Well-Defined Highly Active Heterogeneous Catalyst System for the Coupling Reactions of Carbon Dioxide and Epoxides

The poly(4-vinylpyridine)-supported zinc halide catalysts, prepared from a reaction of ZnX2 and poly(4-vinylpyridine), exhibit high selectivity and activity for the coupling reaction of CO2 and ethylene oxide or propylene oxide. Solid NMR characterization of the poly(4-vinylpyridine)-supported ZnBr2 catalyst and its reaction product with propylene oxide and/or CO2 show that a pyridinium-alkoxy ion-bridged zinc bromide complex is functioning as an active species, such as in the homogeneous catalysis with L2ZnBr2 (L = pyridine or methyl-substituted pyridine).