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Studies Of Immobilized Homogeneous Metal Catalysts On Silica Supports
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Book Synopsis Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports by :
Download or read book Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The tethered, chiral, chelating diphosphine rhodium complex, which catalyzes the enantioselective hydrogenation of methyl-[alpha]-acetamidocinnamate (MAC), has the illustrated structure as established by[sup 31]P NMR and IR studies. Spectral and catalytic investigations also suggest that the mechanism of action of the tethered complex is the same as that of the untethered complex in solution. The rhodium complexes, [Rh(COD)H][sub 4], [Rh(COD)[sub 2]][sup+]BF[sub 4][sup -], [Rh(COD)Cl][sub 2], and RhCl[sub 3][center-dot] 3H[sub 2]O, adsorbed on SiO[sub 2] are optimally activated for toluene hydrogenation by pretreatment with H[sub 2] at 200 C. The same complexes on Pd-SiO[sub 2] are equally active without pretreatments. The active species in all cases is rhodium metal. The catalysts were characterized by XPS, TEM, DRIFTS, and mercury poisoning experiments. Rhodium on silica catalyzes the hydrogenation of fluorobenzene to produce predominantly fluorocyclohexane in heptane and 1,2-dichloroethane solvents. In heptane/methanol and heptane/water solvents, hydrodefluorination to benzene and subsequent hydrogenation to cyclohexane occurs exclusively. Benzene inhibits the hydrodefluorination of fluorobenzene. In DCE or heptane solvents, fluorocyclohexane reacts with hydrogen fluoride to form cyclohexene. Reaction conditions can be chosen to selectively yield fluorocyclohexane, cyclohexene, benzene, or cyclohexane. The oxorhenium(V) dithiolate catalyst[-S(CH[sub 2])[sub 3]s-]Re(O)(Me)(PPh[sub 3]) was modified by linking it to a tether that could be attached to a silica support. Spectroscopic investigation and catalytic oxidation reactivity showed the heterogenized catalyst's structure and reactivity to be similar to its homogeneous analog. However, the immobilized catalyst offered additional advantages of recyclability, extended stability, and increased resistance to deactivation.
Book Synopsis Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports by : Keith James Stanger
Download or read book Studies of Immobilized Homogeneous Metal Catalysts on Silica Supports written by Keith James Stanger and published by . This book was released on 2003 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rhodium complexes of the chiral, chelating diphosphine (2S,4S)-4-(diphenylphosphino)-2-(diphenylphosphinomethyl)pyrrolidine tethered on silica were characterized by 31P NMR and IR. The tethered complex catalyzes the enantioselective hydrogenation of methyl-[alpha]-acetamidocinnamate (MAC). Spectral and catalytic investigations indicate that the tethered complex reacts by the same mechanism as the untethered complex in solution. The rhodium complexes, [Rh(COD)H]4, [Rh(COD)2]BF4−, [Rh(COD)Cl]2, and RhCl3·3H2O, adsorbed on SiO2 are optimally activated for toluene hydrogenation by pretreatment with H2 at 200°C. The same complexes on Pd-SiO2 are equally active without pretreatments. The active species in all cases is rhodium metal. The catalysts were characterized by XPS, TEM, DRIFTS, and mercury poisoning experiments. Rhodium on silica catalyzes the hydrogenation of fluorobenzene to produce predominately fluorocyclohexane in heptane and 1,2-dichloroethane (DCE) solvents. In heptane/methanol and heptane/water solvents, hydrodefluorination to benzene and subsequent hydrogenation to cyclohexane occurs exclusively. Benzene inhibits the hydrodefluorination of fluorobenzene. In DCE or heptane solvents, fluorocyclohexane reacts with hydrogen fluoride to form cyclohexene. Reaction conditions can be chosen to selectively yield fluorocyclohexane, cyclohexene, benzene, or cyclohexane. The oxorhenium(V) dithiolate catalyst [-S(CH2)3S-]Re(O)(Me)(PPh3) was modified by linking it to a tether that could be attached to a silica support. Spectroscopic investigation and catalytic oxidation reactivity showed the heterogenized catalyst's structure and reactivity to be similar to its homogeneous analog. However, the immobilized catalyst offered additional advantages of recycleability, extended stability, and increased resistance to deactivation.
