Tefluthrin

• 2,3,5,6-Tetrafluor-4-methylbenzyl-(1S,3S)-rel-3-[(Z)-2-chlor-3,3,3-trifluorprop-1-enyl]-2,2-dimethylcyclopropancarboxylat
• 2,3,5,6-Tetrafluor-4-methylbenzyl-(1S*,3S*)-3-[(Z)-2-chlor-3,3,3-trifluorprop-1-enyl]-2,2-dimethylcyclopropancarboxylat

Colorless solid

Fixed

1.48 g · cm -3

44.6 ° C

156 ° C at 1 mm Hg

8.4 · 10-3 Pa (20 ° C)

• Practically insoluble in water (0.016 mg · l-1 at 20 ° C)
• Soluble in acetone, dichloromethane, toluene, ethyl acetate and hexane

Risk

• 21.8 mg · kg -1 ( LD50, rat, oral)
• 177 mg · kg -1 ( LD50, rat, transdermal)

Template: Infobox chemical / molecular formula search available

Tefluthrin is a chemical compound from the group of pyrethroids.

Production and representation

The synthesis of tefluthrin starts from two precursors obtained in Synthesis two branches. The synthesis of the first precursor is carried out from 1,2,4,5- tetrafluorobenzene, which via a two-fold by metallation butyllithium with methyl iodide in the first step to the 1,2,4,5- Tetrafluortoluol and the second step with carbon dioxide to 4-methyl- 2,3,5,6- tetrafluorobenzoic is implemented. The carboxylic acid is converted with thionyl chloride and methanol as an intermediate via the acid chloride to the methyl ester, which is then reduced ,3,5,6- tetrafluorobenzene by lithium aluminum hydride to the precursor 1 -hydroxymethyl -4-methyl -2. The second precursor is obtained in a multistep synthesis starting from 3,3- dimethyl-4- pentenoate. Here first is carried out by the reaction with 1,1,1-trichloro- 2 ,2,2-trifluoroethane in the presence of copper ( I) chloride, a C- chain extension, and the introduction of the halogen functionality. In the implementation of the resulting 4,6,6 -trichloro -7 ,7,7 -trifluoro -3 ,3- dimethylheptansäureethylesters with sodium ethoxide is formed by dehydrohalogenation reactions of the cyclopropane ring and the double bond. 3 - [2 -chloro-3 ,3,3- trifluorpropenyl ] -2,2- dimethylcyclopropancarbonsäureethylester obtained as racemic cis-/trans-Gemisch, from which the trans-isomer of interest [ racemate, ie 1:1 mixture of ( 1S, 3S ) - and ( 1R, 3R )-form ] obtained by means of distillation. The ester is then saponified with sodium hydroxide solution and reacted with thionyl chloride to give the acid chloride precursor. Both precursors produce finally in an esterification reaction, the target compound as well as a 1:1 mixture of enantiomers of ( 1S, ​​3S ) - and ( 1R, 3R ) form.

Properties

Tefluthrin is a colorless solid that is practically insoluble in water. The technical product is a racemate of the (Z ) - ( 1R, 3R) - and (Z ) - ( 1S, ​​3S ) enantiomer. It is stable under neutral conditions.

Use

Tefluthrin is used as an insecticide against soil pests (eg sugar beet and maize). It was first approved in 1986 in Belgium and affects the nerve signal transmission of the sodium channels. In contrast to other pyrethroids tefluthrin also acts on the bottom.

Regulation

EU

The currently valid authorization expires December 31, 2021. At the national level tefluthrin is approved in 19 EU countries. The Permitted daily dose and the Acute Reference Dose be 0.005 and the Acceptable Operator Exposure 0.0015 milligrams per kilogram of body weight per day.

The European Commission decided in December 2008 after the withdrawal of a marketing authorization application, tefluthrin not in the list of active substances included in Annex I to Directive 91/414/EEC. The drug was finally approved with effect from 1 January 2012 for use as insecticide.

In Germany Force 20 CS is Syngenta is currently the only authorized plant protection product containing the active substance tefluthrin. The BVL prolonged effect since 6 December 2000 approval with Stand February 20, 2014 to July 31, 2014. Force 20 CS is a mordant for sugar and fodder beet against the moss beetles button. The BVL had in the past also the pesticides Force 1.5 G for use in corn against western corn rootworm granted exemptions, the last one ran out on 28 July 2012.

In Austria and Switzerland pesticides are authorized (eg Force 20 CS) with this drug for seed dressing in sugar beet and fodder beet.