Pattern of Addition of Hydroxyl Radicals to the Spin Traps α-Pyridyl 1-Oxide N-tert-Butyl Nitrone

Article abstract of DOI:10.1021/j100442a017

Hydroxyl radicals react with α-2, α-3, and α-4-pyridyl 1-oxide N-tert-butyl nitrones (POBN) with rate constants of 3.2E9, 4.8E9, and 3.5E9 M^-1 s^-1, respectively, via addition to two distinct sites.Addition to the pyridine ring yields short-lived radicals of the hydroxyazacyclohexadienyl type, while addition to the nitrone function in the side chain yields long-lived nitroxide radicals.The distribution of OH addition at the two molecular sites was determined by using differences in reducing power upon reaction of the different types of radicals with IrCl6^2-.The fraction of OH attack on the pyridine ring is ca. 0.6, relatively independent of the isomeric structure of the POBN.