Theoretical Elucidation of Glucose Dehydration to 5-Hydroxymethylfurfural Catalyzed by a SO3H-Functionalized Ionic Liquid
Theoretical Elucidation of Glucose Dehydration to 5-Hydroxymethylfurfural Catalyzed by a SO3H-Functionalized Ionic Liquid
复制标题
SO3H 功能化离子液体催化葡萄糖脱水生成 5-羟甲基糠醛的理论阐明
DOI：
10.1021/acs.jpcb.5b07773
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发表时间：
2015-10-22
影响因子：
3.3
通讯作者：
Liu, Chengbu
中科院分区：
文献类型：
--
作者：
Li, Jingling;Li, Jinghua;Liu, Chengbu
虽然SO3H功能化离子液体(ILS)催化葡萄糖转化为5-羟甲基呋喃(HMF)已取得成功，但其分子机理仍不十分清楚。本文以1-丁基-3-甲基咪唑氯[C(4)SO(3)HimCl]为代表，对葡萄糖转化为HMF的催化机理进行了密度泛函理论研究。研究发现，转化可能通过两条可能的途径进行，并且在大多数基本步骤中，IL的阳离子起着重要的作用，起着促进反应的质子穿梭的作用。氯离子通过氢键与底物和咪唑环上的酸性质子相互作用，并与咪唑阳离子一起提供一个极性环境来稳定中间体和过渡态。计算的两个可能途径的催化转化总势垒分别为32.9千卡/摩尔和31.0千卡/摩尔，这与在温和条件下(100℃)观察到的IL的催化性能是一致的。本研究结果为进一步优化SO3H功能化离子液体催化葡萄糖转化为HMF提供了依据，也为设计用于生物质转化化学的离子液体催化剂提供了依据。
While the catalytic conversion of glucose to 5-hydroxymethyl furfural (HMF) catalyzed by SO3H-functioned ionic liquids (ILs) has been achieved successfully, the relevant molecular mechanism is still not understood well. Choosing 1-butyl-3-methylimidazolium chloride [C(4)SO(3)HmimCl] as a representative of SO3H-functioned IL, this work presents a density functional theory (DFT) study on the catalytic mechanism for conversion of glucose into HMF. It is found that the conversion may proceed via two potential pathways and that throughout most of elementary steps, the cation of the IL plays a substantial role, functioning as a proton shuttle to promote the reaction. The chloride anion interacts with the substrate and the acidic proton in the imidazolium ring via H-bonding, as well as provides a polar environment together with the imidazolium cation to stabilize intermediates and transition states. The calculated overall barriers of the catalytic conversion along two potential pathways are 32.9 and 31.0 kcal/mol, respectively, which are compatible with the observed catalytic performance of the IL under mild conditions (100 degrees C). The present results provide help for rationalizing the effective conversion of glucose to HMF catalyzed by SO3H-functionalized ILs and for designing IL catalysts used in biomass conversion chemistry.