title: Time evolution and competing pathways in photodegradation of trifluralin and three of its major degradation products.
abstract: The herbicide trifluralin (I)(N,N-di-n-propyl-2,6-dinitro-4-trifluoromethylaniline) decomposes, by the action of UV-Vis light (lambda > 300 nm), to several products, the most important (because they give subsequent photochemical reactions) being N-n-propyl-2,6-dinitro-4-trifluoromethylaniline (VI), 2-ethyl-7-nitro-5-trifluoromethyl-1H-benzimidazole 3-oxide (VII) and 2,6-dinitro-4-trifluoromethylaniline (XII). The time evolution of degradation of trifluralin (I) and the aforementioned three main photoproducts was studied in water and acetonitrile as solvents. The pseudo-first order rate constants allow one to calculate the branching ratios for some of the reactions involved. The preference for either N-dealkylation or cyclization depends on the solvent employed. Dissolved oxygen accelerates the photodegradation, especially the dealkylation.
authors.affiliation: Instituto de Investigaciones en Fisicoquímica de Córdoba, INFIQC, Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000 Córdoba, Argentina.
authors.forename: Martín G Sarmiento
authors.initials: MG
authors.lastname: Tagle
authors.forename: María
authors.initials: M
authors.lastname: Laura Salum
authors.forename: Elba I
authors.initials: EI
authors.lastname: Buján
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Argüello
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D010573:Pesticide Residues / Q000737:chemistry*; D010777:Photochemistry; D012995:Solubility; D013997:Time Factors; D014274:Trifluralin / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D000097:Acetonitriles; D010573:Pesticide Residues; D014867:Water; D014274:Trifluralin; C032159:acetonitrile