三唑鎓基离子液体:一类新型纤维素溶剂。

Triazolium-Based Ionic Liquids: A Novel Class of Cellulose Solvents.

机构信息

Institut für Chemie , Martin-Luther-Universität Halle-Wittenberg , Von-Danckelmann-Platz 4 , D-06120 Halle (Saale), Germany.

出版信息

J Phys Chem B. 2019 May 9;123(18):3994-4003. doi: 10.1021/acs.jpcb.8b12082. Epub 2019 Feb 27.

Abstract

We present first results on triazolium-based ionic liquids (ILs) as a novel class of nonderivatizing solvents for cellulose. Despite their chemical similarity to imidazolium cations, the 1,2,3-triazolium cation lacks the isolated ring proton, leading to reduced formation of N-heterocyclic carbenes (NHCs) and therefore to lower reactivity and less unwanted side reactions. We synthesized six ILs based on 1,2,3-triazolium and 1,2,4-triazolium cations. The acetates are room-temperature ionic liquids and dissolve a similar amount of cellulose as the corresponding imidazolium salt. From NMR spectroscopy of the solution, we rule out polymer degradation. The cellulose solubility rises with increasing anion basicity, while being almost independent of the cation. We perform molecular dynamics simulations and compute enthalpies of solvation, which quantitatively fit the experimental solubilities. Trajectory analysis reveals strong hydrogen bonds between acetate anions and cellulose hydroxyl groups, while the cations do not form strong hydrogen bonds with cellulose. Thus, the simulations provide an atomistic explanation of our experimental observations.

摘要

我们首次提出了三氮唑鎓基离子液体(ILs)作为纤维素的新型非衍生化溶剂。尽管它们在化学上与咪唑阳离子相似,但 1,2,3-三氮唑鎓阳离子缺乏孤立的环质子,从而导致 N-杂环卡宾(NHC)的形成减少,因此反应性降低,副反应减少。我们合成了基于 1,2,3-三氮唑和 1,2,4-三氮唑阳离子的六种 ILs。它们的醋酸盐是室温离子液体,可溶解与相应的咪唑盐相似量的纤维素。通过溶液的 NMR 光谱,我们排除了聚合物降解。纤维素的溶解度随阴离子碱性的增加而增加,而与阳离子几乎无关。我们进行了分子动力学模拟并计算了溶剂化焓,其定量拟合了实验溶解度。轨迹分析表明,醋酸根阴离子与纤维素羟基之间存在强氢键,而阳离子与纤维素之间则没有形成强氢键。因此,模拟为我们的实验观察结果提供了原子水平的解释。

文献AI研究员

20分钟写一篇综述,助力文献阅读效率提升50倍

立即体验

用中文搜PubMed

大模型驱动的PubMed中文搜索引擎

马上搜索