Thermodynamics of Mixtures Containing Aromatic Alcohols. 1. Liquid–Liquid Equilibria for (Phenylmethanol + Alkane) Systems

The liquid–liquid equilibrium (LLE) curves for (phenylmethanol + CH3(CH2) n CH3) mixtures (n = 5, 6, 8, 10, 12) have been obtained by the critical opalescence method using a laser scattering technique. All of the systems show an upper critical solution temperature (UCST). In addition, the LLE curves have a rather horizontal top, and their symmetry depends on the alkane size. The UCST increases almost linearly with n. For systems including a given alkane and phenol or phenylmethanol, the UCST is much higher than that of the corresponding mixtures with hexan-1-ol or heptan-1-ol. This reveals that dipolar interactions are stronger in solutions with aromatic alcohols. Preliminary DISQUAC interaction parameters for OH/aliphatic contacts in the investigated systems were obtained. It is remarkable that the coordinates of the critical points of (phenol or phenylmethanol + alkane) mixtures can be described using the same quasichemical interaction parameters for the OH/aliphatic and OH/aromatic contacts.