Download or read book The Catalytic Oxidation of Organic Substrates Utilizing Molecular Oxygen and Peroxides written by Douglas E. Patton and published by . This book was released on 1993 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Catalytic Oxidations with Hydrogen Peroxide as Oxidant written by G. Strukul and published by Springer Science & Business Media. This book was released on 2013-03-14 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen peroxide is a chemical that is becoming increasingly fashionable as an oxidant, both in industry and in academia and whose production is expected to increase significantly in the next few years. This growth in interest is largely due to environmental considerations related to the clean nature of hydrogen peroxide as an oxidant, its by-product being only water. To date this chemical has largely been employed as a non-selective oxidant in operations like the bleaching of paper, cellulose and textiles, or in the formulation of detergents, and only to a minimal extent in the manufacture of organic chemicals. This book has been organized to cover the different aspects of the chemistry of hydrogen peroxide. The various chapters into which the book is divided have been written critically by the authors with the general aim of stimulating new ideas and emphasizing those aspects that are likely to lead to new developments in organic synthesis in the coming future.

Download or read book The Activation of Dioxygen and Homogeneous Catalytic Oxidation written by D.H.R. Barton and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 503 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph consists of the proceedings of the Fifth International Symposium on the Activation of Dioxygen and Homogeneous Catalytic Oxidation, held in College Station, Texas, March 14-19, 1993. It contains an introductory chapter authored by Professors D. H. R. Barton and D. T. Sawyer, and twenty-nine chapters describing presentations by the plenary lecturers and invited speakers. One of the invited speakers, who could not submit a manuscript for reasons beyond his control, is represented by an abstract of his lecture. Also included are abstracts of forty-seven posters contributed by participants in the symposium. Readers who may wish to know more about the subjects presented in abstract form are invited to communicate directly with the authors of the abstracts. This is the fifth international symposium that has been held on this subject. The first was hosted by the CNRS, May 21-29, 1979, in Bendor, France (on the Island of Bandol). The second meeting was organized as a NATO workshop in Padova, Italy, June 24-27, 1984. This was followed by a meeting in Tsukuba, Japan, July 12-16, 1987. The fourth symposium was held at Balatonfured, Hungary, September 10-14, 1990. The sixth meeting is scheduled to take place in Delft, The Netherlands (late Spring, 1996); the organizer and host will be Professor R. A. Sheldon.

Download or read book The Technology of Catalytic Oxidations written by Philippe Arpentinier and published by Editions Technip. This book was released on 2001 with total page 378 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 1 covers the most important technological aspects of the use of molecular oxygen for catalytic oxidation reactions.Volume 2 addresses the safety issues associated with the use of oxygen in catalytic oxidation reactions.Contents Vol. 1: 1. Introduction. 2. Chemical-physical properties of molecular oxygen. 3. Oxygen production technologies. 4. Chemical fundamentals of oxidation reactions. 5. Reactor technologies for multiphase systems. 6. Liquid phase oxidations. 7. Gas phase selective oxidations. 8. Selective oxidation of paraffins. References. Index. Vol. 2: 9. Introduction to safety problems in the chemical industry. 10. Chemical aspects of combustion in the gaseous phase. 11. Homogeneous chemical explosions: autoignition or spontaneous ignition. 12. Deflagration or propagation of flame. 13. Conditions governing flame propagation capability. 14. Detonation in the gaseous phase. 15. Prevention of and protection against explosions. References. Index.

