title: Photolysis of natural β-triketonic herbicides in water.
abstract: The fate of four natural β-triketones (leptospermone, isoleptospermone, grandiflorone and flavesone, pKa = 4.0-4.5) in aqueous solution, in the dark and upon simulated solar light irradiation was investigated. In anionic form, β-triketones undergo slow dark oxidation and photolysis with polychromatic quantum yields varying from 1.2 × 10(-4) to 3.7 × 10(-4). Leptospermone and grandiflorone are the most photolabile compounds. In molecular form, β-triketones are rather volatile. Polychromatic quantum yields between 1.2 × 10(-3) and 1.8 × 10(-3) could be measured for leptospermone and grandiflorone. They are 3-5 times higher than for the anionic forms. Photooxidation on the carbon atom bearing the acidic hydrogen atom is the main oxidation reaction, common to all the β-triketones whatever their ionization state. However, leptospermone shows a special photoreactivity. In molecular form, it mainly undergoes photoisomerization. Based on this work, the half-lives of β-triketones in surface waters should be comprised between 7 and 23 days.
authors.affiliation: Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000, Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63171, Aubière, France; Université de Bordeaux, EPOC-Laboratoire de Physico et Toxico Chimie de l'Environnement, Talence, F-33405, France; CNRS, UMR 5805, EPOC-LPTC, Talence, F-33405, France.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Trivella
authors.affiliation: Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000, Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63171, Aubière, France.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Stawinoga
authors.affiliation: USDA-ARS, Natural Products Utilization Research Unit, University, MS, 38677, USA.
authors.forename: Franck E
authors.initials: FE
authors.lastname: Dayan
authors.affiliation: USDA-ARS, Natural Products Utilization Research Unit, University, MS, 38677, USA.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Cantrell
authors.affiliation: Université de Bordeaux, EPOC-Laboratoire de Physico et Toxico Chimie de l'Environnement, Talence, F-33405, France; CNRS, UMR 5805, EPOC-LPTC, Talence, F-33405, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Mazellier
authors.affiliation: Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000, Clermont-Ferrand, France; CNRS, UMR 6296, ICCF, F-63171, Aubière, France. Electronic address: claire.richard@univ-bpclermont.fr.
authors.forename: Claire
authors.initials: C
authors.lastname: Richard
mesh_terms: D006207:Half-Life; D006540:Herbicides / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D009822:Oils, Volatile / Q000737:chemistry*; D010084:Oxidation-Reduction; D010696:Phloroglucinol / Q000031:analogs & derivatives; D010782:Photolysis; D013472:Sunlight; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D006540:Herbicides; D007659:Ketones; D009822:Oils, Volatile; D014874:Water Pollutants, Chemical; C508521:leptospermone; C508520:flavesone; D010696:Phloroglucinol
keywords: Dissipation; Natural herbicides; Photolysis; Photoproducts; Water