Download or read book First Row Transition Metal Perfluoro Alkyls and Carbenes written by Alexander Daniels and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Organofluorine compounds are highly sought-after products owing to the unique physical and chemical properties imparted by fluorine. However, the use of hazardous HF, reactive F2 and environmentally persistent long chain fluorosurfactants, all staples of the industrial processes used to prepare refrigerants, pharma-/agrochemicals and fluoropolymers, make the preparation of organofluorine compounds difficult. Therefore, new routes to some or all of these value-added products are desirable. Efficient transition metal-mediated or -catalyzed processes within the arena of fluoro-organic chemistry, however, are significantly less well developed than similar processes for both non-fluorinated and even halogenated compounds. For example, analogs of Group 4 metallocene catalysts for controlled polyolefin formation, or Ru and Group 6 catalysts for alkene metathesis are not generally useful with fluoroalkene substrates. Recent progress has focused on first row metal fluoroalkyl (M-RF) and fluorocarbene (M=CFRF) complexes that tend to have weaker M-C bonds than their second and third row counterparts. The synthesis, electronic structure and chemistry of such complexes is summarized in Chapter 1 along with an assessment of their potential for catalyzed C-C bond formation with fluoroalkenes via insertion or cycloaddition reactions. In Chapter 2 the synthesis and reactivity of new d8 [Co]-CF3 carbonyl complexes and their corresponding electrophilic {[Co]=CF2}+ complexes is described. In Chapter 3 we introduce the first examples of d10 metal fluorocarbenes, P3Ni=CF2 [P = P(OiPr)3; P3 = dppe, P(OiPr)3] along with their facile cycloaddition reactions with tetrafluoroethylene and some reactivity of the resulting stable perfluoronickelacyclobutanes (dppe = 1,2-bis(diphenylphos-phino)ethane). In Chapter 4 exploration of the more reactive Ni fluorocarbenes, Ni=CF(CF3)- [P(OR)3]3, (R = Me, iPr) leads, in reactions with fluoroalkenes, to formation of both metalla-cycles and metathesis products via separate pathways, in the first example of metathesis of fluoro-alkenes with a perfluoro-carbene. Detailed analysis of the latter by Texas A&M collaborators Guan and Hall using density functional theory showed that the nature of the reaction products depends on the geometry of the four-coordinate C-C bond forming transition state. In Chapter 5 this novel fluoroalkene metathesis process is probed further by extending the substrate scope to additional fluoroalkenes and several non-fluorinated variants. In Chapter 6 a series of new Mn-CF3 carbonyl complexes are prepared with a view to enabling fluoroalkene insertion reactions. Although this goal has not yet been achieved, fluoride abstraction using Lewis acids afforded the first examples of [Mn]=CF2 complexes. Finally, in Chapter 7 the findings of this thesis are placed in the context of the current state of the art and logical next steps for further understanding and catalytic process development are proposed.
Download or read book Advances in the Fluorine Chemistry of Transition Metals and N Heterocyclic Carbenes written by Matthew Leclerc and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of fluorine in a wide array of different areas within chemistry and biochemistry has been demonstrated time and time again. Fluorine-containing products range from essential substituents in pharmaceuticals and relatively long-lived tracers for PET imagining, to fluoropolymers with outstanding properties, to essential components in most of the strongest acids available to chemists today. Fluorine's extreme electronegativity makes it a truly unique element, but its acute toxicity in its elemental F2 form makes it difficult to handle, prompting researchers to explore different options for incorporating this important element into a variety of different molecular scaffolds. Due to the remarkable thermodynamic and kinetic stabilities of C-F bonds, methods for forming and breaking these cleanly, and under relatively mild conditions, are in high demand. Fortunately, transition metals have greatly aided in this process. However, fluoroorganometallic chemistry is much less developed than transition metal chemistry involving hydrocarbons, and certainly less understood. One of the primary reasons for this relative dearth of fluoroorganometallic complexes is the difficulty associated with their synthesis. In this work, important steps towards perfluoroalkyl chain-growth within the coordination sphere of a transition metal will be presented, stemming in part from the synthesis and characterization of novel cobalt fluoride and bis(perfluoroalkyl) complexes. As important electrophiles, fluoroalkenes have primarily been used as monomers for the formation of important fluoropolymers. However, their direct reactivity with organics remains rare and is usually difficult to control, with limited substrate scopes. Herein, the formation of stable N-heterocyclic fluoroalkene adducts as versatile synthons for the incorporation of fluoroalkene fragments into various chemical environments will be introduced. By forming these adducts, the inconvenience of manipulating fluorinated gases in further reactions can be avoided, and the N-heterocyclic fragment is shown to aid in directing substitutions involving polyfluoroalkenyl imidazolium salts and organic nucleophiles to form a variety of C-E (E = C, N, O, S) and C-M bonds (M = Mn, Mo). The ease with which C-F bonds are manipulated in these systems is quite remarkable, as the substitution reactions occur cleanly and efficiently at room temperature, to form a variety of new bonds without the need for a transition metal. By expanding on the fundamental reactivity between N-heterocyclic carbenes and fluoroalkenes, attempts were made to correlate the observed reactivity with certain electronic and steric parameters unique to the utilized carbenes. Although a correlation has not yet been established, the effects of atypical steric constraints in a cyclic (alkyl)(amino)carbene were demonstrated, wherein the initial point of attack by the carbene on the fluoroalkene was modified. It is hoped that this work will eventually lead to new roles for organocatalysts in fluoroalkene transformations.