Download or read book Metal Catalyzed Oxidations of Organic Compounds written by Roger Sheldon and published by Elsevier. This book was released on 2012-12-02 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metal-Catalyzed Oxidations of Organic Compounds: Mechanistic Principles and Synthetic focuses on the oxidative transformations of functional groups. This book explores oxidation as being extensively used in the laboratory synthesis of fine organic chemicals and in the manufacture of large-volume petrochemicals. Organized into two parts encompassing 13 chapters, this book starts with an overview of the mechanistic principles of oxidation–reduction in biochemical, organic, and inorganic systems. This text then proceeds with a discussion of the use of molecular oxygen, hydrogen peroxide, and alkyl hydroperoxides as primary oxidants. Other chapters explore stoichiometric oxidations with metal oxidants, which include permanganate and chromic acid. This book discusses as well the synthetic applications of catalytic oxidations as well as the technology of petrochemical oxidation. The final chapter deals with the autoxidations of sulfur, phosphorus, and nitrogen compounds. This book is intended for chemists involved in organic synthesis, catalysis, and organometallic chemistry, both in academic institutions and in industrial laboratories.

Download or read book Mechanistic Studies of Cu catalyzed Aerobic Oxidation Reactions written by Scott Douglas McCann and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical copper-catalyzed aerobic oxidation reactions exhibit complexities not present in similar oxidation reactions employing noble metal catalysts with traditional chemical oxidants like hypervalent iodines or peroxides. The oxidation of organic molecules involves the removal of two protons and two electrons. This inevitably requires two CuII catalyst molecules to participate in the net oxidation reaction due to the one-electron redox-state changes typically associated with Cu. Additionally, CuI must react with molecular oxygen, a ground-state triplet molecule and net four-electron oxidant, to regenerate the active CuII catalyst. Aspects of these complexities are addressed in this thesis. Nature has evolved to use Cu catalysts (often together with redox-active organic cocatalysts) to perform oxidation reactions that use O2 as the terminal oxidant. The oxidation of CuI by O2 has been the subject of extensive investigation over the past several decades, and many of these studies were inspired by enzyme active sites in biological systems. Biological systems have also revealed pathways whereby CuII can oxidize organic substrates, and several chemical Cu-based catalyst systems exhibit intriguing similarities to enzymatic active sites. Herein, studies of several chemical copper-catalyzed aerobic oxidation reactions are reported, and, in many cases, the reactivity is compared to closely related enzymatic reactions. Chapter 1 summarizes challenges, opportunities, and progress made by our research group toward achieving selective and efficient Cu-catalyzed aerobic oxidation reactions. Chapter 2 describes a mechanistic study of aerobic alcohol oxidation catalyzed by Cu together with redox-active organic azodicarboxylates. Chapter 3 explains how Cu produces a redox-active organic nitroxyl cocatalyst under catalytic conditions from a simple diamine precursor. Chapter 4 details the investigation of single-electron transfer from phenol substrates to CuII.

Download or read book Active Oxygen in Chemistry written by Christopher S. Foote and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: Taking an interdisciplinary approach, this book and its counterpart, Active Oxygen in Biochemistry, explore the active research area of the chemistry and biochemistry of oxygen. Complementary but independent, the two volumes integrate subject areas including medicine, biology, chemistry, engineering, and environmental studies.

Download or read book Aspects of Homogeneous Catalysis written by R. Ugo and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 247 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, the liquid phase oxidation of organic substrates using transition metal compounds as catalysts has become a profitable means of obtaining industrially important chemicals. Millions of tons of valuable petrochemicals are produced in this manner annually [1]. Typical examples of such processes are the production of vinyl acetate or acetaldehyde via the Wacker process, equations (1) and (2); the Mid Century process for the oxidation of methyl aromatics, such as p-xylene to tereph thalic acid, equation (3); and the production of propylene oxide from propylene using alkyl hydroperoxides, equation (4). PdCI , CuCI 2 2 (1) CH2 = CH2 + 1/2 O2 -H 0 ~ CH3CHO 2 (2) Co(OAcjz ~ (3) (4) The vast majority of liquid phase transition metal catalyzed oxidations of organic compounds fall into these three broad categories: (a) free radical autoxidation reactions, (b) reactions involving nucleophilic attack on coordinated substrate such as the Wacker process, or (c) metal catalyzed reactions of organic substrates with hydroperoxides. Of these three classes of oxidations only the first represents the actual interaction of dioxygen with an organic substrate. The function of oxygen in the Wacker process is simply to re-oxidize the catalyst after each cycle [2].

