Electroselective α-bromination of acetophenone using: In situ bromonium ions from ammonium bromide

A greener and expeditious method for the side chain bromination of acetophenone using in situ generated bromonium ions from NH₄Br and a catalytic amount of H₂SO₄ as a supporting electrolyte in a H₂O:CH₃CN medium at ambient temperature has been developed in an undivided cell equipped with a Pt/Pt electrode. This method results in a good yield (80%) of α-bromo acetophenone with high selectivity when only 2F of electricity was passed. Optimization studies such as variation of the current density, charge passed, solvent, solvent/water ratio, acid, acid strength, bromide salt, bromide salt concentration, etc., are carried out and reported.