Partial molar volume of tertiary amines in methanol at T = 298.15 K. Solvation, shape and specific interactions

Limiting partial molar volumes for six tertiary amines in methanol were obtained from accurate experimental density data at 298.15 K. Data analysis has been performed using the “non H-bonded methanol” approach and a model obeying the accurate Mansoori et al. equation of state for hard sphere mixtures. Volumetric contributions for the specific interaction between the lone pair of electrons of the amine group and the methanol have been obtained. Aliphatic hydrocarbons were used as reference compounds to account for the destruction of the methanol structure and non-polar solute-solvent interaction. Three types of differently shaped aliphatic hydrocarbons were considered aiming at analyzing the effect of the solute structure. Specific interactions between tertiary amines and methanol could then be derived. Hydrocarbons which are homomorphic forms of the amines were chosen as reference.

► Densities are measured in dilute solutions of tertiary amines in methanol, at 298.15 K.
► Partial molar volumes at infinite dilution were calculated from experimental data and theoretical approach.
► Specific interactions methanol-tertiary amines were derived.