Phototransformation of azoxystrobin fungicide in organic solvents. Photoisomerization vs. photodegradation
| Autor: | Mounir Traïkia, Guillaume Voyard, Pascal de Sainte Claire, Alexandra ter Halle, Claire Richard, Jeoffrey Chastain |
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| Rok vydání: | 2013 |
| Předmět: |
Antifungal Agents
Light Photoisomerization Double bond Quantum yield 010501 environmental sciences Photochemistry 01 natural sciences Mass Spectrometry Heptanes 2-Propanol chemistry.chemical_compound Isomerism Physical and Theoretical Chemistry Photodegradation Bond cleavage 0105 earth and related environmental sciences chemistry.chemical_classification Photolysis Aqueous solution 010401 analytical chemistry Strobilurins 0104 chemical sciences Kinetics Pyrimidines Models Chemical chemistry Azoxystrobin Solvents Methacrylates Solvent effects |
| Zdroj: | Photochemical & Photobiological Sciences. 12:2076-2083 |
| ISSN: | 1474-9092 1474-905X |
| Popis: | Azoxystrobin is a systemic fungicide that has a tendency to accumulate at the surface of crop leaves or inside their cuticle where it undergoes photodegradation. Its photochemistry was investigated in n-heptane and isopropanol to mimic the polarity of wax leaves. Using analytical and kinetic data, we demonstrate that azoxystrobin (isomer E) undergoes efficient photoisomerization into the isomer Z with a quantum yield of 0.75 ± 0.08. This value is 30-fold higher than that reported in aqueous solution. The photoisomerization of isomer Z into azoxystrobin is more efficient with a chemical yield of 0.95 ± 0.1. In addition, a pseudo photostationary equilibrium is reached when the ratio [azoxystrobin]/[isomer Z] is 2.0 ± 0.1. Photodegradation also takes place from azoxystrobin (quantum yield = 0.073 ± 0.008). Photoproducts mainly arise from bond cleavage between rings and from demethylation of the ether with or without saturation of the acrylate double bond. Theoretical calculations were undertaken to investigate the photoisomerization mechanism and the solvent effect. These data show that the photochemical reactivity of azoxystrobin is enhanced when the solvent polarity decreases and thus should be significant in leaf waxes. |
| Databáze: | OpenAIRE |
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