Thermodynamic Studies of Molecular Interactions in Mixtures Containing Tetrahydropyran, 1,4-Dioxane, and Cyclic Ketones

Abstract

The densities ρ, speeds of sound u, and molar heat capacities CP of tetrahydropyran or 1,4-dioxane (1) + cyclohexanone or cycloheptanone (2) mixtures at 293.15, 298.15, 303.15, and 308.15 K, and excess molar enthalpies, HE at 308.15 K and atmospheric pressure 0.1 MPa have been measured over the entire composition range. The excess molar volumes VE, excess isentropic compressibilities κSE, and excess heat capacities, CPE of the studied mixtures have been determined using the measured experimental data. The observed VE, κSE, HE, and CPE data have been tested in terms of graph theory. The analyses of VE data by graph theory suggest that while tetrahydropyran or 1,4-dioxane exists as a mixture of monomer and dimer; cyclohexanone or cycloheptanone exists as a mixture of open and cyclic dimer. Further, (1 + 2) mixtures are characterized by interactions between oxygen atom/s and hydrogen atom of tetrahydropyran or 1,4-dioxane with hydrogen atom/s and oxygen atom of cyclohexanone or cycloheptanone. The quantum mechanical calculations and analysis of IR spectral data of (1 + 2) mixtures also support this viewpoint. It has been observed that graph theory correctly predicts the VE, κSE, HE, and CpE data of the present mixtures.