Coupling of epoxides and carbon dioxide catalyzed by Brönsted acid ionic liquids

A series of Brönsted acid ionic liquids (BAILs) containing a long chain Brönsted acid site in the cationic part and a Lewis basic site in the anionic part were designed, synthesized, and used as catalyst for the coupling of epoxides and carbon dioxide to cyclic carbonates without a co-catalyst or co-solvent. The effects of catalyst structure and other parameters on the catalytic performance were investigated. The long chain 2-(N,N-dimethyldodecylammonium) acetic acid bromide ([(CH2COOH)DMDA]Br) showed high catalytic activity and good reusability. This protocol was expanded to various epoxides, which gave the corresponding cyclic carbonates in good yields. The acidity of the catalyst influenced its catalytic activity.

Graphical AbstractBrönsted acid ionic liquids were synthesized and gave high catalytic activity for the coupling of epoxides and CO2 under mild conditions without an organic solvent. The acidity of the catalyst influenced the activity.Figure optionsDownload as PowerPoint slide