Towards Dimetallic Biologically Inspired Aerobic Oxidation Catalysts

Heterogeneously catalyzed selective oxidations of alcohols is a highly topical field. The first chapter of this brief describes the importance of the selective oxidation of alcohols and advantages of heterogeneous catalysts over conventional catalysts, use of environmentally benign oxidants, and the design of selective catalysts by tailoring of polyoxometalates at the molecular level. Chapter 2 describes synthesis, characterization 11-molybdophosphate based supported materials and their use as heterogeneous catalysts for oxidation of alcohols with molecular oxygen under solvent free mild reaction condition. ZrO2, Al2O3, MCM-41 and zeolite Hβ were used as supports. Chapter 3 describes synthesis, characterization of transition metals (Mn, Co, Ni, Cu)- substituted phosphomolybdates and their use as heterogeneous catalysts for oxidation of alcohols with molecular oxygen under solvent free mild reaction condition. Chapter 4 describes conclusive remarks for present catalytic systems.

The first book to place recent academic developments within the context of real life industrial applications, this is a timely overview of the field of aerobic oxidation reactions in the liquid phase that also illuminates the key challenges that lie ahead. As such, it covers both homogeneous as well as heterogeneous chemocatalysis and biocatalysis, along with examples taken from various industries: bulk chemicals and monomers, specialty chemicals, flavors and fragrances, vitamins, and pharmaceuticals. One chapter is devoted to reactor concepts and engineering aspects of these methods, while another deals with the relevance of aerobic oxidation catalysis for the conversion of renewable feedstock. With chapters written by a team of academic and industrial researchers, this is a valuable reference for synthetic and catalytic chemists at universities as well as those working in the pharmaceutical and fine chemical industries seeking a better understanding of these reactions and how to design large scale processes based on this technology.

Oxidation reactions are an important chemical transformation in both academia and industry. Among the major advances in the field has been the development of catalytic processes, which are not only selective and efficient, but also allow the replacement of common stoichiometric oxidants with molecular oxygen, ideally from air at atmospheric pressure. This results in processes with higher atom efficiency, where water is the only side product in line with the principles of green chemistry. Focusing on the use of molecular oxygen as the terminal oxidant, this book covers recent advances in both heterogeneous and homogeneous systems, with and without metals and on the "taming" of the highly reactive oxygen gas by use of micro-flow reactors and membranes. A useful reference for industrial and academic chemists working on oxidation processes, as well as green chemists.

This book deals with the search for environmentally benign procedures for the oxidation of alcohols and gives an overview of their transition-metal-catalyzed aerobic oxidation.

Advanced Catalysts Based on Metal-organic Frameworks is a comprehensive introduction to advanced catalysts based on MOFs. It covers basic information about MOF catalysts with industrial and environmental applications. It updates readers on current applications and strategies to apply MOF-based catalysts in industrial processes geared for sustainability initiatives such as renewable energy, pollution control and combating carbon emission. Key Features - 13 structured, easy to read chapters that comprehensively cover MOF catalysts - An introduction to basic information about MOF catalysts - In-depth coverage of advanced applications of MOF catalysts - Explanation of MOF modifications and applications of derivative compounds - In-depth coverage of MOF catalysts used for electrocatalysis and photocatalysis - Detailed explanation of environmental-friendly and sustainable technologies (biomass upgrading, water purification, CO2 capture) - Updated references for advanced readers The is an essential reference for chemical engineers, scientists in the manufacturing and sustainability industry and post-graduate scholars working on MOFs and chemical catalysis.

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.

The selective oxidation of organic compounds is a prominent challenge in organic chemistry. Towards this goal, molecular oxygen is an ideal oxidant. Uncatalyzed aerobic oxidation reactions have found important application in the commodity scale synthesis of certain compounds. However, such autoxidation reactions are intrinsically substrate-controlled. More frequently, selective aerobic oxidations are achieved by using a catalyst to promote the desired transformation. Under such a regime the identity of the catalyst -- and therefore the reaction mechanism -- dictates the chemical outcome of the reaction. The development of new catalysts which promote aerobic oxidation reactions is therefore of great significance. This thesis highlights two classes of catalyst that promote selective aerobic oxidation reactions. Chapters 1-4 describe the development of a family of o-quinone catalysts based on o-quinone cofactors found in certain oxidase and dehydrogenase enzymes. Unlike the natural cofactors, which have limited substrate scope, we find evidence for an unnatural reaction pathway that broadens the synthetic utility of these reagents. This family of bioinspired o-quinone catalysts is particularly effective in the aerobic dehydrogenation of C---N bonds. Subsequently, in chapters 5 and 6 I discuss the application of Cu-based catalysts to aerobic oxidation reactions, emphasizing an apparent mechanistic bifurcation between single electron transfer-based mechanisms and organometallic mechanisms within the published literature. Further work describes an application of CuII reagents in the aerobic oxidative cyclization of enamides to oxazoles.

This book presents recent advances in dinuclear complexes in which the metal-metal cooperative effect operates for obtaining substrate activation and high performance catalysts. Catalysis continues to be a fast expanding area to design efficient tools in synthesis and in industrial chemistry. It allows performing syntheses with short reaction times, atom economy, reduced consumption of energy and loss of reagents, and low level of wastes. Dinuclear complexes are known to be more efficient than the mononuclear analogues for the reaction rates and the selectivities. This book analyses the latest research, focusing on the key concepts, in building and using these dinuclear complexes. The book is aimed at researchers, graduate students and chemists at all levels in academia and industry.