Mutual solubility measurements and correlations of imidazolium-based ionic liquid mixtures with alcohols

The mutual solubility of ionic liquids (ILs), 1-butyl-3-ethylimidazolium tetrafluoroborate, 1-butyl-3-propylimidazolium tetrafluoroborate, and 1,3-dibutylimidazolium tetrafluoroborate with alcohols, 1-propanol, 1-butanol, 1-pentanol, and 1-hexanol were measured at atmospheric pressure. Upper critical solution temperatures (UCSTs) were estimated from experimental results using a polynomial equation. The UCSTs increased as increasing the chain length of alcohol. On other hand, the decreasing UCSTs occurred when the alkyl chain length on the cation of ionic liquids increased. The (liquid + liquid) equilibrium data were correlated by the original UNIQUAC, extended UNIQUAC, and modified UNIQUAC models. The temperature dependence of the solubility of ILs in alcohols and alcohols in ILs is represented successfully using the UNIQUAC, extended UNIQUAC, and modified UNIQUAC models with a quadratic function of temperature for binary energy parameters.     

Solubility of selected dibasic carboxylic acids in water,in ionic liquid of [Bmim][BF4], and in aqueous [Bmim][BF4] solutions

The solubilities of three dibasic carboxylic acids (adipic acid, glutaric acid, and succinic acid) in water, in the ionic liquid of 1-butyl-3-methyl-imidazolim tetrafluoroborate ([Bmim][BF₄]), and in the aqueous [Bmim][BF₄] solutions have been measured by a solid-disapperance method. The binodal curve of water + [Bmim][BF₄] was also determined experimentally from solid–liquid–liquid coexistence temperature up to near the upper critical solution temperature. Experimental results showed that each acid-containing binary behaved as a simple eutectic system. The solid–liquid equilibrium (SLE) data were correlated with the NRTL model for each binary system. The NRTL model with these determined binary parameters predicted the solid-disappearance temperatures of the aqueous ternary mixtures containing [Bmim][BF₄] and the dibasic acids to within an average absolute deviation of 2.0%.     

Solid–liquid equilibria for systems containing 1-butyl-3-methylimidazolium chloride

The solubility of 1-butyl-3-methylimidazolium chloride [C₄mim][Cl] in alcohols {ethanol, 1-butanol, 1-hexanol, 1-octanol, 1-decanol, 1-dodecanol, 2-butanol, 2-methyl-2-propanol (tert-butanol)} has been measured by a dynamic method from 270 K to the melting point of the ionic liquid or to the boiling point of the solvent. The melting point, enthalpy of fusion, and the temperature of the glass phase transition were determined by differential scanning calorimetry.The solubility data were correlated by means of the Wilson, UNIQUAC ASM and modified NRTL1 equations utilizing parameters derived from the solid–liquid equilibrium data. The root-mean-square deviations of the solubility temperatures for all calculated data were higher than 0.9 K and depended on the particular equation used.     

Mutual solubilities of selected solvents and 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate

1-(2-Hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HYDEMIM][BF₄]) ionic liquid was characterised by infrared spectroscopy, nuclear magnetic resonance, ultraviolet-visible spectra and thermogravimetric analysis. Mutual mass fraction solubilities of the 12 selected solvents (ethanol, 1-propanol, 1-butanol, benzene, toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, dichloromethane, chloroform and carbon tetrachloride) and [HYDEMIM][BF₄] in the temperature range from 283.16 to 353.61?K were measured using a cloud-point method. Measured solubility value S was correlated as a function of temperature by a second-order polynomial.     

Thermodynamic properties of the N-butylisoquinolinium bis(trifluoromethylsulfonyl)imide

