Abstract: The resolution of (R,S)-4-hydroxy-3-methyl-2-(2-propenyl)-2-cyclopenten-1-one ((R,S)-HMPC) by lipase was studied using ionic liquids and vinyl acetate as the reaction medium, respectively. The effects of the reaction medium, water activity, temperature, pH value, and cosolvent on the resolution were studied. The results showed that the ionic liquid ［bmim］PF6 was suitable for the reaction, and the initial rate of lipase in ［bmim］PF6 was 18.48 μmol/(g•min), which was much higher than that in vinyl acetate (9.18 μmol/(g•min). The half life of lipase in the ionic liquid was 74.53 h, which was higher than that in vinyl acetate (64.29 h), but the conversion of (R,S)-HMPC in ionic liquids was lower than that in vinyl acetate. The addition of an acyl donor could improve the conversion of (R,S)-HMPC in ionic liquids. The optimum reaction conditions in ［bmim］PF6 were water activity of 0.17, 40 ℃, and pH=7 same as those in vinyl acetate. When the cosolvent was added into the reaction system, the conversion in ［bmim］PF6 decreased whereas increased in vinyl acetate, which might be due to the different properties of the reaction media.

Key words: ionic liquid, (R,S)-4-hydroxy-3-methyl-2-(2-propenyl)-2-cyclopenten-1-one, lipase, resolution