Thermodynamic behaviour of binary systems of 1,4-dioxane with 1,2-dichloroethane, dichloromethane, trichloroethene, tetrachloroethene and cyclohexane. Vapour pressures and excess molar Gibbs energies

Abstract

Measurements of vapour pressures have been made for the systems 1,4-dioxane with dichloromethane and 1,2-dichloroethane at 298.15 K, for 1,4-dioxane with trichloroethene and tetrachloroethene at 303.15 K, and for 1,4-dioxane with cyclohexane (c-C₆H₁₂) at 288.15 K. The total vapour pressure vs. liquid phase composition data have been used to obtain the activity coefficients γ_A and γ_B, and activities a_A and a_B of 1,4-dioxane (A) and the other component (B) in the various systems, and excess molar Gibbs energies G^E_m for the above systems, by using Barker's procedure. G^E_m is found to be positive throughout the whole composition range for mixtures containing c-C₆H₁₂ and CCl₂CCl₂, and negative for those containing CH₂Cl₂, CH₂ClCH₂Cl and CHClCCl₂. Analysis of the experimental data of G^E_m, and a_A and a_B has shown that 1,4-dioxane forms AB and AB₂ complexes with CH₂Cl₂, CH₂ClCH₂Cl and CHClCCl₂ in the liquid state. The equilibrium constants K₁ and K₂ for the formation of the complexes AB and AB₂ have been evaluated from the data of the activities of the two components of the systems of 1,4-dioxane with CH₂Cl₂, CH₂ClCH₂Cl and CHClCCl₂. The four species A, AB, AB₂ and B that are present in mutual equilibrium in mixtures of 1,4-dioxane with CH₂Cl₂, CH₂ClCH₂Cl and CHClCCl₂, conform accurately to the theory of ideal associated mixtures due to McGlashan and Rastogi.