SYNTHESIS OF AROMATIC POLYESTERS BASED ON BISPHENOL A AND PHTHALIC ACIDS - A NEW PREPARATIVE PROCESS

A new bulk process for the preparation of polyarylates, based on Bisphenol A and phthalic acids, is described. The two-stage process, useful for the synthesis of a variety of polyarylates, employs preformed Bisphenol A polycarbonate and dimethyl esters of phthalic acids. In the first stage, a mixture of oligomeric (ester-carbonate)s and dimethyl carbonate is obtained via catalyzed interchange reactions. The second stage involves the elimination, under vacuum, of dimethyl carbonate, which drives the equilibria of the reversible reactions to the formation of aromatic polyesters. Polyarylates can also be obtained starting from Bisphenol A bis(methyl carbonate) instead of the Bisphenol A polycarbonate. The process seems to be quite efficient and flexible, permits the use of commercial products as starting materials, and leads to volatile byproducts that are less toxic and hazardous than those derived from the presently used methods. High molecular weight polyarylates are obtained.