Excess enthalpies and excess heat capacities of the ternary system ethanol + N,N-dimethylformamide + tetrahydrofuran at 298.15 K

Excess enthalpies and excess heat capacities at 298.15 K for the ternary system ethanol + dimethylformamide + tetrahydrofuran were determined by means of a flow calorimetric apparatus built in our laboratory. Experimental data were described with a Redlich-Kister type equation and compared with those of other ternary systems previously studied (ethanol + tetrahydrofuran + cyclohexane, ethanol + dimethylformamide + cyclohexane, dimethylformamide + tetrahydrofuran + cyclohexane). A peculiar behaviour was observed for mixtures containing dimethylformamide, namely the negative values of both HE and CpE ternary contributions. sfactory prediction of experimental HE data is provided by the UNIQUAC model, while UNIFAC (Dortmund, Germany) clearly fails probably owing to an unsufficient definition of interaction parameters involving dimethylformamide.