A New, Nonphosgene Route to Poly(bisphenol A Carbonate) by Melt-Phase Interchange Reactions of Alkylene Diphenyl Dicarbonates with Bisphenol A

This article describes a new, nonphosgene method for the synthesis of poly(bisphenol A carbonate) (PC). The method involves three steps: the reaction of an aliphatic diol with phenyl chloroformate to form an alkylene diphenyl dicarbonate, the reaction of the alkylene diphenyl dicarbonate with bisphenol A to produce an aromatic-aliphatic polycarbonate, and the thermal treatment of the polycarbonate at 180-210 degrees C under a stream of nitrogen with Ti(OBu)(4) to give PC and a cyclic alkylene carbonate. The method furnished low to moderate molecular masses of PC upon the complete elimination of the aliphatic moieties. The approach may be considered a new method, based on polycarbonate thermochemical degradation, for the synthesis of cyclic aliphatic carbonates. The obtained polymers were characterized by intrinsic viscosity and IR, H-1-NMR, and C-13-NMR spectroscopy. The thermal treatment step was conducted in a glass reaction tube at 180-210 degrees C under a stream of nitrogen, and the reaction was completed by heating to 250 degrees C. In the thermal treatment step, semisolid effluents composed of cyclic alkylene carbonates were formed and subsequently eliminated from the reaction mixture. Heating to 250 degrees C under nitrogen or under a dynamic vacuum furnished the pure aromatic PC residue. This intrachange reaction provides a flexible method for the synthesis of polycarbonates with alkylene diols containing two or three methylene groups, from which the pure PC homopolymer can be prepared. The potential of this approach was demonstrated by the successful synthesis of PC homopolymer from five different polycarbonates with a bisphenol A unit linked to 1,2-propylene, 1,3-propylene, 2methyl-1,3-propylene, 2,2-dimethyl-1,3-propylene, and 1,3-butylene as the alkane chains. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 2278-2292, 2008