Ultrasound in Synthesis

The effect of ultrasound on chemical and biological systems has been under investigation for over 60 years and yet its use as a tool for the synthetic chemist scarcely predates 1980. The purpose of this monograph is to provide a critical introduction for those intrigued by the synthetic potential of ultrasound, and this is reflected in the examples discussed. In addition, a brief overview of the physics of acoustic cavitations is included in order to explain the origin of sonochemical reactivity and the means by which ultrasound can be exploited to its full potential.

The effects of heat and light on chemical reactions have long been known and un- derstood. 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 exclu- sively 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 atten- tion 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 sonochem- istry and to catalogue the instances in which ultrasound has proved useful in tack- ling 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.

From the contents: The Origin of Sonochemical Reactivity.- Generation of Ultrasound.- Aqueous Sonochemistry.- Preparation of Activated Magnesium, Organoaluminium Compounds, Organolithiums and Their Reaction, Carbonyl Compounds, Organozincs and Zinc Mediated Reactions.- Intercalation Reactions.- The Effects of Ultrasound on Enzyme-Catalysed Reactions.- Ultrasonic Acceleration of Organic Reactions and of Redox Reactions.- The Effects of Ultrasound on Transition Metal Catalysts.- Transition Metal Carbonyls and Ultrasound.