- Phototransformation of linuron and chlorbromuron in aqueous solution
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The main photoproducts initially formed in the phototransformation of linuron and chlorbromuron in aqueous solution result from photohydrolysis, i.e. hydroxylation with release of halide ion, and from elimination of a methoxy group. Reductive debromination was also observed with chlorbromuron. The transformation is less specific than with diuron. The orientation of the reaction depends on the wavelength: short wavelengths (254 nm) favour demethoxylation and photohydrolysis in the meta position whereas, with 'black light', i.e. wavelengths longer than 330 nm, photohydrolysis in the para position is the main reaction observed.
- Faure,Boule
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- Fungal biodegradation of a phenylurea herbicide, diuron: Structure and toxicity of metabolites
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Microbial degradation, organic synthesis and ecotoxicology were used to investigate the fate of diuron after spreading on soils. Quantitative biodegradation assays were performed with fungal strains, showing that diuron was degraded but not entirely mineralized. The modifications observed consisted in demethylation of the terminal nitrogen atom. The identified metabolites were synthesized in sufficient amounts to confirm their structures and determine their non-target toxicity using four biotests. The two metabolites exhibited higher effects than parent diuron. This limited biodegradability and potential aquatic toxicity suggest that diuron is of higher environmental concern than previously recognized. (C) 2000 Society of Chemical Industry.
- Tixier, Celine,Bogaerts, Philippe,Sancelme, Martine,Bonnemoy, Frederique,Twagilimana, Landoald,Cuer, Annie,Bohatier, Jacques,Veschambre, Henri
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p. 455 - 462
(2007/10/03)
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- Degradation of diuron photoinduced by iron(III) in aqueous solution
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The degradation of diuron photoinduced by iron(III) in aqueous solution has been investigated with different iron(III) species (monomeric species Fe(OH)2+, dimeric species Fe2(OH)2/4+ and water-soluble oligomeric species) under monochromatic excitation at 365 nm and under sunlight. The rate of degradation depends on the concentration in Fe(OH)2+, the most reactive species in terms of ·OH radical formation. The major photoproduct is 3-(3,4-dichlorophenyl)-1-formyl-1-methylurea which represents more than 60% of diuron disappearance. The mechanism only involves the attack by ·OH radicals arising from iron(III) excited species. The half-lives of diuron when submitted to such a process in the environment were estimated to be 1-2 h and a few days according to the concentration of Fe(OH)2+ (respectively 70% and 10% of total iron(III) concentration).
- Mazellier,Jirkovsky,Bolte
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p. 259 - 267
(2007/10/03)
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- Substituted ureas as herbicides
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Novel urea derivatives of the formula STR1 wherein R and R1 are individually selected from the group consisting of hydrogen, chlorine, bromine, nitro, trifluoromethyl, lower alkyl of 1 to 6 carbon atoms and lower alkoxy of 1 to 6 carbon atoms, n is 0 or 1, X is selected from the group consisting of lower alkyl of 1 to 6 carbon atoms optionally substituted with halogen and a nitrogen heterocyclic optionally containing 1 or more other heteroatoms, Y is selected from the group consisting of hydrogen, alkyl of 1 to 4 carbon atoms and S--Z wherein Z is a nitrogen heterocyclic optionally containing 1 or more other heteroatoms and the dotted lines indicate that the compound of formula I may contain no oxygen bound to the sulfur atom or may be in sulfoxide or sulfonyl form which are useful as herbicides and thereon preparation.
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