Book Synopsis Immobilized Catalysts by : Andreas Kirschning
Download or read book Immobilized Catalysts written by Andreas Kirschning and published by Springer Science & Business Media. This book was released on 2004-11-22 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: R. Haag, S. Roller: Polymeric Supports for the Immobilisation of Catalysts .- J. Horn, F. Michalek, C.C. Tzschucke, W. Bannwarth: Non-Covalently Solid-Phase Bound Catalysts for Organic Synthesis .- Y. Uozumi: Recent Progress in Polymeric Palladium Catalysts for Organic Synthesis .- D.E. Bergbreiter, J. Li: Applications of Catalysts on Soluble Supports .- B. Desai, C.O. Kappe: Microwave-Assisted Synthesis Involving Immobilized Catalysts .- A. Kirschning, G. Jas: Applications of Immobilized Catalysts in Continuous Flow Processes .- N. End, K.-U. Schöning: Immobilized Catalysts in Industrial Research and Application .- N. End, K.-U. Schöning: Immobilized Biocatalysts in Industrial Research and Production
Book Synopsis Synthesis, Characterization, and Evaluation of Silica and Polymer Supported Catalysts for the Production of Fine Chemicals by : Rebecca Anne Shiels
Download or read book Synthesis, Characterization, and Evaluation of Silica and Polymer Supported Catalysts for the Production of Fine Chemicals written by Rebecca Anne Shiels and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalysis is an important field of study in chemical engineering and chemistry due to its application in a vast number of chemical transformations. Traditionally, catalysts have been developed as homogeneous molecular species or as heterogeneous insoluble materials. While homogeneous catalysts are typically very active and selective, they are difficult to recover. Conversely, heterogeneous catalysts are easy to recover and reuse, but they generally are less selective. To address these issues, the immobilization of homogeneous catalyst analogs onto solid supports has been a subject of research for the past few decades. Nonetheless, the effects of immobilization are still not completely predictable, and so continued effort is required to develop new immobilized catalysts as well as to develop a better understanding of how different parameters affect catalytic behavior. This dissertation presents the synthesis, characterization, and evaluation of new immobilized catalysts for different applications. First, a solid base catalyst supported on silica was developed and studied in the synthesis of cyclic carbonates from epoxides and carbon dioxide. Next, polymer and silica supported vanadium Schiff base catalysts were developed and evaluated for use in the oxidative kinetic resolution of alpha-hydroxy esters, an enantioselective reaction. Lastly, salen catalyst analogs with amine reactive functional groups were synthesized and characterized for grafting onto aminosilicas with different degrees of amine group isolation. The grafted catalysts were then tested to determine how catalyst spacing on the surface affects their behavior. Throughout the presentation of these results, comparisons are made amongst the new supported catalysts and relevant existing catalysts to discern general trends which could be applied to a wider range of immobilized catalysts. Finally, research opportunities for further improvements in these areas are suggested.
Book Synopsis Supported Metal Complexes by : F.R. Hartley
Download or read book Supported Metal Complexes written by F.R. Hartley and published by Springer Science & Business Media. This book was released on 1985-11-30 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is now IS years since the first patents in polymer supported metal complex catalysts were taken out. In the early days ion-exchange resins were used to support ionic metal complexes. Soon covalent links were developed, and after an initially slow start there was a period of explosive growth in the mid to late 1970s during which virtually every homogeneous metal complex catalyst ever reported was also studied bound to a support. Both polymers and inorganic oxides were studied as supports, although the great preponderance of workers studied polymeric supports, and of these polystyrene was by far the commonest used. This period served to show that by very careful design polymer-supported metal complex catalysts could have specific advantages over homogeneous metal complex catalysts. However the subject was a complicated one. Merely immobilising a successful metal complex catalyst to a functionalised support rarely yielded other than an inferior version of the catalyst. Amongst the many discouraging results of the 1970s, there were more than enough results that were sufficiently encouraging to demonstrate that, by careful design, supported metal complex catalysts could be prepared in which both the metal complex and the support combined together to produce an active catalyst which, due to the combination of support and complex, had advantages of activity, selectivity and specificity not found in homogeneous catalysts. Thus a new generation of catalysts was being developed.
