In room temperature ionic liquids based on 1-n-butyl-3-methylimidazolium and n-butylpyridinium salts, cycloaddition of carbon dioxide to propylene oxide without any additional organic solvents has been investigated. It was found that 1-n-butyl-3-methylimidazolium tetraÑuoroborate was the most active catalyst with almost 100% selectivity, and a suitable CO oxide molar ratio was needed for high conversion. The ionic liquid used 2Èpropylene as catalyst for the reaction was recyclable.

★★★☆☆ Jiajian Peng and Youquan Deng. New J. Chem., 2001, 25, 639È641