resumo
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, Delta fHmo(g), from their enthalpies of formation in the condensed phase, Delta fHmo(cr), determined by static bomb combustion calorimetry, and from their enthalpies of sublimation, Delta crgHmo, determined by Calvet microcalorimetry. Finally, combining the Delta fHmo(g) 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, DH1(NO), were obtained and compared with existing data. Copyright (c) 2011 John Wiley & Sons, Ltd.
palavras-chave
1,4-DI-N-OXIDE DERIVATIVES; 1,4-DIOXIDES; ENERGETICS; AGENTS; QUINOXALINE-1,4-DIOXIDE; CALORIMETRY
categoria
Chemistry
autores
Viveiros, MLF; Freitas, VLS; Vale, N; Gomes, JRB; Gomes, P; da Silva, MDMCR
nossos autores
José R. B. Gomes
Investigador Principalagradecimentos
Thanks are due to Fundacao para a Ciencia e Tecnologia (FCT), Lisbon, Portugal, for financial support to Centro de Investigacao em Quimica - UP and CICECO. V. L. S. Freitas thanks the FCT and European Social Fund for the award of a Ph. D. Research Grant SFRH/BD/41672/2007.