Book Synopsis Bridging Heterogeneous and Homogeneous Catalysis by : Can Li
Download or read book Bridging Heterogeneous and Homogeneous Catalysis written by Can Li and published by John Wiley & Sons. This book was released on 2014-04-03 with total page 860 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are two main disciplines in catalysis research -- homogeneous and heterogeneous catalysis. This is due to the fact that the catalyst is either in the same phase (homogeneous catalysis) as the reaction being catalyzed or in a different phase (heterogeneous catalysis). Over the past decade, various approaches have been implemented to combine the advantages of homogeneous catalysis (efficiency, selectivity) with those of heterogeneous catalysis (stability, recovery) by the heterogenization of homogeneous catalysts or by carrying out homogeneous reactions under heterogeneous conditions. This unique handbook fills the gap in the market for an up-to-date work that links both homogeneous catalysis applied to organic reactions and catalytic reactions on surfaces of heterogeneous catalysts. As such, it highlights structural analogies and shows mechanistic parallels between the two, while additionally presenting kinetic analysis methods and models that either work for both homogeneous and heterogeneous catalysis. Chapters cover asymmetric, emulsion, phase-transfer, supported homogeneous, and organocatalysis, as well as in nanoreactors and for specific applications, catalytic reactions in ionic liquids, fluorous and supercritical solvents and in water. Finally, the text includes computational methods for investigating structure-reactivity relations. With its wealth of information, this invaluable reference provides academic and industrial chemists with novel concepts for innovative catalysis research.
Book Synopsis Catalyst Immobilization by : Maurizio Benaglia
Download or read book Catalyst Immobilization written by Maurizio Benaglia and published by John Wiley & Sons. This book was released on 2020-04-06 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive resource on techniques and applications for immobilizing catalysts Catalyst Immobilization: Methods and Applications covers catalyst immobilization topics including technologies, materials, characterization, chemical activity, and recyclability. The book also presents innovative applications for supported catalysts, such as flow chemistry and machine-assisted organic synthesis. Written by an international panel of expert contributors, this book outlines the general principles of catalyst immobilization and explores different types of supports employed in catalyst heterogenization. The book?s chapters examine the immobilization of chiral organocatalysts, reactions in flow reactors, 3D printed devices for catalytic systems, and more. Catalyst Immobilization offers a modern vision and a broad and critical view of this exciting field. This important book: -Offers a guide to supported and therefore recyclable catalysts, which is one of the most important tools for developing a highly sustainable chemistry -Presents various immobilization techniques and applications -Explores new trends, such as 3D printed devices for catalytic systems -Contains information from a leading international team of authors Written for catalytic chemists, organic chemists, process engineers, biochemists, surface chemists, materials scientists, analytical chemists, Catalyst Immobilization: Methods and Applications presents the latest developments and includes a review of the innovative trends such as flow chemistry, reactions in microreactors, and beyond.
Book Synopsis Heterogeneous Catalysis and Fine Chemicals IV by : H.U. Blaser
Download or read book Heterogeneous Catalysis and Fine Chemicals IV written by H.U. Blaser and published by Elsevier. This book was released on 1997-06-19 with total page 693 pages. Available in PDF, EPUB and Kindle. Book excerpt: After three meetings in Poitiers, France, the 4th International Symposium on Heterogeneous Catalysis and Fine Chemicals was held under the auspices of the New Swiss Chemical Society in Basel, Switzerland. Fundamental as well as applied contributions on the use of heterogeneous catalysis for the preparation of fine chemicals were presented and discussed. The program consisted of 4 plenary lectures, 28 oral contributions and around 90 posters covering a broad range of reactions and catalytic aspects. 82 of these contributions are collected in the present proceedings, grouped into the following 8 topical areas: - Industrial and engineering problems (7 contributions) - Alkylation and acylation reactions (11 contributions) - Enantio- and diastereoselective hydrogenation reactions (9 contributions) - Chemoselective hydrogenation reactions (12 contributions) - Oxidation reactions (14 contributions) - Immobilized and encapsulated complex catalysts (12 contributions) - Zeolite and clay catalysts (12 contributions) - Miscellaneous topics (5 contributions)
Book Synopsis In -Situ Spectroscopic Investigation of Immobilized Organometallic Catalysts by :
Download or read book In -Situ Spectroscopic Investigation of Immobilized Organometallic Catalysts written by and published by . This book was released on 2007 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Immobilized organometallic catalysts, in principle, can give high rates and selectivities like homogeneous catalysts with the ease of separation enjoyed by heterogeneous catalysts. However, the science of immobilized organometallics has not been developed because the field lies at the interface between the homogeneous and heterogeneous catalysis communities. By assembling an interdisciplinary research team that can probe all aspects of immobilized organometallic catalyst design, the entire reacting system can be considered, where the transition metal complex, the complex-support interface and the properties of the support can all be considered simultaneously from both experimental and theoretical points of view. Researchers at Georgia Tech and the University of Virginia are studying the fundamental principles that can be used to understand and design future classes of immobilized organometallic catalysts. In the framework of the overall collaborative project with Georgia Tech, our work focused on (a) the X-ray absorption spectroscopy of an immobilized Pd-SCS-O complex (b) the mode of metal leaching from supported Pd catalysts during Heck catalysis and (c) the mode of deactivation of Jacobsen's Co-salen catalysts during the hydrolytic kinetic resolution of terminal epoxides. Catalysts containing supported Pd pincer complexes, functionalized supports containing mercapto and amine groups, and oligomeric Co-salen catalysts were synthesized at Georgia Tech and sent to the University of Virginia. Incorporation of Pd onto several different kinds of supports (silica, mercapto-functionalized silica, zeolite Y) was performed at the University of Virginia.
