Electron spin resonance studies of the reaction of hypochlorite with 5,5-dimethyl-1-pyrroline-N-oxide.
The reaction of hypochlorous acid with the spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was found to yield 5,5-dimethyl-2-pyrrolidone-N-oxyl (DMPOX). In addition to DMPOX, 5,5-dimethyl-2-hydroxypyrrolidine-N-oxyl (DMPO-OH) and an unidentified chlorine-containing radical species were also observed under neutral and near-neutral conditions. Through the use of [17O]HOCl and the hydroxyl radical scavengers ethanol and formate, it was established that DMPO-OH was derived from hydration of DMPO rather than the spin-trapping of hydroxyl radical. Furthermore, kinetic studies and the incorporation of 17O showed that DMPO-OH was readily oxidized to DMPOX and that this reaction was acid and base catalyzed. Under strongly alkaline conditions, DMPOX reversibly formed another species, presumably the enolate, that had a four-line ESR signal identical to that of DMPO-OH. Eventually, carbon-centered adducts appeared whose ESR signals were consistent with the formation of DMPO condensation products.
Bernofsky
C
C
Department of Biochemistry, Tulane University School of Medicine, New Orleans, LA 70112.
Bandara
B M
BM
Hinojosa
O
O
D002021:Buffers; D003497:Cyclic N-Oxides; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006863:Hydrogen-Ion Concentration; D006997:Hypochlorous Acid; D015394:Molecular Structure
D002021:Buffers; D003497:Cyclic N-Oxides; D005609:Free Radicals; D006997:Hypochlorous Acid; C017245:5,5-dimethyl-1-pyrroline-1-oxide