ph)═CH-CH═C(Ph)-PPh2 [R/R' = Ph/Ph (1), Ph/Me (2), and pTol/Me (3)] in the presence of catalytic amounts of [(THF)4Ca(PPh2)2] or of the same calciate K2[Ca{N(H)Dipp}4]. Whereas the hydroamination is regio- (amino group in 1-position) but not stereoselective (formation of E and Z isomers), this second hydrofunctionalization step is regio- (phosphanyl group in 4-position) and stereoselective (only E isomers are formed), finally leading to mixtures of (E,E)- and (Z,E)-1-(diorganylamino)-1,4-diphenyl-4-(diphenylphosphanyl)buta-1,3-dienes. PMID:27082254

  4. Synthesis of buoyant metal-coated fly ash cenosphere and its excellent catalytic performance in dye degradation.

    Science.gov (United States)

    Wang, Wei; Zhai, Jianping; Li, Qin

    2015-04-15

    In this work, Ag(+) and Ag(0) were absorbed onto the surface of 3-mercaptopropyltriethoxysilane modified fly ash cenospheres (FACs) in two Ag activation processes. The activation methods, avoiding traditional surface sensitization by SnCl2, successfully initiated electroless copper particles deposition for the preparation of buoyant Cu-FAC and CuAg-FAC composites. The CuAg-FAC had a much more uniform morphology than the Cu-FAC. The catalytic performance of the Cu-FAC and CuAg-FAC was examined by the reduction of Orange IV azo dye with the presence of NaBH4. 98.4% of Orange IV was rapidly reduced within 25 min by the CuAg-FAC, whereas 76.4% of Orange IV was removed by the Cu-FAC. The results reveal that the degradation processes matched well with the pseudo-first-order kinetics model, and rate constants of 0.057 and 0.186 min(-1) were obtained for the Cu-FAC and CuAg-FAC, respectively. Moreover, two other dyes of Orange II and Reactive Black 5 were also efficiently reduced by the CuAg-FAC which could be easily recycled and stably reused at least four times. These buoyant metal-coated FAC composites would be very useful in various catalytic reductions. PMID:25585281

  5. Mono(boratabenzene) rare-earth metal dialkyl complexes: synthesis, structure and catalytic behaviors for styrene polymerization.

    Science.gov (United States)

    Wang, Xiufang; Leng, Xuebing; Chen, Yaofeng

    2015-03-28

    Four mono(boratabenzene) rare-earth metal dialkyl complexes, [(3,5-Me2-C5H3BR)Ln(CH2SiMe3)2(THF)] (1: R = NEt2, Ln = Sc; 2: R = NEt2, Ln = Lu; 3: R = Ph, Ln = Sc; 4: R = Ph, Ln = Lu), were synthesized efficiently via a one-pot strategy with Li[3,5-Me2-C5H3BR] (R = NEt2, Ph), LnCl3(THF)x (Ln = Sc, x = 3; Ln = Lu, x = 0), and LiCH2SiMe3. The solid-state structures of 1 and 2 were determined by single-crystal X-ray diffraction. Variable-temperature NMR studies indicated that the energy barrier for the rotation of aminoboratabenzene in 1 (ΔG‡ ≈ 71 kJ mol−1) is higher than that of phenylboratabenzene in 3 (ΔG‡ ≈ 59 kJ mol−1). These mono(boratabenzene) rare-earth metal dialkyl complexes’ catalytic behaviors for styrene polymerization were investigated, and found that mono(boratabenzene) scandium dialkyl complexes show high catalytic activities for syndiotactic polymerization upon activation with cocatalysts. PMID:25714489

  6. High-temperature hydrothermal synthesis of crystalline mesoporous TiO2 with superior photo catalytic activities

    International Nuclear Information System (INIS)

