Electrocarboxylation of haloacetophenones at silver electrode

Electrocarboxylation of haloacetophenones 1 has been carried out in an undivided cell equipped with silver cathode and Mg sacrificial anode in N,N-dimethylformamide. The electroreduction behavior of these haloacetophenones at the Ag electrode was investigated using cyclic voltammetry. The electrocatalytic ability of Ag facilitated C-X bond cleavage. Methyl 4-acetylbenzoate 2 was obtained as the principal product, accompanied by acetophenone 3 and methyl 2-hydroxy-2-phenylpropanoate 4. The performances of the process were found to be dependent on synthetic conditions, such as cathode material, supporting electrolyte, electric charge, current density, and temperature. Higher yields were obtained by changing from chloro to bromo to iodo derivatives, and from ortho to para to meta isomers.