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 pyridiniumalkoxy 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).