a method is described for the simultaneous preparation of p - bromophenols and p - benzoquinones , intermediates useful in the preparation of hydroquinones and 4 , 4 ′- dihydroxybiphenyls , respectively . hydroquinones and 4 , 4 ′- dihydroxybiphenyls are useful monomers for the preparation of a variety of polymers . the method also comprises reducing the p - benzoquinone to its corresponding hydroquinone in the presence of the p - bromophenol . limiting the amount of hbr present in the reaction mixture was shown to control the amount of benzoquinone produced . the method also allows for the recycling of many of the reagents used , thereby reducing the cost of producing each monomer .