Tefluthrin

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Structural formula
Structural formula of tefluthrin
1: 1 mixture ( racemate ) of the (1 R , 3 R ) form (above)
and the (1 S , 3 S ) form (below)
General
Surname Tefluthrin
other names
  • 2,3,5,6-Tetrafluoro-4-methylbenzyl- (1 S , 3 S ) - rel -3 - [( Z ) -2-chloro-3,3,3-trifluoroprop-1-enyl] -2, 2-dimethylcyclopropanecarboxylate
  • 2,3,5,6-Tetrafluoro-4-methylbenzyl- (1 S * , 3 S * ) -3 - [( Z ) -2-chloro-3,3,3-trifluoroprop-1-enyl] -2, 2-dimethylcyclopropanecarboxylate
Molecular formula C 17 H 14 ClF 7 O 2
Brief description

colorless solid

External identifiers / databases
CAS number 79538-32-2
EC number 616-699-6
ECHA InfoCard 100.124.968
PubChem 11534837
Wikidata Q424921
properties
Molar mass 418.73 g mol −1
Physical state

firmly

density

1.48 g cm −3

Melting point

44.6 ° C

boiling point

156 ° C at 1 mmHg

Vapor pressure

8.4 · 10 −3 Pa (20 ° C)

solubility
  • practically insoluble in water (0.016 mg l −1 at 20 ° C)
  • soluble in acetone, dichloromethane, toluene, ethyl acetate and hexane
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
06 - Toxic or very toxic 09 - Dangerous for the environment

danger

H and P phrases H: 300-310-330-410
P: 262-273-280-301 + 310 + 330-302 + 352 + 310-304 + 340 + 311
Toxicological data
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Tefluthrin is a mixture of two enantiomeric chemical compounds from the group of pyrethroids .

Extraction and presentation

The synthesis of tefluthrin starts from two precursors, which are obtained in two branches of synthesis. The synthesis of the precursor is carried out first from the 1,2,4,5-tetrafluorobenzene from which about a two-fold metallation using butyllithium in the first step with methyl iodide to 1,2,4,5-Tetrafluortoluol and second step with carbon dioxide to 4-methyl- 2,3,5,6-tetrafluorobenzoic acid is implemented. The carboxylic acid is reacted with thionyl chloride and methanol intermediately via the acid chloride in the Methylester transferred, which then by means of lithium aluminum hydride to the pre -hydroxymethyl-4-methyl-2,3,5,6-tetrafluorobenzene 1 reduced is. The second precursor is obtained in a multistage synthesis starting from ethyl 3,3-dimethyl-4-pentenoate . In this case, the reaction with 1,1,1-trichloro-2,2,2-trifluoroethane in the presence of copper (I) chloride initially results in a carbon chain extension and introduction of the halogen functions. When the resulting 4,6,6-trichloro-7,7,7-trifluoro-3,3-dimethylheptanoic acid ethyl ester is reacted with sodium ethoxide , the cyclopropane ring and the double bond are formed by dehydrohalogenation reactions . The ethyl 3- [2-chloro-3,3,3-trifluoropropenyl] -2,2-dimethylcyclopropanecarboxylate is obtained as a racemic cis / trans mixture, from which the interesting trans isomer [racemate, i.e. 1: 1 mixture 1 S , 3 S ) - and (1 R , 3 R ) form] is obtained by means of distillation . The ester is then saponified with sodium hydroxide solution and reacted with thionyl chloride to form the acid chloride precursor. Both precursors finally produce the target compound in an esterification reaction, likewise as a 1: 1 enantiomer mixture of (1 S , 3 S ) - and (1 R , 3 R ) form.

Synthesis of tefluthrin

properties

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

use

Tefluthrin is used as an insecticide against soil pests (e.g. in sugar beet and corn). It was first approved in Belgium in 1986 and affects the nerve signal transmission of the sodium channels. Unlike other pyrethroids, tefluthrin also works through the ground.

regulation

EU

The currently valid approval expires on December 31, 2021. At national level, Tefluthrin is approved in 19 EU countries. The permitted daily dose and the acute reference dose are 0.005 and the acceptable user exposure 0.0015 milligrams per kilogram of body weight and day.

