The chemical literature

We are the beneficiaries of almost one and a half centuries of research in organic chemistry. The accumulated output of that effort is an enormous body of data collected in a vast literature. It is estimated that well over half a million articles (papers, patents, books, etc.) are published each year and the volume of publications will probably continue to rise. Searching such a huge body of work is a formidable problem but it must be emphasized that the time spent reading the literature is often more than repaid by the experimental time saved as a result 

This chapter is intended as a practical guide to efficient searching of the chemical literature the main part is devoted to a description of the most important access routes to the primary literature, and a discussion of methods of tackling some common types of literature search. The chapter concludes with a section on methods of keeping in touch with the current literature. The reader is referred to a number of recent texts for more detailed information. 

In order to aid discussion of these information sources we have split them into two categories paper-based information sources (journals, books, series, etc.) and electronic sources (computer databases), because although the type of information available from each source may be the same, the coverage and methods for searching them often differ significantly. 

Wiggins, Chemical Information Sources, McGraw-Hifl, New York, 1991. 

Wolman, Chemical Information, A Practical Guide to Utilization, 2nd ed., 

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Similarity is often used as a general term to encompass either similarity or dissimilarity or both (see Section 6.4.3, on similarity measures, below). The terms "proximity" and distance are used in statistical software packages, but have not gained wide acceptance in the chemical literature. Similarity and dissimilarity can in principle lead to different rankings. 

This volume is intended to present a comprehensive description of the chemistry of thiazole and its monocyclic derivatives, based on the chemical literature up to December, 1976. It is not concerned with polycyclic thiazoles, such as benzo- or naphthothiazole, nor with hydrogenated derivatives, such as thiazolines or thiazolidines later volumes in this series are devoted to these derivatives. The chemistry of thiamine has also been excluded from the present volume because of the enormous amount of literature corresponding to the subject and is developed in another volume. On the other hand, a discussion of selenazole and its monocyclic derivatives has been included, and particular emphasis has been given to the cyanine dyes derived from thiazolium salts. 

Each of the following reactions has been described in the chemical literature and involves an organic starting matenal somewhat more complex than those we have encountered so far Nevertheless on the basis of the topics covered in this chapter you should be able to wnte the structure of the principal organic product of each reaction... 

Evidence has been reported in the chemical literature that the reaction... 

Often more than one synthetic route may be available to prepare a particular com pound Indeed it is normal to find m the chemical literature that the same compound has been synthesized m a number of different ways As we proceed through the text and develop a larger inventory of functional group transformations our ability to evaluate alternative synthetic plans will increase In most cases the best synthetic plan is the one with the fewest steps... 

All the following reactions have been reported in the chemical literature Give the structure of the pnncipal organic product in each case... 

All these reactions of octadecyl p toluenesulfonate have been reported in the chemical literature and all proceed in synthetically useful yield You should begin by identifying the nucleophile in each of the parts to this problem The nucleophile replaces the p toluenesulfonate leaving group in an Sn2 reaction In part (a) the nucleophile is acetate ion and the product of nucleophilic substitution IS octadecyl acetate... 

Each of the following nucleophilic substitution reactions has been reported in the chemical literature Many of them involve reactants that are somewhat more complex than those we have dealt with to this point Nevertheless you should be able to predict the product by analogy to what you know about nucleophilic substitution in simple systems... 

All the following reactions have been descnbed in the chemical literature and proceed in good yield In some cases the reactants are more complicated than those we have so far encoun tered Nevertheless on the basis of what you have already learned you should be able to predict the pnncipal product in each case... 

A very large number of Diels-Alder reactions are recorded in the chemical literature many of which involve relatively complicated dienes dienophiles or both On the basis of your knowl edge of Diels-Alder reactions predict the constitution of the Diels-Alder adduct that you would expect to be formed from the following combinations of dienes and dienophiles... 

The reaction of N bromosuccimmide with the following com pounds has been reported in the chemical literature Each compound yields a single product in 95% yield Identify the product formed from each starting material (a) p-tert Butyltoluene (b) 4 Methyl 3 nitroanisole... 

Each of the following reactions has been descnbed in the chemical literature and gives a single organic product in good yield Identify the product of each reaction... 

The following conversion has been reported in the chemical literature It was earned out in two steps the first of which involved formation of a p toluenesulfonate ester Indicate the reagents for this step and show how you could convert the p toluenesulfonate to the desired product... 

As actually carried out and reported in the chemical literature diethyl malonate has been alkylated with 2 bromobutane in 83-84% yield and the product of that reaction converted to 3 methylpentanoic acid by saponification acidification and decarboxylatlon in 62-65% yield j... 

Each of the following reactions has been reported m the chemical literature and proceeds m good yield What are the principal organic products of each reaction" In some of the exercises more than one diastereomer may be theoretically possible but m such instances one diastereomer is either the major product or the only product For those reactions m which one diastereomer is formed preferentially indicate its expected stereochemistry... 

WE BELIEVE that a need exists for a book to help the chemist or biochemist who wishes to purify the reagents she or he uses. This need is emphasised by the previous lack of any satisfactory central source of references dealing with individual substances. Such a lack must undoubtedly have been a great deterrent to many busy research workers who have been left to decide whether to purify at all, to improvise possible methods, or to take a chance on finding, somewhere in the chemical literature, methods used by some previous investigators. 

Only a small amount of work has been done up to now concerning the prediction of bond strengths and other properties based on the results of the analysis of the resin. Ferg et al. [59] worked out correlation equations evaluating the chemical structures in various UF-resins with different F/U molar ratios and different types of preparation on the one hand and the achievable internal bond as well as the subsequent formaldehyde emission on the other hand. These equations are valid only for well defined series of resins. The basic aim of such experiments is the prediction of the properties of the wood-based panels based on the composition and the properties of the resins used. For this purpose various structural components are determined by means of - C NMR and their ratios related to board results. Various papers in the chemical literature describe examples of such correlations, in particular for UF, MF, MUF and PF resins [59-62]. For example one type of equation correlating the dry internal bond (IB) strength (tensile strength perpendicular to the plane of the panel) of a particleboard bonded with PF adhesive resins is as follows [17]... 

Bromochlorofluoromethane is a known compound, and samples selectively enriched in each enantiomer have been described in the chemical literature. In 1989 two chemists at Polytechnic University (Brooklyn, New York) described a method for the preparation of BrClFCH that is predominantly one enantiomer. 

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