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
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 γA and γB, and activities aA and aB of 1,4-dioxane (A) and the other component (B) in the various systems, and excess molar Gibbs energies GEm for the above systems, by using Barker's procedure. GEm 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 GEm, and aA and aB 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.