Abstract: Cyclic polycarbonate oligomers are converted to linear polycarbonates by the catalytic action of a chelate of a transition metal with a ketone, diester or keto ester such as acetylacetone. The metal chelates vary in catalytic action with the position of the metal in the Periodic Table.

Abstract: Cyclic polycarbonate oligomers are converted to linear polycarbonate resins by heating with a polycarbonate formation catalyst which generates benzyl carbanions at temperatures up to about 300.degree. C. The preferred catalysts are unsubstituted or nuclearly substituted phenylacetic acids and their salts.

Abstract: Cyclic polycarbonate (or thiol analog) oligomer mixtures are prepared by the reaction of bishaloformates or their thio analogs, or mixtures thereof with dihydroxy or dimercapto compounds, with alkali metal hydroxides and various amines. The oligomer mixtures may be converted to polycarbonates or their thiol analogs by a method which is particularly adaptable to integration with polycarbonate processing operations. Polymerization may be conducted simultaneously with molding, extrusion and the like. The oligomer mixtures are adaptable to the preparation of filled prepregs.