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[ChCl]:[Lev] (1:2) DES was synthesized in the laboratory with choline chloride, and levulinic acid, in a 1:2 relationship, stirring both components at 333.15 K and at 101.3 kPa. A thermophysical study of the pure [ChCl]:[Lev] (1:2) DES was realized. Densities, speeds of sound, dynamic viscosities, and refractive indices of the pure [ChCl]:[Lev] (1:2) DES are measured in the temperature range (293.15–343.15 K) and at 101.3 kPa of pressure. Density and refractive index data were additionally used to calculate other properties such as thermal expansion coefficient and molar refractions for the pure DES. The experimental values of density, speed of sound and refractive index showed a linear relationship with temperature, while the viscosity data were fitted using common equations such as Arrhenius, Vogel–Fulcher–Tamman (VFT), Litovitz, and fluidity. Besides, this paper reports experimental data, at different temperatures T = (298.15, 308.15 and 318.15) K, of density, speed of sound, refractive index, and viscosity for binary mixtures with alcohols. The derived properties, excess molar volume, refractive index, and viscosity deviations, were determined over the whole composition range at temperatures of 298.15, 308.15, and 318.15 K. The excess properties were fitted to the Redlich–Kister equation and have been qualitatively discussed in terms of interaction and structural factors. The excess properties were satisfactorily fitted by the Redlich–Kister equation.

The densities of four ionic liquids: 1-ethyl-3-methylimidazolium bis­(fluorosulfonyl)­imide ([E3Mim]­[Nf2]), n-propyl-n-methylpyrrolidinium bis­(fluorosulfonyl)­imide ([PMpyr]­[Nf2]), 1-butyl-1-methylpyrrolidinium bis­(fluorosulfonyl)­imide ([BMpyr]­[Nf2]), and 1-butyl-1-methylpyrrolidinium bis­(trifluoromethylsulfonil)­imide ([BMpyr]­[NTf2]) were measured at temperatures (293.15 to 413.15) K and pressures (0.1 to 60) MPa. The experimental density data were modeled using the modified Tammann–Tait equation and the average absolute percentage deviations between measured and calculated values for all studied ionic liquids were less than 0.004%. The optimized parameters were used to calculate the isothermal compressibility, the isobaric thermal expansivity, the internal pressure, and the difference between specific heat capacities at constant pressure and at constant volume. The cation and anion influences on the properties of the ionic liquids were examined. The longer alkyl chains on cations are related to lower density of ionic liquids and ionic liquids with imidazole based cation are denser than those with pyrrolidinium cation. The presence of more stabile [NTf2]− anion in ionic liquids leads to greater densities comparing to [Nf2]− anion.

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