Polymorphism of phenobarbitone: the crystal structure of 5-ethyl-5-phenylbarbituric acid monohydrate

Williams, P. P.

doi:10.1107/s0567740873005078

Cited by 29 publications

(24 citation statements)

References 14 publications

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“…It is also consistent with the conformation assigned experimentally for 5-ethyl-5-phenylbarbituric acid. 24 The calculated bonds lengths and angles are very similar to the experimental ones established for the 5-ethyl-5-phenylbarbituric acid molecule and other similar compounds 25,26 found in the Cambridge Structural Database System. 27 The situation for compound D is different due to the RATIONAL OF CHIRAL SEPARATION BY AM1 METHOD presence of the second ethyl group connected to one of the nitrogen atoms.…”

Section: Results and Discussion Theoretical Structures Of Ligands Andsupporting

confidence: 63%

Enantioselective chromatography of alkyl derivatives of 5‐ethyl‐5‐phenyl‐2‐thiobarbituric acid studied by semiempirical AM1 method

Zborowski

Żuchowski

2002

Chirality

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Complexation of alkyl derivatives of 5-ethyl-5-phenyl-2-thiobarbituric acid (2-thiophenobarbital) enantiomers by beta-cyclodextrin was investigated by the AM1 method. The inclusion complexes of beta-cyclodextrin with neutral and anionic forms of these enantiomers have been modeled and energetically optimized. The chiral discrimination of enantiomers was analyzed in terms of differences in the interaction energies. The calculated interaction energies between each enantiomer of the investigated 2-thiobarbiturates and beta-cyclodextrin confirm the ability of beta-cyclodextrin to act as a mobile phase additive in reversed-phase HPLC to separate enantiomers by liquid chromatography and rationalize their order of elution.

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Section: Results and Discussion Theoretical Structures Of Ligands Andsupporting

confidence: 63%

Enantioselective chromatography of alkyl derivatives of 5‐ethyl‐5‐phenyl‐2‐thiobarbituric acid studied by semiempirical AM1 method

Zborowski

Żuchowski

2002

Chirality

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“…The C(2)-O(2) bond is significantly (about 5a) shorter than the C(4) and C(6) carbonyl bonds. This is probably due to the participation of 0(4) and 0(6) in intermolecular hydragen bonds, an effect that has been noted before (Craven, Vizzini & Rodrigues, 1969), and which was observed in phenobarbitone XIII in part I (Williams, 1973).…”

Section: Molecular Geometrymentioning

confidence: 90%

“…In part I (Williams, 1973), the crystal structure of the monohydrate of 5-ethyl-5-phenylbarbituric acid (Ci2HlzO3N2) was described. Phenobarbitone also crystallizes in perhaps as many as twelve anhydrous modifications (e.g.…”

Section: Introductionmentioning

confidence: 99%

Polymorphism of phenobarbitone. II. The crystal structure of modification III

Williams¹

1974

Acta Crystallogr Sect B

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The crystal structure of modification III of 5-ethyl-5-phenylbarbituric acid has been determined and refined to a conventional R of 0.066 on 2296 reflexions. Form III is monoclinic, P2a/C; a= 9"534, b= 11"855, c= 10"794 A, t= 111"56°; Z= 4. Intensity data were collected on a four-circle diffractometer using Mo K~ radiation. The structure was solved by direct methods, the hydrogen atoms located, and the positions of all atoms except hydrogens were refined independently with anisotropic temperature factors. Molecules in the structure are linked together by pairs of hydrogen bonds into infinite chains lying along 2x axes. The conformation of the ethyl and phenyl groups is largely controlled by packing requirements.

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“…En effet, par analogie avec le ph6nobarbital dont l'hydrate est connu [17], on peut supposer que l'endotherme ~t a >> correspond ~ la .p6ritexie d'un hydrate de barbital non isol6 mais pr6sent en faible quantit6 dans les cristaux X obtenus scion la pr6paration 3. Le diagramme obtenu avec la forme II se distingue par l'existence d'une ligne d'invariance qui se situe ~t 146 ~ et que nous attribuons ~t la transition de phases barbital II ~-barbital I. Notons que cette transition avait 6t6 signal6e h 160 ~ pour le barbital II pur'(,sans eau), 6tudi6 par ATD en 10 K .mn-1.…”

Section: R~sultats D'analyse Thermogravim6triqueunclassified

Sur le Polymorphisme du barbital et le systeme eau-barbital

Fournival

Rouland

Céolin

1987

Journal of Thermal Analysis

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The crystal structures of three forms (I, II and IV) of barbital are well known. The DTA curve of barbital 1 is marked by only one endotherm, at 186 ~ which is the melting point of this crystalline form. For barbital II, the DTA curve shows a first endotherm at 160 ~ which indicates the transition point II ~ I, and then an endotherm at 186 ~ for the melting of form I. By fast cooling of a boiling saturated aqueous solution, another crystalline form of barbital (form X) can be obtained. The DTA curve of this new sample shows another endotherm, at 119 ~ preceding the endotherms at 160 and 186 ~ Though the TG curve does not indicate any weight loss at this temperature, this endotherm does not indicate a new phase transition, but a monotectic equilibrium.This monotectic equilibrium (XLL = 78 mol % H20, XL2 = 98 tool % H20 ) is observed at 1197 in the phase diagrams (isochoric sections at V/m = 7 cm3.g -1) of the water--barbital systems established for form I, form II and form X.Le barbital CsH 12N203 (di6thyl-5,5' 1 H, 3H, 5H-pytimidine trione-2,4,6, masse molaire M = 184,2) est utilis6 en th6rapeutique pour ses propri&6s hypnotiques d6couvertes en 1903 par Fischer et Von Meting.Son polymorphisme a fait l'objet de nombreuses &udes. Kofler [1, 2] a caractdris6 quatre formes cristallines sur la base de la morphologie des cristaux, de letirs points de fusion et des donn6es de diffraction des rayons X des poudres cristaUines. Ces r6sultats ont 6t6 confirm6s par Huang [3] qui pr6cise les distances r&iculaires.

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Polymorphism of phenobarbitone: the crystal structure of 5-ethyl-5-phenylbarbituric acid monohydrate

Cited by 29 publications

References 14 publications

Enantioselective chromatography of alkyl derivatives of 5‐ethyl‐5‐phenyl‐2‐thiobarbituric acid studied by semiempirical AM1 method

Enantioselective chromatography of alkyl derivatives of 5‐ethyl‐5‐phenyl‐2‐thiobarbituric acid studied by semiempirical AM1 method

Polymorphism of phenobarbitone. II. The crystal structure of modification III

Sur le Polymorphisme du barbital et le systeme eau-barbital

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