Thiamethoxam

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Structural formula
Structural formula of thiamethoxam
General
Surname Thiamethoxam
other names

3- (2-chloro-thiazol-5-ylmethyl) -5-methyl (1,3,5) oxadiazinan-4-ylidene- N -nitroamine

Molecular formula C 8 H 10 ClN 5 O 3 S
Brief description

brown solid

External identifiers / databases
CAS number 153719-23-4
EC number 428-650-4
ECHA InfoCard 100.102.703
PubChem 5485188
Wikidata Q1040678
properties
Molar mass 291.71 g mol −1
Physical state

firmly

density

1.57 g cm −3

Melting point

139.1 ° C

boiling point

147 ° C (decomposition)

Vapor pressure

6.6 10 −9 Pa (25 ° C)

solubility
  • sparingly soluble in water (4.1 g l −1 at 25 ° C)
  • soluble in dichloromethane (110 g l −1 ), acetone (48 g l −1 ) and methanol (13 g l −1 )
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
07 - Warning 09 - Dangerous for the environment

Caution

H and P phrases H: 302-410
P: 273-501
Toxicological data
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Thiamethoxam is a chemical compound belonging to the neonicotinoid group .

Extraction and presentation

Thiamethoxam may be prepared by reaction of N -methyl- N 'nitroguanidine to N -methyl-4- ( N -nitro-imino) -perhydro-1,3,5-oxadiazine and subsequent ring coupling with 2-chloro-5-chloromethyl-1 , 3-thiazole can be obtained in the presence of a base.

Synthesis of thiamethoxam

properties

Thiamethoxam is a brownish solid. It is stable to hydrolysis at a pH of 5 and 7, but decomposes at a pH of 9. Thiamethoxam is described as an ( E / Z ) mixture. It is generally assumed that the activation energy for the E↔Z interconversion for the C = N bond is low and that the equilibrium mixture is established quickly at room temperature.

use

Estimated US application rate in 2011

Thiamethoxam is used as a wood preservative and insecticide . It is used against termites ( yellow-footed soil termites , Reticulitermes hageni , Reticulitermes santonensis ) and beetles (house buck ). The effect is based on the irreversible blockade of the postsynaptic nicotinergic acetylcholine receptors in the central nervous system. It was developed from neonicotinoids as part of a research program started in 1985 by Ciba-Geigy (now Syngenta ), first synthesized in 1991 and brought to market in 1998.

In 2011, around 550 t of thiamethoxam were used in the USA, around a third each in soy and corn and a quarter in cotton.

Admission

EU

The use of thiamethoxam was approved in the EU and 26 member states, but severely restricted for several important uses, such as the seed dressing of maize and rapeseed, for two years from December 1, 2013 due to risks for honey bees (see Neonicotinoids # EU- Restrictions from 2013 ). The permitted daily dose is 0.026, the acute reference dose 0.5 and the acceptable user exposure 0.08 milligrams per kilogram of body weight and day.

Most of the approvals for seed dressings containing thiamethoxam applied to sugar beet, maize, rape and potatoes, along with a number of other plant species.

In the European Union, with effect from February 1, 2007, thiamethoxam was added to the list of permitted active ingredients in pesticides for use as an insecticide . The approval was supplemented in 2010 by regulations designed to reduce the emission of thiamethoxane-containing dusts during seed dressing, storage and sowing.

In Germany, the Federal Office for Consumer Protection and Food Safety (BVL) decided on May 15, 2008 to suspend the approval of seed treatments for maize and rapeseed with clothianidin, thiamethoxam and imidacloprid due to the high toxicity of neonicotinoids for bees and proven bee deaths due to clothianidin . The suspension of approvals for the treatment of rapeseed was lifted on June 25, 2008. The use of thiamethoxam, clothianidin and imidacloprid for seed dressing on maize was prohibited by a regulation issued by the BMELV on February 11, 2009.

An EFSA opinion published on February 28, 2018 finally confirmed the risks for wild and honey bees in field applications. This report is the basis for further approval decisions or restrictions.

The term of the permit was extended to April 30, 2019 in spring 2018.

On April 27, 2018, the EU Commission passed a vote to ban outdoor crops.

In August 2018, the approval for outdoor use was revoked on September 18, 2018. Pesticides with this active ingredient may only be used in permanent greenhouses and for the treatment of seeds that are intended for application in the greenhouse. Treated seeds, which are intended for sowing in the open, may be sown until December 18, 2018.

Switzerland

In Switzerland, plant protection products with this active ingredient are approved.

