Rationalizing the diverse solid-liquid equilibria of binary mixtures of benzene and its fluorinated derivatives
Diana Ruivo1, Ana B Pereiro, José M S S Esperança
1Instituto de Tecnologia Química e Biológica, (www.itqb.unl.pt), UNL, Av. República, Apartado 127, 2780-901 Oeiras, Portugal.
Abstract:
The solid-liquid phase behavior of benzene plus hexafluorobenzene binary mixtures is characterized by a stable congruent-melting binary solid, (C(6)H(6)·C(6)F(6)). In this work, differential scanning calorimetry (DSC) was used to build, for the first time, the temperature-composition phase diagrams of ten other binary mixtures involving benzene and its fluorinated derivatives. Distinct types of solid-liquid equilibria were observed, namely those exhibiting the usual eutectic behavior associated with ideal or quasi-ideal solubility conditions, or, in other cases, systems with equimolar congruent-melting solids. Data have been interpreted and rationalized using a unifying framework that takes into account the molecular dipole and quadrupole moments of the two components of each binary system and the structural motifs associated with each type of crystal.
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