Effects of imidazolium salts as cocatalysts on the copolymerization of CO2 with epoxides catalyzed by (salen)CrIIICl complex

Imidazolium salts, most of which are room temperature ionic liquids (ILs), have been introduced as effective and tunable cocatalysts in the copolymerization of CO2 with epoxides catalyzed by (salen)(CrCl)-Cl-III complex for the first time. Effects of imidazolium salts with different alkyl chains as well as with different anions on the copolymerization were investigated. The results showed that the copolymerization was influenced obviously by the property of anion. In addition, the cation of imidazolium salts with longer alkyl chain length such as n-dodecyl (TOF, 242.5 h(-1). carbonate linkages > 99%) displays better activities and selectivity in the copolymerization as compared with N-Melm (TOF, 72.5 h(-1). carbonate linkages 94%). These results are instructive for further design of task-specific lLs as effective cocatalysts to improve the copolymerization of CO2 with epoxides. (c) 2007 Elsevier Ltd. All rights reserved.