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H-1, C-13 AND O-17 NMR-STUDY OF SUBSTITUTED NITROPYRIDINES
被引:25
作者:
KOLEHMAINEN, E
[1
]
LAIHIA, K
[1
]
RASALA, D
[1
]
GAWINECKI, R
[1
]
机构:
[1] PEDAGOG UNIV,INST CHEM,PL-25020 KIELCE,POLAND
关键词:
H-1 NMR CHEMICAL SHIFTS AND COUPLING CONSTANTS;
C-13;
NMR;
CHEMICAL SHIFTS AND COUPLING CONSTANTS;
O-17 NMR CHEMICAL SHIFTS AND LINE WIDTHS;
SUBSTITUTED 2-NITROPYRIDINES AND 3-NITROPYRIDINES;
MOLECULAR MECHANICS;
D O I:
10.1002/mrc.1260290904
中图分类号:
O6 [化学];
学科分类号:
0703 ;
摘要:
H-1, C-13 and O-17 NMR spectra for 22 substituted nitropyridines were measured and their H-1 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, O-17 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 O-17 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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页码:878 / 884
页数:7
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