Liquid–Liquid equilibria for systems containing 4-phenylbutan-2-one or benzyl ethanoate and selected alkanes

Abstract

The method of the critical opalescence with a laser scattering technique has been employed for the determination of the liquid-liquid equilibrium (LLE) curves for the systems 4-phenylbutan-2-one + CH3(CH2)nCH3 (n = 10,12,14) and for benzyl ethanoate + CH3(CH2)nCH3 (n = 12,14). The mixtures are characterized by having an upper critical solution temperature (UCST), which increases with n. The corresponding LLE curves have a rather horizontal top and become shifted to higher concentration of the polar compound when n is increased. Calorimetric data and LLE measurements show that the aromaticity effect leads to stronger interactions between molecules of the polar compound considered with respect to those between homomorphic linear molecules with the same functional group. This has been ascribed to proximity effects arising from the presence of the polar group and the aromatic ring within the same molecule. Proximity effects become weaker in the sequence: 1-phenylpropan-2-one > 4-phenylbutan-2-one > 1-phenylethanone, and are more relevant in benzyl ethanoate than in ethyl benzoate molecules. The DISQUAC group contribution model represents correctly the coordinates of the critical points of the investigated systems and the symmetry of the LLE curves.