Book Synopsis Studies of Silica Supported Metal Catalysts by : Carole Elizabeth Brown
Download or read book Studies of Silica Supported Metal Catalysts written by Carole Elizabeth Brown and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Enantioselective Homogeneous Supported Catalysis by : Radovan Sebesta
Download or read book Enantioselective Homogeneous Supported Catalysis written by Radovan Sebesta and published by Royal Society of Chemistry. This book was released on 2011-11-02 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt: Immobilization of chiral catalysts is an important tool for improving overall efficiency of catalytic processes. However, heterogeneous catalysts often suffer from decreased activities and supported but still homogeneous catalysts can help overcome this issue. This book covers the most important concepts of homogeneous supported catalysis with an emphasis on enantioselective processes. It describes the state-of-the-art and latest developments in each area whilst critically evaluating the strengths and weaknesses of this important method. The book encompasses ionically-tagged catalysts, supported organocatalysts, supported ionic liquid phases, catalysis using soluble polymers, catalytic dendrimers, fluorous catalysts, water soluble catalysts and non-covalent immobilization methods. Potential developments and ideas for the future are also highlighted. There is a growing demand for effective and recyclable catalysts so this book, covering all the important methods in the field of supported homogeneous catalysis, will appeal to many researchers in academia and industry.
Book Synopsis Nanostructured Catalysts by : Susannah L. Scott
Download or read book Nanostructured Catalysts written by Susannah L. Scott and published by Springer Science & Business Media. This book was released on 2008-04-06 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the recent advent of nanotechnology, research and development in the area of nanostructured materials has gained unprecedented prominence. Novel materials with potentially exciting new applications are being discovered at a much higher rate than ever before. Innovative tools to fabricate, manipulate, characterize and evaluate such materials are being developed and expanded. To keep pace with this extremely rapid growth, it is necessary to take a breath from time to time, to critically assess the current knowledge and provide thoughts for future developments. This book represents one of these moments, as a number of prominent scientists in nanostructured materials join forces to provide insightful reviews of their areas of expertise, thus offering an overall picture of the state-- the art of the field. Nanostructured materials designate an increasing number of materials with designed shapes, surfaces, structures, pore systems, etc. Nanostructured materials with modified surfaces include those whose surfaces have been altered via such techniques as grafting and tethering of organic or organometallic species, or through various deposition procedures including electro, electroless and vapor deposition, or simple adsorption. These materials find important applications in catalysis, separation and environmental remediation. Materials with patterned surfaces, which are essential for the optoelectronics industry, constitute another important class of surface-modified nanostructured materials. Other materials are considered nanostructured because of their composition and internal organization.
Book Synopsis In {u2013}Situ Spectroscopic Investigation of Immobilized Organometallic Catalysts by :
Download or read book In {u2013}Situ Spectroscopic Investigation of Immobilized Organometallic Catalysts written by and published by . This book was released on 2007 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Immobilized organometallic catalysts, in principle, can give high rates and selectivities like homogeneous catalysts with the ease of separation enjoyed by heterogeneous catalysts. However, the science of immobilized organometallics has not been developed because the field lies at the interface between the homogeneous and heterogeneous catalysis communities. By assembling an interdisciplinary research team that can probe all aspects of immobilized organometallic catalyst design, the entire reacting system can be considered, where the transition metal complex, the complex-support interface and the properties of the support can all be considered simultaneously from both experimental and theoretical points of view. Researchers at Georgia Tech and the University of Virginia are studying the fundamental principles that can be used to understand and design future classes of immobilized organometallic catalysts. In the framework of the overall collaborative project with Georgia Tech, our work focused on (a) the X-ray absorption spectroscopy of an immobilized Pd-SCS-O complex (b) the mode of metal leaching from supported Pd catalysts during Heck catalysis and (c) the mode of deactivation of Jacobsen’s Co-salen catalysts during the hydrolytic kinetic resolution of terminal epoxides. Catalysts containing supported Pd pincer complexes, functionalized supports containing mercapto and amine groups, and oligomeric Co-salen catalysts were synthesized at Georgia Tech and sent to the University of Virginia. Incorporation of Pd onto several different kinds of supports (silica, mercapto-functionalized silica, zeolite Y) was performed at the University of Virginia.
