Download or read book Studies Directed Toward the Synthesis of Griseolic Acids and a New Catalyst for a Palladium Catalyzed Alder Ene Reaction written by Yong Li and published by . This book was released on 1996 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 1996 with total page 712 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Superbases for Organic Synthesis written by Tsutomu Ishikawa and published by John Wiley & Sons. This book was released on 2009-01-26 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: Guanidines, amidines and phosphazenes have been attracting attention in organic synthesis due to their potential functionality resulting from their extremely strong basicity. They are also promising catalysts because of their potential for easy molecular modification, possible recyclability, and reduced or zero toxicity. Importantly, these molecules can be derived as natural products – valuable as scientists move towards “sustainable chemistry”, where reagents and catalysts are derived from biomaterial sources. Superbases for Organic Synthesis is an essential guide to these important molecules for preparative organic synthesis. Topics covered include the following aspects: an introduction to organosuperbases physicochemical properties of organic superbases amidines and guanidines in organic synthesis phosphazene: preparation, reaction and catalytic role polymer-supported organosuperbases application of organosuperbases to total synthesis related organocatalysts: proton sponges and urea derivatives amidines and guanidines in natural products and medicines Superbases for Organic Synthesis is a comprehensive, authoritative and up-to-date guide to these important reagents for organic chemists, drug discovery researchers and those interested in the chemistry of natural products.
Download or read book Van Nostrand s Encyclopedia of Chemistry written by Glenn D. Considine and published by Wiley-Interscience. This book was released on 2005-02-03 with total page 1856 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientists, engineers, and technologists in many fields need a knowledge of chemistry because of the importance of chemistry in diverse technologies. In addition, to "classical" topics of chemistry, the new Encyclopedia covers nanotechnology, fuel cell technology, green chemistry, forensic chemistry, supramolecular chemistry, combinatorial chemistry, materials chemistry, and proteomics. This fifth print edition has been revised and updated, and includes over 200 new articles, as well as 1,300 updated articles.
Download or read book The Chemistry of Amidines and Imidates written by Saul Patai and published by . This book was released on 1975 with total page 952 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Indoles written by Richard J. Sundberg and published by Elsevier. This book was released on 1996-05-28 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: Indoles continue to be of great interest to the pharmaceutical industry and at the current time several thousand specific new derivatives are reported annually. Research has been driven by the wide range of indole derivatives which occur in nature and through the biological activity of many indole derivatives, of both natural and synthetic origin.This book provides a systematic guide to the most useful and important reactions in the field for both synthesis and synthetic modification of the indole ring. While including the most recently developed and promising methods, it also updates informationavailable on classical methods to give the reader an up-to-date and comprehensive view of the subject. The methods are illustrated by procedures drawn from the literature and by tables including examples chosen to indicate both the scope of applicabilityand variations in methodology. The organization of the book is based on the retrosynthetic concept of identifying the bond(s) formed in the reaction, which in turn identifies potential starting materials. - Includes systematic summaries of the most important methods for the construction of indoles from aromatic precursors - Discusses methods for preparing indoles by annelation of pyrroles - Covers methods for adding or modifying substituent groups, including methods for introducing the tryptamine and tryptophan side-chainsExamines reduction/oxidation reactions that are specific for indoles - Considers use of cycloaddition reactions for synthetic elaboration of indoles
Download or read book Spectrophotometry Luminescence and Colour written by Christopher Burgess and published by Elsevier Publishing Company. This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains papers presented at the Second Joint Meeting of the UV Spectrometry Group of the UK and the Council for Optical Radiation Measurements of the USA. Topics included are: compliance and validation in spectrophotometry, advances in spectrophotometric measurements, instrument manufacturers' approaches to compliance, advances in fluorescence techniques and advances in spectrophotometry. The balance of the conference has shifted from the 1986 mix towards more applications but once again the National Laboratories have provided an excellent update on the state-of-the-art in many areas.
