Phenomenology of polymorphism (I): Pressure-Temperature representation of trimorphism. General rules. Application to the case of dimethyl 3,6-dichloro-2,5-dihydroxyterephthalate
1992; Elsevier BV; Volume: 98; Issue: 2 Linguagem: Inglês
10.1016/s0022-4596(05)80247-6
ISSN1095-726X
AutoresR. Céolin, Siro Toscani, V. Agafonov, Jerôme Dugué,
Tópico(s)Chemical Thermodynamics and Molecular Structure
ResumoTrimorphism is presented in the form of a topological description as the capability of a chemical substance to exist under five aggregation states: three crystalline solid forms, the liquid, and the vapor. The general rules to construct the corresponding (p, T) diagram and to locate the 10 triple points are given and discussed. Several theoretical diagrams are presented in the case in which one deals with only three stable triple points. An example of application is given for the dimethyl 3,6-dichloro-2,5-dihydroxyterephthalate. Hierarchies of stability among the three forms are inferred qualitatively as a function of increasing pressure and, quantitatively, also in domains of temperatures lower than those investigated by other authors in a previous experimental work. These stability hierarchies show a great sensitivity to the choice of an enthalpy change value, with respect to another of the same quantity, in determining the slopes of the two-phase equilibrium curves.
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