Bifunctional Ionic Liquids for the Multitask Fixation of Carbon Dioxide into Valuable Chemicals

A series of task-specific ionic liquids (ILs) such as mono-, dicationic, and polymer-supported ILs were synthesized. These ILs were applied as multitasking organocatalysts for transformations of carbon dioxide into valuable chemicals through a range of reactions, including (i) cycloaddition reactions of CO2/CS2 with epoxides to form cyclic carbonates and 1,3-oxathiolane- 2-thiones, (ii) transesterification of cyclic carbonates with methanol to form dimethyl carbonate, and (iii) synthesis of quinazoline-2,4(1H, 3H)-diones and quinazoline-2,4(1H, 3H)dithiones from 2-aminobenzonitriles and CO2/CS2. The developed methodology is transition-metal free, solvent free, and additive free. Remarkably, the developed ILs were recyclable in up to seven consecutive cycles; thus, making this protocol green and cost effective.