Preferential solvation and mixing behaviour of the essential oil 1,8-cineole with short–chain hydrocarbons

This work deals with the structure and solvation ability of the binary mixtures of the essential oil 1,8-cineole with n-hexane, n-octane and n-decane. The relevant derived properties excess isobaric heat capacity, molar excess volume, mixing viscosity, excess isentropic compressibility and activation Gibbs free energy were calculated from the measurements of the respective thermophysical properties carried out at atmospheric pressure in a wide range of temperatures. The data obtained were correlated with the solvent composition over the whole range and interpreted in terms of structural features and molecular interactions. The observed effect of temperature and the underlying interactions stress the propensity of the pure hydrocarbons for packing and folding. The solvation ability of the mixed solvents was assessed with the preferential solvation model, using the solvatochromic probes 2-nitroanisole and 4-nitroaniline, and the Hansen solubility parameters as well, the mixtures displaying stronger solvation power than the pure constituents.