研究了离子液体和有机溶剂中(dl)-薄荷醇立体选择性酯化反应。结果表明,在疏水性离子液体[BMIM][PF6]和正己烷介质中的薄荷醇酯化率较高。通过对反应温度、孵育时间和回收次数等影响因素的测定,发现离子液体[BMIM][PF6]作为酶催化反应介质具有比正己烷更大的优势。尤其是酯酶在离子液体中孵育60d后表现出的活性增大为原来的2.5倍,而正己烷中的酶活性则在两天内变为原来的60%。此外,离子液体在回收利用中表现的优势更说明它作为绿色溶剂替代传统有机溶剂的巨大潜力。
Enantioselective esterification of (dl)-menthol was studied in ionic liquids and organic solvents of different hydrophobicities. Because the enzyme showed comparable conversion yield and enantioselectivity in [BMIM] [ PF6 ] and hexane, more work focused on these two reaction media. Comparison of the activity, stability and enantioselectivity was carried out by examining the effects of temperature, incubation time and enzyme recycling. It was found that temperature control was more crucial in the ionic liquid than in hexane to reach high conversion and enantioselectivity. The ionic liquid system showed an advantage of using less acid anhydride to achieve higher (dl)-menthol conversion yield and better enantioselectivity. Moreover, during an incubation of 4 d to 60 d in the ionic liquid, CRL activity was 2.5 times higher than its initial value, while that in hexane decreased to 60% in 2 d. In addition, the enzyme showed potentiality of recycled use in the ionic liquid. These advantages of the ionic liquid suggest that it would be used as a green alternative of organic solvents for the enantioseleetive esterification of ( dl)-menthol.