Download or read book Fluorocarbene Fluoroalkyl and Fluoride Complexes of First Row Transition Metals written by Graham Mark Lee and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fluorinated organic compounds play important roles in our society, as these products range from life-saving pharmaceuticals and agrochemicals, to fluoropolymers with extremely high thermal and chemical stability. Although elemental fluorine (F2) is the most reactive element, some fluoro-organic compounds are chemically inert. As such, controlled reactivity of fluorine or highly-fluorinated organic fragments is a considerable, yet important challenge for synthetic chemists. Fluoro-organometallic chemistry has been studied for decades, as researchers attempt to maximize the potential of metal mediated/catalyzed processes for the synthesis of fluorinated organic molecules. Within this framework, metal fluorocarbene complexes are particularly interesting because of their highly tunable reactivity, and are proposed for use in important metathesis/polymerization reactions of perfluorinated alkenes. While considerable work is still needed to make these proposed reactions a reality, this thesis outlines contributions from our research group. We showed that cobalt fluorocarbene complexes CpCo(=CFRF)(PPh2Me) (RF = F, CF3) undergo [2+2] cycloaddition reactions with tetrafluoroethylene (TFE) and phenylacetylene to form perfluorometallacyclobutane and partially fluorinated metallacyclobutene products, respectively. For both reactions, computational studies reveal a stepwise ring-closing mechanism, which proceeds through a singlet 1,4-diradical intermediate. Next, the formation of CpCo(=CF2)(L) complexes is achieved via the direct addition of difluorocarbene, generated in situ, to a cobalt(I) precursor. Subsequent addition of CF2 to cobalt fluorocarbene complexes results in [2+1] cycloaddition and formation of perfluorinated alkene complexes. The [2+1] addition is highly favored as the cobalt fluorocarbenes readily react with electrophilic CF2. A series of experiments provide evidence for the stepwise nature of fluoroalkene complex formation. From Co(I) fluorocarbene complexes, the focus shifts to preparing metal fluorocarbenes with electrophilic-type reactivity. The synthesis of bis(perfluoroalkyl) complexes serve as precursors for preparation of perfluoroalkyl cobalt(III) fluorocarbenes, which undergo migratory insertion reactions of the fluorocarbene into the perfluoroalkyl ligand. Using a similar synthetic approach, nickel(II) and palladium(II) difluorocarbene complexes are prepared from their corresponding trifluoromethyl precursors. The synthesis, characterization and reactivity of cobalt(III) fluoride complexes is also described, including the catalytic fluorination of acyl chlorides, demonstrating the first example of a cobalt(III) catalyzed fluorination reaction. The effects of the various ancillary ligands on these cobalt catalysts are investigated using high-throughput experimentation technology, and the scope of the reaction is expanded to include the synthesis of a variety of acyl fluoride compounds. Finally, the results and learnings from this work will be summarized and highlighted. The future directions and novel research which could result from the continuation of these projects is discussed, with an emphasis placed on the areas believed to have the highest potential impact.
Download or read book Transition Metal Carbene Complexes written by Karl Heinz Dötz and published by . This book was released on 1983 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Some First Row Transition Metal Complexes of Pyrrole 2 aldehyde 2 2 1 pyrrolinyl pyrrole and 2 2 pyridyl pyrrole written by and published by . This book was released on 1969 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Organometallic Chemistry of the Transition Metals written by Robert H. Crabtree and published by John Wiley & Sons. This book was released on 2005-06-14 with total page 600 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fully updated and expanded to reflect recent advances, this Fourth Edition of the classic text provides students and professional chemists with an excellent introduction to the principles and general properties of organometallic compounds, as well as including practical information on reaction mechanisms and detailed descriptions of contemporary applications.
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
Download or read book Catalysis with Earth abundant Elements written by Uwe Schneider and published by Royal Society of Chemistry. This book was released on 2020-10-30 with total page 431 pages. Available in PDF, EPUB and Kindle. Book excerpt: Considering the limited resources of our planet, earth-abundant elements will have to be explored increasingly in the future. This book highlights the uses of the most earth-abundant elements in catalysis and will be of interest to graduates, academic researchers and practitioners in catalysis.
