Kinetic study on the synthesis of some benzo[g]quinoxalin-2(1H)-one derivatives

Autor: M. Inés Abasolo, Sergio G. Renou, Beatriz M. Fernández, Diana G. Bekerman, Gabriela A. Rodrigo
Rok vydání: 1997
Předmět:
Zdroj: Journal of Heterocyclic Chemistry. 34:505-508
ISSN: 1943-5193
0022-152X
Popis: Some novel 3-substituted benzoquinoxalinones [R = H, CH3, C6H5, (CH2)2COOH] were synthesized by the Hinsberg reaction between 2,3-diaminonaphthalene and several α-dicarbonyl compounds. The course of the reactions was followed by the second uv/visible Derivative Spectroscopy Method at different pH values (-0.89 to 9.0) and also in organic solvents at 25°. The compound non-substituted at C-3 was the only one that could be obtained in every media in good yields (80%), having pseudo first-order anelation rate constants of relative high values (1 × 10−1 — 1 × 10−2 min−1). On the other hand, only methanol could be used as the organic solvent for the synthesis of all of the other compounds; aqueous media always provided better results. In the 3-methyl derivative, as well as in the 3-phenyl derivative the change of the reaction pH medium modified the stoichiometry of the anelation, turning a non-quantitative reaction into a quantitative one. This is explained by a change in the mechanism of the reaction on going to lower hydrogen concentrations, a fact that was supported by complementary quantitative hptlc experiments. In general, pseudo first-order rate constants for the anelation were one or two logarithmic units lower than those of the non-substituted compound (RC-3 = H), but yields were above 60% in every case. A reaction scheme is presented which includes a probable mechanism.
Databáze: OpenAIRE
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