Excess Molar Enthalpies and Vapor−Liquid Equilibrium for N-Methyl-2-pyrrolidone with Ketones

Abstract

Excess enthalpies (HE), at ambient pressure and 298.15 K, have been measured by using a solution calorimeter for the binary liquid mixtures of N-methyl-2-pyrrolidone (NMP) with ketones, as a function of composition. The ketones chosen in the present investigation were methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), and cyclohexanone (CH). The HE values were measured using a new Parr 1451 solution calorimeter and were negative over the entire mole fraction range for NMP with MEK and were positive for NMP with MIBK or CH. The excess enthalpy data have also been correlated with the Redlich−Kister equation. Furthermore, the vapor−liquid equilibrium (VLE) data were measured at 95.3 kPa for these mixtures, of different compositions, with the help of the Swietoslawski ebulliometer. The experimental temperature−mole fraction (T−x) data were used to compute Wilson parameters and then used to calculate the equilibrium vapor-phase compositions. The intermolecular interactions and structural effects were analyzed on the basis of the measured and derived properties.