1H and 13C NMR study of substituted 3-OH pyridines

nJHH, nJCH and δ13C values have been measured for a series of X substituted 3-hydroxypyridines (X = 2-NH2, 2-NO2, 5-Cl, 6-CH3, 2-Cl, 2-Br, 2-I). The results show that the additivity of δ13C provides a valuable criterion to differentiate the phenolic from the zwitterion structure. This conclusion is...

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Publicado: 1990
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222860_v221_nC_p299_DeKowalewski
http://hdl.handle.net/20.500.12110/paper_00222860_v221_nC_p299_DeKowalewski
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_00222860_v221_nC_p299_DeKowalewski
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spelling paper:paper_00222860_v221_nC_p299_DeKowalewski2023-06-08T14:48:53Z 1H and 13C NMR study of substituted 3-OH pyridines nJHH, nJCH and δ13C values have been measured for a series of X substituted 3-hydroxypyridines (X = 2-NH2, 2-NO2, 5-Cl, 6-CH3, 2-Cl, 2-Br, 2-I). The results show that the additivity of δ13C provides a valuable criterion to differentiate the phenolic from the zwitterion structure. This conclusion is based on the fact that in the first case, for 2-NH2-, 2-NO2-, 5-Cl- and 6-CH3-3-hydroxypyridines, there is agreement between the experimental and the additivity δ13C values, while in the three halogen derivatives (2-Cl-, 2-Br- and 2-I-3-hydroxypyridines) the δexp-add C3 values of -4.95, -7.25 and 9.05 are probably due to the negative charge present on the three position of the zwitterion. Since the additivity of 1JCH values holds in all substances examined (unlike the case of the 2-pyridone derivatives) it is not possible to use that criterion to differentiate between the phenolic and dipolar structures. The above conclusions are in agreement with IR, pK, NQR, RX, kinetics experiments and quantum chemical calculations of other authors. © 1990. 1990 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222860_v221_nC_p299_DeKowalewski http://hdl.handle.net/20.500.12110/paper_00222860_v221_nC_p299_DeKowalewski
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description nJHH, nJCH and δ13C values have been measured for a series of X substituted 3-hydroxypyridines (X = 2-NH2, 2-NO2, 5-Cl, 6-CH3, 2-Cl, 2-Br, 2-I). The results show that the additivity of δ13C provides a valuable criterion to differentiate the phenolic from the zwitterion structure. This conclusion is based on the fact that in the first case, for 2-NH2-, 2-NO2-, 5-Cl- and 6-CH3-3-hydroxypyridines, there is agreement between the experimental and the additivity δ13C values, while in the three halogen derivatives (2-Cl-, 2-Br- and 2-I-3-hydroxypyridines) the δexp-add C3 values of -4.95, -7.25 and 9.05 are probably due to the negative charge present on the three position of the zwitterion. Since the additivity of 1JCH values holds in all substances examined (unlike the case of the 2-pyridone derivatives) it is not possible to use that criterion to differentiate between the phenolic and dipolar structures. The above conclusions are in agreement with IR, pK, NQR, RX, kinetics experiments and quantum chemical calculations of other authors. © 1990.
title 1H and 13C NMR study of substituted 3-OH pyridines
spellingShingle 1H and 13C NMR study of substituted 3-OH pyridines
title_short 1H and 13C NMR study of substituted 3-OH pyridines
title_full 1H and 13C NMR study of substituted 3-OH pyridines
title_fullStr 1H and 13C NMR study of substituted 3-OH pyridines
title_full_unstemmed 1H and 13C NMR study of substituted 3-OH pyridines
title_sort 1h and 13c nmr study of substituted 3-oh pyridines
publishDate 1990
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222860_v221_nC_p299_DeKowalewski
http://hdl.handle.net/20.500.12110/paper_00222860_v221_nC_p299_DeKowalewski
_version_ 1768542350897840128

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