Download or read book Analytical Instrumentation Handbook written by Jack Cazes and published by CRC Press. This book was released on 2004-11-30 with total page 1066 pages. Available in PDF, EPUB and Kindle. Book excerpt: Compiled by the editor of Dekker's distinguished Chromatographic Science series, this reader-friendly reference is as a unique and stand-alone guide for anyone requiring clear instruction on the most frequently utilized analytical instrumentation techniques. More than just a catalog of commercially available instruments, the chapters are wri
Download or read book Water soluble Polymers written by J. Edward Glass and published by . This book was released on 1986 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: Brings together the diverse experience of those working with and using water-soluble polymers. Gives a detailed description of important advances in inversion emulsion polymerization of synthetic water-soluble monomers. Reports on the tremendous increase in research and the state-of-the-art in fundamental concepts and application performance of water-soluble polymers. Looks at the solution properties of some important carbohydrate polymers, and examines recent developments in the characterization of water-soluble polymers by chromatographic and NMR techniques.
Download or read book Adsorption Technology and Design written by W John Thomas, FEng and published by Butterworth-Heinemann. This book was released on 1998-04-27 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: The aim of this book is to provide all those involved in designing and running adsorption processes with a guide to adsorption technology and design.
Download or read book Histamine and Histamine Antagonists written by Börje Uvnäs and published by Springer. This book was released on 2011-12-03 with total page 763 pages. Available in PDF, EPUB and Kindle. Book excerpt: Together with the two previous volumes of the Handbook of Experimental Pharmacology on histamine and antihistamines the present publication yields a picture of a still rapidly developing field of research. New techniques and new experimental approaches have brought us new knowledge and deeper insight into the biomedical significance of histamine, even if many questions remain to be answered about the functional and medical implications of this old biogenic amine. The present volume covers the progress in histamine research during the past two decades. A significant chapter concerns techniques for histamine determination. As the result of a consensus meeting in Munich in December 1988, a panel of eminent specialists arrived at common recommendations as to the usefulness of the available histamine assays for the most common experimental biomedical conditions. The heterogeneity of mast cells, with great differences in their reactivity to various stimuli, has become apparent, not only among species but also among the tissues of a species. New informa tion is presented about the mechanism of exocytosis. The old questions about the role of histamine in the mechanism of gastric secretion and in cardio vascular and respiratory functions have been studied with new techniques, and the role of HI and H2 receptors discussed. New observations have been made on the occurrence and possible functions of histaminergic neurons and histamine receptors in CNS where a new type of receptor, the H , seems to 3 be widely represented.
Download or read book Phthalocyanine Compounds written by Frank H Moser and published by Hassell Street Press. This book was released on 2021-09-09 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. To ensure a quality reading experience, this work has been proofread and republished using a format that seamlessly blends the original graphical elements with text in an easy-to-read typeface. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
Download or read book Agricultural Control Chemicals written by American Chemical Society. Division of Agricultural and Food Chemistry and published by . This book was released on 1950 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Copper Catalyzed Multi Component Reactions written by Yusuke Ohta and published by Springer. This book was released on 2011-01-30 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: A copper-catalyzed direct synthesis of 2-(aminomethyl)indoles by catalytic domino reaction including multi-component coupling was developed, and is the first example of a three-component indole formation without producing salts as a byproduct. Based on this reaction, a copper-catalyzed synthesis of 3-(aminomethyl)isoquinoline was accomplished which represents an unprecedented isoquinoline synthesis through a four-component coupling reaction. Following these results, extensive application studies using one-pot palladium-, acid-, or base-promoted cyclization revealed that indole- or isoquinoline-fused polycyclic compounds can be readily synthesized through multi-component reactions. As the concept of Green Chemistry becomes ever more important, these findings may provide efficient and atom-economical approaches to the diversity-oriented synthesis of bioactive compounds containing a complex structure. This could lead to development of promising drug leads with structural complexity. The work of this thesis will go on to inspire the synthetic research of many readers.
