| Résumé | Laser flash photolysis (LFP) at wavelengths within the charge-transfer absorption present in CCl 4 solutions of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) yields the oxoammonium chloride of TEMPO, 1 (λ max = 460 nm), and the trichloromethyl radical in an essentially instantaneous (≤18 ps) process. The primary photochemical event is an electron transfer from TEMPO to CCl 4, and this is followed by immediate decomposition of the CCl 4 •- radical anion to Cl - and Cl 3C •. An independent synthesis of 1 confirmed that the absorption attributed to this species had been correctly assigned. The formation of Cl 3C • was inferred by its trapping by molecular oxygen. LFP of TEMPO in other halogenated solvents and of other nitroxides in halogenated solvents has confirmed the generality of these photoreactions. Published 1990 by the American Chemical Society. |
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