Volumetric Properties of Binary Mixtures of Two 1-Alkyl-3-Methylimidazolium Tetrafluoroborate Ionic Liquids with Molecular Solvents

Abstract

The densities have been determined for the binary systems of ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate, [Emim] [BF 4 ] and 1-hexyl-3-methylimidazolium tetrafluoroborate, [Hmim] [BF 4 ], with the molecular solvents dimethyl sulfoxide (DMSO) and acetonitrile (ACN) at atmospheric pressure over the entire range of composition and temperatures from (298.15 to 353.15) K. From experimental densities, the excess molar volumes, V E , were calculated and fitted to a Redlich−Kister equation. Moreover, the V E results have been discussed in terms of the Prigogine−Flory−Patterson (PFP) theory. The V E variation was interpreted in terms of intermolecular interactions and structural effects on mixing. ■ INTRODUCTIONRoom-temperature ionic liquids (ILs) have caught the attention of researchers due to their extraordinary properties as roomtemperature molten salts. Some of these, like negligible vapor pressure, wide liquid range, and an ionic conductivity−viscosity ratio, make them potential green solvents or reaction media for many applications. 1−4 Generally, to design an industrial process involving ILs, it is important to know their physicochemical properties. One attraction of ILs is the possibility to obtain the desired properties by modifying the nature and size of the cations and anions, and a strategy in the application of ILs is to use mixtures of IL + organic (or inorganic) solvent to generate the targeted properties. In addition, by knowing the excess properties we can better understand the structure−property relation, making it easier choosing an appropriate IL. Therefore, IL + solvent mixtures have received growing attention in the past years.Up to now, the most investigated ionic liquids are those containing 1,3-dialkylimidazolium cations. In this context, the thermophysical properties of binary systems of 1-alkyl-3-methylimodazolium tetrafluoroborates with polar organic solvents, like dimethyl sulfoxide and acetonitrile, have been studied in literature. 5−10 As a continuation of our studies involving physicochemical properties of pure 1-alkyl-3-methylimodazolium tetrafluoroborates and its mixtures with traditional organic solvents, 11 we report here the densities of the ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-hexyl-3-methylimidazolium tetrafluoroborate and their binary mixtures with dimethyl sulfoxide (DMSO) and acetonitrile (ACN) from (293.15 to 353.15) K over the whole composition range.To our best knowledge, for the binary systems of both studied ionic liquids with ACN only density data is reported at temperature of 298.15 K 5 ; for the other two studied systems no literature data concerning volumetric properties are available. ■ EXPERIMENTAL SECTIONMaterials. We used the reagents: 1-ethyl-3-methylimidazolium tetrafluoroborate (mass fraction > 0.98) from Sigma

Viscosity of binary mixtures of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid with four organic solvents

“…These results correlate well with our previous results of Prigogine-Flory-Patterson (PFP) theory used to analyse the excess molar volumes [20,21].…”

“…We took the volumetric data necessary in equation (5) from our previously published papers [20,21]. The experimental values of ∆η and G *E have been fitted to the Redlich-Kister type polynomials:…”

“…Combined viscosity and density values were used to calculate the excess Gibbs energy of activation of viscous flow. We already have published the density values for these binary systems [20,21] [20,21]. All measurements were made at atmospheric pressure, p = 0.1 MPa, which was measured in our laboratory by a mercury barometer with an uncertainty of ±0.002 MPa.…”

Properties of Pure 1-Butyl-2,3-dimethylimidazolium Tetrafluoroborate Ionic Liquid and Its Binary Mixtures with Dimethyl Sulfoxide and Acetonitrile

“…This is inspired by our previous studies of ILs with DMSO and ACN. 20 The V E values for [Bmmim][BF 4 ] + DMSO system are less negative than the corresponding system with [Bmim] [BF 4 ]. 19 From the interactional point of view, the differences between the two systems probably comes from the Apparent and Partial Molar Volumes.…”

“…13 Our interest for the trialkyl-substituted imidazolium-based ILs is on the one hand to study the physicochemical properties of solvent systems with ILs that can be used as new media in the synthesis of different metal oxide nanostructures; in this sense we have already studied three 1-alkyl-3-methylimidazolium tetrafluoroborate ILs. 19,20 On the other hand the binary mixtures of such trialkyl-substituted imidazolium-based ILs with organic solvents are interesting from the fundamental research point of view for understanding the relation between structure and mixture properties, especially by comparing them with corresponding dialkyl-substituted mixtures.…”