Binary systems of 1,2-dichloroethane with benzene, toluene, p-xylene, quinoline and cyclohexane. Part 3.—Dielectric properties and refractive indices at 308.15 K

Abstract

Measurements of dielectric constants, ε, and refractive indices, n, have been made for binary liquid mixtures of 1,2-dichloroethane (CH₂ClCH₂Cl) with benzene, toluene, p-xylene, quinoline and cyclohexane at 308.15 K. The values of the quantity Δε, which refers to the deviations of the dielectric constants of the mixtures from the values arising from volume fraction mixture law, have been calculated. The values of Δε have been found to be positive for CH₂ClCH₂Cl–quinoline, and negative for CH₂ClCH₂Cl–benzene, CH₂ClCH₂Cl–toluene, CH₂ClCH₂Cl–p-xylene and CH₂ClCH₂Cl–cyclohexane. The positive values of Δε for CH₂ClCH₂Cl–quinoline are attributed to the existence of a specific interaction leading to the formation of a strong complex between CH₂ClCH₂Cl and quinoline in the liquid state. Values of the equilibrium constant K_f for the formation of a 1 : 1 complex between CH₂ClCH₂Cl and quinoline have also been calculated using the dielectric constant data, and it has been found that these values of K_f are in accord with the theory of Barriol and Weisbecker, which is based upon the electrostatic interactions of the solute with the liquid. The values of the apparent dipole moments µ_app of CH₂ClCH₂Cl at various mole fractions in the non-polar solvents benzene, p-xylene and cyclohexane have also been calculated. The values of µ_app suggest that there exists a specific interaction between CH₂ClCH₂Cl and the aromatic hydrocarbons.