ONE-ELECTRON OXIDATION AND REDUCTION OF AZAPROPAZONE AND PHENYLBUTAZONE DERIVATIVES IN AQUEOUS SOLUTION: A PULSE RADIOLYSIS STUDY

Abstract— Using pulse radiolysis techniques, 3 azapropazone and 3 phenylbutazone derivatives all structurally related to the potentially photosensitive anti-inflammatory drug, azapropazone, have been reacted with the free radical oxidants N₃, Br₂^- and (SCN)₂^- as well as with e^-_aq a strong reductant. It is demonstrated that for 5 derivatives, azapropazone (Az), 2-a-Carboxy-valeryll-3-dimethylamino-7-meth1-1,2-dihydro-1,2,4-benzotriazine (Mi307), phenylbutazone (PB), oxyphenylbutazone (OPB), and ketophenylbutazone (KPB), N₃^- and Br₂^- appear to react via a one-electron removal process. For the other derivative, 8-hydroxy azapropazone (8-OH-Az), Nj and (SCN); oxidise via a one-electron process, while Br₂^- probably fqrms a free radical adduct.
The absolute spectra of the one-electron oxidised and reduced transient species for all six derivatives are thus given in this work and are a basis to the understanding of the action of light on these drugs.