H/D exchange in electrolytic reduction reactions of phenyl ketones

Reduction of phenacyl chloride in DMF containing 1 percent D2O is electrochemically irreversible. The observed products at the reduction potential are acetophenone plus dimeric product. Recovery of the ketone after short reaction times reveals the presence of considerable H/D exchange of the methylene hydrogens in competition with the reduction reaction. Similarly, in the reduction of 1,2-diphenylpropanone, which proceeds with asymmetric induction, H/D exchange of the α hydrogen is very important. The exchange process appears to be part of the electrochemical reaction and is associated with the first electron transfer step