Reaction of peroxyl radicals with ozone in water

• The reactivity of alkylperoxyl radicals and -O3SOO* toward ozone was investigated. The peroxyl radicals were produced by steady-state gamma-radiolysis in the presence Of O-3. The rate constants were extracted from the decay rate of ozone measured during the irradiation. The rate constants vary between 7 x 10(3) and 2 x 10(5) M-1 s(-1) and there is a trend of increasing rate constant with electron-withdrawing substituent. Quantum chemical computations support a mechanism, according to which formation of an alkyl trioxide radical is the rate-determining step. This is followed by rapid expulsion Of O-2 to yield the alkoxyl radical. Conceivably, the alkyl trioxide radical is preceded by an extremely unstable alkyl pentoxide radical in equilibrium with the reactants.

Nyckelord

dissociating organic-compounds

oxygenated aqueous-solutions

pulse-radiolysis

rate constants

inorganic-compounds

gamma-radiolysis

mechanism

ho2

decomposition

oxidation

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