Canada

The responsible federal authority in Canada , Santé Canada , has regulated the active ingredients clothianidin and thiamethoxam from August 2018 with the aim of completely banning them in 5 years (i.e. 2023). Until then, the farmers should check alternatives in use and can use up remaining stocks.

Individual evidence

  1. ↑ a b c Entry on 3- (2-chloro-thiazol-5-ylmethyl) -5-methyl (1,3,5) oxadiazinan-4-ylidene-N-nitroamine in the GESTIS substance database of the IFA , accessed on 5 February 2017(JavaScript required) .
  2. ↑ a b c d e f g EU: Directive 98/8 / EC concerning the placing of biocidal products on the market - Inclusion of active substances in Annex I or IA to Directive 98/8 / EC - Thiamethoxam , February 22, 2008.
  3. ↑ a b BVL: Thiamethoxam , November 2004.
  4. ↑ Entry on 3- (2-chloro-thiazol-5-ylmethyl) -5-methyl [1,3,5] oxadiazinan-4-ylidene-N-nitroamine Template: Linktext-Check / Escaped in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on August 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
  5. ↑ a b data sheet Thiamethoxam, PESTANAL at Sigma-Aldrich , accessed on May 18, 2017 ( PDF ).
  6. ^ Clemens Lamberth, Jürgen Dinges: Bioactive Heterocyclic Compound Classes: Agrochemicals . John Wiley & Sons, 2012, ISBN 3-527-66444-0 , pp. 214 (English, limited preview in Google Book Search).
  7. ^ Basic Biotechnology eJournal, 2006: Neonicotinoid Insecticides ( Memento June 15, 2010 in the Internet Archive ).
  8. ^ Entry on thiamethoxam in the Hazardous Substances Data Bank , accessed March 22, 2013.
  9. ↑ FAO: Microsoft Word - 2010 JMPR Monograph Feb 24 2011 - Thiamethoxam.pdf
  10. ↑ BAUA: Thiamethoxam ( Memento from June 23, 2013 in the Internet Archive ).
  11. ^ Terence Robert Roberts, DH Hutson: Metabolic pathways of agrochemicals . Royal Soc of Chemistry, 1999, ISBN 978-0-85404-499-3 , pp. 124 (English, limited preview in Google Book search).
  12. ↑ Ulrich Schirmer, Peter Jeschke, Matthias Witschel: Modern Crop Protection Compounds: Herbicides . John Wiley & Sons, 2012, ISBN 978-3-527-32965-6 , pp. 1211 (English, limited preview in Google Book search).
  13. ↑ a b Directorate-General for Health and Food Safety of the European Commission: Entry on thiamethoxam in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on December 6, 2019.
  14. ↑ EFSA: Conclusion on the peer review of the pesticide risk assessment for bees for the active substance thiamethoxam . In: EFSA Journal . tape 11 , no. 1 , 2013, p. 3067 , doi : 10.2903 / j.efsa.2013.3067 (English).
  15. ↑ Commission Directive 2007/6 / EC of February 14, 2007 amending Council Directive 91/414 / EEC to include the active substances metrafenone, Bacillus subtilis, spinosad and thiamethoxam
  16. ↑ Directive 2010/21 / EU of the Commission of March 12, 2010 amending Annex I of Directive 91/414 / EEC of the Council with regard to special provisions for clothianidin, thiamethoxam, fipronil and imidacloprid
  17. ^ Reports on plant protection products 2008: Plant protection control program… Springer DE, 2009, ISBN 3-0346-0258-8 , p. 22 ( limited preview in Google Book search).
  18. ↑ Evaluation of the data on clothianidin, imidacloprid and thiamethoxam for the updated risk assessment to bees for seed treatments and granules in the EU. European Food Safety Authority, accessed March 19, 2018 .
  19. ↑ EU Pesticides database. European Commission, accessed March 19, 2018 .
  20. ↑ Fight against bee mortality: EU bans neonicotinoids in fields ( memento of July 24, 2018 in the Internet Archive ) br.de , April 27, 2018.
  21. ↑ Federal Office for Consumer Protection and Food Safety: BVL - Fachmachrichten - Revocation of the approval of plant protection products with the neonicotinoid active ingredients Clothianidin, Imidacloprid and Thiamethoxam on September 18, 2018 , accessed on December 8, 2018.
  22. ↑ Santé Canada lance une concertation pour l'élimination de deux pesticides de la famille des neonicotinoïdes , August 16, 2018 (in French).