In December 2008, after withdrawing an application for approval, the EU Commission decided not to include tefluthrin in the list of active ingredients in Annex I of Directive 91/414 / EEC. The active ingredient was finally approved for use as an insecticide with effect from January 1, 2012.

In Germany, Syngenta's Force 20 CS is currently the only approved crop protection product containing the active ingredient tefluthrin. The BVL extended the approval, which had been valid since December 6, 2000, from February 20, 2014 to July 31, 2014. Force 20 CS is a dressing agent for sugar beet and fodder beetle against the moss button beetle . In the past, the BVL had also granted special permits for the plant protection product Force 1.5 G for use in maize against the western corn rootworm ; the last one expired on July 28, 2012.

In Austria and Switzerland, plant protection products (e.g. Force 20 CS) with this active ingredient are permitted for the seed dressing of sugar beet and fodder beet.

Individual evidence

  1. ↑ a b c d e f g h i j EFSA: Conclusion on the peer review of the pesticide risk assessment of the active substance tefluthrin , 2010. doi : 10.2903 / j.efsa.2010.1709
  2. ↑ a b Entry on formaldehyde in the Hazardous Substances Data Bank , accessed August 14, 2012.
  3. ↑ Entry on tefluthrin in the GESTIS substance database of the IFA , accessed on December 30, 2019(JavaScript required) .
  4. ↑ Entry on tefluthrin (ISO); 2,3,5,6-tetrafluoro-4-methylbenzyl (1RS, 3RS) -3 - [(Z) -2-chloro-3,3,3-trifluoroprop-1-enyl] -2,2-dimethylcyclopropanecarboxylate in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on December 30, 2019. Manufacturers or distributors can expand the harmonized classification and labeling .
  5. ↑ Tefluthrin data sheet from Sigma-Aldrich , accessed on December 30, 2019 ( PDF ).
  6. ↑ a b Patent US4370346 Imperial Chemical Industries 1981 .
  7. ↑ a b c d e Patent US4332815 FMC Corporation 1980 .
  8. ↑ Thomas A. Unger: PESTICIDE SYNTHESIS HDBK . William Andrew, 1996, ISBN 0-8155-1853-6 , pp. 959 ( limited preview in Google Book Search).
  9. ↑ a b c M. Bahadir, H. Parlar, Michael Spiteller: Springer Umweltlexikon . Gabler Wissenschaftsverlage, 2000, ISBN 3-540-63561-0 , p. 1151 ( limited preview in Google Book search).
  10. ^ UK Poison Information Documents (UKPID) for Tefluthrin , accessed December 9, 2014.
  11. ↑ Terry R. Roberts, David H. Hutson, Philip W. Lee, Peter H. Nicholls: Metabolic Pathways of Agrochemicals: Part 2: Insecticides and Fungicides . Royal Society of Chemistry, 1999, ISBN 0-85404-499-X , pp. 714 ( limited preview in Google Book search).
  12. ↑ a b Directorate General for Health and Food Safety of the European Commission: Entry on Tefluthrin in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 13, 2016.
  13. ↑ Implementing Regulation (EU) No. 800/2011 of the Commission of August 9, 2011 for the approval of the active substance tefluthrin ... (PDF)
  14. ↑ BVL: List of approved plant protection products . Retrieved February 25, 2014.
  15. ↑ BVL: extensions of approvals (last change: February 20, 2014). Retrieved February 25, 2014.
  16. ↑ proplanta: Plant protection products: Force 20 CS (024006-00) . Retrieved February 25, 2014.
  17. ↑ BVL - Press and background information - BVL approves plant protection products to control the corn rootworm. Retrieved October 21, 2019 .
  18. ↑ BVL: Approvals for emergency situations ( Memento from September 16, 2014 in the Internet Archive ). Retrieved October 21, 2019.