4002. Fenthion

Nomenclature

CAS number: 55-38-9
Phosphorothioic acid O,O-dimethyl O-[3-methyl-4-(methylthio)phenyl] ester; O,O-dimethyl O-[3-methyl-4-(methylthio)phenyl] phosphorothioate; O,O-dimethyl O-4-(methylthio)-m-tolyl phosphorothioate; O,O-dimethyl O-(4-methylmercapto-3-methylphenyl) thiophosphate; Bayer 29493; ENT-25540; S-1752; Baycid (Bayer CropSci.); Baytex (Bayer CropSci.); Lebaycid (Bayer CropSci.); Queletox (Bayer CropSci.); Tiguvon (Bayer).
C10H15O3PS2; mol wt 278.33.
C 43.15%, H 5.43%, O 17.25%, P 11.13%, S 23.04%.

Description and references

Organophosphate insecticide; cholinesterase inhibitor. Prepn: E. Schlegk, G. Schrader, DE 1116656; eidem, US 3042703 (1961, 1962 both to Bayer). Properties: H. F. Jung, Bull. WHO 21, 215 (1959) PubMed; Schrader, Die Entwicklung neuer insektizider Phosphorsure-Ester (Verlag Chemie, 3rd ed., 1963) pp 298-313. Toxicity: Gaines, Toxicol. Appl. Pharmacol. 2, 88 (1960) DOI PubMed. Degradation and persistence in treated oranges: Y. Picó et al., Anal. Chem. 79, 9350 (2007) DOI PubMed. Determn in olive oil and in river water: T. G. Díaz et al., Talanta 76, 809 (2008) DOI PubMed.

Chemical structure

Properties

Pale yellow oil, slight odor of garlic. Poisonous. bp0.01 105°. d420 1.250. nD20 1.5698. Log P (octanol/water): 4.8. Vapor pressure at 20°: 3×105 mm Hg. Thermally stable up to 210°; resistant to alkalies up to pH 9. Readily sol in methanol, ethanol, ether, acetone and many other organic solvents, esp chlorinated hydrocarbons. Practically insol in water (55 mg/l). LD50 in male, female rats (mg/kg): 215, 245 orally (Gaines).

Caution

Potential symptoms of overexposure are nausea, vomiting, abdominal cramps, diarrhea, salivation; headache, giddiness, vertigo, weakness; rhinorrhea, chest tightness; blurred vision, miosis; cardiac irregularities; muscle fasciculations; dyspnea. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 144.

Use

Insecticide; acaricide.

Therapeutic Category (Veterinary)

Ectoparasiticide.