SOLVENT EFFECT ON THE VALENCE TAUTOMERISM OF BENZENE OXIDE/OXEPIN MOLECULAR SYSTEM

Thermodynamic parameters for the benzene oxide <=> oxepin system have been calculated at MP4(SDQ)/6-31+G**//HF/6-31G** level of theory. The calculated enthalpy for this valence tautomeric equilibrium differs from that reported by Vogel et al in 1967, but agree well with the value calculated by...

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Autores principales:	CONTRERAS,J.GUILLERMO, MADARIAGA,SANDRA T.
Lenguaje:	English
Publicado:	Sociedad Chilena de Química 2001
Materias:	benzene oxide/oxepin equilibrium valence tautomerism solvent effect
Acceso en línea:	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442001000400011
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spelling	oai:scielo:S0366-164420010004000112002-09-05SOLVENT EFFECT ON THE VALENCE TAUTOMERISM OF BENZENE OXIDE/OXEPIN MOLECULAR SYSTEMCONTRERAS,J.GUILLERMOMADARIAGA,SANDRA T. benzene oxide/oxepin equilibrium valence tautomerism solvent effect Thermodynamic parameters for the benzene oxide <=> oxepin system have been calculated at MP4(SDQ)/6-31+G//HF/6-31G level of theory. The calculated enthalpy for this valence tautomeric equilibrium differs from that reported by Vogel et al in 1967, but agree well with the value calculated by Kollman using the MINDO/3 method. Large deviations in the experimental tautomerization entropies lead to unreliable delta Gº values. The differences in delta Hº and delta Sº can be due to the lack of band shape analysis of the ¹H-NMR spectra. The effect of solvent polarity on the above equilibrium has been studied using the isodensity polarized continuum method (IPCM). Low polar solvents favor the oxepin formation whereas medium to high polar solvents leads to benzene oxide formation. The transition state for the tautomerization reaction has been fully characterized and the activation energies for the forward and reverse reaction are estimated to be ca. 9.5 and 11.0 kcal/mol,respectively. The solvent polarity exerts a reasonable effect decreasing the activation energies up to 4 kcal/mol.info:eu-repo/semantics/openAccessSociedad Chilena de QuímicaBoletín de la Sociedad Chilena de Química v.46 n.4 20012001-12-01text/htmlhttp://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442001000400011en10.4067/S0366-16442001000400011
institution	Scielo Chile
collection	Scielo Chile
language	English
topic	benzene oxide/oxepin equilibrium valence tautomerism solvent effect
spellingShingle	benzene oxide/oxepin equilibrium valence tautomerism solvent effect CONTRERAS,J.GUILLERMO MADARIAGA,SANDRA T. SOLVENT EFFECT ON THE VALENCE TAUTOMERISM OF BENZENE OXIDE/OXEPIN MOLECULAR SYSTEM
description	Thermodynamic parameters for the benzene oxide <=> oxepin system have been calculated at MP4(SDQ)/6-31+G//HF/6-31G level of theory. The calculated enthalpy for this valence tautomeric equilibrium differs from that reported by Vogel et al in 1967, but agree well with the value calculated by Kollman using the MINDO/3 method. Large deviations in the experimental tautomerization entropies lead to unreliable delta Gº values. The differences in delta Hº and delta Sº can be due to the lack of band shape analysis of the ¹H-NMR spectra. The effect of solvent polarity on the above equilibrium has been studied using the isodensity polarized continuum method (IPCM). Low polar solvents favor the oxepin formation whereas medium to high polar solvents leads to benzene oxide formation. The transition state for the tautomerization reaction has been fully characterized and the activation energies for the forward and reverse reaction are estimated to be ca. 9.5 and 11.0 kcal/mol,respectively. The solvent polarity exerts a reasonable effect decreasing the activation energies up to 4 kcal/mol.
author	CONTRERAS,J.GUILLERMO MADARIAGA,SANDRA T.
author_facet	CONTRERAS,J.GUILLERMO MADARIAGA,SANDRA T.
author_sort	CONTRERAS,J.GUILLERMO
title	SOLVENT EFFECT ON THE VALENCE TAUTOMERISM OF BENZENE OXIDE/OXEPIN MOLECULAR SYSTEM
title_short	SOLVENT EFFECT ON THE VALENCE TAUTOMERISM OF BENZENE OXIDE/OXEPIN MOLECULAR SYSTEM
title_full	SOLVENT EFFECT ON THE VALENCE TAUTOMERISM OF BENZENE OXIDE/OXEPIN MOLECULAR SYSTEM
title_fullStr	SOLVENT EFFECT ON THE VALENCE TAUTOMERISM OF BENZENE OXIDE/OXEPIN MOLECULAR SYSTEM
title_full_unstemmed	SOLVENT EFFECT ON THE VALENCE TAUTOMERISM OF BENZENE OXIDE/OXEPIN MOLECULAR SYSTEM
title_sort	solvent effect on the valence tautomerism of benzene oxide/oxepin molecular system
publisher	Sociedad Chilena de Química
publishDate	2001
url	http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0366-16442001000400011
work_keys_str_mv	AT contrerasjguillermo solventeffectonthevalencetautomerismofbenzeneoxideoxepinmolecularsystem AT madariagasandrat solventeffectonthevalencetautomerismofbenzeneoxideoxepinmolecularsystem
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SOLVENT EFFECT ON THE VALENCE TAUTOMERISM OF BENZENE OXIDE/OXEPIN MOLECULAR SYSTEM

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