Chemical Identification
Common Name
S-2-ethylthioethyl O,O-dimethyl phosphorothioate
S-[2-(ethylthio)ethyl] O,O-dimethyl phosphorothioate
Molecular Formula
Molecular Structure
Physical Properties
Tech: Pale yellow oil. At 20°C: Specific gravity 1.21; vapor pressure 4.0 mPa. Readily soluble in dichloromethane, 2-propanol, toluene. Soluble in n-hexane. Molecular weight:230.3; Physical form:Tech. is a pale yellow oil. Density:1.207 (20 °C); Composition:A reaction mixture containing demeton-S-methyl and demeton-O-methyl is known as demeton-methyl ( BSI) or methyl demeton ( ESA). Vapour pressure:40 mPa (20 °C); Henry constant:4.19×10-4 Pa m3 mol-1 ( calc.); Partition coefficient(n-octanol and water):logP = 1.32 (20 °C); Solubility:In water 22 g/l (20 °C). Readily soluble in common polar organic solvents (e.g. alcohols, ketones, chlorinated hydrocarbons, c. 200 g/l in dichloromethane, isopropanol, toluene).; Stability:Hydrolysed rapidly in alkaline media, and more slowly in acidic and neutral aqueous media; DT50 ( est.) 63 d ( pH 4), 56 d ( pH 7), 8 d ( pH 9) (22 °C).
Oral:Acute oral LD50 for rats c. 30 mg/kg. Percutaneous:Acute percutaneous LD50 for rats c. 30 mg/kg. Not irritating to eyes; mildly irritating to skin (rabbits). Inhalation: LC50 (4 h) for rats c. 0.13 mg/l air (as aerosol). Phytotoxicity:Non-phytotoxic when used as directed, except to some ornamentals (particularly certain chrysanthemum varieties). ADI
Environmental Profile
Algae: ErC50 for Scenedesmus subspicatus 22.1 mg/l.Bees:Toxic to bees.Birds: LD50 for male Japanese quail 50, female Japanese quail 44 mg/kg. Daphnia: LC50 (48 h) 0.023 mg/l.Fish: LC50 (96 h) for rainbow trout 6.4, golden orfe 23.2 mg/l (both 250 EC).Worms: LC50 for Eisenia foetida 250 mg/kg dry soil. Environmental fate: 
Animals:In mammals, following oral administration, metabolism involves oxidation of the thioethyl group to give the sulfoxide (oxydemeton-methyl) and sulfone (demeton-S-methylsulphon), and hydrolysis to dimethyl phosphate. Rapidly eliminated in the urine (97-99% Soil:Degradation of demeton-S-methyl in soil is extremely rapid.Plant:In plants, the thioethyl group is oxidised to give the sulfoxide (oxydemeton-methyl) and sulfone (demeton-S-methylsulphon). Hydrolysis gives dimethyl phosphate.
WATER SOLUBILITY: 22 g/l at 20° C
Transport Information
Signal Word:DANGER; Hazard Class:Ib (Highly hazardous)

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