Book Synopsis Catalytic Amination for N-Alkyl Amine Synthesis by : Feng Shi
Download or read book Catalytic Amination for N-Alkyl Amine Synthesis written by Feng Shi and published by Academic Press. This book was released on 2018-03-16 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Catalytic Amination for N-Alkyl Amine Synthesis provides a useful survey of this key type of reaction for chemistry researchers in academia and industry. Beginning with an introduction to amination and the development of the field, the book focuses on useful and high potential methods, such as the catalytic amination of alcohol with homogeneous and heterogeneous catalysts, the coupling reaction of olefin and amine, and the reductive amination of carbon dioxide with different reducing agents. The work also discusses two key examples of one-pot synthesis, the oxidative amination of alkane and amine and synthesis of N-alkyl amine with nitrobenzene and nitrile as starting materials. Valuable for chemists, materials scientists, chemical engineers and others, the book offers a unique overview of this growing area and its future possibilities.
Book Synopsis Soft Matters for Catalysts by : Qingmin Ji
Download or read book Soft Matters for Catalysts written by Qingmin Ji and published by CRC Press. This book was released on 2019-09-25 with total page 329 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the increasing demand for optimization of energy storage, maintenance of the environment, and effective production, control on nanostructures of catalysts and optimization of their organization have become key to achieving high efficiency and specificity in energy and material conversion systems. This book emphasizes and summarizes the novel design of soft matters (molecules, polymers, assembled motifs, etc.) for nanocatalysts and nanocatalyst supports. The diversity or specialty of soft matters offers a new perspective and great promise for the development of new nanocatalytic systems for future requirements. Soft matters can provide a simple and well-defined space for the discovery of new catalysts. This book covers nonmetallic organocatalysts, organometallic compounds, dendrimers, ionic liquids, enzymes, polymers, various organized nanoarchitectures for supporting catalysts, and molecular dynamics in catalytic surface reactions. It gives readers a complete picture of the catalysis systems based on soft matters and is a useful reference for advanced undergraduate- and graduate-level students and researchers in chemistry, biology, materials science, nanoscience, polymer science, and catalysis.
Book Synopsis Homogeneous and Heterogeneous Catalysis by :
Download or read book Homogeneous and Heterogeneous Catalysis written by and published by VSP. This book was released on 1986-06 with total page 1206 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Proceedings contains plenary lectures and selected poster communications spanning the entire field of catalysis --- from catalysis by protons to catalysis by multinuclear clusters and ultra-disperse particles. It includes discussion of the recent results of fundamental research conducted at the juncture between homogeneous and heterogeneous catalysis. New ideas, based on modern physical and quantum-chemical methods, and concerning the mechanism of formation and functioning of active sites of catalysts are suggested. It is shown how the cyclic change of atomic distribution in the active site occurs during catalytic transformations. In addition, the Proceedings report new data on methods of ''assembling'' molecularly organized catalytic systems and on the mechanisms of their action. The various problems such as the effect of strong metal--support interaction, migration of atoms in active sites, and design of catalytic properties of substances are also widely discussed. Similarities and differences in mechanisms of action of homogeneous and heterogeneous catalysts are considered, using as examples CO hydrogenation, hydrogenolysis of saturated hydrocarbons, selective hydrogenation and oxidation of olefins, metathesis and polymerization of olefins, hydrosilylation and hydroformylation of olefins, etc.
Book Synopsis Catalysis of Organic Reactions by : Stephen R. Schmidt
Download or read book Catalysis of Organic Reactions written by Stephen R. Schmidt and published by CRC Press. This book was released on 2006-12-07 with total page 547 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bringing together academic, industrial, and governmental researchers and developers, Catalysis of Organic Reactions comprises 57 peer-reviewed papers on the latest scientific developments in applied catalysis for organic reactions. The volume describes the use of both heterogeneous and homogeneous catalyst systems and includes original resea
