Methamidophos

Identification

Synonyms: O,S-dimethyl phosphoramidothioate (IUPAC)
CAS No.: 10265-92-6
EC No.: 233-606-0
Molecular Weight: 141.13
Molecular Formula: C2H8NO2PS
Structural Formula:
Form Colourless crystals, with a mercaptan-like odour.
M.p.: 45 °C (purified a.i.)
B.p.: Decomp. >160 °C

F.p. c. 42 °C (EU A9/ASTN-D56)
V.p.: 2.3 mPa (20 °C); 4.7 mPa (25 °C)

S.g.: 1.27 (20 °C)
Solubility: water >200 g/l at 20 °C. Iso-propanol and dichloromethane >200, hexane 0.1–1 (all in g/l, 20 °C).
Stability: Stable at ambient temperature, but decomposes on heating without boiling. Stable at pH 3–8. Hydrolysed in acids and alkalis,.
Compatibility: Incompatible with alkaline materials.

Application

As a Cholinesterase inhibitor, methamidophos is a broad-spectrum insecticdie and acaricide with effection of stomach poisoning, systemic and contact toxicity, and with long-period (7 to 10 days) effection. Used to control chewing and sucking insects, and spider mites.

Specification*

73% TC, 585g/l SL, 500g/l EC, 250g/l EC

Standard Packaging

Risks and Safety Information

Methamidophos is regulated by UN as hazardous substance
T+ Very toxic; N Dangerous for the environment
UN 2811 Class 6.1 PG: II
Acute oral LD50(male rats) 15.6, (female rats):13.0 mg/kg. Birds Acute oral LD50(bobwhite quail) 10 mg/kg.

(Note: Methamidophos is a restricted chemical by Rotterdam Convention, users should be aware of state/local regulations limit on certain applications)