The Immobilization of Glycidyl-Group-Containing Ionic Liquids and Its Application in CO2 Cycloaddition Reactions

Covalent immobilization of glycidyl-group-containing ionic liquids (ILs) on organic and inorganic supports with functional surfaces was achieved, based on the fact that the glycidyl group can actively react with almost all nucleophilic, electrophilic, neutral, and free-radical species. By using polymer spheres with amino- and carboxyl-group-functionalized surfaces as organic supports and silicas (including SBA15 and silica gel) with amino groups attached as inorganic supports, the ionic liquid 1-glycidyl-butylimida-zolium chloride was successfully grafted onto these polymer and silica supports, respectively, through reactions between the glycidyl group in the IL and the polar groups on the support surfaces. The resultant samples were examined by transmission electron microscopy, solid-state C-13 NMR spectroscopy, IR spectroscopy, and ion chromatography. The activities of these resultant polymer- and silica-based catalysts were investigated for CO2 cycloaddition reactions with epoxides. It was demonstrated that these catalysts could effectively catalyze CO2 cycloaddition. In particular, the polymer supports generated synergistic effects with the IL in the coupling reaction of CO2 with propylene oxide, and the turnover frequency could reach about 1700 h(-1) when the IL attached to the NH2-functionalized polymer was used as the catalyst.