title: Elimination of the azeotropic point of acetone and methanol by 1,3-dimethylimidazolium dimethylphosphate: an ab initio calculation study.
abstract: 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. Graphical Abstract Elimination of azeotropic point of acetone and methanol by [C1mim][DMP].
authors.affiliation: College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, 100029, People's Republic of China.
authors.forename: Guangren
authors.initials: G
authors.lastname: Yu
authors.affiliation: Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Key Laboratory of Green Process and Engineering. Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Liu
authors.affiliation: Beijing Key Laboratory of Ionic Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Key Laboratory of Green Process and Engineering. Institute of Process Engineering, Chinese Academy of Sciences, Beijing, 100190, People's Republic of China.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Zhang
authors.affiliation: College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, 100029, People's Republic of China.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Chen
authors.affiliation: College of Chemical Engineering, Beijing University of Chemical Technology, Beijing, 100029, People's Republic of China. liuzhp@mail.buct.edu.cn.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Liu
authors.affiliation: Department of Chemistry, College of Science, King Saud University, Riyadh, 11451, Saudi Arabia.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Abdeltawab
keywords: Ab initio; Azeotropic point elimination; Hydrogen bond; Ionic liquid