    Mesoporous titanium dioxide with crystalline mesopore walls (M-TiO2-ns) have been successfully synthesized through the self-assembly of poly 4-Vinylpyridine template and tetrabutyl titanate precursor based on their complex bond interaction under high temperature (180 °C) hydrothermal conditions. X-ray diffraction shows that M-TiO2-ns have highly crystalline mesopore walls with anatase phase characters; N2 sorption-desorption isotherms, SEM and TEM images show that M-TiO2-ns have high BET surface areas (85 and 120 m2/g, respectively), large pore volumes (0.32 and 0.34 cm3/g, respectively) and crystalline mesopore walls, which exhibit monolithic morphology with crystal sizes around 3-5 μm. Interestingly, M-TiO2-ns exhibit much higher catalytic activities and good recyclability in both induced reduction of decabromodiphenyl and oxidation of Rhodamine B under UV light than those of nonporous crystalline TiO2 and M-TiO2 templated by hydrocarbon surfactant of F127, which is even comparable with that of commercial P25. Combination of the unique characters such as crystallinity, stable mesostructure, large BET surface areas and superior photo catalytic activities make M-TiO2-ns a kind of potentially important material for removing of organic pollutions in environment through green photo irradiation processes.

  7. Hydrothermal synthesis of Yttrium Orthovanadate (YVO4) and its application in photo catalytic degradation of sewage water

    International Nuclear Information System (INIS)

    In this paper; YVO4 powder was successfully synthesized from Vanadium Pentaoxide (V2O5), Yttrium Oxide (Y2O3) and ethyl acetate as a mineralizer by hydrothermal method at a low temperature (T=.230degreeC, and P=100 bars). The as-prepared powders were characterized by X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, UV-V Spectroscopy and Chemical Oxygen Demand of the sewage water, respectively. The results show that hydrothermal method can greatly promote the crystallization and growth of YVO4 phase. X-ray Diffraction pattern clearly indicates the tetragonal structure and crystallinity. An fourier transform infrared spectrum of the YVO4 shows the presence of Y-O and V-O bond, respectively. The presence of these two peaks indicates that yttrium vanadate has been formed. UV-V is absorption spectra suggesting that YVO4 particles have stronger UV absorption than natural sunlight and subsequent photo catalytic degradation data also confirmed their higher photo catalytic activity.

  8. Synthesis, electronic structure and catalytic activity of ruthenium-iodo-carbonyl complexes with thioether containing NNS donor ligand

    Science.gov (United States)

    Jana, Subrata; Jana, Mahendra Sekhar; Biswas, Sujan; Sinha, Chittaranjan; Mondal, Tapan Kumar

    2014-05-01

    The ruthenium carbonyl complexes 1 and 2 with redox noninnocent NNS donor ligand, 1-methyl-2-{(o-thiomethyl)phenylazo}imidazole (L) have been synthesized and characterized by various analytical and spectroscopic (IR, UV-Vis and 1H NMR) techniques. The complexes exhibit a quasi-reversible one electron Ru(II)/Ru(III) oxidation couple at 1.11 V for 1 and 0.76 V for 2 along with two successive one electron ligand reductions. Catalytic activity of the compounds has been investigated to the oxidation of PhCH2OH to PhCHO, 2-butanol (C4H9OH) to 2-butanone, 1-phenylethanol (PhC2H4OH) to acetophenone, cyclopentanol (C5H9OH) to cyclopentanone, cyclohexanol to cyclohexanone, cycloheptanol to cycloheptanone and cycloctanol to cycloctanone using N-methylmorpholine-N-oxide (NMO) as oxidant. The catalytic efficiency of 2 is greater than complex 1 and well correlate with the metal oxidation potential. DFT, NBO and TDDFT calculations in DFT/B3LYP/6-31G(d)/lanL2TZ(f) method are employed to interpret the structural and electronic features of the complexes.

