Cross-linked polymer grafted with functionalized ionic liquid as reusable and efficient catalyst for the cycloaddition of carbon dioxide to epoxides

• A series of cross-linked polymer that grafted with functionalized ILs (P-ILs) were fabricated.
• The P-ILs show high catalytic activity and selectivity for the cycloaddition reaction.
• The P-ILs also show good stability and reusability.
• It is indicated that the moderate hydrogen bonding is benefit for the cycloaddition reaction.
• A plausible mechanism for cycloaddition reaction over P-ILs was proposed.

A series of cross-linked polydivinylbenzene polymers covalently grafted with various (hydroxyl, carboxyl, and amino) functional ionic liquid were fabricated by a simple method and evaluated as heterogeneous catalysts for the synthesis of cyclic carbonates from CO2 and epoxides. The as-fabricated catalysts show good performance across a wide range of epoxides in the absence of solvent and co-catalyst, especially the one that was grafted with hydroxyl ionic liquid. The effects of functional groups in ionic liquid, reaction temperature, initial CO2 pressure, and reaction time on the cycloaddition reaction were investigated. It is suggested that synergetic effect between functional groups and bromide ions facilitates the catalytic reaction. It is noted that the hydroxyl group with moderate hydrogen bonding is more crucial for the cycloaddition reaction than the other groups. In addition, the recycling test showed that the catalyst could be reused for as many as six times without any loss of catalytic activity.

Divinylbenzene polymer grafted with functionalized ionic liquids was fabricated by a simple method and evaluated for solventless synthesis of cyclic carbonates from CO2 and epoxides. The catalysts show good activity, selectivity, stability and reusability toward the coupling reaction under mild conditions.Figure optionsDownload as PowerPoint slide