Elimination of the azeotropic point of acetone and methanol by 1,3-dimethylimidazolium dimethylphosphate: an ab initio calculation study

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• 作者：Guangren Yu ; Xiaomin Liu ; Xiaochun Zhang ; Xiaochun Chen…
• 关键词：Azeotropic point elimination ; Ionic liquid ; Ab initio ; Hydrogen bond
• 刊名：Journal of Molecular Modeling
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：23
• 期：3
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Computer Applications in Chemistry; Molecular Medicine; Computer Appl. in Life Sciences; Characterization and Evaluation of Materials; Theoretical and Computational Chemistry;
• 出版者：Springer Berlin Heidelberg
• ISSN：0948-5023
• 卷排序：23

文摘

1,3-Dimethylimidazolium dimethylphosphate ([C₁mim][DMP]) was observed experimentally to be able to eliminate the atmospheric azeotropic point of acetone and methanol, which is an important azeotrope generally encountered in furfural production and the Fischer-Tropsch process. Here, we employed ab initio calculation to understand the underlying mechanism of [C₁mim][DMP] in eliminating the azeotropic point of acetone and methanol. Structure, energy and interaction in binary-, ternary- and quaternary-clusters composed of methanol, acetone, [C₁mim]+ or/and [DMP]‾ were calculated. The σ-hole, AIM and NBO analyses were performed to understand intermolecular interaction with electron density, electron occupancy, charge transfer and molecular orbital interaction. Hydrogen bond interaction plays a key role in azeotropic point elimination; due to the much stronger hydrogen bond interaction between methanol and [C₁mim][DMP] than that between acetone and [C₁mim][DMP], [C₁mim][DMP] prefers to interact with methanol rather than acetone, and the original interaction between methanol and acetone is separated by [C₁mim][DMP]. The hydrogen bond is from the orbital interaction between O lone-pair-electron orbitals of the hydrogen bond acceptor and σ * (C-H) or σ * (O–H) anti-bonding orbitals of the hydrogen bond donor, where remarkable electron or charge transfer occurs. These theoretical calculation results are in agreement with the experimental observation that [C₁mim][DMP] eliminates the azeotropic point of methanol and acetone. This work shows that ab initio calculation may be employed to rationalize the design or synthesis of ionic liquids for separating azeotropes.