title: Photolysis of tembotrione and its main by-products under extreme artificial conditions: comparison with another β-triketone herbicide.
abstract: The photolytic behaviour of tembotrione, a new chemical herbicide intended for foliar application in corn, was investigated under unnatural and extreme photochemical exposure in aqueous solutions in the laboratory. It appeared that degradation was dependent on pH and occurred more rapidly under acidic and neutral conditions, leading predominantly to the formation of a xanthenedione type compound by intramolecular cyclisation with loss of HCl. Trace amounts of benzoic acid by-products appeared also during UV-C irradiation (λ=254 nm) of the parent compound. Results were comparable to those obtained with sulcotrione, another β-triketone herbicide. These extreme irradiation conditions clearly accelerated the phototransformation of sulcotrione vs. simulated sunlight irradiation. Furthermore, the photolysis of the degradation by-products, resulting from either photolysis, hydrolysis or biotic pathways of the two active ingredients, was also carried out. The benzoic acid by-products appeared more stable to photolysis than their parent molecules. Xanthenedione derivatives were degraded more rapidly with several differences depending on the pH value.
authors.affiliation: Laboratoire de Chimie des Biomolécules et de l'Environnement (LCBE, EA 4215), Université de Perpignan Via Domitia (UPVD), Perpignan, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Calvayrac
authors.forename: Nataly
authors.initials: N
authors.lastname: Bontemps
authors.forename: Achille
authors.initials: A
authors.lastname: Nouga-Bissoue
authors.forename: Sana
authors.initials: S
authors.lastname: Romdhane
authors.forename: Camille-Michel
authors.initials: CM
authors.lastname: Coste
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Cooper
mesh_terms: D019817:Benzoic Acid / Q000737:chemistry; D003512:Cyclohexanones / Q000737:chemistry*; D006540:Herbicides / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008698:Mesylates / Q000737:chemistry; D010782:Photolysis; D013450:Sulfones / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D003512:Cyclohexanones; D006540:Herbicides; D008698:Mesylates; D013450:Sulfones; C079906:sulcotrione; D019817:Benzoic Acid; C585552:tembotrione