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The enthalpies of dissociation of the NO bonds in two quinoxaline derivatives
Author(s) -
Gomes José R. B.,
Monteiro André R.,
Campos Bruno B.,
Gomes Paula,
da Silva Maria D. M. C. Ribeiro
Publication year - 2009
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1419
Subject(s) - chemistry , quinoxaline , standard enthalpy of formation , isothermal microcalorimetry , sublimation (psychology) , calorimetry , dissociation (chemistry) , bond dissociation energy , enthalpy of sublimation , density functional theory , computational chemistry , thermodynamics , organic chemistry , enthalpy , psychology , physics , psychotherapist
The present work reports the first experimental thermochemical study of mono‐ N ‐oxides derived from quinoxaline, namely, 3‐methoxycarbonyl‐2‐methyl‐quinoxaline N ‐oxide and 3‐ethoxycarbonyl‐2‐methyl‐quinoxaline N ‐oxide. The values of the enthalpies of formation, in the condensed state, and of the enthalpies of sublimation, derived from static bomb calorimetry and Calvet microcalorimetry measurements, respectively, are combined to derive the standard molar enthalpies of formation in the gaseous phase for these two compounds. From the latter values, the first and second NO bond dissociation enthalpies for the corresponding di‐ N ‐oxides have been obtained. The gas‐phase experimental results are also compared with calculated data obtained with a density functional theory approach. Copyright © 2008 John Wiley & Sons, Ltd.