NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study
In order to study the effect of substituents on the preferential keto/enol forms of six mono-substituted 2-OH-pyridines, the energies corresponding to their DFT-optimized structures for both tautomeric forms were compared. To obtain an idea of how solvent dielectric effects affect such a tautomeric...
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Acceso en línea: | https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00268976_v102_n23-24_p2607_DeKowalewski http://hdl.handle.net/20.500.12110/paper_00268976_v102_n23-24_p2607_DeKowalewski |
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paper:paper_00268976_v102_n23-24_p2607_DeKowalewski2023-06-08T14:53:59Z NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study Contreras, Rubén Horacio Computational geometry Concentration (process) Dielectric materials Fermi level Molecular physics Nuclear magnetic resonance Paramagnetic resonance Probability density function Solubility Ultraviolet detectors Gas phase Liquid phase Scalar coupling analysis Tautomeric equilibrium Organic solvents In order to study the effect of substituents on the preferential keto/enol forms of six mono-substituted 2-OH-pyridines, the energies corresponding to their DFT-optimized structures for both tautomeric forms were compared. To obtain an idea of how solvent dielectric effects affect such a tautomeric equilibrium, geometry optimizations were performed considering both an isolated molecule and an infinitely diluted dimethylsulfoxide solution (ε = 46.7). It was found that, for all these compounds, the dielectric solvent effect tends to increase the presence of the keto form. NMR 1J( 13C,13C) and 3J(13C,13C) isotropic couplings were measured for the same mono-substituted 2-OH-pyridines as well as for the corresponding mono-substituted pyridines. These isotropic coupling constants were also calculated within the DFT framework, where all four isotropic contributions, Fermi contact, spin dipolar, paramagnetic spin-orbit and diamagnetic spin-orbit, were taken into account. For the mono-substituted-2-OH-pyridines studied in this work, coupling constants were calculated using both the optimized keto and enol forms. The possible use of these couplings as probes to detect the keto and enol forms is discussed. Fil:Contreras, R.H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 2004 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00268976_v102_n23-24_p2607_DeKowalewski http://hdl.handle.net/20.500.12110/paper_00268976_v102_n23-24_p2607_DeKowalewski |
institution |
Universidad de Buenos Aires |
institution_str |
I-28 |
repository_str |
R-134 |
collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
topic |
Computational geometry Concentration (process) Dielectric materials Fermi level Molecular physics Nuclear magnetic resonance Paramagnetic resonance Probability density function Solubility Ultraviolet detectors Gas phase Liquid phase Scalar coupling analysis Tautomeric equilibrium Organic solvents |
spellingShingle |
Computational geometry Concentration (process) Dielectric materials Fermi level Molecular physics Nuclear magnetic resonance Paramagnetic resonance Probability density function Solubility Ultraviolet detectors Gas phase Liquid phase Scalar coupling analysis Tautomeric equilibrium Organic solvents Contreras, Rubén Horacio NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study |
topic_facet |
Computational geometry Concentration (process) Dielectric materials Fermi level Molecular physics Nuclear magnetic resonance Paramagnetic resonance Probability density function Solubility Ultraviolet detectors Gas phase Liquid phase Scalar coupling analysis Tautomeric equilibrium Organic solvents |
description |
In order to study the effect of substituents on the preferential keto/enol forms of six mono-substituted 2-OH-pyridines, the energies corresponding to their DFT-optimized structures for both tautomeric forms were compared. To obtain an idea of how solvent dielectric effects affect such a tautomeric equilibrium, geometry optimizations were performed considering both an isolated molecule and an infinitely diluted dimethylsulfoxide solution (ε = 46.7). It was found that, for all these compounds, the dielectric solvent effect tends to increase the presence of the keto form. NMR 1J( 13C,13C) and 3J(13C,13C) isotropic couplings were measured for the same mono-substituted 2-OH-pyridines as well as for the corresponding mono-substituted pyridines. These isotropic coupling constants were also calculated within the DFT framework, where all four isotropic contributions, Fermi contact, spin dipolar, paramagnetic spin-orbit and diamagnetic spin-orbit, were taken into account. For the mono-substituted-2-OH-pyridines studied in this work, coupling constants were calculated using both the optimized keto and enol forms. The possible use of these couplings as probes to detect the keto and enol forms is discussed. |
author |
Contreras, Rubén Horacio |
author_facet |
Contreras, Rubén Horacio |
author_sort |
Contreras, Rubén Horacio |
title |
NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study |
title_short |
NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study |
title_full |
NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study |
title_fullStr |
NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study |
title_full_unstemmed |
NMR J(C,C) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-OH-n-X-pyridines. An experimental and DFT study |
title_sort |
nmr j(c,c) scalar coupling analysis of the effects of substituents on the keto-enol tautomeric equilibrium in 2-oh-n-x-pyridines. an experimental and dft study |
publishDate |
2004 |
url |
https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00268976_v102_n23-24_p2607_DeKowalewski http://hdl.handle.net/20.500.12110/paper_00268976_v102_n23-24_p2607_DeKowalewski |
work_keys_str_mv |
AT contrerasrubenhoracio nmrjccscalarcouplinganalysisoftheeffectsofsubstituentsontheketoenoltautomericequilibriumin2ohnxpyridinesanexperimentalanddftstudy |
_version_ |
1768544674890383360 |