INVESTIGADORES
LUCANGIOLI Silvia Edith
artículos
Título:
ESR characterization of Thallium (III)-mediated nitrones oxidation
Autor/es:
VERSTRAETEN S.,; LUCANGIOLI S.,; GALLEANO M.
Revista:
INORGANICA CHIMICA ACTA
Editorial:
Elsevier
Referencias:
Lugar: Amsterdan, The Netherlands; Año: 2009 vol. 362 p. 2305 - 2310
ISSN:
0020-1693
Resumen:
We characterized the reactions between Tl (III) and the usual nitrone spin traps (DMPO, POBN, and PBN). 2424
The ESR signal obtained with DMPO corresponded to DMPOX which was avoided neither by the enzymes 2525
superoxide dismutase or catalase, nor by the hydroxyl radical scavengers mannitol, ethanol, or methanol. 2626
Only when methanol concentration rose to 90% (v/v), a significant decrease in DMPOX formation was 2727
observed while no detectable DMPOX signal was present at 100% methanol solution. POBN rendered 2828
an unexpected adduct, while no oxidation products were obtained with PBN. Together, the experimental 2929
evidence demonstrates that Tl(III)-supported DMPO oxidation is not mediated by oxygen reactive spe- 3030
cies. Instead, we propose that Tl(III) interacts with the probe, favoring the addition of water. The inter- 3131
mediate is susceptible to be further oxidized by Tl(III) yielding a keto group. Kinetic studies showed 3232
that Tl(III) disappearance rate was higher (1.6 times) than DMPOX formation rate, and equal to Tl(I) for- 33Tl(I) for- 33
mation rate, suggesting a stoichiometry 1.5:1 for Tl(III):DMPOX and 1:1 for Tl(III):Tl(I). The process, an 3434
example of the ForresterHepburns mechanism, was demonstrated for DMPO while the reactions of 35ForresterHepburns mechanism, was demonstrated for DMPO while the reactions of 35
Tl(III) with POBN and PBN are still under elucidation.