Liquid−liquid equilibrium (LLE) phase diagrams
have been determined, by means of the critical opalescence method
with a laser scattering technique, for the mixtures 4-phenylbutan-2-
one + CH3(CH2)nCH3 (n = 10,12,14) and for benzyl ethanoate +
CH3(CH2)nCH3 (n = 12,14). The systems are characterized by
having an upper critical solution temperature (UCST), which
increases with n. The corresponding LLE curves show a rather
horizontal top and become skewed toward higher mole fractions of
the polar compound when n is increased. Calorimetric and LLE
measurements show that, for mixtures with molecules with a given
functional group, interactions between aromatic molecules are
stronger than those between homomorphic linear molecules
(aromaticity effect). 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 important in benzyl ethanoate than
in ethyl benzoate molecules. Values of the critical compositions and temperatures calculated with the DISQUAC group
contribution model are in good agreement with the experimental results. Accordingly, the shape of the LLE curves is also
correctly described by DISQUAC.
