Hydroxy acid-functionalized ionic liquids as green alternatives for the efficient catalytic conversion of epoxides to cyclic carbonates under solvent and co-catalyst-free conditions

Abstract

An innovative, efficient, experimentally simple and environmentally friendly synthesis route of cyclic carbonates from carbon dioxide and epoxide applying novel hydroxy acid-functionalized ionic liquids as efficient catalysts under solvent and co-catalyst-free conditions has been developed. These hydroxy acid-functionalized ionic liquids exhibit outstanding catalytic activity for the conversion of CO₂ and various epoxides to cyclic carbonates. The effects of reaction parameters (amount of catalyst, CO₂ pressure, reaction time and temperature) on the catalytic activity for chloropropene carbonate synthesis from epichlorohydrin and CO₂ are examined and optimized. The catalysts could be reused for at least seven times without any noticeable loss of selectivity and activity. The activation energy was determined to be 66.9 kJ mol⁻¹. Finally, a possible reaction mechanism is proposed.