Methomyl

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Structural formula
Structure of methomyl
Mixture of ( E ) -isomer (top) and ( Z ) -isomer (bottom)
General
Surname Methomyl
other names
  • ( E , Z ) -1- (methylthio) ethylideneamine- N -methyl carbamate
  • 2-methylthiopropionaldehyde- O- (methylcarbamoyl) oxime
  • S -Methyl- N - [(methylcarbamoyl) oxy] thioacetimidate
  • 1-methylthioethylideneamine methyl carbamate
Molecular formula C 5 H 10 N 2 O 2 S
Brief description

colorless crystals with a sulphurous odor

External identifiers / databases
CAS number 16752-77-5
EC number 240-815-0
ECHA InfoCard 100,037,089
PubChem 4109
Wikidata Q423398
properties
Molar mass 162.21 g · mol -1
Physical state

firmly

density

1.29 g cm −3

Melting point

78-79  ° C

boiling point

Decomposes at temperatures above 140 ° C

Vapor pressure

6.5 m Pa at 25 ° C

solubility
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: 300-410
P: 264-270-273-301 + 310 + 330-391-501
MAK

Switzerland: 2.5 mg m −3 (measured as inhalable dust )

Toxicological data

17–24 mg kg −1 ( LD 50 ,  rat ,  oral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Methomyl is a pesticide from the chemical group of carbamates , thioethers and imines . It is used as an insecticide and a nematicide . The technical product is a mixture of ( Z ) and ( E ) isomers and is also sold under the trade names Lannat and Nudrin.

history

Methomyl was launched as a broad spectrum insecticide in 1966.

Extraction and presentation

The thioester is obtained by the reaction of methanethiol with acetic acid with elimination of water :

Methomyl Synthesis 1 of 3 V1.svg

The subsequent reaction with hydroxylamine provides the thio- imidate :

Methomyl Synthesis 2 of 3 V1.svg

Methomyl can be obtained by reacting S -Methyl- N -hydroxy -thioacetimidate (MHTA) (CAS number: 10533-67-2) in methylene chloride with gaseous methyl isocyanate at 30-50 ° C:

Methomyl Synthesis 3 of 3 V1.svg

use

Methomyl is used as an insecticide and nematicide and works by inhibiting cholinesterase . In Germany and Austria no pesticides containing this active ingredient are approved. In Switzerland, some Methomyl preparations are approved, in particular for the control of aphids and leaf-eating caterpillars on vegetables, cherries, hops and ornamental plants. Although its use is prohibited in Germany, residues of it were found in German vegetables in 2005.

According to European legislation (Directive 98/8 / EC of February 16, 1998 on the placing of biocidal products on the market) and a decision of August 14, 2007, a decision has been made not to include the active substance methomyl in the corresponding list (Appendix I / IA of the Directive 98/8 / EC) for biocidal products. The sale of biocidal products containing the active ingredient methomyl is therefore no longer permitted in the EU (Switzerland has adopted this provision) for insecticides (product type 18).

proof

Methomyl can be detected by various chromatographic methods (HPLC and GC).

Web links

Individual evidence

  1. ↑ NIOSH Pocket Guide to Chemical Hazards: Methomyl , accessed April 20, 2016.
  2. ↑ a b c d e f Entry on 1- (methylthio) ethlidenamine-N-methylcarbamate in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .
  3. ↑ a b Environmental Health Criteria (EHC) for Methomyl , accessed November 19, 2014.
  4. ↑ a b WHO / FAO Data Sheet on Pesticides (PDS) for Methomyl ( Memento from July 2, 2014 in the Internet Archive )
  5. ↑ Entry on Methomyl in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
  6. ↑ Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 16752-77-5 or Methomyl ), accessed on November 2, 2015.
  7. ↑ data sheet at EXTOXNET (English) .
  8. ^ Directorate-General for Health and Food Safety of the European Commission: Entry on Methomyl in the EU pesticide database; Entry in the national registers of plant protection products in Switzerland , Austria and Germany ; accessed on March 12, 2016.
  9. ↑ Greenpeace: Vegetables from Germany: sprayed with illegal pesticides , 2005.
  10. ↑ EU: Directive 98/8 / EC of February 16, 1998 on the placing of biocidal products on the market (PDF) Official Journal of the European Communities - L 123/1 - April 24, 1998.
  11. ↑ EU: Decision 2007/565 on the non-inclusion of certain active substances in Annex I of Directive 98/8 / EC (PDF) Official Journal of the European Communities - L 216/17 - August 21, 2004.