  9. O/W/O double emulsion-assisted synthesis and catalytic properties of CeO 2 hollow microspheres

    Science.gov (United States)

    Zhang, DongEn; Xie, Qing; Wang, MingYan; Zhang, XiaoBo; Li, ShanZhong; Han, GuiQuan; Ying, AiLing; Chen, AiMei; Gong, JunYan; Tong, ZhiWei

    2010-09-01

    CeO 2 hollow microspheres have been fabricated through a simple thermal decomposition of precursor approach. The precursor with an average size of 10 μm was prepared in a reverse microemulsions containing Ce(NO 3) 3·6H 2O and CO(NH 2) 2 at 160 °C. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscope (TEM), selected area electron diffraction (SAED) and scanning electron microscopy (SEM). The possible formation mechanism of hollow spheres was discussed. In addition, the CeO 2 hollow microspheres modified glassy carbon electrode exhibit excellent sensing performance towards methyl orange, which provide a new application of CeO 2 hollow spheres. The catalytic activity of CeO 2 hollow spheres on the thermal decomposition of ammonium perchlorate (AP) also was investigated by TGA. The catalytic performance of CeO 2 hollow spheres is superior to that of commercial CeO 2 powder.

  10. Synthesis and characterization of amoxicillin derived silver nanoparticles: Its catalytic effect on degradation of some pharmaceutical antibiotics

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Amp-Ag (0) NPs were prepared by simple one-pot chemical reduction method. • Ampicillin as an antibiotic was used as both reducing and capping agents in this study. • Amp-Ag (0) NPs have proved as the remarkably efficient catalysts with enhanced rate of reduction for cefdinir, cefditoren, cefixime, ceftriaxone sodium and doxycycline. • Amp-Ag (0) NPs were showed excellent catalytic activity as catalyst for the 100% reduction of these antibiotics. - Abstract: We synthesized novel amoxicillin derived silver nanoparticles (Amp-Ag (0) NPs) in aqueous solution by one-pot simple synthetic method by reducing silver nitrate by the help of amoxicillin antibiotic as a reducing/capping agent and NaOH as the catalyst for reaction enhancement. The formation of the Amp-Ag (0) NPs was monitored using UV–Vis absorption spectroscopy which confirmed the formation of Amp-Ag (0) NPs by exciting the typical surface plasmon absorption maxima at 404 nm. Transmission electron microscopy (TEM) confirmed the spherical morphology and monodispersed Amp-Ag (0) NPs with particle size 6.87 ± 2.2 nm. The antibacterial activities of the antibiotics were evaluated against Gram-negative bacteria Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa and Gram-positive bacteria Streptococcus pneumonia, Streptococcus pyogenes, Staphylococcus aureus by the disk diffusion method. Whereas standard antibiotics showed normal zone of inhibition, the reduced ones with Amp-Ag (0) NPs showed no inhibition zone. The antimicrobial results therefore reveal that newly synthesized Amp-Ag (0) NPs had an excellent catalytic activity as catalyst for the 100% reduction of antibiotics i.e. cefdinir, cefditoren, cefiximee, ceftriaxone sodium and doxycycline, which was carried out in just 2–5 min. They were recovered easily from reaction medium and reused with enhanced catalytic potential five times. Based upon these results it has been concluded that Amp-Ag (0) NPs

  11. Synthesis and characterization of amoxicillin derived silver nanoparticles: Its catalytic effect on degradation of some pharmaceutical antibiotics

    Energy Technology Data Exchange (ETDEWEB)

    Junejo, Y. [National Center of Excellence in Analytical Chemistry, University of Sindh Jamshoro, Jamshoro 76080 (Pakistan); Department of Chemistry, Fatih University, Buyukcekmece, 34500 Istanbul (Turkey); Güner, A., E-mail: aguner@fatih.edu.tr [Department of Biology, Fatih University, Buyukcekmece, 34500 Istanbul (Turkey); Baykal, A. [Department of Chemistry, Fatih University, Buyukcekmece, 34500 Istanbul (Turkey)