Download or read book Mechanism Based Design of Green Oxidation Catalysts written by and published by . This book was released on 2015 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: In modern era of scarce resources, developing chemical processes that can eventually generate useful materials and fuels from readily available, simple, cheap, renewable starting materials is of paramount importance. Small molecules, such as dioxygen, dinitrogen, water, or carbon dioxide, can be viewed as ideal sources of oxygen, nitrogen, or carbon atoms in synthetic applications. Living organisms perfected the art of utilizing small molecules in biosynthesis and in generating energy; photosynthesis, which couples carbohydrate synthesis from carbon dioxide with photocatalytic water splitting, is but one impressive example of possible catalytic processes. Small molecule activation in synthetic systems remains challenging, and current efforts are focused on developing catalytic reactions that can convert small molecules into useful building blocks for generating more complicated organic molecules, including fuels. Modeling nature is attractive in many respects, including the possibility to use non-toxic, earth-abundant metals in catalysis. Specific systems investigated in our work include biomimetic catalytic oxidations with dioxygen, hydrogen peroxide, and related oxygen atom donors. More recently, a new direction was been also pursued in the group, fixation of carbon dioxide with transition metal complexes. Mechanistic understanding of biomimetic metal-catalyzed oxidations is critical for the design of functional models of metalloenzymes, and ultimately for the rational synthesis of useful, selective and efficient oxidation catalysts utilizing dioxygen and hydrogen peroxide as terminal oxidants. All iron oxidases and oxygenases (both mononuclear and dinuclear) utilize metal-centered intermediates as reactive species in selective substrate oxidation. In contrast, free radical pathways (Fenton chemistry) are common for traditional inorganic iron compounds, producing hydroxyl radicals as very active, non-selective oxidants. Recent developments, however, changed this situation. Growing families of synthetic iron complexes that resemble active sites of metalloenzymes produce metal-based intermediates (rather than hydroxyl radicals) in reactions with oxygen donors. These complexes are very promising for selective oxygen and peroxide activation. In order to understand the mechanisms of metal-based small molecule activation, kinetically competent metal-oxygen intermediates must be identified. One of the grand challenges identified by the Department of Energy workshop "Catalysis for Energy" is understanding mechanisms and dynamics of catalyzed reactions. The research summarized herein focuses on detailed characterization of the formation and reactivity of various iron-peroxo- and iron-oxo intermediates that are involved in catalysis. Rates of rapid reactions were studied at low temperatures by a specialized technique termed cryogenic stopped-flow spectrophotometry. These measurements identified reaction conditions which favor the formation of catalytically competent oxidants. Chemical structures of reactive complexes was determined, and new, efficient catalysts for hydrocarbon oxidation were synthesized. Importantly, these catalysts are selective, they promote oxidation of hydrocarbons at a specific site. The catalysts are also efficient and robust, hundreds of cycles of substrate oxidation occur within minutes at room temperature. Furthermore, they enable utilization of environmentally friendly oxidants, such as hydrogen peroxide, which produces water as the only byproduct. Mechanistic insights uncovered the role of various acid-containing additives in catalytic oxidations. Proton delivery to the active catalytic sites facilitated oxidations, similarly to the catalytic pathways in metal-containing enzymes. Under certain conditions, two metals in one complex can act in concert, modeling the reactivity of a bacterial enzyme which converts methane into methanol. In related studies, a family of nickel complexes that react with carbon ...

