Vapor–liquid equilibria and excess molar volumes of N-methyl-2-pyrrolidone with 2-alkoxyethanols

Consistent vapor–liquid equilibria (VLE) data at 95.3 kPa have been determined for the binary mixtures of N-methyl-2-pyrrolidone (NMP) +2-methoxyethanol (2-ME), +2-ethoxyethanol (2-EE), +2-butoxyethanol (2-BE) over the entire composition range using a Swietoslawski ebulliometer. The VLE data have been correlated by the Wilson model. The investigated binary systems show negative deviation from Raoult's law. None of the binary systems form maximum or minimum boiling point azeotropic mixtures. Also, densities of all three binary liquid mixtures over the entire mole fraction range are measured at 303.15, 308.15, 313.15, and 318.15 K using densimeter. Excess molar volumes are computed with variation in composition and temperature, and are correlated by the Redlich–Kister polynomial equation. The results of activity coefficients, excess Gibb's energies and excess molar volumes are correlated, and are discussed in terms of molecular interactions. Also, the effects of temperature and chain length of alkoxyethanols are studied and are discussed in terms of molecular interactions.

Graphical abstractHydrogen bonding interactions between oxygen atom of CO group of N-methyl-2-pyrrolidone and hydrogen atom of OH groups of 2-ethoxyethanol molecules.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► VLE data and density of the systems of NMP + 2-alkoxyethanols are measured. ► The experimental data are well correlated with the Wilson model. ► The activity coefficients, excess Gibb's energy and molar volumes are computed. ► All the binary systems exhibited nonideal behavior. ► VLE data and excess molar volume are correlated.