The preparation and purification of diphenylolpropane 4,4′-dioxyacetic acid (bisacid A2)

Earlier work on the synthesis of bisacid A2 is reviewed. The problems associated with the achievement of a pure product in good yield are pointed out. The procedure for obtaining same is described. It is believed that the melting point (or rather melting range) of bisacid A2 prepared from specially pure bisphenol-A and purified as described is higher than that of any bisacid A2 previously reported in the literature.