Title: Chlorpyrifos
CAS Registry Number: 2921-88-2
CAS Name: Phosphorothioic acid O,O-diethyl O-(3,5,6-trichloro-2-pyridinyl) ester
Additional Names: O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate; chlorpyrifos-ethyl
Manufacturers' Codes: Dowco 179; ENT-27311
Trademarks: Affront (Wellmark); Dursban (Dow AgroSci.); Empire (Dow AgroSci.); Lock-On (Dow AgroSci.); Lorsban (Dow AgroSci.); Pyrinex (Makhteshim-Agan)
Molecular Formula: C9H11Cl3NO3PS
Molecular Weight: 350.59
Percent Composition: C 30.83%, H 3.16%, Cl 30.34%, N 4.00%, O 13.69%, P 8.83%, S 9.15%
Literature References: Prepn: R. H. Rigterink, FR 1360901; idem, US 3244586 (1964, 1966 both to Dow); R. H. Rigterink, E. E. Kenaga, J. Agric. Food Chem. 14, 394 (1966). Activity: E. E. Kenaga et al., J. Econ. Entomol. 58, 1043 (1965). Metabolism: G. N. Smith et al., J. Agric. Food Chem. 15, 132 (1967); W. H. Gutenmann et al., ibid. 16, 45 (1968). Toxicity study: Schafer, Toxicol. Appl. Pharmacol. 21, 315 (1972). Review of environmental fate: K. D. Racke, Rev. Environ. Contam. Toxicol. 131, 1-154 (1993); of toxicology and human exposure: Toxicological Profile for Chlorpyrifos (PB98-103088, 1997) 217 pp.
Properties: White granular crystals, mp 41-42°. Vapor pressure at 25°: 1.87 ´ 10-5 mm Hg. Soly at 25°: water 2 ppm; isooctane 79% w/w; methanol 43% w/w. Soly (g/100g): acetone 650, benzene 790, carbon disulfide 590, carbon tetrachloride 310, chloroform 630, diethyl ether 510, ethanol 63, ethyl acetate >200, isooctane 79, kerosene 60, methanol 45, methylene chloride 400, propylene glycol 4, toluene 150, 1,1,1-trichloroethane 400, triethylene glycol 5, xylene 400. Readily sol in other org solvents. uv max: 208, 230, 290 nm. LD50 orally in rats: 145 mg/kg (Schafer).
Melting point: mp 41-42°
Absorption maximum: uv max: 208, 230, 290 nm
Toxicity data: LD50 orally in rats: 145 mg/kg (Schafer)
Derivative Type: O,O-Dimethyl analog
CAS Registry Number: 5598-13-0
Additional Names: Chlorpyrifos-methyl
Manufacturers' Codes: Dowco 214; ENT-27520
Trademarks: Reldan (Dow AgroSci.)
Molecular Formula: C7H7Cl3NO3PS
Molecular Weight: 322.53
Percent Composition: C 26.07%, H 2.19%, Cl 32.98%, N 4.34%, O 14.88%, P 9.60%, S 9.94%
Properties: Crystals, mp 45.5-46.5°. Vapor pressure at 25°: 4.22 ´ 10-5 mm Hg. Soly in water at 25°: 5 mg/l.
Melting point: mp 45.5-46.5°
CAUTION: Potential symptoms of overexposure are wheezing, laryngeal spasms, salivation; bluish lips and skin; miosis, blurred vision; nausea, vomiting, abdominal cramps, diarrhea. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 70.
Use: Insecticide; acaricide.
Therap-Cat-Vet: Ectoparasiticide.
Chlorquinaldol Chlorsulfuron Chlortetracycline Chlorthalidone Chlorthenoxazin(e)

CAS number 2921-88-2 YesY
PubChem 2730
ChemSpider 2629 YesY
KEGG D07688 YesY
ChEBI CHEBI:34631 YesY
Jmol-3D images Image 1
Molecular formula C9H11Cl3NO3PS
Molar mass 350.59 g/mol
Appearance colourless crystals[1]
Density 1.398 g/cm3 (43.5 °C)
Melting point 42 °C[2]
Solubility in water 2 mg/L (25 °C)
log P 4.96 (octanol/water)[3]
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Chlorpyrifos (IUPAC name: O,O-diethyl O-3,5,6-trichloropyridin-2-yl phosphorothioate) is a crystalline organophosphate insecticide. It was introduced in 1965 by Dow Chemical Company and is known by many trade names (see table), including Dursban and Lorsban. It acts on the nervous system of insects by inhibiting acetylcholinesterase.

Chlorpyrifos is moderately toxic to humans and chronic exposure has been linked to neurological effects, developmental disorders, and autoimmune disorders. Exposure during pregnancy retards the mental development of children, and most use in homes has been banned since 2001 in the U.S.[4] In agriculture, it remains "one of the most widely used organophosphate insecticides", according to the United States Environmental Protection Agency (EPA).[5]