Pd catalyzed polycarbonate synthesis from bisphenol A and CO: control of polymer chain - end structure

Direct polymerization of bisphenol A with CO was carried out using a catalyst system constituted of a Pd carbonylation catalyst, an inorganic redox catalyst, an organic redox cocatalyst, a base and a dehydrating agent. Usage of Cu(OAc)(2) as inorganic redox cocatalyst led to the synthesis of polycarbonate of M-w 3600 but the formation of o-phenylene carbonate (o-PC) and salicylic acid type groups at the chain ends was observed. In an attempt to eliminate end group formation and explore the possibility of higher molecular weight polymer synthesis, various modifications were made in the catalyst system. On replacing Cu with Ce, o-PC formation could be eliminated completely. In addition, the usage of bis(triphenylphosphoranylidene) ammonium bromide (PPNBr) instead of tetrabutylammonium bromide [n(Bu)(4)NBr] resulted in elimination of acid group formation leading to the synthesis of polymer of M-w 3.8 x 10(3) (determined by GPC), with hydroxy group at both chain terminii. polymer structure was investigated in detail by IR, NMR, and MALDI-TOF-MS studies. (C) 1999 Elsevier Science Ltd, All rights reserved.