Thermodynamics of mixtures containing organic carbonates: Part XIII. Solid–liquid equilibria of long-chain 1-alkanol + dimethyl or diethyl carbonate systems: DISQUAC and ERAS analysis of the hydroxyl/carbonate interactions

Abstract

Solid–liquid equilibrium temperatures for systems of 1-tetradecanol, 1-hexadecanol, 1-octadecanol, or 1-icosanol with dimethyl or diethyl carbonate have been measured using a dynamic method. The alcohols present two first order transitions. 1-Alkanols+linear organic carbonates mixtures are studied using DISQUAC and ERAS models. The corresponding interaction parameters are reported. They behave similarly in both models. In DISQUAC, the QUAC parameters are independent of the mixture compounds, as in many other alcoholic solutions previously analyzed. The DIS parameters increase with the size of the alcohol. They remain constant for the longer alcohols. In ERAS, Δv AB ∗ is independent of the mixture components, while Δh AB ∗ depends only on the carbonate. DISQUAC yields a consistent description of the thermodynamic properties examined: vapor–liquid equilibria molar excess Gibbs energies, Solid–liquid equilibria and molar excess enthalpies. DISQUAC improves ERAS results on excess molar enthalpies, as the calculated curves using ERAS are shifted to the region of low concentration in alcohol. This means that, in terms of ERAS, the contribution to the excess molar enthalpy from the self-association of the alcohol is overestimated. Molar excess volumes are well represented by ERAS. From the analysis of the excess molar enthalpy curves, it is concluded that they are determined mainly by dipolar interactions between carbonate molecules. Excess molar volumes are relatively low indicating strong structural effects.