Download or read book C X Bond Formation written by Arkadi Vigalok and published by Springer. This book was released on 2010-06-30 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents: Kilian Muñiz: Transition Metal Catalyzed Electrophilic Halogenation of C-H bonds in alpha-Position to Carbonyl Groups; Arkadi Vigalok * and Ariela W Kaspi: Late Transition Metal-Mediated Formation of Carbon-Halogen Bonds; Paul Bichler and Jennifer A. Love*: Organometallic Approaches to Carbon-Sulfur Bond Formation; David S. Glueck: Recent Advances in Metal-Catalyzed C-P Bond Formation; Andrei N. Vedernikov: C-O Reductive Elimination from High Valent Pt and Pd Centers; Lukas Hintermann: Recent Developments in Metal-Catalyzed Additions of Oxygen Nucleophiles to Alkenes and Alkynes; Moris S. Eisen: Catalytic C-N, C-O and C-S bond formation promoted by organoactinide complexes.
Download or read book N Heterocyclic Carbenes in Organocatalysis written by Akkattu T. Biju and published by John Wiley & Sons. This book was released on 2019-01-07 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt: Summarizing the emerging field of N-heterocyclic carbenes used in organocatalysis, this is an excellent overview of the synthesis and applications of NHCs focusing on carbon-carbon and carbon-heteroatom bond formation. Alongside comprehensive coverage of the synthesis, characteristics and applications, this handbook and ready reference also includes chapters on NHCs for polymerization reactions and natural product synthesis.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1994 with total page 730 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book N Heterocyclic Carbenes written by Silvia Diez-Gonzalez and published by Royal Society of Chemistry. This book was released on 2016-11-04 with total page 637 pages. Available in PDF, EPUB and Kindle. Book excerpt: In less than 20 years N-heterocyclic carbenes (NHCs) have become well-established ancillary ligands for the preparation of transition metal-based catalysts. This is mainly due to the fact that NHCs tend to bind strongly to metal centres, avoiding the need of excess ligand in catalytic reactions. Also, NHC‒metal complexes are often insensitive to air and moisture, and have proven remarkably resistant to oxidation. This book showcases the wide variety of applications of NHCs in different chemistry fields beyond being simple phosphine mimics. This second edition has been updated throughout, and now includes a new chapter on NHC‒main group element complexes. It covers the synthesis of NHC ligands and their corresponding metal complexes, as well as their bonding and stereoelectronic properties and applications in catalysis. This is complemented by related topics such as organocatalysis and biologically active complexes. Written for organic and inorganic chemists, this book is ideal for postgraduates, researchers and industrialists.
Download or read book Modern Catalytic Methods for Organic Synthesis with Diazo Compounds written by Michael P. Doyle and published by Wiley-Interscience. This book was released on 1998-01-19 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt: This much-needed resource brings together a wealth of procedures for the synthesis and practical use of diazocarbonyl compounds. It features methods for the preparation of important catalysts and for applications of diazocarbonyl compounds within each of the main transformation categories-including in-depth coverage of cyclopropanation, C-H and X-H insertion, Wolff rearrangement, ylide formation, aromatic cycloaddition and substitution, and many other useful reactions. Written by leading experts in the field, this book contains cutting-edge material on highly enantioselective transformations, and presents new ways of thinking about diazocarbonyl compounds and their applications, from donor-acceptor cyclopropanes in organic synthesis to macrocyclic cyclopropanation. Complete with illustrative examples of procedures in each chapter, clear diagrams, and a detailed bibliography, this practical reference gives readers the tools they need to put diazocarbonyl compounds to work for their own projects-an invaluable source of guidance for synthetic organic chemists, chemical scientists, and advanced students.
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2676 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Journal of the American Chemical Society written by American Chemical Society and published by . This book was released on 1974 with total page 1128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the Society are included in v. 1-59, 1879-1937.
Download or read book Comprehensive Coordination Chemistry II written by J. A. McCleverty and published by Newnes. This book was released on 2003-12-03 with total page 11845 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Coordination Chemistry II (CCC II) is the sequel to what has become a classic in the field, Comprehensive Coordination Chemistry, published in 1987. CCC II builds on the first and surveys new developments authoritatively in over 200 newly comissioned chapters, with an emphasis on current trends in biology, materials science and other areas of contemporary scientific interest.
Download or read book Advances in Cycloaddition written by Michael Harmata and published by Elsevier. This book was released on 2000-01-21 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents work from six different groups working on various aspects of cycloaddition chemistry. José Mascareñas gives us a very interesting account of the chemistry of &Bgr;-alkoxy-&ggr;-pyrones and related species. Al Padwa and Chris Staub discuss further advances in rhodium carbenoid chemistry and the unusual cycloaddition processes possible with these intermediates. Higher order cycloadditions mediated by transition metals highlight Jim Rigby's update on his group's efforts in this area. Lily Lee and John Snyder present us with a detailed account of the indole ring as a dienophile, challenging us to consider the untapped potential in this area. Brian Keay and Ian Hunt discuss the intramolecular Diels-Alder reactions of furan; a report that is both top-notch science, and what could be a great learning tool for students who need to see how fundamental chemical principles can and should be applied to synthetic problems. Finally, Kay Brummond introduces us to a new version of the Pauson-Khand reactions, one that will no doubt be further exploited in productive ways by her group well into the future.