A new isoquinolinium ionic liquid (IL) has been synthesised as a continuation of our work with quinolinium-based ionic liquids (ILs). The work includes specific basic characterization of synthesized compounds: N-isobutylquinolinium bromide, [BiQuin][Br] and N-isobutylquinolinium bis{(trifluoromethyl)sulfonyl}imide [BiQuin][NTf₂] by NMR spectra, elementary analysis and water content. The basic thermal properties of the pure [BiQuin][NTf₂], i.e. melting and glass-transition temperatures, the enthalpy of fusion as well as heat capacity at glass transition have been measured using a differential scanning microcalorimetry technique (DSC). Densities and viscosities were determined as a function of temperature. The temperature-composition phase diagrams of 8 binary mixtures composed of organic solvent dissolved in the IL: {[BiQuin][NTf₂] + aromatic hydrocarbon (benzene, or toluene, or ethylbenzene, or n-propylbenzene), or an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol)} were measured at ambient pressure. A dynamic method was used over a broad range of mole fraction and temperature from (270 to 320) K. For all the binary systems with benzene and alkylbenzenes, the eutectic diagrams were observed with an immiscibility gap in the liquid phase existing at low mole fraction of the IL with a very high upper critical solution temperature (UCST). For mixtures with alcohols, complete miscibility was observed for 1-butanol and also an immiscibility gap with UCST in the liquid phase for the remaining alcohols. The typical dependence was observed that with increasing chain length of an alcohol, the solubility decreases. The well-known NRTL equation was used to correlate experimental (solid + liquid), SLE and (liquid + liquid), LLE phase equilibrium data sets.     

The physicochemical properties of some imidazolium-based ionic liquids and their binary mixtures

The density, viscosity and conductivity of ionic liquids (ILs), 1-octyl-3-methylimidazolium tetrafluoroborate ([omim][BF4]), 1-octyl-3-methylimidazolium chloride ([omim][Cl]), 1-hexyl-3-methylimidazolium tetrafluoroborate ([hmim] BF4]), 1-hexyl- 3-methylimidazolium chloride ([hmim][Cl]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF6]), and the [omim][BF4] + [omim][Cl], [hmim][BF4] + [hmim][Cl], and [hmim][PF6] + [hmim][Cl] binary mixtures were studied at dif- ferent temperatures. It was demonstrated that the densities of both the neat ILs and their mixtures varied linearly with temper- ature. The density sensitivity of a binary mixture is between those of the two components. The excess molar volumes (VE) of [hmim][BF4] + [hmim][Cl] and [hmim][PF6] + [hmim][Cl] mixtures are positive in the whole composition range. For [omim][BF4] + [omim][Cl], the VE is also positive in the [omim][Cl]-rich region, but is negative in the [omim][BF4]-rich re- gion. The viscosity or conductivity of a mixture is in the intermediate of those of the two neat ILs. For all the neat ILs and the binary mixtures studied, the order of conductivity is opposite to that of the viscosity. The Vogel-Tammann-Fulcher (VTF) equations can be used to fit the viscosity and conductivity of all the neat ILs and the binary mixtures. The neat ILs and their mixtures obey the Fractional Walden Rule very well, and the values of the Walden slopes are all smaller than unit, indicating obvious ion associations in the neat ILs and the binary mixtures.     

Physical and Excess Properties for Binary Mixtures of 1-Methyl-3-Octylimidazolium Tetrafluoroborate, [Omim][BF4], Ionic Liquid with Different Alcohols

In recent years, ionic liquids have increasingly gained importance as green solvents. The potential of these organic salts, which are moisture and air stable at room temperature, for new chemical processes and technologies is beginning to be recognized. Research on the thermophysical properties of ionic liquids and their mixtures form the basis for future applications. In this contribution, densities, refractive indices, speeds of sound and dynamic viscosities of 1-methyl-3-octylimidazolium tetrafluoroborate, [Omim][BF₄], the room temperature ionic liquid (IL) in binary mixtures with methanol, ethanol, 1-propanol and 2-propanol were measured at 298.15K and atmospheric pressure. The excess molar volumes and molar refraction, isentropic compressibility and dynamic viscosity changes of mixing have been calculated and were satisfactorily correlated by the Redlich–Kister polynomial.     

Dramatic Change in Viscosities of Pure Ionic Liquids upon Addition of Molecular Solvents

Viscosities of binary mixtures of pyridinium based ionic liquids (1-butyl pyridinium tetrafluoroborate, [BP][BF₄], 1-butyl 3-methyl pyridinium tetrafluoroborate [3-MBP][BF₄], 1-butyl 4-methyl pyridinium tetrafluoroborate, [4-MBP][BF₄]), and phosphonium based ionic liquids, (tetrabutyl phosphonium alaninate, [TBP][Ala]; tetrabutyl phosphonium valinate, [TBP][Val]) with the molecular solvents, water, methanol and dichloromethane, have been measured at 298.15 K. A Brookfield ultra-rheometer was employed to measure the reported viscosities. The drop in viscosity in the close vicinity of pure ionic liquid is more prominent in polar solvents like water compared to less polar solvents. The temperature dependence of this observation was also studied for binary mixtures of [4-MBP][BF₄] with water in range of 298.15–323.15 K. The Vogel-Fulcher-Tamman (VFT) equation was employed to investigate the temperature dependence of the viscosities of pure pyridinium-based ionic liquids in the temperature range from 298.15–323.15 K.     

