Hydrolysis and photolysis of insecticide metofluthrin in water

摘要

Metofluthrin [ I , 2,3,5,6-tetrafluoro-4-(methoxymethyl)benzyl ( EZ )-(1 R ,3 R )-2,2-dimethyl-3-(prop-1-enyl)cyclopropanecarboxylate] was resistant to hydrolysis at pH 4 and 7 but moderately hydrolyzed with a half-life of 36.8 days at pH 9 and 25°C to form the corresponding acid and alcohol via ester cleavage. The activation energy was estimated to be 105 kJ mol?1 based on the hydrolysis rates at 25–50oC. By continuous exposure to light at >290 nm from a Xenon arc lamp at hydrolytically stable pH 4 and 25°C, I was rapidly photodegraded with half-lives of 1.1–3.4 days, mainly via ester cleavage and successive oxidation followed by mineralization to carbon dioxide. Spectroscopic analyses together with co-chromatography with authentic standards showed that the major degradates having an ester linkage were the aldehyde and carboxylic acid derivatives formed via oxidative cleavage of the prop-1-enyl group together with the diol formed possibly through an oxidative intermediate, such as an epoxide.