Zn-containing ionic liquids bearing dialkylphosphate ligands for the coupling reactions of epoxides and CO2

Zn-containing room temperature ionic liquids (Zn-RTILs), prepared from the reactions of ZnBr2 with 1-alkyl-3-methylimidazolium dialkyphosphates ([RMIm][R2PO4]), were highly active for the coupling reactions of CO2 with epoxides, producing corresponding cyclic carbonates in high yields. FAB-mass spectral and computational results suggest that [ZnBr(R2PO4)2]− could be an active species for the coupling reaction. Decomposition of cyclic carbonates into epoxides and CO2 during the product recovery process via vacuum distillation was almost negligible even in the presence of a Zn-RTIL up to 130 °C.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis of Zn-containing room temperature ionic liquids (Zn-RTILs). ► Zn-RTILs as highly active catalysts for the cycloaddition of CO2 with epoxides. ► Mechanistic investigation on the roles of Zn-RTILs by computational calculations. ► Reduction of ethylene carbonate decomposition by a catalyst during the distillation.