Thermodynamics of mixtures with strongly negative deviations from Raoult's law Part 2. Application of the DISQUAC model to mixtures of CHCl3 or CH2Cl2 with oxaalkanes. Comparison with Dortmund UNIFAC results

Abstract

Binary mixtures of linear and cyclic oxaalkanes and CHCl₃ or CH₂Cl₂ are characterized in the framework of the DISQUAC model. The interaction parameters for the corresponding O/Cl contacts are reported. The enthalpic quasichemical interchange coefficients are negative, as in other mixtures which also show strong negative deviations from Raoult's law. There are proximity effects on both dispersive and quasichemical interaction parameters of diethers and acetals. DISQUAC represents fairly well the thermodynamic properties examined: vapor–liquid equilibria (VLE), molar excess enthalpies (H^E), molar excess heat capacities at constant pressure (C_p^E) or natural logarithms of activity coefficients at infinite dilution (ln γ_i^∞). DISQUAC provides much better results than the Dortmund version of UNIFAC using the published geometrical and interaction parameters. From this comparison, it seems that one should distinguish, at least, between linear monoethers, polyethers or acetals. Each cyclic molecule should be treated separately. A short comparison between DISQUAC and the ideal associated solution theory is also included. Both models yield similar results.