SOME NOVEL CONCEPTS IN AROMATIC REACTIVITY

Suggestions1 that radical-chain reactions of aryl halides with alkoxide ions, nucleophiles and alkenes occur via attack of these reagents on the aryl halide radical anion, rather than on the radical that results from fragmentation of the radical anion, are examined in detail. Several conceivable mechanisms for the suggested direct displacement of halide ion from the radical anion by a nucleophile are examined; all are unacceptable because of violation of quantum-mechanical principles or incompatibility with experimental observations. Steps involving attachment of a hydrogen atom or an alkene molecule to C-1 of an aryl halide radical anion, to form a cyclohexadienide ion intermediate, lack experimental precedent.