The excess molar volume and the molar surface Gibbs energy of the binary of the ether-functionalized ionic liquids [C22O1IM][TfO] with ethanol and isomeric propanols at T = (288.15–318.15) K
Graphical abstract
Introduction
Traditionally, the common molecular organic solvents (VOCs) is often used to be the solvents or dispersants in most reactions, however, they have many disadvantages especially in terms of environmental friendliness. To solve the problem, as green and designer solvents [1,2], ionic liquids (ILs) have been applied to replace VOCs as reaction media [3], which have attracted significant amount of interest from scientific communities working in various fields of chemistry [4,5], especially these are useful from the point of view chemical and industrial engineering [6]. However, ILs typically exhibit higher viscosities relative to conventional organic solvents and it is the main reason for limiting their applications all the time.
In recent years, the ether-functionalized ionic liquids, in which the ether groups substitute for alkyl groups onto the cation structure have been designed [7,8], and successfully employed in various applications due to the ether groups, which are well-known for their unique contribution to low viscosity and high conductivity, in particular, these kinds of ionic liquids are widely used in postcombustion CO2 capture from flue gas [9,10], gas separation [11] and organic reactions [12,13]. The properties of pure ether-functionalized ionic liquids are limited reported [14], and as a subject of crucial research based on both potential technological application and theoretical interest, the physicochemical properties of the binary mixtures of ether-functionalized ionic liquids and organic solvents are very scarce, which can be valuable on the basis of presenting different molecular interactions leading to characteristic aggregation formation [15,16]. Actually, it is not only reduce the viscosity but also the costs and pollutions efficaciously, as we all know that the experimental study in properties is still primarily important for ILs to be more properly applied, as well as for providing reference data for more reliable predictions. Thus, the physicochemical properties of ether-functionalized ionic liquids mixtures are needed from both the practical applications and theoretical, above all, these mixtures are widely applied in biomass treatment [17] and drug delivery systems [18].
Thus, the main purpose of this paper is to explore comprehensively the physicochemical properties of the binary mixtures of ether-functionalized ionic liquids and alcohols. Firstly, this ether functionalized ILs 1-ethyl-3-(2-methoxyethyl)-imidazolium trifluoromethanesulfonate [C22O1IM][TfO] was prepared and characterized, and then, the density and surface tension of the binary mixtures of ether-functionalized ionic liquids with alcohols (ethanol, 1-propanol and 2-propanol) were measured across the entire range of mole fraction (x1 = 0.0000–1.0000) at T = (288.15–318.15) K, the excess molar volumes, VE, of the binary mixtures were calculated from the experimental density. The relationships between the excess molar volumes, VE, and molar fractions and temperatures are discussed respectively; The molar surface Gibbs energy for binary mixtures of [C22O1IM][TfO] with alcohols were obtained based on the density and surface tension, and it is usually used to estimate the surface tension and improve the traditional Eӧtvӧs equation and at the same time, the polarity of the binary mixtures of [C22O1IM][TfO] with alcohols is explored in this paper.
Section snippets
Chemicals
All the chemicals including 1-ethylimidazole, 1-bromo-2-methoxyethane, silver nitrate, silver trifluoromethanesulfonate, acetonitrile and diethyl ether are all purchased from Sinopharm Chemical Reagent Co., Ltd, and the details of the chemicals used in the present work with their purity and method used for purification are given in Table 1.
Synthesis of [C22O1IM][TfO]
According to the provided method reported in literature [19], the intermediate product is synthesized in the lab, that is, under the protection of argon, a
The experimental densities and surface tensions of the ethanol, 1-propanol, 2-propanol and their deviations
From Table 2, Table 3, it can been seen that the densities and surface tensions of binary mixtures increase with the increase of x1 while decrease with the temperature elevating, and the relationship between density and surface tensions and composition is nonlinear (see Fig. S6 and Fig. S7). In addition, the comparison with available literature data [14] is shown in the Table 2, Table 3, and the experimental data have been compared graphically (see Fig. S8 and S9), the relative deviations of
Conclusions
This ether functionalized ILs 1-ethyl-3-(2-methoxyethyl)-imidazolium trifluoromethanesulfonate [C22O1IM][TfO] was prepared and characterized, and then, the density and surface tension for the binary mixtures of ionic liquid [C22O1IM][TfO] with ethanol, 1-propanol and 2-propanol were measured across the entire range of mole fraction (x1 = 0.0000–1.0000) at T = (288.15–318.15) K, and the relationship between density and composition is nonlinear, it can been seen that the densities of binary
Acknowledgments
This project was financially supported by National Nature Science Foundation of China NSFC (No. 21673107 and 21703090), and Liaoning BaiQianWan Talents Program (2017).
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