Thermodynamic properties of the N-octylquinolinium bis{(trifluoromethyl)sulfonyl}imide

This work is a continuation of our wide ranging investigation on quinolinium based ionic liquids (ILs). The study includes specific basic characterisation of the synthesized compounds N-octylquinolinium bromide, [OQuin][Br] and N-octylquinolinium bis{(trifluoromethyl)sulfonyl}imide [OQuin][NTf₂] by NMR spectra, elementary analysis and water content. Differential scanning calorimetry (DSC) measurements gave us properties of the pure [OQuin][NTf₂] i.e. melting and glass-transition temperatures, the enthalpy of fusion as well as heat capacity at the glass transition. Densities and viscosities were determined as a function of temperature. The temperature-composition phase diagrams of 10 binary mixtures composed of organic solvent dissolved in the IL: {[OQuin][NTf₂] + aromatic hydrocarbon (benzene, or thiophene, or toluene, or ethylbenzene, or n-propylbenzene), or an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol, or 1-dodecanol)} were measured at ambient pressure. A dynamic method was used over a broad range of mole fractions and temperatures from (250 to 370) K. For mixtures with benzene and alkylbenzenes, the immiscibility gap in the liquid phase in a low mole fraction of the IL was observed with upper critical solution temperature (UCST) higher than the boiling point of the solvent. In the system with thiophene, the immiscibility gap is lower and UCST was measured. For binary mixtures with alcohols, complete miscibility in the liquid phase was observed for 1-butanol and 1-hexanol. In the systems with longer chain alcohols, the immiscibility gap with UCST was noted. Typical behaviour for ILs was observed with an increase of the chain length of an alcohol the solubility decreases. The well-known NRTL equation was used to correlate experimental (solid + liquid), SLE and (liquid + liquid), LLE phase equilibrium data sets.     

Solubility of CO2 in imidazolium-based tetrafluoroborate ionic liquids

The solubility of CO₂ in imidazolium ionic liquids (ILs), 1-butyl-3-methyl imidazolium tetrafluoroborate ([bmim][BF₄]), 1-hexyl-3-methyl imidazolium tetrafluoroborate ([hmim][BF₄]) and 1-octyl-3-methyl imidazolium tetrtafluoroborate ([omim][BF₄]) was determined at 305-25 K and pressures from 1 to 9 MPa. The influence of chain length of alkyl substituents on the imidazolium cation on the solubility of CO₂ was investigated. The differences in solubility with chain length are in the sequence [omim][BF₄] > [hmim][BF₄] > [bmim][BF₄]. The solubility data were correlated by the extended Henry's law, and enthalpy, Gibbs free energy and entropy changes were obtained.     

Solubility of ethyl-(2-hydroxyethyl)-dimethylammonium bromide in alcohols (C2–C12)

The solubilities of a novel third generation of the precursor of ionic liquids, named ethyl-(2-hydroxyethyl)-dimethylammonium bromide, C₂Br, in alcohols {ethanol, 1-butanol, 1-hexanol, 1-octanol, 1-decanol, 1-dodecanol, 2-butanol, 2-methyl-2-propanol (tert-butyl alcohol)} have been measured by a dynamic method from 240 to 440 K.The solubility of ethyl-(2-hydroxyethyl)-dimethylammonium bromide in primary alcohols decreases with an increase of the molecular weight of the alcohol from C₂ to C₁₂. The differences in solubilities between the primary and secondary alcohols are not significant. The solubility of C₂Br in tert-butyl alcohol is much lower than in 1-butanol and 2-butanol.The data were correlated by means of the UNIQUAC ASM, NRTL1 and NRTL2 equations, utilizing parameters derived from the (solid + liquid) equilibrium (SLE) data. The root-mean-square deviations of the solubility temperatures for all calculated data are from 2.36 to 7.17 K and depend on the particular equation used. In the calculations, the existence of a solid–solid first-order phase transition in pure C₂Br has also been taken into account.     

