Direct bromination of hydroxy aromatic compounds by electrolysis of
mixtures comprising the hydroxy aromatic compound, a source of bromide
ion, and an organic solvent provides product brominated hydroxy aromatic
compounds at synthetically useful rates with high para-selectivity. The
process does not require the use or handling of molecular bromine or
bromine complexes and allows the full use of the bromide source without
generating hydrogen bromide as a by-product of the reaction. The simple
electrochemical equipment required by the present process, for example an
undivided electrochemical cell, makes the process less capital intensive
than analogous electrochemical processes carried out in divided cells. The
use of hydrobromic acid as the source of bromide ion provides clean
reaction with nearly exclusive formation of the target brominated product.
