title: A mechanistic study of the photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid in aqueous solution.
abstract: Photodegradation of herbicide 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in aqueous solution was investigated by stationary (254 nm) and nanosecond laser (266 nm) flash photolysis techniques. It was shown that in the primary photochemical step both photoionization (which generates a hydrated electron-radical cation pair) and heterolytic cleavage of a C-Cl bond takes place. The major products of substitution of one of the chlorine atoms in the 2-, 4- or 5-position by a hydroxyl group as well as the products of hydroxylation of the benzene ring in 3- and 6-positions were identified by HPLC and LC-MS methods. The complexation of 2,4,5-T with β- and γ-cyclodextrins (β(γ)CD) was investigated. The influence of such complexation on the quantum yield of herbicide photolysis and on the ratio of photodegradation products was determined.
authors.affiliation: Institute of Chemical Kinetics and Combustion, 3 Institutskaya St., 630090 Novosibirsk, Russian Federation.
authors.forename: Maria P
authors.initials: MP
authors.lastname: Yurkova
authors.forename: Ivan P
authors.initials: IP
authors.lastname: Pozdnyakov
authors.forename: Victor F
authors.initials: VF
authors.lastname: Plyusnin
authors.forename: Vycheslav P
authors.initials: VP
authors.lastname: Grivin
authors.forename: Nikolay M
authors.initials: NM
authors.lastname: Bazhin
authors.forename: Alexandr I
authors.initials: AI
authors.lastname: Kruppa
authors.forename: Tatiana A
authors.initials: TA
authors.lastname: Maksimova
mesh_terms: D015085:2,4,5-Trichlorophenoxyacetic Acid / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D006540:Herbicides / Q000737:chemistry*; D006900:Hydroxylation; D007700:Kinetics; D013058:Mass Spectrometry; D010782:Photolysis; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry; D047392:beta-Cyclodextrins / Q000737:chemistry; D047408:gamma-Cyclodextrins / Q000737:chemistry
chemical_list: D006540:Herbicides; D047392:beta-Cyclodextrins; D047408:gamma-Cyclodextrins; D014867:Water; D015085:2,4,5-Trichlorophenoxyacetic Acid; C031215:betadex