Thermophysical properties and phase equilibria study of the binary systems {N-hexylquinolinium bis(trifluoromethylsulfonyl)imide + aromatic hydrocarbons,or an alcohol}

The new quinolinium ionic liquid has been synthesised as a continuation of our work with quinolinium-based ionic liquids (ILs). The work includes specific basic characterisation of synthesized compounds: N-hexylquinolinium bromide, [HQuin][Br] and N-hexylquinolinium bis{(trifluoromethyl)sulfonyl}imide [HQuin][NTf₂] by NMR spectra, elementary analysis and water content. The basic thermal properties of the pure [HQuin][NTf₂] i.e. melting and glass-transition temperatures, the enthalpy of fusion as well as heat capacity have been measured using a differential scanning microcalorimetry technique (DSC) and thermal analysis instrument (TA). Densities and viscosities were determined as a function of temperature. Phase equilibria for the binary systems: {[HQuin][NTf₂]) + aromatic hydrocarbon (benzene, or toluene, or ethylbenzene, or n-propylbenzene), or an alcohol (1-butanol, or 1-hexanol, or 1-octanol, or 1-decanol)} have been determined at ambient pressure. A dynamic method was used over a broad range of mole fractions and temperatures from (270 to 320) K. For all the binary systems with benzene and alkylbenzenes, the eutectic diagrams were observed with immiscibility gap in the liquid phase beginning from (0.13 to 0.28) mole fraction of the IL with very high an upper critical solution temperature (UCST). For mixtures with alcohols, the complete miscibility was observed for 1-butanol and immiscibility with UCST in the liquid phase for the remaining alcohols. The typical dependence was observed, that with increasing chain length of an alcohol the solubility decreases. The well-known NRTL equation was used to correlate experimental (solid + liquid), SLE and (liquid + liquid), LLE phase equilibria data sets. For the systems containing immiscibility gaps, (IL + an alcohol) parameters of the LLE correlation were used to the prediction of SLE.     

Effect of temperature and composition on the density,viscosity, surface tension,and thermodynamic properties of binary mixtures of N-octylisoquinolinium bis{(trifluoromethyl)sulfonyl}imide with alcohols

Density and viscosity were determined for the binary mixtures containing the ionic liquid N-octylisoquinolinium bis{(trifluoromethyl)sulfonyl}imide ([C₈iQuin][NTf₂]) and 1-alcohol (1-butanol, 1-hexanol, and 2-phenylethanol) at five temperatures (298.15, 308.15, 318.15, 328.15, and 338.15) K and ambient pressure. The density and viscosity correlations for these systems were tested by an empirical second-order polynomial and by the Vogel–Fucher–Tammann equation. Excess molar volumes were described by the Redlich–Kister polynomial expansion. The density and viscosity variations with compositions were described by polynomials. Viscosity deviations were calculated and correlated by the Redlich–Kister polynomial expansions. The surface tensions of pure ionic liquid and binary mixtures of [C₈iQuin][NTf₂] with 1-hexanol were measured at atmospheric pressure at three temperatures (298.15, 308.15, and 318.15) K. The surface tension deviations were calculated and correlated by the Redlich–Kister polynomial expansion. The surface thermodynamic functions such as surface entropy and enthalpy were derived from the temperature dependence of the surface tension values. The critical temperature, parachor, and speed of sound for pure ionic liquid were described. A qualitative analysis on these quantities in terms of molecular interactions is reported. The obtained results indicate that ionic liquid interactions with alcohols are strong dependent on the special trend of packing effects and hydrogen bonding of this ionic liquid with hydroxylic solvents. As previously observed, an increase by a 1-alcohol carbon chain length leads to lower interactions on mixing.     

