A Work of ArtThe Art of Writing Reasonable Organic Reaction Mechanisms. By R. B. Grossman. Springer, Heidelberg, 1999. xv, 331 pp., hardcover DM 78.00. -- ISBN 0-387-98540-9
In every city that I have occasion to visit I enjoy seeing art exhibitions with paintings from different periods. Often these works cause me to ponder about what they depict. Regardless of whether they are agreeable or provocative, all such exhibits have one thing in common, namely that in the interplay between the phantasies of the artist and the beholder they can convey a variety of messages and emotions. Against the background of those experiences, I was surprised by the title of this book by Robert B. Grossman, in which the words "art" and "organic reaction mechanisms" are linked together. Would any of my students describe the writing of a reasonable reaction mechanism as "art"? I can only guess at the answer to that question. However, there remains the second and much more important question of whether studying the ideas and concepts of Grossman can help in establishing a link between the words "reaction mechanism" and "art". That consideration should certainly be sufficient reason to devote some time and attention to the book. From first reading its opening pages to working through the details of the individual chapters, one is left with a very positive impression and, thanks to its modest length of 331 pages, the task is not an onerous one. Grossman's aims are clearly defined in the introduction, and he follows them consistently through to the last paragraph. The author has not set out to produce yet another large compilation of reaction mechanisms. He points out, with justification, that there are already many excellent publications on that subject. Instead his idea was to write a book for students who have already attended up to two semesters of organic chemistry lectures, dealing with the sorts of difficulties that they might have when trying to formulate plausible reaction mechanisms. The kind of problem that he has in mind is not that of merely writing down the scheme for a simple reaction such as the preparation of chlorobenzene from benzene, but of clearly analyzing multistage transformations, in which the student may be uncertain about the number, nature, and sequence of the individual stages. A typical situation is one where, in an examination, the student is temporarily surprised and perhaps confused. The author's intention is that, after reading this book, the student should be able to analyze a reaction for the preparation of a complex molecule, applying modern concepts of reactivity and selectivity with an understanding of the sequence of the stages.
The book has a second purpose which is directed towards teachers of chemistry, as they too continue to be students. Scarcely anyone has the ability to construct perfect lectures or seminars right from the beginning of his or her teaching career. First one has to undergo an essential learning process, during which the art of conveying knowledge and presenting complex topics successfully is continually analyzed and improved. Grossman aims to help teachers to a better appreciation of that need.
The author treats the various aspects of reaction mechanisms under six main headings.
The section entitled "Basics" briefly sets out the fundamentals of some important relevant concepts. The author explains the conventions used in the book, shows how to deal properly with different ways of writing formulas, and discusses concepts such as partial charges, electron shifts, thermodynamic and kinetic aspects, and the meaning of the term "reaction mechanism". This is followed by the central part of the book, beginning with two chapters that embrace all types of polar reactions under the headings "Polar Reactions under Basic Conditions" and "Polar Reactions under Acidic Conditions". The conventional division into aromatic and aliphatic chemistry is not treated separately as such, nor are the processes of elimination, addition, and rearrangement. For many readers this approach will certainly lead to a good understanding of the different reactive properties of substrates under the polar conditions described, whereas in some more comprehensive textbooks that is often lost due to separating the concepts too rigidly in dedicated chapters. The treatment of polar reactions is followed by sections dealing with "Pericyclic Reactions", "Free Radical Reactions", and "Transition-Metal-Catalyzed and -Mediated Reactions".
Each chapter consists of a main text, examples, and paragraphs entitled "Common Error Alert", which are cleverly worked into the main text. The clearly presented schemes are complemented by well chosen examples, which often include not only the likeliest reaction paths but others which, for reasons that are explained, are unlikely. The "Common Error Alerts" describe typical difficulties that may arise in writing down a plausible reaction mechanism. These alerts should often enable the reader to avoid the errors in the first place. Each chapter ends with a large collection of exercise problems, and all these, as well as a further collection of questions in Chapter 7, are taken from recent literature. They relate mainly to the sorts of difficulties described in the text, and should therefore be easy to understand. There are also notes to help in solving the problems, which the reader can download from the Internet (at no cost, and with clear documentation in the usual form), so that even a beginner should be able to overcome difficulties with such help.
This is an excellent and well presented work which is timely in its subject matter. In contrast to the tendency of many books nowadays, in which difficult concepts are developed by subdividing them into ever more compartments, the author of this book has succeeded well in treating the central ideas of reactivity and selectivity in an integrated whole. The clear style of writing, the well chosen examples, and the clear concise summaries of the main points provided at the end of each chapter should enable the reader to easily consolidate what has been learned. Suggestions for improving the work in a later edition quickly come to mind. For example, the unnecessary division into metal-catalyzed and metal-mediated reactions leads to repetitions that could be avoided, and although the examples of modern reactions involving metals are excellent and well chosen, the subdivision makes the discussion of these longer than it need be. On the other hand, photochemical reactions are, in my opinion, treated too briefly. It would certainly have been appropriate to include in this book a short treatment of fundamental photophysical processes and the resulting chemical transformations. Another criticism concerns the surprisingly little space devoted to the stereochemical aspects of key steps in reaction mechanisms. However, the author has consciously chosen this point of view which is therefore part of his overall concept.
In this book Robert B. Grossman has set himself a demanding task. In my view he has succeeded very well, and has established a close connection between "art" and "organic reaction mechanisms". The book is indeed a little work of art!
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