EXCESS PROPERTIES FOR BINARY-LIQUID MIXTURES OF PROPIONIC-ACID WITH ANILINE DERIVATIVES

Excess viscosities, excess volumes, and excess free energies of activation for flow of the binary mixtures containing propionic acid with aniline, o-toluidine, o-anisidine, and o-chloroaniline were determined at five different temperatures from density and viscosity measurements. Based on the Regular Solutions Theory, the empirical parameter theta was calculated; this parameter is related to the viscosity, and also denotes the extent of the non-ideality of the system. The results obtained suggest the existence of acid-base interactions, as well as the formation of 1:2 complexes for the three first mixtures, and 2:1 complexes for o-chloroaniline + propionic acid. The extent of the specific interaction decreases with an increase in the strength of the base, and increases with an increase in the dipole moments. The equation V = V1X1.V2X2 is proposed for predicting the mole volume of the mixtures, V, at any composition, X(i), as a function of the mole volumes of the pure components, V(i).