Study On The Preparation Of 2-Octanol By Enzymatic Method

(S)-2-Octanol is the key material for the preparation of high-performance liquid crystal. Its chirality is very important for the improvement of the quality of liquid crystal. It is also the intermediate for the preparation of chiral drugs and pestcides, such as steroid, ectohormone and etc. In China, the output of octanol racemate is beyond the requirement while the chiral octanol only could be get from overseas. It is very urgent for the domestic enterprises to develop the technology to produce chiral octanol.The preparation of (S)-2-octanol was investigated in this work. The transesteration reaction by lipase in organic phase and catalysis by yeast had been applied in this work.(1) The transestesation reaction by lipase in organic phase was investigated. Chloroform was used as solvent, Lipase(Sigma) was used as catalyst and vinyl acetate was used for the transferesteration. The optimized reaction condition was as below: lipase 0.5g/ml 2-octanol, 2-octanol:vinyl acetate = 1:1.2-1.5 (mol/mol), quantity of water 0.6%(V/V), reaction temperature 30℃, reaction time 19h.Moreover, the effect of surfactants, DMSO, and ultrasonic-aided method on the resolution was investigated. When Tween-80 at 0.8%(V/V) and DMSO at 0.6(V/V) were added into the reaction solution, the enzyme enantioselectivity was improved. Ultrasonic-aided method improved the reaction yield, in the mean while it had no help to the enzyme enantioselectivity.(S)-2-Octanol was prepared by lipase in this work. The resolution yield was not good mainly because the used lipase was raw enzyme which only contained 25% protein. Enzymatic reaction in' organic phase has many advantages such as the high substrate solubility, very low water concentration, avoidance of side reaction. It is the key to enhance the enzyme activity and resolution yield for the application of this route.(2)Asymmetric reduction by redoxase from microorganism is aenvironment-friendly route for the preparation of (S)-2-octanol. It's good for the regeneration of coenzyme, also simplifies the separation process which helps to lower the cost.Asymmetric reduction by redoxase from yeast was investigated for the preparation of (s)-2-octanol. The reaction yield and the e.e. value of (s)-2-octanol were improved obviously by adding glucose to the reaction solution, which maybe resulted from the solution of the regeneration of coenzyme caused by coupling of the metabolism of glucose and the asymmetric hydrogenation occurred in cells.The optimized reaction condition was as below: concentration of octanone 5-10mmol/L, pH7.6, reaction temperature 30°C, shaker rotation 150-20rpm, reaction time 24h.2-Octanol was successfully prepared by transesteration and asymmetric hydrogenation. Though the reaction yield and resolution ratio were not very good, many results had been reached which was helpful for the preparation of (S)-2-octanol in large-scale.