Liquid−liquid equilibrium and excess enthalpies were studied for the two binary systems: methylcyclohexane + methanol and methylcyclohexane + N,N-dimethylformamide. Points of the binodal curve in
the vicinity of the critical point were established in both of the systems by means of the cloud-point
method. Equilibrium compositions were determined at different temperatures using the direct analytical
method and the volume method. Excess enthalpies as functions of composition were determined at 298.15
K and 313.15 K using a Hart 4410 microcalorimeter with continuous-flow mixing cells. The results were
correlated by the modified Wilson equation. A prediction of the liquid−liquid equilibrium and the excess
enthalpy by the modified UNIFAC contribution method (Dortmund) was compared to the experimental
values.
Isothermal vapor−liquid equilibrium data were measured for two binary systems, ethanol + 2,4,4-trimethyl-1-pentene and 2-propanol + 2,4,4-trimethyl-1-pentene, at 343 K. The measurements were made
with a circulation still. The composition of liquid and condensed vapor phase was determined with a gas
chromatograph. Excess molar enthalpy data were measured for the same binary systems at 298 K. Both
systems indicate positive deviations from Raoult's law and exhibit azeotropic behavior.
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 was determined for three ternary systems water + ethanol + dialkyl phthalates (dimethyl, diethyl, and dibutyl phthalate) at 298.15 K. The turbidimetry titration method was used to obtain the binodal curves. Direct analytical methods were used to determine the composition of coexisting phases. The critical point composition was extrapolated from equilibrium data for each of the ternary systems using the Coolidge method. Excess enthalpy data were obtained for the system dimethyl phthalate + ethanol at 298.15 K. These, along with ternary and literature binary data, allowed a thorough thermodynamic description of the system water + ethanol + dimethyl phthalate. The modified Wilson equation was employed for this purpose.
Excess molar enthalpies were measured for the binary systems 2-methyl-2-propanol + 2,4,4-trimethyl-1-pentene at 300 K and for 2-butanol + 2,4,4-trimethyl-1-pentene at 298 K. Vapor−liquid equilibria were
also measured for the same systems at atmospheric pressure with a circulation still, and the liquid and
condensed vapor phase samples were analyzed with a gas chromatograph. The experimental data were
correlated with a Wilson activity coefficient model. Experimental results and the fitted model were also
compared with the predictive activity coefficient model UNIFAC (Dortmund).
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