INIFTA   05425
INSTITUTO DE INVESTIGACIONES FISICO-QUIMICAS TEORICAS Y APLICADAS
Unidad Ejecutora - UE
artículos
Título:
Alloxan-dialuric acid cycling: a complex redox mechanism
Autor/es:
J. A. ROSSO; M. A. ASTORGA; D. O. MÁRTIRE; M. C. GONZALEZ
Revista:
FREE RADICAL RESEARCH
Editorial:
TAYLOR & FRANCIS LTD
Referencias:
Año: 2009 vol. 43 p. 93 - 99
ISSN:
1071-5762
Resumen:
Time-resolved kinetic studies involving the reactions of alloxan (A.H2O) with the reducing species superoxide and carbon dioxide radical anions, and the reaction of dialuric acid (HA-) with sulphate radicals showed that the same radical (AH.) was formed either by the one-electron reduction of alloxan or by the one-electron oxidation of dialuric acid. A mechanism including several reversible reactions was proposed and validated. A detailed kinetic analysis yields the following bimolecular rate constants: k(A.H2O + SO4.-) < 105 M-1 s-1, k(A.H2O + O2.-) = (3.4 ± 0.5) × 106 M-1 s-1, k(HA- + SO4.-) = (8 ± 1) × 107 M-1 s-1 and k(AH. + AH.) = (1.7 ± 0.8) × 108 M-1 s-1. From these values, the redox potentials E°(A.H2O,H+/AH.) = (-290 ± 20) mV, E°(AH./HA-) = (277 ± 20) mV and E°(A.H2O,H+/HA-) = (-15 ± 20) mV, were obtained.