Download or read book Asymmetric and Selective Biocatalysis written by Jose M. Palomo and published by MDPI. This book was released on 2019-04-12 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Issue contains one communication, six articles, and two reviews. The communication from Paola Vitale et al. represents a work where whole cells were used as biocatalysts for the reduction of optically active chloroalkyl arylketones followed by a chemical cyclization to give the desired heterocycles. Among the various whole cells screened (baker’s yeast, Kluyveromyces marxianus CBS 6556, Saccharomyces cerevisiae CBS 7336, Lactobacillus reuteri DSM 20016), baker’s yeast provided the best yields and the highest enantiomeric ratios (95:5) in the bioreduction of the above ketones. In this respect, valuable chiral non-racemic functionalized oxygen-containing heterocycles (e.g., (S)-styrene oxide, (S)-2-phenyloxetane, (S)-2-phenyltetrahydrofuran), amenable to be further elaborated on, can be smoothly and successfully generated from their prochiral precursors. Studies about pure biocatalysts with mechanistical studies, application in different reactions, and new immobilization methods for improving their stability were reported in five different articles. The article by Su-Yan Wang et al. describes the cloning, expression, purification, and characterization of an N-acetylglucosamine 2-epimerase from Pedobacter heparinus (PhGn2E). For this, several N-acylated glucosamine derivatives were chemically synthesized and used to test the substrate specificity of the enzyme. The mechanism of the enzyme was studied by hydrogen/deuterium NMR. The study at the anomeric hydroxyl group and C-2 position of the substrate in the reaction mixture confirmed the epimerization reaction via ring-opening/enolate formation. Site-directed mutagenesis was also used to confirm the proposed mechanism of this interesting enzyme. The article by Forest H. Andrews et al. studies two enzymes, benzoylformate decarboxylase (BFDC) and pyruvate decarboxylase (PDC), which catalyze the non-oxidative decarboxylation of 2-keto acids with different specificity. BFDC from Pseudomonas putida exhibited very limited activity with pyruvate, whereas the PDCs from S. cerevisiae or from Zymomonas mobilis showed virtually no activity with benzoylformate (phenylglyoxylate). After studies using saturation mutagenesis, the BFDC T377L/A460Y variant was obtained, with 10,000-fold increase in pyruvate/benzoylformate. The change was attributed to an improvement in the Km value for pyruvate and a decrease in the kcat value for benzoylformate. The characterization of the new catalyst was performed, providing context for the observed changes in the specificity. The article by Xin Wang et al. compares two types of biocatalysts to produce D-lysine L-lysine in a cascade process catalyzed by two enzymes: racemase from microorganisms that racemize L-lysine to give D,L-lysine and decarboxylase that can be in cells, permeabilized cells, and the isolated enzyme. The comparison between the different forms demonstrated that the isolated enzyme showed the higher decarboxylase activity. Under optimal conditions, 750.7 mmol/L D-lysine was finally obtained from 1710 mmol/L L-lysine after 1 h of racemization reaction and 0.5 h of decarboxylation reaction. D-lysine yield could reach 48.8% with enantiomeric excess (ee) of 99%. In the article by Rivero and Palomo, lipase from Candida rugosa (CRL) was highly stabilized at alkaline pH in the presence of PEG, which permitted its immobilization for the first time by multipoint covalent attachment on different aldehyde-activated matrices. Different covalent immobilized preparation of the enzyme was successfully obtained. The thermal and solvent stability was highly increased by this treatment, and the novel catalysts showed high regioselectivity in the deprotection of per-O-acetylated nucleosides. The article by Robson Carlos Alnoch et al. describes the protocol and use of a new generation of tailor-made bifunctional supports activated with alkyl groups that allow the immobilization of proteins through the most hydrophobic region of the protein surface and aldehyde groups that allows the covalent immobilization of the previously adsorbed proteins. These supports were especially used in the case of lipase immobilization. The immobilization of a new metagenomic lipase (LipC12) yielded a biocatalyst 3.5-fold more active and 5000-fold more stable than the soluble enzyme. The PEGylated immobilized lipase showed high regioselectivity, producing high yields of the C-3 monodeacetylated product at pH 5.0 and 4 °C. Hybrid catalysts composed of an enzyme and metallic complex are also treated in this Special Issue. The article by Christian Herrero et al. describes the development of the Mn(TpCPP)-Xln10A artificial metalloenzyme, obtained by non-covalent insertion of Mn(III)-meso-tetrakis(p-carboxyphenyl)porphyrin [Mn(TpCPP), 1-Mn] into xylanase 10A from Streptomyces lividans (Xln10A). The complex was found able to catalyze the selective photo-induced oxidation of organic substrates in the presence of [RuII(bpy)3]2+ as a photosensitizer and [CoIII(NH3)5Cl]2+ as a sacrificial electron acceptor, using water as oxygen atom source. The two published reviews describe different subjects with interest in the fields of biocatalysis and mix metallic-biocatalysis, respectively. The review by Anika Scholtissek et al. describes the state-of-the-art regarding ene-reductases from the old yellow enzyme family (OYEs) to catalyze the asymmetric hydrogenation of activated alkenes to produce chiral products with industrial interest. The dependence of OYEs on pyridine nucleotide coenzyme can be avoided by using nicotinamide coenzyme mimetics. In the review, three main classes of OYEs are described and characterized. The review by Yajie Wang and Huimin Zhao highlights some of the recent examples in the past three years that combine transition metal catalysis with enzymatic catalysis. With recent advances in protein engineering, catalyst synthesis, artificial metalloenzymes, and supramolecular assembly, there is great potential to develop more sophisticated tandem chemoenzymatic processes for the synthesis of structurally complex chemicals. In conclusion, these nine publications give an overview of the possibilities of different catalysts, both traditional biocatalysts and hybrids with metals or organometallic complexes to be used in different processes—particularly in synthetic reactions—under very mild reaction conditions.
