Halogenated meso-phenyl Mn(III) porphyrins as highly efficient catalysts for the synthesis of polycarbonates and cyclic carbonates using carbon dioxide and epoxides

Abstract

Introduction of halogen electron withdrawing atoms (chloro and fluoro) in the ortho position of the aryl groups of meso-tetraphenylporphyrin manganese(III) complexes increased their activity as catalysts in the reaction of carbon dioxide with epoxides, when compared with the meso-tetraphenylporphyrin manganese(III) counterpart, even in the absence of co-catalysts. In the polymerization reaction of carbon dioxide and cyclohexene oxide, almost ten-fold increase of the TOF was observed when 5,10,15,20-tetra(2,6-dichlorophenyl)porphyrinatomanganese(III) acetate or 5,10,15,20-tetra(2,6-difluorophenyl)porphyrinatomanganese(III) acetate complexes were used as catalysts.Under similar conditions, when terminal epoxides were used as substrates, the selective cycloaddition of CO2 with styrene oxide, epichlorohydrin, propylene oxide, and 1,2-epoxytetradecane yielded exclusively the corresponding cyclic carbonates (conversion 6–98%).