Effects of electronic resonance interaction on the methoxy group NMR parameters. Theoretical and experimental study of substituted 2-methoxypyridines

In order to increase the understanding of the interactions which define the planar conformation of the methoxy group with respect to the aryl ring in methyl aryl ethers and the effect these interactions have on the methoxy NMR parameters, 17O and 13C spectra were measured and ab initio optimized geo...

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Autores principales: Contreras, Rubén Horacio, Biekofsky, Rodolfo Roberto, Facelli, Julio César
Publicado: 1993
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00223654_v97_n1_p91_Contreras
http://hdl.handle.net/20.500.12110/paper_00223654_v97_n1_p91_Contreras
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling paper:paper_00223654_v97_n1_p91_Contreras2023-06-08T14:50:13Z Effects of electronic resonance interaction on the methoxy group NMR parameters. Theoretical and experimental study of substituted 2-methoxypyridines Contreras, Rubén Horacio Biekofsky, Rodolfo Roberto Facelli, Julio César In order to increase the understanding of the interactions which define the planar conformation of the methoxy group with respect to the aryl ring in methyl aryl ethers and the effect these interactions have on the methoxy NMR parameters, 17O and 13C spectra were measured and ab initio optimized geometries were calculated for three different conformations of the methoxy group in 2-methoxy-5-X-pyridines (X = H, NO2, and NH2). 17O and 13C chemical shifts were also calculated using the LORG approach. It was found that, contrary to what has been commonly assumed, the oxygen and the carbon of the methoxy group are deshielded when the electronic resonance interaction is increased. Therefore, the large 13C deshielding effect observed for a conformation with an out-of-plane methoxy group in aryl methyl ethers and related compounds has to be attributed to the inhibition of the attractive van der Waals forces between the methyl moiety and the aromatic ortho-cis carbon atom. © 1993 American Chemical Society. Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Biekofsky, R.R. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Facelli, J.C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1993 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00223654_v97_n1_p91_Contreras http://hdl.handle.net/20.500.12110/paper_00223654_v97_n1_p91_Contreras
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description In order to increase the understanding of the interactions which define the planar conformation of the methoxy group with respect to the aryl ring in methyl aryl ethers and the effect these interactions have on the methoxy NMR parameters, 17O and 13C spectra were measured and ab initio optimized geometries were calculated for three different conformations of the methoxy group in 2-methoxy-5-X-pyridines (X = H, NO2, and NH2). 17O and 13C chemical shifts were also calculated using the LORG approach. It was found that, contrary to what has been commonly assumed, the oxygen and the carbon of the methoxy group are deshielded when the electronic resonance interaction is increased. Therefore, the large 13C deshielding effect observed for a conformation with an out-of-plane methoxy group in aryl methyl ethers and related compounds has to be attributed to the inhibition of the attractive van der Waals forces between the methyl moiety and the aromatic ortho-cis carbon atom. © 1993 American Chemical Society.
author Contreras, Rubén Horacio
Biekofsky, Rodolfo Roberto
Facelli, Julio César
spellingShingle Contreras, Rubén Horacio
Biekofsky, Rodolfo Roberto
Facelli, Julio César
Effects of electronic resonance interaction on the methoxy group NMR parameters. Theoretical and experimental study of substituted 2-methoxypyridines
author_facet Contreras, Rubén Horacio
Biekofsky, Rodolfo Roberto
Facelli, Julio César
author_sort Contreras, Rubén Horacio
title Effects of electronic resonance interaction on the methoxy group NMR parameters. Theoretical and experimental study of substituted 2-methoxypyridines
title_short Effects of electronic resonance interaction on the methoxy group NMR parameters. Theoretical and experimental study of substituted 2-methoxypyridines
title_full Effects of electronic resonance interaction on the methoxy group NMR parameters. Theoretical and experimental study of substituted 2-methoxypyridines
title_fullStr Effects of electronic resonance interaction on the methoxy group NMR parameters. Theoretical and experimental study of substituted 2-methoxypyridines
title_full_unstemmed Effects of electronic resonance interaction on the methoxy group NMR parameters. Theoretical and experimental study of substituted 2-methoxypyridines
title_sort effects of electronic resonance interaction on the methoxy group nmr parameters. theoretical and experimental study of substituted 2-methoxypyridines
publishDate 1993
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00223654_v97_n1_p91_Contreras
http://hdl.handle.net/20.500.12110/paper_00223654_v97_n1_p91_Contreras
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AT biekofskyrodolforoberto effectsofelectronicresonanceinteractiononthemethoxygroupnmrparameterstheoreticalandexperimentalstudyofsubstituted2methoxypyridines
AT facellijuliocesar effectsofelectronicresonanceinteractiononthemethoxygroupnmrparameterstheoreticalandexperimentalstudyofsubstituted2methoxypyridines
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