Download or read book A Study on Catalytic Conversion of Non Food Biomass into Chemicals written by Mizuho Yabushita and published by Springer. This book was released on 2016-01-13 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: The topic of this thesis is catalytic conversion of non-food, abundant, and renewable biomass such as cellulose and chitin to chemicals. In biorefinery, chemical transformation of polymers to valuable compounds has attracted worldwide interest for building sustainable societies. First, the current situation of this hot research area has been summarized well in the general introduction of the thesis, which helps readers to become familiar with this topic. Next, the author explains high-yielding production of glucose from cellulose by using an alkali-activated carbon as a catalyst, resulting in a yield of glucose as high as 88%, which is one of the highest yields ever reported. The characterization of carbon materials has indicated that weak acid sites on the catalyst promote the reaction, which is markedly different from reported catalytic systems that require strong acids. In addition, the first catalytic transformation of chitin with retention of N-acetyl groups has been developed. The combination of mechanocatalytic hydrolysis and thermal solvolysis enables the production of N-acetylated monomers in good yields of up to 70%. The catalytic systems demonstrated in this thesis are unique in the fields of both chemistry and chemical engineering, and their high efficiencies can contribute to green and sustainable chemistry in the future. Meanwhile, mechanistic studies based on characterization, thermodynamics, kinetics, and model reactions have also been performed to reveal the roles of catalysts during the reactions. The results will be helpful for readers to design and develop new catalysts and reaction systems.
Download or read book Asymmetric and Selective Biocatalysis written by Cesar Mateo and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This Issue contains one communication, six articles, and two reviews. The communication from Paola Vitale and others represents a work where whole cells were used as biocatalysts for the reduction of optically active chloroalkyl arylketones followed by a chemical cyclization to give the desired heterocycles. Among the various whole cells screened (baker's yeast, Kluyveromyces marxianus CBS 6556, Saccharomyces cerevisiae CBS 7336, Lactobacillus reuteri DSM 20016), baker's yeast provided the best yields and the highest enantiomeric ratios (95:5) in the bioreduction of the above ketones. In this respect, valuable chiral non-racemic functionalized oxygen-containing heterocycles (e.g., (S)-styrene oxide, (S)-2-phenyloxetane, (S)-2-phenyltetrahydrofuran), amenable to be further elaborated on, can be smoothly and successfully generated from their prochiral precursors. Studies about pure biocatalysts with mechanistical studies, application in different reactions, and new immobilization methods for improving their stability were reported in five different articles. The article by Su-Yan Wang and others describes the cloning, expression, purification, and characterization of an N-acetylglucosamine 2-epimerase from Pedobacter heparinus (PhGn2E). For this, several N-acylated glucosamine derivatives were chemically synthesized and used to test the substrate specificity of the enzyme. The mechanism of the enzyme was studied by hydrogen/deuterium NMR. The study at the anomeric hydroxyl group and C-2 position of the substrate in the reaction mixture confirmed the epimerization reaction via ring-opening/enolate formation. Site-directed mutagenesis was also used to confirm the proposed mechanism of this interesting enzyme. The article by Forest H. Andrews and others studies two enzymes, benzoylformate decarboxylase (BFDC) and pyruvate decarboxylase (PDC), which catalyze the non-oxidative decarboxylation of 2-keto acids with different specificity. BFDC from Pseudomonas putida exhibited very limited activity with pyruvate, whereas the PDCs from S. cerevisiae or from Zymomonas mobilis showed virtually no activity with benzoylformate (phenylglyoxylate). After studies using