Physico-Chemical Characterization of Binary and Ternary Mixtures of Imidazolium Based Cation and Common Anion Ionic Liquids with Lactams

Excess molar volumes, V-E, excess isentropic compressibilities, kappa(E)(S) of binary 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [C(4)dmim][BF4] (1) + 1-methylpyrrolidin-2-one (NMP) or pyrrolidin-2-one (2-py) (2) and ternary 1-ethyl-3-methylimidazolium tetrafluoroborate [C(2)mim][BF4] or [C(4)dmim][BF4] (1) + NMP (2) + 2-py (3) mixtures have been determined from measured densities and speeds of sound at 293.15, 298.15, 303.15 and 308.15 K. V-E and kappa(E)(S) have been fitted to Redlich-Kister (binary, ternary mixtures) and Cibulka (ternary mixtures) equations respectively. Binary, ternary parameters and standard deviations between the experimental and calculated V-E and kappa(E)(S) values have been computed. Molecular interactions have been characterized qualitatively and quantitatively. IR studies and quantum concepts also support the presence of proposed molecular interactions.