Download or read book The Catalytic Oxidation of Organic Compounds in the Vapor Phase written by Leroy Frank Marek and published by . This book was released on 1932 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Technology of Catalytic Oxidations written by Philippe Arpentinier and published by Editions Technips. This book was released on 2001 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 1 covers the most important technological aspects of the use of molecular oxygen for catalytic oxidation reactions.Volume 2 addresses the safety issues associated with the use of oxygen in catalytic oxidation reactions.Contents Vol. 1: 1. Introduction. 2. Chemical-physical properties of molecular oxygen. 3. Oxygen production technologies. 4. Chemical fundamentals of oxidation reactions. 5. Reactor technologies for multiphase systems. 6. Liquid phase oxidations. 7. Gas phase selective oxidations. 8. Selective oxidation of paraffins. References. Index. Vol. 2: 9. Introduction to safety problems in the chemical industry. 10. Chemical aspects of combustion in the gaseous phase. 11. Homogeneous chemical explosions: autoignition or spontaneous ignition. 12. Deflagration or propagation of flame. 13. Conditions governing flame propagation capability. 14. Detonation in the gaseous phase. 15. Prevention of and protection against explosions. References. Index.

Download or read book Catalyst and Reactor Development for Aerobic Oxidation of Organic Substrates written by Yuliya Preger and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Safe and selective aerobic oxidation of organic substrates represents a grand challenge in catalysis. The productive utilization of oxygen is key to many, seemingly disparate, systems, for example, enzymatic catalysis, fine chemical production, and energy generation in fuel cells. This thesis describes new methods for carrying out aerobic oxidation in the latter two applications. Fuel cells are a promising technology for generating electrical energy from the energy in chemical bonds. However, the high loadings of Pt needed to catalyze oxygen reduction at the cathode have hindered broad adoption. To address this, a new fuel cell design was developed wherein oxygen reduction is executed off-electrode in an external reactor with non-Pt catalysts, using quinones as electron-proton transfer mediators. This represents the first instance of organic mediator use outside of low-power, enzymatic fuel cells. The latter part of this thesis details the development of new reactors and catalysts for general aerobic alcohol oxidations. Safe execution of aerobic oxidation in the presence of organic solvents is typically achieved by operating below the limiting oxygen concentration with inert diluents. 'Tube in shell' membrane reactors offer an intriguing alternative, permitting passage of O2 from the gas phase into a liquid-phase reaction through semi-permeable membranes. Use of a membrane reactor with inexpensive PTFE tubing enabled alcohol oxidation at rates an order of magnitude higher than previously reported. Heterogeneous catalysts, particularly noble metals such as Pt and Pd, have been extensively studied for alcohol oxidation. However, these catalysts exhibit low rates and limited substrate scopes due to poisoning by excess oxygen or various heterocycles; thus, various species were explored as catalyst 'promoters.' In the oxidative coupling of alcohols and ammonia to make nitriles, the addition of Bi to a Pt catalyst accelerated the rate of alcohol oxidation and enabled high yields with challenging heterocyclic alcohols. Furthermore, the addition of Bi and Te to a Pd catalyst increased the yield and rate for the oxidative coupling of alcohols with methanol to make methyl esters. Collectively, the above work highlights the opportunities for reaction engineering to enable the safe and selective utilization of oxygen in a range of chemistries.