    2014-10-30

    Graphical abstract: - Highlights: • Amp-Ag (0) NPs were prepared by simple one-pot chemical reduction method. • Ampicillin as an antibiotic was used as both reducing and capping agents in this study. • Amp-Ag (0) NPs have proved as the remarkably efficient catalysts with enhanced rate of reduction for cefdinir, cefditoren, cefixime, ceftriaxone sodium and doxycycline. • Amp-Ag (0) NPs were showed excellent catalytic activity as catalyst for the 100% reduction of these antibiotics. - Abstract: We synthesized novel amoxicillin derived silver nanoparticles (Amp-Ag (0) NPs) in aqueous solution by one-pot simple synthetic method by reducing silver nitrate by the help of amoxicillin antibiotic as a reducing/capping agent and NaOH as the catalyst for reaction enhancement. The formation of the Amp-Ag (0) NPs was monitored using UV–Vis absorption spectroscopy which confirmed the formation of Amp-Ag (0) NPs by exciting the typical surface plasmon absorption maxima at 404 nm. Transmission electron microscopy (TEM) confirmed the spherical morphology and monodispersed Amp-Ag (0) NPs with particle size 6.87 ± 2.2 nm. The antibacterial activities of the antibiotics were evaluated against Gram-negative bacteria Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa and Gram-positive bacteria Streptococcus pneumonia, Streptococcus pyogenes, Staphylococcus aureus by the disk diffusion method. Whereas standard antibiotics showed normal zone of inhibition, the reduced ones with Amp-Ag (0) NPs showed no inhibition zone. The antimicrobial results therefore reveal that newly synthesized Amp-Ag (0) NPs had an excellent catalytic activity as catalyst for the 100% reduction of antibiotics i.e. cefdinir, cefditoren, cefiximee, ceftriaxone sodium and doxycycline, which was carried out in just 2–5 min. They were recovered easily from reaction medium and reused with enhanced catalytic potential five times. Based upon these results it has been concluded that Amp-Ag (0) NPs

  12. Green synthesis, characterization and catalytic activity of natural bentonite-supported copper nanoparticles for the solvent-free synthesis of 1-substituted 1H-1,2,3,4-tetrazoles and reduction of 4-nitrophenol

    Science.gov (United States)

    Alizadeh, Mohammad; Bagherzadeh, Mojtaba

    2015-01-01

    Summary In this study, Cu nanoparticles were immobilized on the surface of natural bentonite using Thymus vulgaris extract as a reducing and stabilizing agent. The natural bentonite-supported copper nanoparticles (Cu NPs/bentonite) were characterized by FTIR spectroscopy, X-ray diffraction (XRD), X-ray fluorescence (XRF), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and Brunauer–Emmett–Teller (BET) analysis. Afterward, the catalytic performance of the prepared catalyst was investigated for the solvent-free synthesis of 1-substituted 1H -1,2,3,4-tetrazoles and reduction of 4-nitrophenol (4-NP) in water. It was found that the Cu NPs/bentonite is a highly active and recyclable catalyst for related reactions. PMID:26732060

  13. Green synthesis, characterization and catalytic activity of natural bentonite-supported copper nanoparticles for the solvent-free synthesis of 1-substituted 1H-1,2,3,4-tetrazoles and reduction of 4-nitrophenol

    Directory of Open Access Journals (Sweden)

    Akbar Rostami-Vartooni

    2015-12-01

    Full Text Available In this study, Cu nanoparticles were immobilized on the surface of natural bentonite using Thymus vulgaris extract as a reducing and stabilizing agent. The natural bentonite-supported copper nanoparticles (Cu NPs/bentonite were characterized by FTIR spectroscopy, X-ray diffraction (XRD, X-ray fluorescence (XRF, field emission scanning electron microscopy (FE-SEM, energy dispersive X-ray spectroscopy (EDS, transmission electron microscopy (TEM, selected area electron diffraction (SAED and Brunauer–Emmett–Teller (BET analysis. Afterward, the catalytic performance of the prepared catalyst was investigated for the solvent-free synthesis of 1-substituted 1H-1,2,3,4-tetrazoles and reduction of 4-nitrophenol (4-NP in water. It was found that the Cu NPs/bentonite is a highly active and recyclable catalyst for related reactions.

