Brominated phenols prodn. - by reacting phenols with bromine in 2-phase system contg. alkali bromate and electrolytically oxidising resulting bromide back to bromate

摘要

A phenol is reacted with Br2 in a solvent consisting of a non-polar organic solvent and an aq. soln. contg. in soln., alkali bromate and, at least temporarily, alkali bromide. The alkali bromide formed from the alkali bromate in the reaction is subsequently re-oxidised electrolytically to alkali bromate. The pref. starting material is bisphenol A. Halogenated phenols (e.g. chlorophenol, dimethylchlorophenol) and xylenols can also be used. Pref. non-polar solvents are benzene, benzene derivs., and dibromoethane. The ratio of aq. to organic phase is pref. 1:1 to 2:1 v/v. Br2 is pref. used in 1-10% excess over the stoichiometric amt. The reaction temp. is pref. 20-40 degrees C. Brominated phenols such as tribromophenol and tetrabromophenol A are useful, e.g. as intermediates for pharmaceuticals and as flameproofing components for plastics.