Studies in Organic Chemistry

11 Books

This book provides the most up-to-date and comprehensive coverage of the structures and properties of polysaccharides, methods for their characterization, de novo synthesis, and modification, as well as advances in structure/function correlations. Many of these topics are summarized for the first time.

A brief survey of polysaccharide structures is given highlighting the most significant advances in analytical and spectroscopic technology (NMR, MS, etc.). A chapter is devoted to glycan properties, including conformational aspects, rheological and compatibility characteristics, etc. There is a comprehensive overview of the de novo synthesis of carbohydrate polymers, the transformation of glycans into novel types of polymers, and the preparation of linear and branched polysaccharide analogues and conjugates with synthetic polymers via chemical and enzymatic approaches. The book also details the factors controlling the uniformity of substitutions in homogeneous and heterogeneous derivatization processes and the elucidation of the substitution patterns of partially modified polysaccharides, through combined spectroscopic and statistical methods.

One of the important developments in the glycan field is based on the increasing demand for greater control of the functional properties of these biopolymers. The book provides a very extensive account of various types of modifications, including selective and non-selective chemical techniques, biological methods that facilitate alterations or specific functional groups and properties through the application of synthetic or degradative enzymes, and mutational or recombinant DNA techniques. The coverage extends to the control of glycan integrity and molecular weight through chemical enzymatic, physical or other methods. Electrochemical modification techniques are also discussed.

A particularly up-to-date and comprehensive review is given of polysaccharide structure/property relations. Here, the effects of primary structural parameters (composition, molecular size, branching, polyelectrolyte character and non-carbohydrate substituents) are discussed, as are factors which affect glycan solubility, viscosity and gel-forming capacity. Also included are the phenomena resulting from the interactions of polysaccharides with solvents, salts, polyols, surfactants, synthetic and biological polymers. The impact of glycan structural parameters on various biological activities, such as immunological, anticoagulant, and antitumour properties, is surveyed.

The book features a foreword by Dr. R.H. Marchessault, and contains almost 2,000 references to the state-of-the-art in the field, as well as an extensive subject index, over 40 tables, and 130 schemes and illustrations. It provides a wealth of valuable information for specialists in polysaccharides, biochemists, biotechnologists, enzymologists, microbiologists, organic chemists, polymer scientists, and others whose work involves these biopolymers.

This detailed treatise is written for chemists who are not NMR spectroscopists but who wish to use carbon-13 NMR spectroscopy. It shows why measurement of carbon-13 NMR is needed and explains how the method can - or should - be used for rapid characterization of flavonoids, one of the most diverse and widespread groups of natural constituents.

The first part of the book presents background information and discussion of the essential aspects of flavonoids and carbon-13 NMR spectroscopy and demonstrates its significant role in the revision of several earlier established chemical structures. It discusses various one- and two-dimensional NMR spectroscopic techniques and other relevant experimental methodologies for the interpretation of spectral details which enable individual resonance lines to be associated with the appropriate carbons in a molecule. The second part provides a comprehensive coverage of the carbon-13 chemical shifts of various classes and subclasses of flavonoids. It also illustrates how to utilize carbon-13 data to gain information for the determination of the nature, number and site of any substituent in flavonoids. Vital information for the differential and complete structure elucidation of the various classes of flavonoids by carbon-13 NMR shielding data is described in-depth in the third part of the book.

The book will be welcomed by all those working in natural product chemistry who will appreciate the non-mathematical approach and the fact that such a wealth of theoretical and practical information has been assembled in a single volume.

Since the discovery of crown ethers by Pedersen in 1967, several thousands of crown ethers and analogous compounds have been synthesized. Their specific characteristics have been investigated and a variety of applications developed. These developments have led to new fields of chemistry called host-guest chemistry and supramolecular chemistry. This book presents the state-of-the-art of the chemistry of crown ethers and analogous compounds.

The first chapter provides an orientation in the new fields of chemistry. Chapter 2 reviews advances in synthetic procedures for crown ethers and analogous compounds including azacrown ethers, thiacrown ethers, functionalized crown ethers, cryptands and others. The focus of chapter 3 is on the concept and synthetic strategies for the molecular design of new crown compounds. Chapters 4-7 are concerned with noteworthy topics in the applications of crown compounds. Chapter 4 deals with the application to ion-selective electrodes and liquid chromatography, both of which are the most important targets in the analytical application of crown compounds. One major application of crown ethers is the design and syntheses of artificial molecules which can catalyze a useful synthetic reaction in an enzyme-mimetic reaction manner, through novel non-covalent complexes. The strategies for enzymatic modelling with crown ethers are covered in chapter 5, while chapter 6 presents the principle of amine-selective colour complexation and its application. In chapter 7 switched-on crown ethers that can respond to environmental stimuli are reviewed. The final chapter is devoted to a wide-ranging discussion of developments in macrocyclic polyamine chemistry. Unlike crown ethers, macrocyclic polyamines, bearing nitrogen donor atoms which belong to a soft base, form complexes with ions of transition metals and heavy metals which are classified as soft acids. Therefore, macrocyclic polyamines are expected to have very versatile applications.

Scientists in chemistry, biochemistry, physical organic chemistry, pharmaceutical chemistry and industrial chemistry will find this book a helpful summary and a stimulating contribution to research in this specialized field of crown compounds.

These proceedings contain most of the oral presentations and posters of the international symposium on Stability and Stabilization of Enzymes held in Maastricht in November 1992. They provide a comprehensive overview of the state-of-the-art in this field.

The possible applications of enzymes are enormous. Years of development have seen many enzymes brought onto the market, but they are still expensive to use. Therefore, their efficient application is a prerequisite for common usage. One of the main factors for this efficiency is the stability of the enzymes. The topics thus ranged from the extensive fundamental thermodynamic knowledge gathered in academic research to the practical applied knowledge built up in industry during the time that enzymes have been produced commercially.

The subject Stability and Stabilization of Enzymes was discussed from various points of view, as was reflected in the themes of the symposium sessions. In the session on Fundamentals of Enzyme Stabilisation the thermodynamic background of the phenomenon was highlighted. In yet another session, the recently developed analytical tools to measure enzyme stability and stabilisation were discussed. Further sessions comprised the physical, chemical and biological ways to obtain enzyme stabilisation and finally, the industrial practice of enzyme stabilisation was treated by representatives of the world's most important enzyme producers. The book will be of interest to researchers in universities and industry in the fields of biochemistry, enzymology and biotechnology.

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