Methidathion

• Methidathion
• O, O -dimethyl- S-(2 -methoxy -1, 3,4 (4H)- thiadiazol- 5 -on-4 -yl) methyldithiophosphat

Colorless solid

Fixed

1.51 g · cm -3

39-40 ° C.

Slightly soluble in water (240 mg · l-1 at 20 ° C)

Risk

• 20 mg · kg -1 ( LD50, rat, oral)
• 196 mg · kg -1 ( LD50, Rabbit, transdermal)

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Methidathion is a chemical compound from the group of Thiophosphoric.

Production and representation

Methidathion can by a multistage reaction, starting from a reaction between methanol, carbon disulfide and hydrazine, and further reaction of the intermediate with phosgene Thiocarbamidsäuremethylester, formaldehyde, thionyl chloride and O, O- Dimethylhydrogendithiophosphat obtained.

Properties

Methidathion is a colorless solid which is sparingly soluble in water. It is stable under neutral and slightly acidic conditions, but rapidly hydrolyzed under alkaline conditions.

Use

Methidathion is a non- systemic organophosphate insecticide and acaricide with contact action and corrosion. It is used for control of insects and mites on fruit, vegetables, tobacco, alfalfa and sunflower and is particularly effective against scale insects. It is sold for example under the trade names Ultrazid and Supracid and acts by inhibiting acetylcholinesterase.

In the European Union methidathion is no longer permitted as an active ingredient in plant protection products since 2004. Some EU countries was for certain applications ( for Germany during oilseed rape ) granted a transitional period until 30 June 2007. In Switzerland, pesticides are approved with this drug, in Germany and Austria not.