Regulation of Novel Multi‐Center Ionic Liquids for Synergetically Catalyzing CO2 Conversion into Cyclic Carbonates

Abstract

AbstractA family of novel multi‐center ionic liquids (ILs) were designed for the target of efficient transformation of CO2 into cyclic carbonates. The multi‐center structures could expose more active sites than single‐center ones in cycloaddition reaction. Among these ILs, with the chain‐regulation strategy, the multi‐center hexabutylimidazole bromobenzene (BIM‐6) exhibited the performance with 95 % propylene epoxide (PO) conversion and 99 % selectivity (130 °C, 2.5 MPa, ILs amount 0.15 mol%, 1 h). Moreover, the multi‐center ILs showed good reusability after 5 cycles and extensive suitability for different terminal epoxides. Density functional theory (DFT) and noncovalent interactions (NCI) illustrated that hydrogen‐bond formed between the multi‐center ILs and epoxides, together with hindrance of side chain lengths setting bromide free, synergistically activated reactants. Thus, the possible mechanism based on hydrogen‐bond induction and hindrance regulation was proposed. This study provides a new approach for development of highly efficient ILs in the green chemical process.