Mechanically Induced Phase Change in Barbituric Acid
| Autor: | Roberto Gobetto, Michele R. Chierotti, Luciano Milone, Luca Pellegrino, Paolo Venturello |
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| Rok vydání: | 2008 |
| Předmět: |
Barbituric acid
STABILITY Hydrogen bond MECHANOCHEMICAL PREPARATION DICARBOXYLIC-ACIDS ANTHRANILIC ACID VARIABLE CHAIN-LENGTH General Chemistry Nuclear magnetic resonance spectroscopy Crystal structure Condensed Matter Physics Tautomer STATE CRYSTAL STRUCTURE chemistry.chemical_compound Crystallography X-RAY-DIFFRACTION chemistry NMR-SPECTROSCOPY POLYMORPHS Anthranilic acid Proton NMR General Materials Science Methylene |
| Zdroj: | Crystal Growth & Design. 8:1454-1457 |
| ISSN: | 1528-7505 1528-7483 |
| Popis: | By grinding a commercial sample of barbituric acid in its trioxo form (polymorph II, 99%) for 24 h, a new compound has been isolated. The new phase has been identified as the trihydroxyl isomer. The characterization of the new isomer has been carried out by means of X-ray powder diffraction, solid-state NMR (1H MAS, 13C and 15N CPMAS, 2D PASS, and FSLG-HETCOR), IR and Raman spectroscopies. The conversion results from the complete tautomeric shift of a methylene and of two N−H hydrogen atoms. 1H MAS spectra allow the characterization of the hydrogen bond interactions on the basis of their strength in the starting compound and in the new isomer. In solution, the trihydroxyl isomer immediately converts to the trioxo form as demonstrated by 1H NMR experiments in protic, aprotic, and amphiprotic solvents (D2O, MeOH-d4, DMSO-d6, acetone-d6). |
| Databáze: | OpenAIRE |
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