13C- and 1H-NMR spectra of 2-pyridone derivatives

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13C- and 1H-NMR spectroscopy was used to obtain njHH, nJCH and δC-13 for a series of substituted 2-hydroxypyridines (3-hydroxy; 4-hydroxy; 5-chloro; 3-methyl-5-chloro; 6-chloro; 6-amino; 6-hydroxy). It is shown that the additivity of δC-13 and 1JCH values provides a valuable criterion for differenti...

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Autor principal: Contreras, Rubén Horacio
Publicado: 1989
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222860_v213_nC_p201_DeKowalewski
http://hdl.handle.net/20.500.12110/paper_00222860_v213_nC_p201_DeKowalewski
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_00222860_v213_nC_p201_DeKowalewski
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spelling paper:paper_00222860_v213_nC_p201_DeKowalewski2023-06-08T14:48:52Z 13C- and 1H-NMR spectra of 2-pyridone derivatives Contreras, Rubén Horacio 13C- and 1H-NMR spectroscopy was used to obtain njHH, nJCH and δC-13 for a series of substituted 2-hydroxypyridines (3-hydroxy; 4-hydroxy; 5-chloro; 3-methyl-5-chloro; 6-chloro; 6-amino; 6-hydroxy). It is shown that the additivity of δC-13 and 1JCH values provides a valuable criterion for differentiating between quinoidal and aromatic structures and in defining conformations. The first conclusion is based on the fact that for 3-substituted compounds there is accordance between experimental values and the additivity 1JCH and δC-13 values calculated for 2-pyridone. In the 6-substituted compounds there is marked deviation from additivity in 1JCH. On the other hand, it seems that the substituent effect on δC-13 in the hypothetical 2-hydroxypyridine and the real 2-pyridone are markedly different for C6, since there is no accordance between additivity and experimental values for the chemical shifts of this carbon. These conclusions are in agreement with results obtained from IR and pK studies and quantum-chemical calculations which indicate that a substituent in position 3 favours a pyridone structure, while a pyridinol structure is favoured when the substituent is at ring-position 6. © 1989. Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1989 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222860_v213_nC_p201_DeKowalewski http://hdl.handle.net/20.500.12110/paper_00222860_v213_nC_p201_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 13C- and 1H-NMR spectroscopy was used to obtain njHH, nJCH and δC-13 for a series of substituted 2-hydroxypyridines (3-hydroxy; 4-hydroxy; 5-chloro; 3-methyl-5-chloro; 6-chloro; 6-amino; 6-hydroxy). It is shown that the additivity of δC-13 and 1JCH values provides a valuable criterion for differentiating between quinoidal and aromatic structures and in defining conformations. The first conclusion is based on the fact that for 3-substituted compounds there is accordance between experimental values and the additivity 1JCH and δC-13 values calculated for 2-pyridone. In the 6-substituted compounds there is marked deviation from additivity in 1JCH. On the other hand, it seems that the substituent effect on δC-13 in the hypothetical 2-hydroxypyridine and the real 2-pyridone are markedly different for C6, since there is no accordance between additivity and experimental values for the chemical shifts of this carbon. These conclusions are in agreement with results obtained from IR and pK studies and quantum-chemical calculations which indicate that a substituent in position 3 favours a pyridone structure, while a pyridinol structure is favoured when the substituent is at ring-position 6. © 1989.
author Contreras, Rubén Horacio
spellingShingle Contreras, Rubén Horacio
13C- and 1H-NMR spectra of 2-pyridone derivatives
author_facet Contreras, Rubén Horacio
author_sort Contreras, Rubén Horacio
title 13C- and 1H-NMR spectra of 2-pyridone derivatives
title_short 13C- and 1H-NMR spectra of 2-pyridone derivatives
title_full 13C- and 1H-NMR spectra of 2-pyridone derivatives
title_fullStr 13C- and 1H-NMR spectra of 2-pyridone derivatives
title_full_unstemmed 13C- and 1H-NMR spectra of 2-pyridone derivatives
title_sort 13c- and 1h-nmr spectra of 2-pyridone derivatives
publishDate 1989
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00222860_v213_nC_p201_DeKowalewski
http://hdl.handle.net/20.500.12110/paper_00222860_v213_nC_p201_DeKowalewski
work_keys_str_mv AT contrerasrubenhoracio 13cand1hnmrspectraof2pyridonederivatives
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