Synthesis of cyclic carbonate from allyl glycidyl ether and carbon dioxide using ionic liquid-functionalized amorphous silica

Ionic liquid functionalized mesoporous silica (IFMS) was prepared from the coupling of 1-(triethoxysilylpropyl)-3-n-alkylimidazolium halides with tetraethyl orthosilicate (TEOS) through template-free condensation under strong acidic conditions. The immobilized ionic liquid (IM-IL) catalysts showed 0.61–0.93 mmol of ionic liquid on SiO2 and surface area in the range of 189–647 m2/g with pore sizes from 3.2 to 4.2 nm. Elemental analysis and SEM image showed that the immobilized ionic liquid groups were well incorporated on the support. The silica-supported ionic liquids were proved to be an effective heterogeneous catalyst for the solventless synthesis of cyclic carbonate from allyl glycidyl ether (AGE) and carbon dioxide. Im-IL of longer alkyl chain length and more nucleophilic nature showed higher conversion of AGE. High temperature, high carbon dioxide pressure, and the presence of ZnBr2 co-catalyst were favorable for the conversion of AGE. Im-IL can be reused for the reaction up to three consecutive runs without any considerable loss of its catalytic activity.