Silica grafted ammonium salts based on DABCO as heterogeneous catalysts for cyclic carbonate synthesis from carbon dioxide and epoxides

Abstract

1,4-diazabicyclo[2.2.2]octane (DABCO) based ammonium salts immobilized on functionalized silica ascertained to be an effective heterogeneous catalyst for the cycloaddition reaction of carbon dioxide with epoxide under green reaction conditions without utilization of metals and any organic solvents. N-Benzyl DABCO bromide as a homogeneous analog of catalyst exhibited a lower catalytic activity than the supported catalyst. This is probably due to Si–OH groups on the silica surface which exhibited a synergistic effect with the halide anions. The effects of the grafted ammonium salts' structures and various reaction parameters on the catalytic activity were also investigated. The catalyst could be recovered in a facile way from the reaction mixture and also exhibited good reusability.