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

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 x 1 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 ( V m E ), deviations in refractive indices (Δ n ), partial molar volumes ( V m,1 °∞ and V m,2 °∞ ), and excess partial molar volumes ( V m,1 °E,∞ and V m,2 °E,∞ ) of the components at infinite dilution were calculated. The V m E 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 V m E 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 V m E values follow the order benzene < toluene < p -xylene < m -xylene < o -xylene < mesitylene. It is observed that V m E values depend on the number and position of the methyl groups in these aromatic hydrocarbons.