Liquid−Liquid Equilibrium and Excess Enthalpies in the Binary System 2-Methylpentane + N,N-Dimethylformamide

Abstract

Liquid-liquid equilibrium and excess enthalpies were measured for the binary system 2-methylpentane + N,N-dimethylformamide. Equilibrium data were obtained at different temperatures by the direct analytical and volume methods; points of the binodal curve in the vicinity of the upper critical solution temperature of this system were acquired by means of the cloud-point method. Excess enthalpies were measured at 298.15 K and 313.15 K. Binary data were correlated by the modified Wilson equation. To estimate the critical composition and the upper critical solution temperature, the liquid-phase behavior data were also described by the extended scaling-law equation proposed by Ewing et al. 5 The liquidliquid equilibrium and excess enthalpies in the binary system were predicted by the modified UNIFAC (Dortmund) model so that the prediction could be compared to the experimentally achieved data.

Liquid–liquid equilibrium in ternary systems N,N-dimethylformamide + 2-methylpentane + methanol and N,N-dimethylformamide + methylcyclohexane + methanol

“…The experimental liquid-liquid equilibrium data acquired for the investigated systems N,N-dimethylformamide (1) + 2-methylpentane (2) + methanol (3) and N,N-dimethylformamide (1) + methylcyclohexane (2) + methanol (3) by the direct analytical and the cloud-point interpolation methods are given in Tables 2 and 3 and represented in Figs. 5 and 6.…”

“…Tie-lines were obtained in the ternary systems N,N-DMF (1) + 2-methylpentane (2) + methanol (3) and N,N-DMF (1) + methylcyclohexane (2) + methanol (3) by the direct analytical method. The direct analytical method is based on analyzing samples of the conjugated phases.…”

“…The method consists in measuring solution temperatures of mixtures in definite concentration series. To study ternary systems N,N-dimethylformamide (1) + 2-methylpentane (2) + methanol (3) and N,N-dimethylformamide (1) + methylcyclohexane (2) + methanol (3) concentration series issuing from the subsystems (2) + (3) and (1) To measure solution temperatures, a cloud-point apparatus working on the principle of measurement of the intensity of the light scattered by the measured mixture as function of linearly decreasing temperature was used. The apparatus was described in a previous work [2].…”

“…Experimental liquid-liquid equilibrium data for binary systems methylcyclohexane + methanol, methylcyclohexane + N,N-dimethylformamide, and 2-methylpentane + N,N-dimethylformamide were already published [2,3], data for the system 2-methylpentane + methanol being equally available [4]. To describe the binary systems, the regular solution model was used:…”

“…Their experimental data are available [2][3][4]. (B) Both ternary systems have a homogeneous subsystem N,N-dimethylformamide + methanol, for which literature vapour-liquid and excess enthalpy data are known [5][6][7][8][9][10][11][12].…”