Polymorphism of 2,2-Dichloropropane:  Crystallographic Characterization of the Ordered and Disordered Phases

Négrier, Philippe; Pardo, Luis Carlos; Salud, J.; Tamarit, J. Ll.; López, David; Würflinger, A.; Mondieig, D.

doi:10.1021/cm011000g

Cited by 34 publications

(51 citation statements)

References 36 publications

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“…For α V,I , it leads to 2.50×10 -4 K -1 and for α V,II 1.98×10 -4 K -1 can be found. Both expansivity coefficients are close to the average value of about 2×10 -4 K -1 found for molecular solids [10][11][12][13][14][15][16][17][18][19] and active pharmaceutical ingredients. [20][21][22][23] However, a closer study of the two expressions 2 and 3 and the data in Table 1 demonstrates that although form I appears to be denser at low temperature, it exhibits the largest thermal expansion (α V,I > α V,II ) and at room temperature its density is actually less than that of form II.…”

Section: Available Data From the Literaturesupporting

confidence: 78%

The Pressure-Temperature Phase Diagram of Metacetamol and Its Comparison to the Phase Diagram of Paracetamol

Huguet

Rietveld

Robert

et al. 2017

Journal of Pharmaceutical Sciences

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Understanding the polymorphic behavior of active pharmaceutical ingredients is important for formulation purposes and for regulatory reasons. Metacetamol is an isomer of paracetamol and it similarly exhibits polymorphism. In the present paper, it has been found that one of the polymorphs of metacetamol is only stable under increased pressure, which has led to the conclusion that metacetamol like paracetamol is a monotropic system under ordinary (= laboratory) conditions and that it becomes enantiotropic under pressure with the I-II-L triple point coordinates for metacetamol T I-II-L = 535±10 K and P I-II-L = 692±70 MPa. However, whereas for paracetamol the enantiotropy under pressure can be foreseen, because the metastable polymorph is denser, in the case of metacetamol this is not possible, as the metastable polymorph is less dense than the stable one. The existence of the stability domain for the less dense polymorph of metacetamol, can only be demonstrated by the construction of the topological phase diagram as presented in this paper. It is a delicate interplay between the specific volume differences and the enthalpy differences causing the stability domain of the less dense polymorph to be sandwiched between the denser polymorph and the liquid. It is a characteristic that metacetamol shares with bicalutamide and fluoxetine nitrate.

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Section: Available Data From the Literaturesupporting

confidence: 78%

The Pressure-Temperature Phase Diagram of Metacetamol and Its Comparison to the Phase Diagram of Paracetamol

Huguet

Rietveld

Robert

et al. 2017

Journal of Pharmaceutical Sciences

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“…Within the E phase the obtained p parameters vary from 0.584 to 0.568 for 11BT and from 0.577 to 0.590 for 12BT with rising temperature. These values are typical of the plastic crystalline (ODIC) phases [21,22], and are smaller than those calculated for other compounds in the E phase [16,23] (p ≈ 0.63-0.67) having, however, shorter alkyl chains.…”

Section: Discussioncontrasting

confidence: 57%

“…It facilitates the long--range fluctuations of the molecular centers of mass which creates a space necessary for the voluminous flip-flop jumps of molecules. A large number of the "lattice" defects, typical of the ODIC phases [21,22], is a favorable factor in creation of the space.…”

Section: Discussionmentioning

confidence: 99%

Dielectric and X-ray Studies of Eleventh and Twelfth Members of Two Isothiocyanato Mesogenic Compounds

et al. 2006

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Results of the dielectric and X-ray studies of the long-alkyl-chain members (n = 11, 12) of two homologous series: nBT (4-n-alkyl--4 -isothiocyanato-biphenyl) and nCHBT (4-trans-4 -n-alkyl-cyclohexyl--isothiocyanato-benzene) in their liquid crystalline phases are presented. These compounds exhibit different polymorphisms: the nematic phase for nCHBTs and the smectic E and smectic A phases for nBTs. The dielectric measurements were performed in a wide frequency range of 1 kHz-3 GHz. The layer thickness in the smectic E and smectic A phases and the orthorhombic unit cell parameters of the smectic E phase were determined using the small angle X-ray diffraction method. In the smectic E phase the layer-thickness-to-molecular-length ratios are found to be close to 1. The corresponding ratios observed for the smectic A phase of nBTs are considerably higher (≈ 1.24), which indicates that an alternating head-to-tail arrangement of molecules in the layers is favored. The rotational dynamics of molecules in the smectic E phases is discussed in relation to their packing in a unit cell.

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“…[14][15][16]18 In addition, the organic molecules 2,2-dichloropropane and tetrachloromethane were found to exhibit overall monotropy. 24,25 Figure Captions Tables Captions Table 1. Single crystal data of form I and form II of nimesulide Table 2.…”

Section: Discussionmentioning

confidence: 99%

Pressure-temperature phase diagram of the dimorphism of the anti-inflammatory drug nimesulide

Huguet

Robert

Rietveld

et al. 2017

International Journal of Pharmaceutics

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Understanding the phase behavior of active pharmaceutical ingredients is important for formulations of dosage forms and regulatory reasons. Nimesulide is an anti-inflammatory drug that is known to exhibit dimorphism. It is shown in the paper that form II is intrinsically monotropic in relation to form I. This result has been obtained by experimental means, involving high-pressure measurements. In addition, it has been shown that with very limited means and statistical melting data, the same conclusion can be obtained, demonstrating that in first instance topological high-pressure phase diagrams can be obtained without measuring any high-pressure data.

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Polymorphism of 2,2-Dichloropropane: Crystallographic Characterization of the Ordered and Disordered Phases

Cited by 34 publications

References 36 publications

The Pressure-Temperature Phase Diagram of Metacetamol and Its Comparison to the Phase Diagram of Paracetamol

The Pressure-Temperature Phase Diagram of Metacetamol and Its Comparison to the Phase Diagram of Paracetamol

Dielectric and X-ray Studies of Eleventh and Twelfth Members of Two Isothiocyanato Mesogenic Compounds

Pressure-temperature phase diagram of the dimorphism of the anti-inflammatory drug nimesulide

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