  14. Acacia nilotica (Babool) leaf extract mediated size-controlled rapid synthesis of gold nanoparticles and study of its catalytic activity

    Science.gov (United States)

    Majumdar, Rakhi; Bag, Braja Gopal; Maity, Nabasmita

    2013-09-01

    The leaf extract of Acacia nilotica (Babool) is rich in different types of plant secondary metabolites such as flavanoids, tannins, triterpenoids, saponines, etc. We have demonstrated the use of the leaf extract for the synthesis of gold nanoparticles in water at room temperature under very mild conditions. The synthesis of the gold nanoparticles was complete in several minutes, and no extra stabilizing or capping agents were necessary. The size of the nanoparticles could be controlled by varying the concentration of the leaf extract. The gold nanoparticles were characterized by HRTEM, surface plasmon resonance spectroscopy, and X-ray diffraction studies. The synthesized gold nanoparticles have been used as an efficient catalyst for the reduction of 4-nitrophenol to 4-aminophenol in water at room temperature.

  15. Saraca indica bark extract mediated green synthesis of polyshaped gold nanoparticles and its application in catalytic reduction

    Science.gov (United States)

    Dash, Shib Shankar; Majumdar, Rakhi; Sikder, Arun Kanti; Bag, Braja Gopal; Patra, Biplab Kumar

    2014-04-01

    The bark extract of the traditional ayurvedic medicinal plant Saraca indica containing redox active polyphenolic compounds has been utilized for the one-step synthesis of gold nanoparticles at room temperature. The polyphenolic compounds acted as the reducing agent as well as the stabilizing agent without any additional capping agent. The synthesis of the gold nanoparticles of 15-23 nm size was complete in several minutes and no photo irradiation or heat treatment was necessary. Surface plasmon resonance, HRTEM, AFM, X-ray diffraction, and FTIR studies have been carried out to characterize the nanoparticles. Gold nanoparticles synthesized were of triangular, tetragonal, pentagonal, hexagonal, and spherical shapes. The synthesized gold nanoparticles have been used as a catalyst for the reduction of 4-nitrophenol to 4-aminophenol at room temperature and the kinetics of the reduction reaction has been studied spectrophotometrically.

  16. Effect of Precursor Synthesis on Catalytic Activity of Co3O4 in N2O Decomposition.

    Czech Academy of Sciences Publication Activity Database

    Chromčáková, Ž.; Obalová, L.; Kovanda, F.; Legut, D.; Titov, A.; Ritz, M.; Fridrichová, D.; Michalik, S.; Kustrowski, P.; Jirátová, Květa

    2015-01-01

    Roč. 257, Part 1 (2015), s. 18-25. ISSN 0920-5861. [AWPAC2014 - International Symposium on Air & Water Pollution Abatement Catalysis. Krakow, 01.09.2014-05.09.2014] R&D Projects: GA ČR GA14-13750S Institutional support: RVO:67985858 Keywords : cobalt spinel * Co3O4 * N2O decomposition * precursor synthesis Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.893, year: 2014

  17. Green Synthesis of Ag and Pd Nanospheres, Nanowires, and Nanorods Using Vitamin B2: Catalytic Polymerisation of Aniline and Pyrrole

    OpenAIRE

    Mallikarjuna N. Nadagouda; Varma, Rajender S.

    2008-01-01

    For the first time, we report green chemistry approach using vitamin B2 in the synthesis of silver (Ag) and palladium (Pd), nanospheres, nanowires, and nanorods at room temperature without using any harmful reducing agents, such as sodium borohydride (NaBH4) or hydroxylamine hydrochloride and any special capping or dispersing agent. Vitamin B2 was used as reducing agent as well as capping agent due to its high-water solubility, biodegradability, and low-toxicity compared with other reducing a...

