Pyridinium‐functionalized metalloporphyrins as bifunctional catalysts for cycloaddition of epoxides and carbon dioxide

Abstract

New pyridinium‐functionalized metalloporphyrins MEtPpBr 4 (M = Zn 2+ , Co 2+ , Ni 2+ , Cu 2+ ; EtPp = 5, 10, 15, 20‐tetra(4‐(3‐(N‐ethyl‐4‐pyridyl)pyrazolyl)phenyl)porphyrin) were synthesized as bifunctional catalysts for the cycloaddition reactions of epoxides and CO 2 . The effects of catalyst loading, CO 2 pressure, reaction temperature and time on catalytic activity were investigated. ZnEtPpBr 4 ( 1 ) and CoEtPpBr 4 ( 2 ) exhibited efficient activities in the cycloaddition reactions of various epoxides with CO 2 as at 120 °C under 2 MPa of CO 2 pressure without solvent. Most of corresponding cyclic carbonates could be obtained in almost quantitative yields and > 99.9% selectivity with molar ratio of epoxide/catalyst 2222 after 8 hr of reaction.