Electroselective alpha-bromination of acetophenone using in situ bromonium ions from ammonium bromide

摘要

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 alpha-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.