Download or read book Kinetic and Spectroscopic Investigations of Copper Metalloenzymes written by Stephen Merritt Jones and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nature uses a wide variety of Cu metalloenzymes to achieve biologically important oxidase and oxygenase reactions. Two such classes of these Cu enzymes are the multicopper oxidases (MCOs) and the lytic polysaccharide monooxygenases (LPMOs). The MCOs couple the four electron oxidation of a range of substrates to the four electron reduction of oxygen to water. They contain a minimum of four Cu ions arranged as a mononuclear Type 1 (T1) Cu site, and a trinuclear Cu cluster (TNC). The TNC is itself composed of a mononuclear Type 2 (T2) Cu site and a binuclear Type 3 (T3) Cu site. The LPMOs utilize a mononuclear Cu active site with an unusual T-shaped ligand geometry known as the His brace for the oxidative cleavage of polysaccharides in carbohydrate degradation by fungi and bacteria. The T1 sites of MCOs span a range from 400-800 mV (vs NHE), grouped into high and low potential MCOs. In both groups, the typical resting form of the enzyme is the Resting Oxidized (RO) form where all four Cu's are fully oxidized (4xCu(II)). In some high potential MCOs, which are important for their role as cathode materials in biofuel cells, there exists an Alternative Resting (AR) form, which is instead a stable, partially reduced form of the enzyme (2xCu(II), 2xCu(I)). The AR form of the TNC is incapable of accepting electrons from the T1 Cu, which is the typical mechanism for the enzyme to enter the catalytic cycle. We have characterized the electron-accepting behavior of the RO and AR forms in a fungal laccase from Posospora anserina (PaL). Selective reduction of the T1 Cu(II) enabled spectroscopic characterization of the singly oxidized Cu of the AR TNC, identifying it as a half-reduced T3 species. This AR form of the TNC was also shown to be generated by outersphere oxidation of a fully reduced TNC via the high potential T1 site, but could not be similarly generated in an enzyme with a low potential T1 site. A reduction titration was evaluated computationally, revealing a mechanism where the protein constraints play an important role in guiding the reduction behavior of the T3 site and avoiding formation of a thermodynamically favored (but inactivated) form of the TNC. In the MCO catalytic mechanism the first 2 electron reduction step of the mechanism forms the Peroxide Intermediate (PI) while the second generates the fully oxidized (4xCu(II)) Native Intermediate (NI). Previous work on the low potential laccase from Rhus vernicifera (RvL) has established that the NI is then rapidly reduced back to the FR form where it can react with another molecule of oxygen, continuing the catalytic cycle. The NI form, rather than RO, is therefore the catalytically relevant fully oxidized form of the enzyme responsible for rapid turnover. In the fungal laccase from Trametes versicolor (TvL), the impact of the increased T1 reduction potential was evaluated in the context of the accepted MCO mechanism. Rapid formation of NI was characterized, followed by its slow decay to the RO form at a rate similar to that observed in RvL. The measured rate of IET to the NI in TvL confimred that NI reduction does occur in the catalytic cycle of the high potential MCOs. However, in contrast to the findings in RvL where the rate determining step is substrate oxidation, the rate determining step in TvL was found to be IET to the NI TNC. MCOs can be broadly divided into two groups based on substrate selectivity: the organic oxidases and the metallooxidases. The organic oxidases utilize organic substrates and have higher substrate turnover frequencies (TOFs). The metallooxidases are selective for transition metal ions and exhibit lower TOFs. To understand the nature of the slow turnover in the metallooxidases, the MCO Fet3p from Saccharomyces cerevisiae was studied to determine the factors responsible for its slow ferroxidase reactivity. The catalytic cycle was found not to proceed through the reduction of NI, but rather via rapid, pH-dependent decay of NI to the RO form. The reduction of RO was therefore found to be the rate limiting process in the catalytic cycle. Constructing a model for RO reduction revealed that slow turnover in this metallooxidase was functionally significant for efficient Fe metabolism while avoiding generation of reactive oxygen species. The LPMOs are a class of enzymes containing a mononuclear Cu active site capable of utilizing oxygen for hydroxylation of C--H bonds in polysaccharide. Many LPMO sequences also contain additional carbohydrate binding modules (CBMs), which are small domains attached to the core catalytic domain by flexible linkers. The enzyme HjLPMO9A contains a CBM1 domain. A variant lacking this CBM was expressed for structural and spectroscopic characterization. Crystal structures of the truncated enzyme revealed the importance of a peptide linker on the structure of the core catalytic domain. Further analysis confirmed that the CBM was important for increasing binding affinity for substrate-protein interactions, but did not impact the active site structure or the regioselectivity of the monooxygenase reaction. Although initially proposed to utilize oxygen directly in the C--H hydroxylation reaction, LPMOs have recently been found to be catalytically competent for regioselective hydroxylation with hydrogen peroxide as cosubstrate. Several mechanisms have been proposed for this reactivity, but a dearth of experimental data persists in the literature. We have therefore undertaken a kinetic analysis and have identified two amino acid radical intermediates coupled to the Cu(II) that form and decay rapidly during single turnover of the reduced enzyme with peroxide. Importantly, these intermediates represent a minor reaction pathway, with the majority of the Cu(I) reaction proceeding through homolytic O-O cleavage. Finally, the use of non-native organic peroxides as cosubstrates excludes the possibility of a ping-pong mechanism. This provides important insight into pathways of LPMO catalysis.

