Abstract: 2-Cyclohexene-1-one was synthesized via the oxidation of cyclohexene using V2O5 as the catalyst and H2O2 as the oxidant in room-temperature ionic liquids (RTILs). Compared with the reaction performed in the organic solvent of acetone, higher conversion of cyclohexene and selectivity for 2-cyclohexene-1-one were obtained in the solvent of [bmim]BF4-acetone. The effects of various RTILs, reaction temperature, and the amount of V2O5 and H2O2 on the oxidation were investigated. A conversion of 88.7% with the selectivity for 2-cyclohexene-1-one of 91.1% was obtained when the reaction was carried out in the neutral solvent of [bmim]BF4-acetone ([bmim]BF4/acetone volume ratio of 2/5) with 2% of V2O5/cyclohexene molar ratio and 110 mmol of H2O2 at 313 K for 10 h. Furthermore, the ionic liquids could be conveniently recovered for recycle use. The conversion of cyclohexene and the selectivity for 2-cyclohexene-1-one decreased slightly with the increase in the reuse times.

Key words: ionic liquid, vanadium pentoxide, cyclohexene, oxidation, 2-cyclohexene-1-one