Pyrrolidine-2,5-dione-derived ionic liquids promoted efficient transformation of flue gas CO2 into α-alkylidene cyclic carbonates at room temperature

Abstract

The combination of pyrrolidine-2,5-dione-derived ionic liquids with silver acetate (AgOAc) were developed as binary catalysts for conversion of simulated flue gas CO2 and propargylic alcohols to α-alkylidene cyclic carbonates. By tuning different catalyst components, the [HTMG][Pyrro]/AgOAc system was confirmed to be the most efficient and exhibited an excellent synergistic action in facilitating the carboxylic cyclization under room temperature and solvent-free conditions. The influence of reaction parameters on carboxylic cyclization of CO2 with 2-methylbut-3-yn-2-ol were optimized. Under the determined conditions, the [HTMG][Pyrro]/AgOAc system was stable enough to show durable high activity in eight recycles, and also versatile in carboxylic cyclization of flue gas CO2 with other propargylic alcohols. Moreover, a thorough comparison of [HTMG][Pyrro]/AgOAc with the reported catalysts was provided and evaluated, the results suggested that the developed catalytic system has significant advantages in practical application. Finally, the mechanistic details for the conversion of CO2 into α-alkylidene cyclic carbonates catalyzed by [HTMG][Pyrro]/AgOAc was also elucidated on the basis of reactants activation.