A green chemo-enzymatic approach for CO2 capture and transformation into bis(cyclic carbonate) esters in solvent-free media

Abstract

A sustainable approach for CO2 capture and chemo-enzymatic transformation into bis(cyclic carbonate) esters from CO2, glycidol and organic anhydrides under solvent-free conditions has been demonstrated. The chemo-enzymatic process is based in two consecutive catalytic steps, which can be executed through separated operations, or within a one-pot combo system, taking advantage of the synergic effects that emerge from integrating ionic liquid (ILs) technologies and biocatalysts. In a first step, lipase-catalyzed transesterification and esterification reactions of different diacyl donors (e.g. glutaric anhydride, succinic anhydride, dimethyl succinate, etc.) with glycidol in solvent-free under mild reaction conditions (70 °C, 6 h), producing the corresponding diglycidyl esters derivatives up to 41% yield. By a second step, the synthesis of bis(cyclic carbonate) esters was carried out as results of the cycloaddition reaction of CO2 (from an exhausted gas source, 15% CO2 purity) on these diglycidyl esters, catalyzed by the covalently attached 1-decyl-2-methylimidazolium IL (Supported Ionic Liquid-Like Phase, SILLP), in solvent-free, leading up to 65% yield after 8 h at 50 °C and 1MPa CO2 pressure. Both key elements of the reaction system (biocatalyst and SILLP) were successfully recovered and reused for at least 5 operational cycles. Finally, different metrics have been applied to assess the greenness of the solvent-free chemo-enzymatic synthesis of bis(cyclic carbonate) esters here reported.