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1H, 13C and 17O NMR study of substituted nitropyridines

✍ Scribed by Erkki Kolehmainen; Katri Laihia; Danuta Rasala; Ryszard Gawinecki

Publisher
John Wiley and Sons
Year
1991
Tongue
English
Weight
492 KB
Volume
29
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

^1^H, ^13^C and ^17^O NMR spectra for 22 substituted nitropyridines were measured and their ^1^H NMR spectra were analysed. The most significant variations in the NMR parameters are found for isomeric hydroxy derivatives, owing to the possibility of keto–enol tautomerism. The prevalence of the keto form is observed in 2‐ and 4‐hydroxy derivatives, while the 3‐hydroxy derivative exists in its enol form. Among the three nuclei studied, ^17^O seems to be the best nucleus for probing the keto–enol tautomerism. No correlation is observed between the torsion angle of the nitro group and its ^17^O NMR chemical shift. Molecular mechanics calculations were performed to clarify the torsional energetics of the nitro group and the preferences for keto–enol tautomerism.

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