Reactivity and Structure Concepts in Organic Chemistry

Transcription

1 Reactivity and Structure Concepts in Organic Chemistry Volume T1 Editors: Klaus Hafner Charles W Rees Barry M. Trost Jean-Marie Lehn P. von Rague Schleyer Rudolf Zahradnik

2 Steven V. Ley Caroline M. R. Low Ultrasound in Synthesis With 23 Figures Springer-Verlag Berlin Heidelberg New York London Paris Tokyo Hong Kong 1989

3 Steven V. Ley Caroline M. R. Low Imperial College of Science and Technology Department of Chemistry South Kensington London SW7 2A Y, UK ISBN-13: DOl: / e-isbn-13: Library of Congress Cataloging in Publication Data Ley S. (Steven), 1945 Ultrasound in synthesis 1 S. Ley, C. Low. p. cm.- (Reactivity and structure: concepts in organic chemistry; v. 27) 1. Chemistry, Organic-Synthesis. 2. Ultrasonic waves. I. Low, C. (Caroline), II. Title. III. Series: Reactivity and structure; v. 27. QD262.L '.2-dc ISBN-13: This work is snbject to copyright. All rights arc reserved, whether the whole or part of the material is concerned, specifically thc rights of translation, reprinting, re-use of illustration, recitation, broadcasting, reproduction on microfilms or in other ways, and storage in data banks. Duplication of this publication or parts thereof is only permitted under the provisions of the German Copyright Law of September 9, 1965, in its version of Jnne 24, 1985, and a copyright fee must always be paid. Violations fall under the prosecution act of the German Copyright Law. Springer-Verlag Berlin Heidelberg 1989 Softcover reprint of the hardcover 1st edition 1989 The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. 2151/ Printed on acid-free paper

4 List of Editors Professor Dr. Klaus Hafner Institut fur Organische Chemie der TH Darmstadt Petersenstr. 15, D-6100 Darmstadt Professor Dr. lean-marie Lehn Institut de Chimie, Universite de Strasbourg 1, rue Blaise Pascal, B.P. 296/R8, F Strasbourg-Cedex Professor Dr. Charles W. Rees, F. R. S. Hofmann Professor of Organic Chemistry, Department of Chemistry Imperial College of Science and Technology South Kensington, London SW7 2A Y, England Professor Dr. Paul v. Rague Schleyer Lehrstuhl fur Organische Chemie der Universitat Erlangen-Nurnberg Henkestr. 42, D-8520 Erlangen Professor Barry M. Trost Department of Chemistry, The University of Wisconsin 1101 University Avenue, Madison, Wisconsin 53706, U.S.A. Professor Dr. Rudolf Zahradnik Tschechoslowakische Akademie der Wissenschaften l.-heyrovsky-institut fur Physikal. Chemie und Elektrochemie Machova 7,12138 Praha 2, C.S.S.R.

5 Preface The effects of heat and light on chemical reactions have long been known and understood. Ultrasound has been known to promote chemical reactions for the past 60 years, but despite this, it did not attract the attention of synthetic chemists until recently. This arose historically from early studies which concentrated almost exclusively on reactions in aqueous media and was also, in some measure, due to the availability of suitable technology. Since the early 1980s a plethora of literature has appeared of direct interest to synthetic chemists and the field has been developing rapidly. The aim of this book is to bring the background of this fascinating field to the attention of a wider audience. It explores the literature to date and attempts to indicate other areas in which ultrasound may be exploited. It also hopes to explode some of the myths surrounding this area which have hitherto been regarded by the synthetic community as a bit of a black art! Existing books and reviews have tended to concentrate on the physics of sonochemistry and to catalogue the instances in which ultrasound has proved useful in tackling synthetic problems. Our aim has been to stress the relevance of this technique to synthetic chemists and we have included a section which deals with the practical aspects of carrying out these reactions. We have also given an indication of the instrumentation that is currently available, although it should be stressed that the majority of the reactions described were carried out using nothing more complex than a standard cleaning bath of the type that can be found in most laboratories. The range of reactions described is extremely diverse and extends from the preparation of a wide variety of both organic and organometallic reagents to enzymecatalyzed reactions and the preparation of novel inorganic materials. In many cases, ultrasound was the method of last resort and has provided solutions to problems in "difficult" areas where standard techniques have been tried and failed. Hence, it is reasonable to speculate that there are many more conventional situations where ultrasound could be used effectively. Many authors have commented on the high yields and purity of products isolated from sonochemical reactions, often in cases where other techniques have produced complex mixtures. Another factor in their favour is the reduction in the length of time required and there are many examples where conventional reactions can be brought to completion within a matter of minutes rather than hours. We hope that this monograph provides a critical introduction for those intrigued by the synthetic potential of this technique. We would like to thank Rod Bates, Howard Broughton, Sarah Houlton and Michael McHugh for their help in proof-reading the manuscript and for their helpful suggestions. London, July 1989 Steven Ley and Caroline Low VII

6 Table of Contents 1 2 Introduction The Physical Basis of Sonochemistry The Origin of So no chemical Reactivity Influencing Sonochemical Reactivity: The Physical Perspectives Introduction Frequency Power Input.., Bulk Temperature Pressure Ambient Gas Choice of Solvent 2.3 The Effects of Ultrasound on Two-phase Systems Generation of Ultrasound Aqueous Sonochemistry Preparation of Activated Magnesium Preparation of Organoaluminium Compounds Application of Ultrasound to the Preparation of Organolithiums Preparation of Organolithium Reagents Reactions of Organolithiums with Carbonyl Compounds Other Reactions of Organolithiums Reactions with Other Alkali Metals Organozinc Reagents Preparation of Organozincs.... The Reformatskii Reaction.... Generation of Allylzinc Reagents Zinc Mediated Cyclopropanation Formation of Trialkylzinc Species IX

7 Table of Contents 8.6 Zinc Mediated Perfluoroalkylation Zinc-mediated Preparation of Reactive Intermediates. 9 Intercalation Reactions The Effects of Ultrasound on Enzyme-Catalysed Reactions Ultrasonic Acceleration of Organic Reactions Ultrasonic Acceleration of Redox Reactions The Effects of Ultrasound on Transition Metal Catalysts Transition Metal Carbonyls and Ultrasound Conclusion References 121 Subject Index 129 x