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From the density (ρ) and speed-of-sound (u) measurements, the interactions of the drug diphenhydramine-hydrochloride (DPH) with three imidazolium-based ionic liquids (ILs) (1-butyl-3-methylimidazolium chloride, [C4mim]­[Cl], 1-hexyl-3-methylimidazolium chloride1, [C6mim]­[Cl], and 1-methyl-3-octylimidazolium chloride, [C8mim]­[Cl]) have been investigated in aqueous medium at T = 293.15–313.15 K and experimental pressure p = 0.1 MPa. From the density calculations, the apparent molar volume (V ϕ) and the apparent partial molar volumes of transfer (Δ t V ϕ o) have been determined for various solutions of DPH in aqueous solutions of different ILs. In addition, from the speed-of-sound data, the apparent molar isentropic compressibility (K ϕ), apparent partial molar isentropic compressibility (K ϕ o), and apparent partial molar isentropic compressibility of transfer (Δ tKϕ ο ) have been calculated. The pair and triplet interaction coefficients are derived from apparent partial molar volumes of transfer. For the present mixtures, the absorption spectra have been also recorded using a UV–visible spectrophotometer. Using Hepler’s constant, the structure-making nature of the solute has been confirmed. All these calculated parameters provide detailed insights into various physicochemical interactions prevailing in the ternary system and confirm the presence of a strong attractive interaction between DPH and ILs.

In this study, the density (ρ), speed of sound (u), and viscosity (η) of the binary liquid mixtures of an industrially important solvent 2-(2-ethoxyethoxy)­ethanol (carbitol) with acrylic esters [methyl acrylate, ethyl acrylate, and butyl acrylate (BA)] have been measured over the entire composition range at temperatures from T = 288.15 to 318.15 K and at atmospheric pressure P = 101 kPa. The excess molar volume (V m E), excess isentropic compressibility (κ s E), and viscosity deviations (Δη) have been calculated from the related experimental data. All excess properties are negative at all temperatures for all the mixtures, suggesting the compactness of binary mixture except the positive V m E values for some concentrations of BA mixtures. Deviation from ideality increases with rising temperature for both excess molar volume and excess isentropic compressibility but a decrease in deviation from ideality with temperature rise has been observed for viscosity deviations. Finally, excess properties have been fitted to the Redlich–Kister polynomial.

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