The degradation in the liquid phase of rimsulfuron and its commercial 250g/kg WG formulation (Titus) was investigated. Photolysis reactions were carried out at 25°C by a highpressure mercury arc (Hg-UV) and a solar simulator (Suntest), while the hydrolysis rate was determined by keeping aqueous buffered samples in the dark. The effects of solvent and water pH on reaction kinetics were studied, and the results compared to literature data. Photoreactions of the commercial product in organic solvents were faster than pure rimsulfuron. Under simulated sunlight in water, the half-life for the photolysis reaction ranged from one to nine days at pH 5 and 9, respectively. The hydrolysis rate was as high as the photolysis rate, but decreased on increasing water pH. The main metabolite identi®ed in neutral and alkaline conditions as well as in acetonitrile was N- [(3-ethylsulfonyl)-2-pyridinyl]-4,6-dimethoxy-2-pyridinamine, while N-(4,6-dimethoxy-2-pyrimidinyl)- N-[(3-(ethylsulfonyl)-2-pyridinyl)]urea and minor metabolites prevailed in acidic conditions
PHOTOLYSIS AND HYDROLYSIS OF RIMSULFURON
SCRANO, Laura;BUFO, Sabino Aurelio;PERUCCI, Piero;
1999-01-01
Abstract
The degradation in the liquid phase of rimsulfuron and its commercial 250g/kg WG formulation (Titus) was investigated. Photolysis reactions were carried out at 25°C by a highpressure mercury arc (Hg-UV) and a solar simulator (Suntest), while the hydrolysis rate was determined by keeping aqueous buffered samples in the dark. The effects of solvent and water pH on reaction kinetics were studied, and the results compared to literature data. Photoreactions of the commercial product in organic solvents were faster than pure rimsulfuron. Under simulated sunlight in water, the half-life for the photolysis reaction ranged from one to nine days at pH 5 and 9, respectively. The hydrolysis rate was as high as the photolysis rate, but decreased on increasing water pH. The main metabolite identi®ed in neutral and alkaline conditions as well as in acetonitrile was N- [(3-ethylsulfonyl)-2-pyridinyl]-4,6-dimethoxy-2-pyridinamine, while N-(4,6-dimethoxy-2-pyrimidinyl)- N-[(3-(ethylsulfonyl)-2-pyridinyl)]urea and minor metabolites prevailed in acidic conditionsI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
