Oxidation of phenol and hydroquinone by chlorine dioxide
Rates of reaction of chlorine dioxide with phenol and with hydroquinone were determined with a stopped-flow spectrophotometer in the pH range 4-8. Second-order rate constants increase with increasing pH, consistent with a mechanism in which both the free phenol and the more reactive phenoxide anion react with ClO/sub 2/. Removal of an electron from the substrate by ClO/sub 2/ to form a phenoxyl radical and ClO/sub 2//sup -/ ion is the rate-determining step. Subsequently, in the case of hydroquinone, ClO/sub 2/ removes another electron from the radical, forming p-benzoquinone and another ClO/sub 2//sup -/ ion. In the case of phenol, ClO/sub 2/ adds to the phenoxyl radical para to the oxygen, and p-benzoquinone is formed with concomitant release of HOCl. The mechanism for phenol reaction accounts for (i) the immediate formation of p-benzoquinone without apparent intermediacy of hydroquinone, (ii) the chlorination observed in solutions containing excess phenol, and (iii) the production of only 0.5 mol of ClO/sub 2//sup -//mol of ClO/sub 2/ consumed.
- Research Organization:
- U.S. Army Medical Bioengineering Research and Development Lab., Frederick, MD
- OSTI ID:
- 6847409
- Journal Information:
- Environ. Sci. Technol.; (United States), Journal Name: Environ. Sci. Technol.; (United States) Vol. 16:7; ISSN ESTHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
520200 -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
AROMATICS
BENZOQUINONES
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORINE COMPOUNDS
CHLORINE OXIDES
DISINFECTANTS
GERMICIDES
HALOGEN COMPOUNDS
HYDROXY COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PH VALUE
PHENOL
PHENOLS
QUINONES
STOICHIOMETRY