Densities, Refractive Indices, and Excess Properties of Binary Mixtures of 1,4-Dioxane with Benzene, Toluene, o-Xylene, m-Xylene, p-Xylene, and Mesitylene at Temperatures from (288.15 to 318.15) K

Abstract

The densities (ρ) and refractive indices (n) of binary mixtures of 1,4-dioxane with benzene, toluene, o-xylene, m-xylene, p-xylene, and mesitylene, including those of pure liquids, over the entire composition range expressed by mole fraction x1 of 1,4-dioxane were measured at temperatures (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 318.15) K under atmospheric pressure. From the experimental data, the excess molar volumes (VmE), deviations in refractive indices (Δn), partial molar volumes (Vm,1°∞ and Vm,2°∞), and excess partial molar volumes (Vm,1°E,∞ and Vm,2°E,∞) of the components at infinite dilution were calculated. The VmE values were negative for 1,4-dioxane + benzene, positive for 1,4-dioxane + o-xylene, + m-xylene, + p-xylene, and + mesitylene mixtures over the entire mole fraction range at all investigated temperatures, and exhibit a sigmoid trend for1,4-dioxane + toluene mixtures wherein VmE changes sign from positive to negative as the mole fraction of 1,4-dioxane in the mixture is increased. The results indicate the presence of weak interactions between 1,4-dioxane and aromatic hydrocarbon molecules. The deviations in VmE values follow the order benzene < toluene < p-xylene < m-xylene < o-xylene < mesitylene. It is observed that VmE values depend on the number and position of the methyl groups in these aromatic hydrocarbons.