Download or read book Science of Synthesis Catalytic Oxidation in Organic Synthesis written by Kilian Muñiz and published by Thieme. This book was released on 2018-03-23 with total page 1425 pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of catalytic systems for the oxidation of organic compounds continues to be of great importance. There is an ongoing and increasing demand for methods that are selective, proceed under mild conditions, and adhere to green chemistry principles. "Science of Synthesis: Catalytic Oxidation in Organic Synthesis" includes the latest developments in the field, as well as selective coverage of more well-established methods. Systems based on metal catalysts, organocatalysts, and biomimetic oxidation are covered, and there is a particular focus on asymmetric processes. Scope, limitations, and mechanism of the reactions are discussed and key experimental procedures are included. Typical examples of target synthesis are often provided to show the utility and inspire further applications.

Download or read book Comprehensive Natural Products III written by and published by Elsevier. This book was released on 2020-07-22 with total page 4266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive Natural Products III, Third Edition, Seven Volume Set updates and complements the previous two editions, including recent advances in cofactor chemistry, structural diversity of natural products and secondary metabolites, enzymes and enzyme mechanisms and new bioinformatics tools. Natural products research is a dynamic discipline at the intersection of chemistry and biology concerned with isolation, identification, structure elucidation, and chemical characteristics of naturally occurring compounds such as pheromones, carbohydrates, nucleic acids and enzymes. This book reviews the accumulated efforts of chemical and biological research to understand living organisms and their distinctive effects on health and medicine and to stimulate new ideas among the established natural products community. Provides readers with an in-depth review of current natural products research and a critical insight into the future direction of the field Bridges the gap in knowledge by covering developments in the field since the second edition published in 2010 Split into 7 sections on key topics to allow students, researchers and professionals to find relevant information quickly and easily Ensures that the knowledge within is easily understood by and applicable to a large audience

Download or read book Modification of Polymers written by Charles E. Carraher and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sheer volume of topics which could have been included under our general title prompted us to make some rather arbitrary decisions about content. Modification by irradiation is not included because the activity in this area is being treated elsewhere. We have chosen to emphasize chemical routes to modification and have striven to pre sent as balanced a representation of current activity as time and page count permit. Industrial applications, both real and potential, are included. Where appropriate, we have encouraged the contributors to include review material to help provide the reader with adequate context. The initial chapter is a review from a historical perspective of polymer modification and contains an extensive bibliography. The remainder of the book is divided into four general areas: Reactions and Preparation of Copolymers Reactions and Preparation of Block and Graft Copolymers Modification Through Condensation Reactions Applications The chemical modification of homopolymers such as polyvinylchlo ride, polyethylene, poly(chloroalkylene sulfides), polysulfones, poly chloromethylstyrene, polyisobutylene, polysodium acrylate, polyvinyl alcohol, polyvinyl chloroformate, sulfonated polystyrene; block and graft copolymers such as poly(styrene-block-ethylene-co-butylene block-styrene), poly(I,4-polybutadiene-block ethylene oxide), star chlorine-telechelic polyisobutylene, poly(isobutylene-co-2,3-dimethyl- 1,3-butadiene), poly(styrene-co-N-butylmethacrylate); cellulose, dex tran and inulin, is described.

Download or read book Advances in Catalysis written by D. D. Eley and published by . This book was released on 1978 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: