Thermodynamics of mixtures containing bromoalkanes. I. Estimation of DISQUAC interchange energy parameters for 1-bromoalkane + n-alkane mixtures. Comparison with other haloalkanes

Abstract

The experimental literature data on vapor-liquid equilibria (VLE), excess molar Gibbs energies, molar excess enthalpies and activity coefficients and partial molar excess enthalpies at infinite dilution of 1-bromoalkane + n-alkane mixtures are interpreted in terms of the DISQUAC group contribution model. The model reproduces fairly well most of the experimental data using a pair (Gibbs energy and enthalpy) of constant quasichemical interchange energies and a pair (Gibbs energy and enthalpy) of dispersive interchange energies. The dispersive interchange energies of bromoethane and of the higher 1-bromoalkanes are constant, but larger than for bromomethane. Several sets of VLE data are likely to be in error. Characteristic discrepancies between calculated and experimental values are observed in mixtures containing molecules of widely different sizes. The dispersive interchange energies of 1-chloro, 1-bromo- and 1-iodoalkanes increase in the order Cl < Br < I, as do the differences between the cohesive energy densities of haloalkanes and n-alkanes. The quasichemical interchange energies decrease in the order Cl > Br > I, almost linearly with the increasing relative surface of the halogen groups. Tentative values for the interchange energies of 1-fluoroalkanes + n-alkanes were estimated from the few available experimental data.