Electrochemical homolytic and heterolytic coupling of activated olefins in the absence and presence of benzyl bromide in microemulsion

Abstract

Electrochemical reduction of four activated olefins namely cyclohexenone (CH), cyclopentenone (CP), methylmethacrylate (MMA), acrylonitrile (AN) in the absence and presence of benzylbromide (BBr) were investigated in CTAB/n-hexane/n-butanol/water based bicontinuous microemulsion (μE). Both cyclic voltammetric studies and galvanostatic preparative electrolysis were carried out. Cyclic voltammetric results in μE were also compared with those in N,N-dimehtylformamide (DMF) medium. Adsorption effects are observed both in DMF and μE. AN undergoes one electron reduction in aprotic solvent and two electron reduction in μE. CH, CP, BBr undergo one electron reduction and yield significant homolytic coupled products under galvanostatic conditions. AN and MMA lead to two electron reduction under identical conditions. In the presence of BBr, CH and CP alone yield significant heterolytic coupled products with simultaneous competitive resin formation. Reduction of AN leads to the formation of a identifiable quantity of propylamine and 3-phenylpropylamine in the absence and in the presence of BBr, respectively.