DIMETHYLVINPHOS

The Uses of DIMETHYLVINPHOS

Dimethylvinphos is used to control stem borers and leaf rollers in rice.

Metabolic pathway

Dimethylvinphos is the dimethyl analogue of chlorf envinphos; however, in contrast to that compound the technical material consists of >95% of the Z-isomer. Dimethylvinphos is also a close chemical analogue of tetrachlorvinphos, having a 2,4-dichloro substitution pattern rather than 2,4,5-trichloro on the phenylvinyl moiety and consequently the metabolism of dimethylvinphos is qualitatively very similar to that of the other two insecticides. In mammals, the principal route of metabolism of dimethylvinphos is via oxidative and glutathione S-alkyltransferase mediated demethylation to desmethyl dimethylvinphos which is hydrolysed to 2,2',4'-trichloroacetophenone. This is further metabolised via a series of glutathione mediated reactions to 1-(2,4-dichlorophenyl)ethanl-ol and 2,4-dichlorophenylethane-1,2-diol which are conjugated as the glucuronides and excreted. 2,4-Dichlorophenylethane-1,2-diol may be further metabolised by oxidation to 2,4-dichloromandelic which is excreted or decarboxylated to 2,4-dichlorobenzoic acid.

Degradation

Dimethylvinphos was hydrolysed in water at pH 7.0 with a half-life of 40 days at 25 °C. It was unstable in sunlight (PM).