Publication Date:
2012-04-15
Description:
The synthesis of three new quinoxaline mono- N -oxides derivatives, namely, 2- tert -butoxycarbonyl-3-methylquinoxaline- N -oxide, 2-phenylcarbamoyl-3-ethylquinoxaline- N -oxide, and 2-carbamoyl-3-methylquinoxaline- N -oxide, from their corresponding 1,4-di- N -oxides is reported. Samples of these compounds were used for a thermochemical study, which allowed derivation of their gaseous standard molar enthalpies of formation, , from their enthalpies of formation in the condensed phase, , determined by static bomb combustion calorimetry, and from their enthalpies of sublimation, , determined by Calvet microcalorimetry. Finally, combining the for the quinoxaline- N -oxides derived in this work with literature values for the corresponding 1,4-di- N -oxides and atomic oxygen, the bond dissociation enthalpies for cleavage of the first N−O bond in the di- N -oxides, DH 1 (N–O), were obtained and compared with existing data. Copyright © 2011 John Wiley & Sons, Ltd. The first N-O bond dissociation enthalpy of three quinoxaline derivatives is obtained from the experimental gas-phase standard molar enthalpies of formation at T = 298.15 K determined for three novel N-oxide derivatives and available literature data.
Print ISSN:
0894-3230
Electronic ISSN:
1099-1395
Topics:
Chemistry and Pharmacology
,
Physics
Permalink