Abstract: Epoxides are industrially important compounds used as pharmaceutical intermediates and fine chemicals. The traditional synthesis is by the way of epoxidation reaction of alkene with oxidant over Mn(salen) catalysts in organic solvent. However, the use of toxic solvents and oxidants is not friendly to the environment. The epoxidation of cyclohexene in ionic liquids catalyzed by Mn(salen) complex with hydrogen peroxide as oxidant was studied. The effects of the reaction medium, structure of Mn(salen) complexes, and reaction conditions on the epoxidation were investigated. It was found that handy hydrogen peroxide could be an alternative to expensive oxidant, and that ionic liquid medium gave higher conversion and selectivity to cyclohexene epoxide in comparison with the reaction performed in conventional organic solvent. The cyclohexene conversion of 100% and selectivity to cyclohexene epoxide of 94% were obtained when the reaction was performed in the solvent of neutral ［bmim］BF4-CH2Cl2[KG20x](3∶2, V/V) at 273 K using Mn(salen) complex prepared by salicylaldehyde and o-phenyldiamine as a catalyst. Moreover, the final products could be easily separated from the reaction system by simple extraction with hexane.

Key words: Mn(salen) complex, ionic liquid, cyclohexene, epoxidation, hydrogen peroxide