Capillary zone electrophoresis of proteins applying ionic liquids for dynamic coating and as background electrolyte component

The use of ionic liquids in capillary electrophoresis, either as coating material or as components of the background electrolyte needs systematic standardization to set up optimal conditions. Excellent separation of the proteins was achieved using 1-ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF₄]) or 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]) ionic liquids using the properly made ionic-liquid–water binary mixtures for the experiments. The binary mixture has a distinctly stable and well perceptible low pH, which depends on the concentration of the ionic liquid, and on the preparation time of the mixture. Optimal conditions for the electrophoretic separation were obtained upon a multivariate analysis of the experimental parameters (applied voltage, migration time, concentration, and type of the ionic liquid). The standardized condition provides a low electroendosmotic flow toward the anode, which, however, did not hinder the proteins to migrate toward the cathode. The migration of cytochrome c, lysozyme, myoglobin, trypsin, and apo-transferrin at a pH around 2, far below the isoelectric points of the proteins, showed RSD values of the migration times less than 7.5% and less than 6.5% when using [emim][BF₄] or [bmim][BF₄], respectively, either in run-to-run or day-to-day experiments. The determination of the extent of the EOF is not possible with the commonly used EOF markers, due to interaction with the ionic-liquid constituents. The interaction of the ionic liquids with the proteins influences the migration order in zone electrophoresis. This method has been applied successfully for the analyses of real biological samples such as proteins from egg whites and human tears.     

Study of the surface properties and surface concentration of ionic liquid–alcohol mixtures

Surface properties for three binary mixtures containing a 1-butyl-3-methylimidazolium thiocyanate ([BMIM][SCN]) and a long-chain alcohol (1-butanol, 1-pentanol and 1-hexanol) were determined by surface tension data at the following temperatures: (298.15, 308.15, 318.15, 328.15 and 338.15) K. The surface tension data over the entire mole fraction range are correlated by the Fu et al.(FLW) and Myers-Scott (MS) models. There is good agreement between the experimental data and the results of correlations for 15 binary systems (the three systems at five temperatures) with an average relative error below 1.5%. In addition, the UNIFAC group contribution method is applied for calculation of activity coefficients of components in solution. Moreover, the relative adsorptions of alcohol at the air/liquid interface are determined using Gibbs adsorption isotherm. The obtained results show that the values of adsorption for mixtures of alcohols/[BMIM][SCN] increase with increasing the alkyl chain length of alcohol and decreasing temperature.     

(Solid + liquid) equilibria predictions of ionic liquid containing systems using COSMO-RS

(Solid + liquid) equilibria (SLE) prediction are an important phase equilibria property for ionic liquid (IL) mixtures especially when the IL exists as a solid. In this work, the SLE for the binary systems of (IL + thiophene) consisting of the ILs: n-butyl-4-methylpyridinium tosylate [BM₄Py][TOS], n-butyl-3-methylpyridinium tosylate [BM₃Py][TOS], n-hexyl-3-methylpyridinium tosylate [HM₃Py][TOS], and 1,4-dimethylpyridinium tosylate [M_1,4Py][TOS] are predicted using the quantum chemical based COSMO-RS (COnductor like Screening MOdel for Real Solvents) model. Initially, benchmarking studies are performed on binary mixtures which are known beforehand. The values of the predicted solubility are then compared with the experimental results by calculating the root mean square error (RMSE). The SLE predictions of the solubility of pyrene and dibenzothiophene in five different solvents were carried out giving an average RMSE of 4%. Further the applicability of COSMO-RS to binary systems consisting of (ionic liquid + alcohol) mixtures and (ionic liquid + hydrocarbons) are predicted. The ionic liquids concerned are n-butyl-3-methylpyridinium tosylate [BM₃Py][TOS] while the alcohols and hydrocarbons are 1-butanol, 1-hexanol, 1-octanol, 1-decanol, and benzene, toluene, ethylbenzene, n-propylbenzene respectively. The experimental data for the ionic liquid [BM₄Py][TOS] with thiophene gave the smallest deviation of 10.2%. The overall RMSE for IL–thiophene, IL–alcohol, and IL–hydrocarbons were 15%, 17.2% and 12.9% respectively. Thus the predicted solubility values were found to be in reasonable agreement with the experimental values.     

