Vapour pressures and excess functions of N, N, N′, N′-tetramethylalkanediamine + cyclohexane. A group contribution study of the NN proximity effect

The vapour pressuresof liquid cyclohexane + N, N, N′, N′-tetramethylalkanediamine, (CH3)2 N(CH2)uN(CH3)2 (u = 1,2) + cyclohexane mixtures were measured by a static method between 303.15 and 343.15 K at 10 K intervals. The excess molar enthalpies at 303.15 K were also measured. lar excess Gibbs energies, calculated from the vapour-liquid equilibrium data, and the molar excess enthalpies compare satisfactorily with group contribution (DISQUAC) predictions. oximity effect of N atoms produces a regular decrease of the interactional parameters.