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化学学报
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化学学报 ›› 2009, Vol. 67 ›› Issue (11): 1252-1258. 上一篇    下一篇

研究论文

新型对称烷基咪唑离子液体介质中酶催化合成l-乙酸薄荷酯

李 明a 方银军b 李在均*,a,b 任国晓b
黄亚茹b 单海霞a 党万雪a

  

  1. (a江南大学化学与材料工程学院 无锡 214122)
    (b 浙江赞宇科技股份有限公司 杭州 310030)

  • 投稿日期:2008-09-28 修回日期:2009-01-10 发布日期:2009-06-14
  • 通讯作者: 李在均

Synthesis of l-Menthyl Acetate Catalyzed by Lipase in New Symmetrical 1,3-Dialkylimidazolium Ionic Liquids

Li, Ming a Fang, Yinjun b Li, Zaijun *,a,b Ren, Guoxiao b
Huang, Yaru b Shan, Haixia a Dang, Wanxue a

  

  1. (a School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122)
    (b Zhejiang Zanyu Technology Limited Corporation, Hangzhou 310030)

  • Received:2008-09-28 Revised:2009-01-10 Published:2009-06-14
  • Contact: Li, Zaijun

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1463

被引次数

23 | 10

设计合成三种新型对称烷基咪唑六氟磷酸盐离子液体——1,3-二正丁基咪唑六氟磷酸盐([DnBIM][PF6]), 1,3-二异丁基咪唑六氟磷酸盐([DiBIM][PF6])和1,3-二仲丁基咪唑六氟磷酸盐([DsBIM][PF6]). 以脂肪酶pseudomonas cepacia催化l-薄荷醇和乙酸酐的酯化过程为模型反应, 分别考察不同介质中酶的活性、反应性和稳定性, 结果表明作为反应介质三种新型离子液体均优于经典离子液体1-正丁基-3-甲基咪唑六氟磷酸盐和有机溶剂正己烷. 在三种新的离子液体中, [DiBIM][PF6]具有最好的亲生物性而被选择作为模型反应介质. 此外, 影响l-薄荷醇转化率的各种因素(包括反应温度、底物投料比、离子液体用量和含水量)及酶的重复利用性也被详细研究. 在最佳反应条件下, l-薄荷醇转化率达到97.4%, 酶促反应速度、平衡转化率和半衰期分别是正己烷中的12.7, 4.6和15.1倍. 脂肪酶重复使用10次后催化活性没有明显减少. 由于三种新型离子液体互为同分异构体, 以上事实还表明除憎水性和亲核性以外离子液体的空间构型也是影响酶行为的一个重要因素.

关键词: 离子液体, 脂肪酶, 薄荷醇, 乙酸薄荷酯

Three new symmetrical 1,3-dialkylimidazolium ionic liquids including 1,3-di(n-butyl)imida- zolium hexafluorophosphate ([DnBIM][PF6]), 1,3-di(iso-butyl)imidazolium hexafluorophosphate ([DiBIM][PF6]) and 1,3-di(s-butyl)imidazolium hexafluorophosphate ([DsBIM][PF6]) were designed and synthesized. The esterification reaction of l-menthol with acetic anhydride catalyzed by Pseudomonas cepacia lipase was used as a model reaction to investigate the activity, reactivity and stability of the lipase in different media. The results indicated that the new ionic liquids as reaction medium were obviously better than classical ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate and organic solvent hexane. Among these, the [DiBIM][PF6] is of best biocompatibility and was then selected as medium of the model reaction. Moreover, various factors on the conversion of l-menthol including reaction temperature, molar ratio of the two substrates, the amounts of the ionic liquid, water content and reuse of the lipase were investigated in detail. Under optimal reaction conditions, the conversion of l-menthol was about 97.4%. Its initial reaction rate, the equilibrium conversion of l-menthol and the half-lifetime of the lipase in the [DiBIM][PF6] medium were about 12.7, 4.6 and 15.1-fold those obtained in hexane. Because the three ionic liquids used in the study are isomeric compounds, the fact also confirmed that besides hydrophobicity and nucleophilicity the spatial configuration of ionic liquids should be considered a key factor effecting enzyme performance in ionic liquid.

Key words: ionic liquid, lipase, menthol, menthyl acetate