Electrochemical reduction of benzyl bromide in the presence of carbon dioxide

Abstract

The electrochemical reduction of benzyl bromide has been investigated in acetonitrile and CO₂-saturated acetonitrile by cyclic voltammetry and contro lled-potential electrolysis. Electroreduction of the halide in the absence of CO₂ leads to a variety of products, the distribution of which depends on the elec trode material, applied potential and proton availability in the medium. The electrocarboxylation process, have been carried out at Hg and graphite cathodes using both a two compartment cell and an undivided cell with dissolving Al anode. The best results (87% phenylacetic yield) are obtained at Hg in the undivided cell. Catalysis by Co(salen) allows the process to be performed at potentials more positive than those required by direct reduction but gives only poor to moderate yields of acid. Results obtained from experiments carried out

with benzyl chloride have been compared with those obtained in the case of benzyl bromide.