Thermodynamics of Mixtures Containing Amines. XV. Liquid-Liquid Equilibria for Benzylamine + CH3(CH2)nCH3 (n=8, 9, 10, 12, 14)

Coexistence curves for the liquid-liquid equilibria (LLE) of 1-phenylmethanamine (benzylamine) + CH3(CH2)(n)CH3 (n = 8, 9, 10, 12, 14) have been determined using the critical opalescence method by means of a laser scattering technique. All of the LLE curves show an upper critical solution temperature (UCST), which increases with increasing n. For systems including a given n-alkane, the UCST decreases in the sequence aniline > 2-methylaniline (o-toluidine) > benzylamine > N-methylaniline > pyridine. This means that amine-amine interactions become weaker in the same order. Most of the DISQUAC interaction parameters for the aliphatic/amine (a,n) and aromatic/amine (b,n) contacts previously determined for solutions with aniline, o-toluidine, or N-methylaniline have been used for the representation of the LLE data. Only the first dispersive interaction parameter of the (a,n) contact has been modified. The coordinates of the critical points are correctly represented by the model.