ABSTRACT

The three common polymorphs of piracetam have been characterized by associating thermal analysis, Xray 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.

Compounds

#	Formula	Name
1	C6H10N2O2	2-oxo-1-pyrrolidineacetamide

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Phase	Method	#Points
POMD	1	Mass density, kg/m3 ; Crystal 1	Temperature, K; Crystal 1 Pressure, kPa; Crystal 1	Crystal 1	X-ray diffraction	1
POMD	1	Mass density, kg/m3 ; Metastable crystal	Temperature, K; Metastable crystal Pressure, kPa; Metastable crystal	Metastable crystal	X-ray diffraction	1
POMD	1	Mass density, kg/m3 ; Crystal 2	Temperature, K; Crystal 2 Pressure, kPa; Crystal 2	Crystal 2	X-ray diffraction	1
POMD	1	Triple point temperature, K ; Crystal 1		Crystal 1 Liquid Air at 1 atmosphere	DSC	1
POMD	1	Triple point temperature, K ; Crystal 2		Crystal 2 Liquid Air at 1 atmosphere	DSC	1
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Crystal 1		Crystal 1 Liquid Air at 1 atmosphere	DSC	1
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2		Crystal 2 Liquid Air at 1 atmosphere	DSC	1
POMD	1	Triple point temperature, K ; Crystal 2		Crystal 2 Crystal 1 Air at 1 atmosphere	DSC	1
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2		Crystal 2 Crystal 1 Air at 1 atmosphere	DSC	1
POMD	1	Triple point temperature, K ; Metastable crystal		Metastable crystal Crystal 1 Air at 1 atmosphere	DSC	1
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Metastable crystal		Metastable crystal Crystal 1 Air at 1 atmosphere	DSC	1
POMD	1	Triple point temperature, K ; Crystal 2		Crystal 2 Crystal 1 Air at 1 atmosphere	X-ray diffraction	1
POMD	1	Triple point temperature, K ; Metastable crystal		Metastable crystal Crystal 1 Air at 1 atmosphere	X-ray diffraction	1
POMD	1	Molar volume, m3/mol ; Crystal 1	Temperature, K; Crystal 1	Crystal 1 Gas	X-ray diffraction	9
POMD	1	Molar volume, m3/mol ; Metastable crystal	Temperature, K; Metastable crystal	Metastable crystal Gas	X-ray diffraction	8
POMD	1	Molar volume, m3/mol ; Crystal 2	Temperature, K; Crystal 2	Crystal 2 Gas	X-ray diffraction	8
POMD	1	Molar volume, m3/mol ; Liquid	Temperature, K; Liquid	Liquid Gas	Vibrating tube method	11

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

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

Corvis, Y.[Yohann], Spasojevic-de Bire, A.[Anne], Alzina, C.[Camille], Guiblin, N.[Nicolas], Espeau, P.[Philippe]

ABSTRACT