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Organic Reaction Mechanisms

Subject area: Organic chemistry.

Description: A workbook to lead students through the process of deducing organic reaction mechanisms.

Authors: William C. Groutas.

Publishers/Suppliers: John Wiley & Sons, Inc. John Wiley and Sons, Ltd. (www.wiley.co.uk).

Date/Edition: 2000.

ISBN: 0-471-28251-0.

Level: Undergraduate.

Price: £27.50.

Review

This book isn't quite what I was expecting from the title, however the sub-title "Selected Problems and Solutions" reveals its purpose. Thus Groutas has provided not a thorough treatise on organic reaction mechanisms to compete with Peter Sykes' "A Guidebook to Mechanism in Organic Chemistry", but what is best regarded as a workbook to lead students through the process of deducing organic reaction mechanisms. Groutas' stated goal is "to use organic reaction mechanisms as a means of facilitating the mastery and understanding of the fundamental principles of organic chemistry, while at the same time sharpening a student's reasoning ability and critical thinking." In my view Groutas has achieved this goal: an undergraduate working through this book would indeed gain significant expertise in deducing organic reaction mechanisms, a command of curly arrows, and a good grasp of the underlying principles of organic chemistry. The book is aimed at students taking a sophomore-level organic chemistry course (Part A) and first year graduate organic chemistry courses (Part B) and the author has road tested the problems in such courses (he is based at Wichita State University, USA); in the UK context Part A would be appropriate for first year undergraduate chemists to study alongside their principle textbook and lecture notes, and Parts B and C for more advanced undergraduate courses or in postgraduate problem classes.

The book contains 210 problems (with solutions) all bar one or two in the format, "Write a mechanism for the following reaction:" followed by a scheme showing reactant(s), reagent(s) and product(s). The vast majority of the problems are taken from the primary literature, with references provided at the back of the book. The schemes and equations are drawn clearly though they do look like somewhat old fashioned in style (probably because they are set in Courier) but this is merely a minor distraction. Similarly the solutions are clearly presented as curly arrow mechanisms, with accompanying notes where necessary, in a section following the questions (so there is no danger of seeing them "by mistake") and are commendably thorough, with proton shuttling steps being shown in full. The schemes and solutions, and the book in general, contain few significant errors, though I found myself in disagreement with three of the mechanisms presented as solutions. I consider that some of the solutions have insufficient accompanying notes, i.e. to explain why one product results rather than an alternative, e.g. 5 vs. 6-membered rings or double bond positional isomers.

As the book is a workbook it is appropriate to comment on the contents in order. The book begins with useful and easy to follow notes on writing reaction mechanisms. These notes (and the subsequent minireviews) are interspersed with a few exercises for which solutions are not provided and which are simpler than the 210 problems. The book is wedded to the Lewis acid / base approach to analysing and solving the mechanistic problems, with mention of nucleophiles and electrophiles only coming later. Hence there are no radical or pericyclic reactions in the book. The introductory notes (and the minireviews) will be useful to students because they put into words much of the subconscious background thinking to the process of writing mechanisms employed by experienced organic chemists, however one "trick of the trade" not mentioned is the numbering of carbon atoms to facilitate mapping atoms between reactants and products, a technique that would aid the solution of the more taxing problems (especially those in Part B). A set of 10 worked examples follows the notes, these are well chosen to illustrate general principles, provide guidelines and highlight exceptions to those principles and guidelines.

It is emphasised throughout that the objective is not memorisation of mechanisms but their deduction.

The first three minireviews cover Lewis structures, etc., resonance (both of which would be revision for UK first year undergraduates) and carbocation chemistry, all include worked examples. There follow the first 34 problems, which may be solved by application of the principles covered in the preceding pages. This pattern continues with Minireviews 4 - 6 covering anions, SN2 and E2 reactions and the opening of strained rings, followed by further problems. Minireview 7 and its associated problems concern nucleophilic addition to aldehydes and ketones, finally minireview 8 and its problems cover nucleophilic acyl substitution. The minireviews and their 100 associated problems constitute Part A of the book.

Part B consists of 100 notably harder problems, the extra difficulty here is partially due to the problems being encountered in isolation, rather than directly after the appropriate background material as in Part A. None of these problems are unduly obscure, and notes are included where necessary to annotate aspects that might not feature in an undergraduate course. These problems may be solved using the methods learnt in Part A. Finally Part C consists of 10 "applied problems" (e.g. related to drug activity) of a comparable level of difficulty to those in Part B, with notes to provide the context.

Overall I regard this as a good book for the purpose it sets itself, i.e. to facilitate students' understanding of organic chemistry through the use of reaction mechanisms. I would prefer there to be greater use of the terms nucleophile and electrophile and more mention of stereochemistry and the shape of molecules, nevertheless it is a valuable source of problems with solutions, space for which in general organic textbooks is usually rather limited. I will recommend it to first year undergraduates and to our library.

From the publisher... Organic Reaction Mechanisms: Selected Problems and Solutions William C. Groutas This hands-on manual allows readers to gain a better understanding of organic reaction mechanisms by solving a wide range of problems. Answers for the problems are included along with mini-reviews that summarize and emphasize fundamental principles. This approach sharpens readers' reasoning ability and critical thinking. 0-471-28251-0     288pp     1999     £27.50

Matthew D. Fletcher
Department of Chemistry
University of Wales, Bangor
Bangor
Gwynedd
LL57 2UW
May 2002