Thermodynamics of Binary Mixtures Containing a Very Strongly Polar Compound. 7. Isothermal VLE Measurements for NMP + 2-Propanol or + 2-Butanol Systems. DISQUAC and ERAS Characterization of NMP or N,N-Dialkylamide + 2-Alkanol Mixtures. Comparison with Results from Dortmund UNIFAC

Abstract

Vapor−liquid equilibria (VLE; P−x1 measurements) for the 1-methylpyrrolidin-2-one (NMP) + 2-propanol system at 353.15 and 373.15 K and for the NMP + 2-butanol mixture at 373.15 K are determined by an ebulliometric method. The data are reduced using Barker's method. The systems show negative deviations from Raoult's law. NMP or N,N-dialkylamide + 2-alkanol mixtures are treated in terms of the DISQUAC, UNIFAC (Dortmund version), and ERAS models. The corresponding interaction parameters for the DISQUAC and ERAS models are reported. In the framework of UNIFAC, parameters available in the literature are used. DISQUAC represents fairly well VLE and excess molar enthalpies, HE, of the binary mixtures investigated. In addition, DISQUAC correctly predicts VLE of the ternary N,N-dimethylformamide + 2-propanol + 1-butanol system using binary parameters only. UNIFAC provides very poor results for systems with NMP, probably because the database used when fitting the required interaction parameters was rather limited. ERAS calculations are carried out taking into account that the considered amides are not self-associated. The symmetry of the excess functions is, in general, poorly described by ERAS. This is attributed to the existence of strong dipole−dipole interactions in the mixtures under study.