Free Radicals in Organic Synthesis (Reactivity and Structure: Concepts in Organic Chemistry, 7)

## VIII Preface relating to particular reactions in which he has interest. We hope the book is sufficiently short to enable the Chemist to study it in its entirety and gain thereby an appreciation of the value of free radical reactions in synthetic organic chemistry. In the photograph Toby Davies is seen guarding his Gomberg bush, on which triarylmethyl radicals grow. For many years he has welcomed free radical chemists to his home, including the editor (Professor C. W. Rees) in 1964 before the Gomberg bush bore fruit. We hope that this book will also bear fruit and be of value to both synthetic and free radical chemists, acting as a spur to the further exploitation of free radical reactions in organic synthesis. We also hope that not only academic and industrial research workers but also postgraduate and advanced undergraduate students, who are interested in synthetic and/or free radical chemistry, will benefit from reading this book. Free Radical Chemistry has a comparatively long history. Before the accep­ tance of the quadrivalence of carbon, various attempts were made to prepare trivalent carbon species like methyl and ethyl. Initial investigations involving reaction between alkyl iodides and zinc were thought to be successful \ but were subsequently branded as failures 2. In fact free methyl and ethyl were transient radicals involved in the reactions, but because of their short lifetimes the radicals were not detected, and only the hydrocarbons formed by dimeri­ th sation of the radicals were isolated. At the beginning of the 20 century Gom­ berg discovered the stable triarylmethyl radicals 3, and then in the 1920's Pa­ neth 4 showed that free alkyl radicals could have a short lifetime in the gas phase. Free radicals as intermediates in reactions in solution were largely un­ recognised until in 1937 Hey and Waters 5 interpreted a number of reactions, which did not fit into the then developing electronic theory of Organic Chem­ istry6,7, by suggesting that they involved the intermediacy of free radicals. The other contemporary pioneer Kharasch 8 also proposed free radicals as interme­ diates in certain reactions in solution, many involving organometallic species. However in the 1930 - 1950 period free radicals were not universally accepted as respectable reaction intermediates as evidenced by the initial rejection of the work of Koelsch 9 and the stand against free radicals made by Hodgson 10 Front Matter....Pages I-XII Free Radical Reactions....Pages 1-14 Alkanes and Alkenes....Pages 15-23 Aromatic, Heteroaromatic, and Fluoroaromatic Compounds....Pages 24-40 Halogen Compounds....Pages 41-50 Alcohols....Pages 51-60 Ethers, Peroxides, and Hydroperoxides....Pages 61-68 Aldehydes and Ketones....Pages 69-80 Carboxylic Acids and Their Derivatives....Pages 81-91 Nitrogen-containing Compounds....Pages 92-110 Sulfur-containing Compounds....Pages 111-120 Organometallic Compounds....Pages 121-133 Stable Free Radicals....Pages 134-140 Naturally Ocurring and Related Compounds....Pages 141-152 Back Matter....Pages 153-172