NMR characterization of hydrate and aldehyde forms of imidazole-2-carboxaldehyde and derivatives.
The existence and stability of the aldehyde-hydrate form of imidazole-2-carboxaldehyde (4) were studied using FTIR together with solution- and solid-state NMR experiments. The results allowed us to conclude that the hydrate form was stable and precipitated at pH = 8.0 and that the aldehyde form was isolated at pH = 6.5 and 9.5. Moreover, the presence of the aldehyde-hydrate form was studied through NMR experiments in D(2)O at both alkaline and acidic pH. In addition, the tautomeric forms of the 2-substituted imidazole compounds were also analyzed to investigate the influence of the hybridization on the carbon adjacent to the imidazole ring, by (13)C NMR in DMSO-d(6), acetone-d(6), and CDCl(3). The presence of the syn- and anti-isomers of oxime 8 obtained from 4 were characterized by solid-state NMR and variable-temperature NMR experiments in acetone-d(6).
Lázaro Martínez
Juan Manuel
JM
Departamento de Química Orgánica, Facultad de Farmacia y Bioquimica, Universidad de Buenos Aires, Junin 956 (C1113AAD), Ciudad Autónoma de Buenos Aires, Argentina.
Romasanta
Pablo Nicolás
PN
Chattah
Ana Karina
AK
Buldain
Graciela Yolanda
GY
D000447:Aldehydes / Q000737:chemistry*; D002247:Carbon Isotopes; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000592:standards; D015394:Molecular Structure; D012015:Reference Standards; D014867:Water / Q000737:chemistry*
D000447:Aldehydes; D002247:Carbon Isotopes; D007093:Imidazoles; D014867:Water