Efficient Synthesis of Cyclic Carbonates from Atmospheric CO2 Using a Positive Charge Delocalized Ionic Liquid Catalyst

Abstract

The chemical fixation of CO2 into value-added products has recently received much attention. One of the most well-known methods is the coupling of CO2 with epoxides to form cyclic carbonates. Although this field has progressed considerably, it is still a challenge to perform the reaction with atmospheric CO2 or flue gas. Herein we described the development of 4-(dimethylamino)pyridine hydrobromide ([DMAPH]Br) as a highly efficient and recyclable catalyst for the formation of cyclic carbonates from atmospheric CO2 and epoxides. In the presence of 1 mol % of [DMAPH]Br, excellent conversions and selectivities for a broad range of terminal epoxides were achieved under solvent-free conditions. Furthermore, the catalyst could be recycled over five times without appreciable loss of catalytic activity. The excellent catalytic performance of [DMAPH]Br is attributed to the enhanced synergistic interplay of acidic proton and bromide to epoxides and CO2 through positive charge delocalization on its cation.