Electrochemical Reduction of Unsymmetrically Substituted Diphenyliodonium Salts at Mercury Cathodes in Dimethylformamide

Article abstract of DOI:10.1021/jo00205a024

A study has been made of the electrochemistry of five unsymmetrically substituted diphenyliodonium salts at mercury cathodes in dimethylformamide containing tetramethylammonium perchlorate.Polarograms indicate that the iodonium cations undergo reduction in three stages: (1) one-electron reduction to yield either (a) iodobenzene and a substituted phenylmercury radical or (b) a substituted iodobenzene and a phenylmercury radical, (2) two-electron reduction of the iodobenzene or substituted iodobenzene, and (3) one-electron reduction of the substituted or unsubstituted phenylmercury radical.When electrolyses are performed at potentials corresponding to the first stage of reduction, electron-withdrawing substituents induce the production of more iodobenzene than substituted iodobenzene, whereas electron-releasing groups favor the formation of less iodobenzene than substituted iodobenzene; the other major products (diphenylmercury and symmetrically disubstituted diphenylmercury) arise via disproportionation of adsorbed phenylmercury radicals.At potentials corresponding to the second stage of reduction, electrolyses yield benzene, substituted benzene, and diorganomercury compounds; at potentials corresponding to the third stage of reduction, benzene and substituted benzene are formed.