PREPARATION AND POLYMERIZATION OF BISPHENOL-A CYCLIC OLIGOMERIC CARBONATES

A selective, high-yielding procedure for the preparation of Bisphenol A cyclic oligomeric carbonates via a triethylamine-catalyzed hydrolysis/condensation reaction of bis(chloroformate) is described. The reaction produces cyclic oligomers in 80-90% yield, along with about 15% high molecular weight polymer, but with almost total exclusion of linear oligomers. The structure of the amine catalyst controls the selectivity of cyclic vs linear vs polymer formation. Use of other amine catalysts can lead to different products. Use of pyridine as catalyst, for example, affords linear oligomers in 99% yield, with very low yields of cyclics. Polymerization of the cyclic oligomers to polycarbonate with M(w) = 50 000-300 000 is achieved by heating at 300-degrees-C for 15 min in the presence of various basic catalysts. The preparation of authentic oligomeric linear and cyclic materials is also described.