Dehalogenation reactions of vicinal dihalides. Part V. Kinetic study of the reactions of 1,2-dihalogeno-1,2-diphenylethanes with triphenylphosphine

Abstract

Triphenylphosphine-promoted dehalogenation reactions of meso-1,2-dibromo-1,2-diphenylethane and some para-substituted derivatives have been studied in dimethylformamide. Substituent effects on the reaction rate are in agreement with a concerted anti-elimination mechanism and do not support a stepwise mechanism involving bridged intermediates. The effect of solvent has also been investigated and the nucleophilicity of triphenylphosphine towards bromine is briefly discussed.