PHOTODEGRADATION OF THE CARBAMATE INSECTICIDE ETHIOFENCARB

In order to study the photoreactivity and possible photodegradation pa thways of ethiofencarb (2-ethylthiomethylphenyl methylcarbamate) on pl ant surfaces, model experiments in the presence of cyclohexane, cycloh exene and isopropanol were performed. Both artificial light (lambda > 280 nm) and natural sunlight were used. Half-lives of the ethiofencarb photodegradation were in the order cyclohexane < isopropanol < cycloh exene and ranged from 75 min to more than 20 h. Depending on the solve nt and the light source chosen, different photoproducts were obtained. When ethiofencarb was irradiated in the presence of cyclohexane, phot o-oxidation to the corresponding sulfoxide was the main degradation pa thway, followed by a cyclization reaction. In the case of isopropanol as model solvent, numerous photoproducts were detected as a result of photooxidation, hydrolysis and the addition to ethiofencarb of the sol vent molecule.