Polymers of Carbonic Acid, 33

Abstract

AbstractThe interfacial, hydrolytic polycondensation of bisphenol‐A‐bischloroformate (BABC) was performed at 5 or 35 °C initial temperature with the following amines as catalysts: isoquinoline, pyridine, 4‐methylpyridine, 4‐tert‐butylpyridine, 4‐(dimethylamino)pyridine, 2,4,6‐trimethylpyridine and ethyldiisopropylamine. The reaction products were characterized by viscosity and SEC measurements and by MALDI‐TOF mass spectrometry. In all products (with the exception of 2,4,6‐trimethylpyridine‐catalyzed samples) cyclic oligo‐ and polycarbonates (identified up to masses around 15 000 Da) were found. Their content was particularly high when 4‐(dimethylamino)pyridine was used or when a neutral salt was added to pyridine catalyzed polycondensations. A higher temperature reduced both molecular weight and content of cycles regardless, if pyridine or ethyldiisopropylamine was used as the catalyst. Furthermore, equimolar amounts of bisphenol‐A and BABC were polycondensed in anhydrous dichloromethane using pyridine or ethyldiisopropylamine as the catalyst and HCl acceptors. In both cases low molar mass polycarbonates mainly consisting of even‐membered cycles were obtained. The reaction mechanisms are discussed. All results prove that both highly nucleophilic and highly basic tert‐amines can efficiently catalyze chain growth and cyclization, provided that the reaction conditions are accordingly optimized. Both chain growth and cyclization mainly occur in the organic phase.MALDI‐TOF mass spectrum of the polycarbonate prepared by pyridine promoted polycondensation of bisphenol‐A and BABC in dry CH2Cl2.magnified imageMALDI‐TOF mass spectrum of the polycarbonate prepared by pyridine promoted polycondensation of bisphenol‐A and BABC in dry CH2Cl2.