6108. Methyl Parathion

Nomenclature

CAS number: 298-00-0
Phosphorothioic acid O,O-dimethyl O-(4-nitrophenyl) ester; O,O-dimethyl O-p-nitrophenyl phosphorothioate; O,O-dimethyl O-p-nitrophenyl thiophosphate; dimethyl parathion; parathion-methyl; metaphos; E-601; ENT-17292; Folidol-M (Bayer CropSci.); Metacide (Bayer CropSci.); Penncap M (Cerexagri).
C8H10NO5PS; mol wt 263.21.
C 36.51%, H 3.83%, N 5.32%, O 30.39%, P 11.77%, S 12.18%.

Description and references

Organophosphate insecticide; cholinesterase inhibitor. Prepn: Fletcher et al., J. Am. Chem. Soc. 72, 2461 (1950) DOI. Manuf: Faith, Keyes & Clark's Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds. (Wiley-Interscience, New York, 4th ed., 1975) pp 552-555. Toxicity data: T. B. Gaines, Toxicol. Appl. Pharmacol. 14, 515 (1969) DOI PubMed. Environmental fate: M. T. Moore et al., Environ. Pollut. 142, 288 (2006) DOI PubMed. Review of carcinogenic risk: IARC Monographs 30, 131-152 (1983); of toxicology and human exposure: Toxicological Profile for Methyl Parathion (PB2001-109105, 2001) 267 pp.

Chemical structure

Properties

Crystals from cold methanol, mp 37-38°. nD25 1.5367. d420 1.358. Log P (octanol/water): 3.5. Soly in water: 55 mg/l; sol in most organic solvents. Poisonous. LD50 in male, female rats (mg/kg): 14, 24 orally; 67, 67 dermally (Gaines).

Caution

Potential symptoms of overexposure are irritation of eyes and skin; 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 214.

Use

Insecticide.