saturation mutagenesis, the BFDC T377L/A460Y variant was obtained, with 10,000-fold increase in pyruvate/benzoylformate. The change was attributed to an improvement in the Km value for pyruvate and a decrease in the kcat value for benzoylformate. The characterization of the new catalyst was performed, providing context for the observed changes in the specificity. The article by Xin Wang and others compares two types of biocatalysts to produce D-lysine L-lysine in a cascade process catalyzed by two enzymes: racemase from microorganisms that racemize L-lysine to give D,L-lysine and decarboxylase that can be in cells, permeabilized cells, and the isolated enzyme. The comparison between the different forms demonstrated that the isolated enzyme showed the higher decarboxylase activity. Under optimal conditions, 750.7 mmol/L D-lysine was finally obtained from 1710 mmol/L L-lysine after 1 h of racemization reaction and 0.5 h of decarboxylation reaction. D-lysine yield could reach 48.8% with enantiomeric excess (ee) of 99%. In the article by Rivero and Palomo, lipase from Candida rugosa (CRL) was highly stabilized at alkaline pH in the presence of PEG, which permitted its immobilization for the first time by multipoint covalent attachment on different aldehyde-activated matrices. Different covalent immobilized preparation of the enzyme was successfully obtained. The thermal and solvent stability was highly increased by this treatment, and the novel catalysts showed high regioselectivity in the deprotection of per-O-acetylated nucleosides. The article by Robson Carlos Alnoch and others describes the protocol and use of a new generation of tailor-made bifunctional supports activated with alkyl groups that allow the immobilization of proteins through the most hydrophobic region of the protein surface and aldehyde groups that allows the covalent immobilization of the previously adsorbed proteins. These supports were especially used in the case of lipase immobilization. The immobilization of a new metagenomic lipase (LipC12) yielded a biocatalyst 3.5-fold more active and 5000-fold more stable than the soluble enzyme. The PEGylated immobilized lipase showed high regioselectivity, producing high yields of the C-3 monodeacetylated product at pH 5.0 and 4 °C. Hybrid catalysts composed of an enzyme and metallic complex are also treated in this Special Issue. The article by Christian Herrero and others describes the development of the Mn(TpCPP)-Xln10A artificial metalloenzyme, obtained by non-covalent insertion of Mn(III)-meso-tetrakis(p-carboxyphenyl)porphyrin [Mn(TpCPP), 1-Mn] into xylanase 10A from Streptomyces lividans (Xln10A). The complex was found able to catalyze the selective photo-induced oxidation of organic substrates in the presence of [RuII(bpy)3]2+ as a photosensitizer and [CoIII(NH3)5Cl]2+ as a sacrificial electron acceptor, using water as oxygen atom source. The two published reviews describe different subjects with interest in the fields of biocatalysis and mix metallic-biocatalysis, respectively. The review by Anika Scholtissek and others describes the state-of-the-art regarding ene-reductases from the old yellow enzyme family (OYEs) to catalyze the asymmetric hydrogenation of activated alkenes to produce chiral products with industrial interest. The dependence of OYEs on pyridine nucleotide coenzyme can be avoided by using nicotinamide coenzyme mimetics. In the review, three main classes of OYEs are described and characterized. The review by Yajie Wang and Huimin Zhao highlights some of the recent examples in the past three years that combine transition metal catalysis with enzymatic catalysis. With recent advances in protein engineering, catalyst synthesis, artificial metalloenzymes, and supramolecular assembly, there is great potential to develop more sophisticated tandem chemoenzymatic processes for the synthesis of structurally complex chemicals. In conclusion, these nine publications give an overview of the possibilities of different catalysts, both traditional biocatalysts and hybrids with metals or organometallic complexes to be used in different processes-particularly in synthetic reactions-under very mild reaction conditions.
