Comparison of polycarbonate precursors synthesized from catalytic reactions of bisphenol‐A with diphenyl carbonate, dimethyl carbonate, or carbon monoxide

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Abstract
Transesterification of bisphenol‐A with diphenyl carbonate or dimethyl carbonate, and direct oxidative carbonylation of bisphenol‐A were compared to obtain polycarbonate precursors for phosgene‐free polycarbonate synthesis. The melt‐transesterification of bisphenol‐A and diphenyl carbonate occurred readily to produce reactive precursors without a significant equilibrium constraint. On the other hand, the transesterification of bisphenol‐A and dimethyl carbonate showed a serious equilibrium limitation in obtaining reactive polycarbonate precursors leading to high molecular weight polymers, and coproduced a significant amount of methylated bisphenol‐A. The direct oxidative carbonylation of bisphenol‐A with CO produced diphenolic‐ended oligomers and a significant amount of by‐products, which are the least reactive in the subsequent polycondensation step of the phosgene‐free polycarbonate process. A novel method to synthesize the reactive polycarbonate precursors was proposed that employed the coupled oxidative carbonylation of both bisphenol‐A and phenol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 937–947, 2002