  18. Mesoporous Silica Based Gold Catalysts: Novel Synthesis and Application in Catalytic Oxidation of CO and Volatile Organic Compounds (VOCs

    Directory of Open Access Journals (Sweden)

    Leonarda F. Liotta

    2013-10-01

    Full Text Available Gold nanoparticles, particularly with the particle size of 2–5 nm, have attracted increasing research attention during the past decades due to their surprisingly high activity in CO and volatile organic compounds (VOCs oxidation at low temperatures. In particular, CO oxidation below room temperature has been extensively studied on gold nanoparticles supported on several oxides (TiO2, Fe2O3, CeO2, etc.. Recently, mesoporous silica materials (such as SBA-15, MCM-41, MCM-48 and HMS possessing ordered channel structures and suitable pore diameters, large internal surface areas, thermal stabilities and excellent mechanical properties, have been investigated as suitable hosts for gold nanoparticles. In this review we highlight the development of novel mesoporous silica based gold catalysts based on examples, mostly from recently reported results. Several synthesis methods are described herein. In detail we report: the modification of silica with organic functional groups; the one-pot synthesis with the incorporation of both gold and coupling agent containing functionality for the synthesis of mesoporous silica; the use of cationic gold complexes; the synthesis of silica in the presence of gold colloids or the dispersion of gold colloids protected by ligands or polymers onto silica; the modification of silica by other metal oxides; other conventional preparation methods to form mesoporous silica based gold catalysts. The gold based catalysts prepared as such demonstrate good potential for use in oxidation of CO and VOCs at low temperatures. From the wide family of VOCs, the oxidation of methanol and dimethyldisulfide has been addressed in the present review.

  19. Novel Cage-Like Hexanuclear Nickel(II) Silsesquioxane. Synthesis, Structure, and Catalytic Activity in Oxidations with Peroxides.

    Science.gov (United States)

    Bilyachenko, Alexey N; Yalymov, Alexey I; Shul'pina, Lidia S; Mandelli, Dalmo; Korlyukov, Alexander A; Vologzhanina, Anna V; Es'kova, Marina A; Shubina, Elena S; Levitsky, Mikhail M; Shul'pin, Georgiy B

    2016-01-01

    New hexanuclear nickel(II) silsesquioxane [(PhSiO1.5)12(NiO)₆(NaCl)] (1) was synthesized as its dioxane-benzonitrile-water complex (PhSiO1,5)12(NiO)₆(NaCl)(C₄H₈O₂)13(PhCN)₂(H₂O)₂ and studied by X-ray and topological analysis. The compound exhibits cylinder-like type of molecular architecture and represents very rare case of polyhedral complexation of metallasilsesquioxane with benzonitrile. Complex 1 exhibited catalytic activity in activation of such small molecules as light alkanes and alcohols. Namely, oxidation of alcohols with tert-butylhydroperoxide and alkanes with meta-chloroperoxybenzoic acid. The oxidation of methylcyclohexane gave rise to the isomeric ketones and unusual distribution of alcohol isomers. PMID:27213319

  20. Facile synthesis of catalytically active CeO2-Gd2O3 solid solutions for soot oxidation

    Indian Academy of Sciences (India)

    D Naga Durgasri; T Vinodkumar; Benjaram M Reddy

    2014-03-01

    CeO2-Gd2O3 oxides were synthesized by a modified coprecipitation method and subjected to thermal treatments at different temperatures to understand their thermal behaviour. The obtained samples were characterized by XRD, BET, TEM, Raman and TPR techniques. Catalytic efficiencies for oxygen storage/release capacity (OSC) and soot oxidation were evaluated by a thermogravimetric (TG) method. XRD and Raman results indicated the formation of Ce0.8Gd0.2O2− (CG) solid solutions at lower calcination temperatures, and TEM studies confirmed nanosized nature of the particles. Raman studies further confirmed the presence of oxygen vacancies and lattice defects in the CG sample. TPR measurements indicated a facile reduction of ceria after Gd3+ addition. Activity studies revealed that incorporation of Gd3+ into the ceria matrix favoured the creation of more structural defects, which accelerates the oxidation rate of soot compared to pure ceria.