Resolution of (R,S)-4-Hydroxy-3-methyl-2-(2-propenyl)-2-cyclopenten-1-one Catalyzed by Lipase in Ionic Liquid

The resolution of (R,S)-4-hydroxy-3-methyl-2-(2-propenyl)-2-cyclopenten-1-one ((R,S)-HMPC) was studied using ionic liquids or vinyl acetate as the reaction medium. The effects of the reaction medium, water activity, temperature, pH value, and the 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 considerably 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 acryl donor could improve the conversion of (R,S)-HMPC in ionic liquids. The optimum reaction conditions in [bmim]PF6 were: water activity 0.17, 40°C, and pH = 7, the same as those in vinyl acetate. When the cosolvent was added to the reaction system, the conversion in [bmim]PF6 decreased, whereas that in vinyl acetate increased, which might be attributed to the different properties of the reaction media.