了解几丁质晶体在离子液体中的溶解过程：理论研究<a href="#fn1" title="现有电子补充信息（ESI）：从MD轨迹获得的几丁质溶解和氢键合的晶体模型的其他结果，以及2-溴乙酸乙酯的1H NMR光谱，以及从AMIMCl与2-溴乙基的等摩尔反应混合物中提取的乙醚提取的结果。醋酸盐（CDCl3）（PDF）; 为AMIMBr（AVI）中的几丁质晶体（9链×10聚体模型）计算的MD轨迹的动画。参见DOI：10.1039 / c8cp02749h">†</a>,Physical Chemistry Chemical Physics

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了解几丁质晶体在离子液体中的溶解过程：理论研究 †
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2018-07-30 00:00:00 , DOI: 10.1039/c8cp02749h
Takuya Uto _{1,

2,

3,

4,

5} , Satoshi Idenoue _{1,

2,

3,

4,

5} , Kazuya Yamamoto _{1,

2,

3,

4,

5} , Jun-ichi Kadokawa _{1,

2,

3,

4,

5}

Affiliation

几丁质是一种有前途的生物质资源，由于其天然的年产量巨大，因此具有很大的工业应用潜力。然而，由于其非常稳定和结晶的特性，它表现出差的可加工性和溶解性。近年来，离子液体（ILs）作为结构多糖的溶剂引起了人们的关注-例如，已发现1-allyl-3-甲基咪唑鎓溴化物（AMIMBr）可溶解甲壳质。由于已知很少可溶解甲壳质的IL，因此对所涉及的溶解机理的研究很少。在这项研究中，我们采用了分子动力学（MD）方法来研究甲壳素晶体在咪唑鎓基ILs中的溶解。在MD模拟中AMIMBr已经证明，溶解过程涉及剥离从晶体表面的几丁质链的，被Br ^-裂解几丁质氢键，以及AMIM ⁺防止剥离后返回到结晶相。相比之下，在乙酸咪唑鎓盐中，据报道，乙酸咪唑鎓盐溶解甲壳质，尽管分子链被剥离，但剥离的链偶尔会返回到结晶相。此外，MD轨迹分析表明，几丁质的溶解度与几丁质晶体中乙酰氨基的分子间氢键数目密切相关。实验已经证明，将少量的作为溴化物生成剂的2-溴乙酸乙酯与1-烯丙基-3-甲基咪唑鎓氯化物混合可以增强几丁质的溶解性，这支持了以上理论结果所表明的溶解机理。

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Understanding dissolution process of chitin crystal in ionic liquids: theoretical study†

Chitin is a promising biomass resource and has high potential for industrial applications owing to its huge annual production in nature. However, it exhibits poor processability and solubility due to its very stable and crystalline character. Recently, ionic liquids (ILs) have attracted attention as solvents for structural polysaccharides – for example, 1-allyl-3-methylimidazolium bromide (AMIMBr) has been found to dissolve chitin. As few ILs are known to dissolve chitin, little research has been conducted on the dissolution mechanism involved. In this study, we have adopted a molecular dynamics (MD) approach to study the dissolution of chitin crystals in imidazolium-based ILs. The MD simulation in AMIMBr has demonstrated that the dissolution process involved peeling of chitin chains from the crystal surface, with Br⁻ cleaving the chitin hydrogen bonds, and AMIM⁺ preventing a return to the crystalline phase after the peeling. By contrast, in imidazolium acetates, which has also been reported to dissolve chitin, although the molecular chains are peeled off, the peeled chains occasionally return to the crystalline phase. Furthermore, the MD trajectory analysis has revealed that the solubility of chitin is well correlated with the number of intermolecular hydrogen bonds by acetamido groups in the chitin crystal. It has been experimentally proven that mixing a small amount of 2-bromoethyl acetate, as a bromide generator, with 1-allyl-3-methylimidazolium chloride can enhance chitin solubility, which supports the dissolution mechanism indicated by the above theoretical results.

更新日期：2018-07-30

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