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Two enamines derived from 1-n-alkyl-3-methylpyrazol-5-ones
Julio Belmar1, Fredy R Pérez, Yanko Moreno
1Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad de Concepción, Casilla 160-C, Concepción, Chile. jbelmar@udec.cl
Acta Crystallographica. Section C, Crystal Structure Communications
|September 4, 2004
Summary
The crystal structures of two novel enamines derived from pyrazolones were determined. Intramolecular hydrogen bonding was confirmed in both compounds, supporting prior spectroscopic findings.
Area of Science:
- Crystallography
- Organic Chemistry
- Supramolecular Chemistry
Background:
- Enamines derived from 1-n-alkyl-3-methyl-5-pyrazolones are of interest.
- Previous studies relied solely on spectroscopic data to elucidate their structures and bonding.
Purpose of the Study:
- To report the first crystal structures of two specific enamine derivatives.
- To provide definitive structural evidence for intramolecular hydrogen bonding in these compounds.
Main Methods:
- Single-crystal X-ray diffraction was employed to determine the molecular structures.
- Analysis of the crystal structures confirmed the presence and geometry of hydrogen bonds.
Main Results:
- The crystal structures of 1-(n-hexyl)-3-methyl-4-[1-(phenylamino)propylidene]-2-pyrazolin-5-one (I) and N,N'-bis[1-[1-(n-hexyl)-3-methyl-5-oxo-2-pyrazolin-4-ylidene]ethyl]hexane-1,6-diamine (II) were determined.
- Molecule (II) exhibits a centrosymmetric arrangement.
- Both compounds (I) and (II) are stabilized by intramolecular N-H...O hydrogen bonds.
Conclusions:
- The crystal structures definitively confirm the presence of intramolecular N-H...O hydrogen bonding in these pyrazolone-derived enamines.
- These findings validate and extend previous conclusions drawn from spectroscopic analysis alone.