Flumethrin

• IUPAC: α -cyano- ( 4-fluoro -3 -phenoxy) -benzyl- 3-[ 2-chloro- 2 - (4- chlorophenyl) ethenyl] -2,2 - dimethyl- cyclopropane carboxylate

QP53AC05

Pyrethroid insecticide

Opening of the Na channels

Risk

Template: Infobox chemical / molecular formula search available

Flumethrin is a drug from the group of type II pyrethroids. It is used in veterinary medicine externally as an antiparasitic agent against insects and ticks. Flumethrin open the sodium channels in the nerve cells in the parasite, leading to over-excitation and finally to the death.

Isomerism

Flumethrin is a complex mixture of isomers. The molecule has three asymmetrically substituted carbon atoms, there is a cis -trans isomerism at the cyclopropane ring and a further cis -trans isomerism at the carbon- carbon double bond of the alkene. So there are 16 different isomers. Commercial flumethrin contains as an active ingredient

• 92% of the isomers having trans geometry at the cyclopropane ring and the cis- configuration at the olefinic carbon-carbon double bond and
• 8% of the isomer with the cis- geometry on the cyclopropane ring and the cis- configuration at the olefinic carbon-carbon double bond.

As these isomers are present in each case as a racemate, but in practice a mixture of four isomers is used, the different efficacy is demonstrated in part by experiment.