Homogeneous palladium catalyst for the oxidative carbonylation of bisphenol A to polycarbonate in propylene carbonate

Polycarbonates (PCs) were prepared in a propylene carbonate solvent by the oxidative carbonylation of bisphenol A with Pd/bithienyl complexes, Pd/bipyridyl complexes, and Pd-C sigma-bonded complexes for comparison as homogeneous Pd catalysts. With the Pd/bipyridyl complexes, the 6,6'-disubstituted 2,2'-bipyridyl ligand showed a stronger substituent effect than the 2,2'-bipyridyl ligand, which lacked substituents at the 6,6' positions. With the Pd/bithienyl complexes, however, the substituent effect was not seen. The Pd/bithienyl complexes, which lacked substituents at the 5,5' positions, gave a PC yield that was the same as the yield of those that had substituents at the 5,5' positions. The combination of the Pd-C sigma-bonded complexes and an inorganoredox cocatalyst showed a PC polymerization behavior that was different from the other two types of complexes. When Co(OAc)(2)center dot 4H(2)O was used as the inorganoredox cocatalyst, all of the Pd-C sigma-bonded complexes gave a good PC yield. (C) 2008 Wiley Periodicals, Inc.