Solubilities of cinnamic acid esters in binary mixtures of ionic liquids and organic solvents

The solubilities of three cinnamic acid esters, namely, methyl ferulate, methyl p-coumarate, and methyl sinapate, have been measured in mixed solvent systems of tert-butanol with 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIM][PF₆]), 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM][BF₄]) and 1-methyl-3-octyl-imidazolium tetrafluoroborate ([OMIM][BF₄]) at 303.15 and 321.15 K, and in mixed solvent systems of ethyl acetate with [BMIM][BF₄] and [OMIM][BF₄] at 303.15 K. In eight cases, out of the 22 data sets, an additive behaviour of the solubility was observed, positive deviations from additivity were observed in six cases, a positive synergistic effect in five cases, and, finally, negative deviations from additivity in the remaining three cases. Prediction of the solubilities of the solutes in the various ternary systems was performed with the NRTL and UNIQUAC activity coefficient models. The binary interaction parameters of the models between solute and solvent molecules were taken from the literature. When the parameters between the solvent molecules are fitted to literature data, satisfactory predictions are not always obtained. On the other hand, very good predictions are obtained when only one of the two interaction parameters between the two solvent molecules is fitted to one single point of the solubility isotherm and the other interaction parameter is set equal to zero.     

Phase equilibria study in binary systems (tetra-n-butylphosphonium tosylate ionic liquid + 1-alcohol, or benzene, or n-alkylbenzene)

Ambient pressure (solid + liquid) equilibria (SLE) and (liquid + liquid) equilibria (LLE) of binary systems--ionic liquid (IL) tetra- n-butylphosphonium p-toluenesulfonate + 1-alcohol (1-butanol, 1-hexanol, 1-octanol, 1-decanol, or 1-dodecanol), benzene, or n-alkylbenzene (toluene, ethylbenzene, n-propylbenzene)-have been determined by using dynamic method in a broad range of mole fractions and temperatures from 250 to 335 K. For binaries containing alcohol, simple eutectic diagrams were observed with complete miscibility in the liquid phase. Only in the case of system [IL + n-propylbenzene] was mutual immiscibility with an upper critical solution temperature (UCST) with low solubility of the IL in the alcohol and high solubility of the alcohol in the IL detected. The basic thermal properties of pure IL, i.e., melting and glass-transition temperatures as well as enthalpy of melting, have been measured with differential scanning microcalorimetry technique (DSC). Well-known UNIQUAC, Wilson, NRTL, NRTL1, and NRTL2 equations have been fitted to obtain experimental data sets. For the system containing immiscibility gap [IL + n-propylbenzene], parameters of the equations have been derived only from SLE data. As a measure of goodness of correlations, root-mean square deviations of temperature have been used. These experimental results were compared to the previously measured binary systems with tetra- n-butylphosphonium methanesulfonate. Changing anion from methanesulfonate to p-toluenesulfonate decreases solubilities in systems with alcohols and increases the solubilities in binary systems with benzene and alkylbenzenes.     

Phase equilibria study of {N-butylquinolinium bis{(trifluoromethyl)sulfonyl}imide + aromatic hydrocarbons,or an alcohol} binary systems

Quinolinium ionic liquid has been prepared from 1-butylquinolinium bromide as a substrate. The work includes specific basic characterization of synthesized compound by NMR spectra, elementary analysis and water content. The basic thermal properties of the pure IL, i.e. melting and glass-transition temperatures, as well as the enthalpy of fusion have been measured using a differential scanning microcalorimetry technique (DSC). (Solid + liquid) phase equilibria (SLE) and (liquid + liquid) phase equilibria (LLE) for the binary systems: ionic liquid (IL) N-butylquinolinium bis{(trifluoromethyl)sulfonyl}imide, {([BQuin][NTf₂]) + aromatic hydrocarbon (benzene, or toluene, or methylbenzene, or propylbenzene, or thiophene), or an alcohol (ethanol, or 1-butanol, or 1-hexanol, or 1-octanol, or 1-dodecanol)} have been determined at ambient pressure. A dynamic method was used over a broad range of mole fractions and temperatures from (260 to 330) K. For the binary systems, the simple eutectic diagrams were observed with immiscibility in the liquid phase with an upper critical solution temperature (UCST). For mixtures with alcohols, it was observed that with increasing chain length of an alcohol the solubility decreases and the UCST increases. In the case of mixture (IL + benzene, or alkylbenzene, or thiophene) the eutectic systems with mutual immiscibility in the liquid phase with very high UCSTs were observed. These points were not detectable with our method and they were observed at low ionic liquid mole fraction. Densities at high temperatures were determined and extrapolated to T = 298.15 K. Well-known UNIQUAC, and NRTL equations have been used to correlate experimental SLE data sets. For the systems containing immiscibility gaps {IL + an alcohol} parameters of the LLE correlation equation have been derived using only the NRTL equation.