Direct Synthesis of Cyclic Carbonates from Olefins and CO 2 via Ionic Liquid Catalysis with Mutual Promoting Bifunctional Groups

Abstract

The oxidative carboxylation of olefins is a thermodynamically and economically favorable strategy for the synthesis of cyclic carbonate. As a common oxidant, hydrogen peroxide aqueous solution serves as a cost-effective and green chemical. Herein, we develop a bifunctional ionic liquid, which has both trifluoroacetyl group as epoxidation reactive site and quaternary ammonium salt for promoting cycloaddition reaction. The two active sites work synergistically through electron effect, thereby resulting in rendering two subsequent steps compatibly and the target reaction proceeding efficiently and selectively accordingly.The introduction of quaternary ammonium salt enhances the selectivity of epoxides at relative high temperature. The trifluoroacetyl group augments the activating capability of the quaternary ammonium site toward epoxides and ultimately allows the cycloaddition reaction to proceed efficiently at a lower temperature. With hydrogen peroxide as the oxidant, the bifunctional ionic liquid catalyst facilitates a two-step process for the synthesis of cyclic carbonate from olefins and CO2 in high yield, reaching up to 90%, in the absence of any transition metal. This work provides a novel, green, and sustainable strategy for the oxidative carboxylation of alkenes to synthesize cyclic carbonates.