Efficient cycloaddition of CO2 to epoxides using novel heterogeneous organocatalysts based on tetramethylguanidine-functionalized porous polyphenylenes

Abstract

The conversion of CO2 into cyclic carbonates by cycloaddition to epoxides is achieved under relatively mild reaction conditions (without solvent, 7 bar of CO2, 100 °C) using easily available heterogeneous tetramethylguanidine(TMG)-polyphenylene organocatalysts. These new highly stable catalysts were easily prepared by reaction of tetramethylurea in the presence of oxalyl chloride with aminomethyl polyphenylenes. The TMG-functionalized polyphenylene (2PhCH2TMG) prepared from a pre-functionalized network was efficient and competitive compared with other reported catalysts achieving high epoxides conversion (>90%) and 100% selectivity towards the corresponding cyclic carbonates. The catalyst was easily separated from the reaction media and reused after basic regeneration without loss of activity.