Kinetics of the solid+solid transformations for the piracetam trimorphic system: Incidence on the construction of the p–T equilibrium phase diagram - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Chemical Thermodynamics Année : 2016

Kinetics of the solid+solid transformations for the piracetam trimorphic system: Incidence on the construction of the p–T equilibrium phase diagram

Résumé

The three common polymorphs of piracetam have been characterized by associating thermal analysis, X-ray diffraction and densimetry. DSC experiments showed that the solid-solid transition temperature between Forms II and I and between Forms III and I is scan-rate dependent. The transition temperatures decrease when the DSC scan rate decreases and the thermodynamic temperatures were confirmed by isothermal X-ray diffraction. These new results in terms of temperature and enthalpy of transition allow us to propose a new equilibrium phase diagram establishing the relative thermodynamic stability of the three common polymorphs of piracetam as a function of the temperature and the pressure. The diagram suggests that Form II presents a small stability domain located just above the stability domain of Form I. As a consequence, Form I should transform into Form II, which itself can turn into Form III when placed under pressure.
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Dates et versions

hal-01284721 , version 1 (31-03-2020)

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Yohann Corvis, Anne Spasojevic - de Biré, Camille Alzina, Nicolas Guiblin, Philippe Espeau. Kinetics of the solid+solid transformations for the piracetam trimorphic system: Incidence on the construction of the p–T equilibrium phase diagram. Journal of Chemical Thermodynamics, 2016, 97, pp.167-172. ⟨10.1016/j.jct.2016.01.016⟩. ⟨hal-01284721⟩
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