Oxidation of Methoxyhydroxycyclohexadienyl radicals by quinones. The influence of the isomeric structure of the radical on the rate constant for electron transfer
o-, m-, and p-Methoxyhydroxycyclohexadienyl radicals, produced in aqueous solution by the reaction of OH with anisole, react with p-benzoquinone by electron transfer with rate constants of 1.2 x 10/sup 9/, less than or equal to 8 x 10/sup 5/, and 4.4 x 10/sup 9/ M/sup -1/ s/sup -1/, respectively, to yield p-benzosemiquinone and o-, m-, and p-hydroxyanisole. The lifetime of intermediate carbocations produced by oxidation of the methoxyhydroxycyclohexadienyl radicals is less than or equal to 1 x 10/sup -6/ s and the production of the hydroxyanisoles occurs synchronously with the reduction of p-benzoquinone. Substitution of H by methyl in p-benzoquinone leads to a decrease in the rate constants for oxidation of the methoxyhydroxycyclohexadienyl radicals. This decrease, which reflects the decrease in the redox potential of the quinone, is much stronger for the ortho isomer than for the para isomer. The distribution of isomeric methoxyhydroxycyclohexadienyl radicals, as determined by analysis of the build-up kinetics of different benzosemiquinones, is equal with that of isomeric hydroxyanisoles formed as final products from the cyclohexadienyl radicals by oxidation.
- Research Organization:
- Univ. of Notre Dame, IN
- OSTI ID:
- 5667499
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 83:24; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400600* -- Radiation Chemistry
ALKOXY RADICALS
AROMATICS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DATA FORMS
DECOMPOSITION
DIENES
ELECTRON TRANSFER
ELECTRONS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
HYDROCARBONS
HYDROXY COMPOUNDS
INFORMATION
IRRADIATION
ISOLATED VALUES
KINETICS
LEPTONS
METHOXY RADICALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDATION
POLYENES
PULSED IRRADIATION
QUINONES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
REACTION KINETICS