coumaphos
Insecticide
IRAC 1B; organophosphate
NOMENCLATURE
Common name coumaphos (BSI, E-ISO, (m) F-ISO, ESA, BAN); no name (Germany)
IUPAC name O-3-chloro-4-methyl-2-oxo-2H-chromen-7-yl O,O-diethyl phosphorothioate; 3-chloro-7-diethoxyphosphinothioyloxy-4-methylcoumarin
Chemical Abstracts name O-(3-chloro-4-methyl-2-oxo-2H-1-benzopyran-7-yl) O,O-diethyl phosphorothioate
CAS RN [56-72-4] EEC no. 200-285-3 Development codes Bayer 21/199 Official codes OMS 485; ENT 17 957
PHYSICAL CHEMISTRY
Mol. wt. 362.8 M.f. C14H16ClO5PS Form Colourless crystals. M.p. 95 ºC; (tech., 90-92 ºC) V.p. 0.013 mPa (20 ºC) KOW logP = 4.13 Henry 3.14 ´ 10-3 Pa m3 mol-1 (calc.) S.g./density 1.474 (20 ºC). Solubility In water 1.5 mg/l (20 ºC). Limited solubility in organic solvents. Stability Stable to hydrolysis in aqueous media, though in dilute alkali the pyrone is opened, reclosing on acidification.
COMMERCIALISATION
History Veterinary insecticide introduced by Bayer AG. Patents US 2748146 (1952), DE 881194 (1953), both to Bayer Manufacturers Sannong; Taiwan Tainan Giant
APPLICATIONS
Biochemistry Cholinesterase inhibitor. Uses Non-systemic insecticide for control of Diptera, and for control of Hypoderma on cattle. Also controls parasitic mites (Varroa jacobsoni) on bees. Formulation types Powder; Spray; Liquid. Selected products: 'Asuntol' (Bayer CropScience); 'Perizin' (Bayer CropScience)
OTHER PRODUCTS
'Co-Ral' (Bayer CropScience) Discontinued products: 'Resitox' * (Bayer)
ANALYSIS
Details available from Bayer CropScience.
MAMMALIAN TOXICOLOGY
Reviews FAO/WHO 59, 61 (see part 2 of the Bibliography). Oral Acute oral LD50 for male rats 41, female rats 16 mg/kg (in peanut oil). Skin and eye Acute percutaneous LD50 for male rats 860 mg/kg. Inhalation LC50 (1 h) for male rats >1081, female rats 341 mg/m3 air. NOEL In 2 y feeding trials, rats tolerated 100 mg/kg diet. ADI (JMPR) No ADI [1990]; for 'Perizin' 0.035 mg/kg. Toxicity class WHO (a.i.) Ib EC classification T+; R28| Xn; R21| N; R50, R53
ECOTOXICOLOGY
Birds LD50 for bobwhite quail 4.3, mallard ducks 29.8 mg/kg. Fish LC50 (96 h) for bluegill sunfish 340, channel catfish 840 mg/l. Daphnia LC50 (48 h) 1.0 mg/l.
ENVIRONMENTAL FATE
EHC 63 (WHO, 1986; a general review of organophosphorus insecticides). Soil/Environment Photolytic DT50 on soil surface 23.8 d. Kd 61-298, Koc 5778-21 120 (4 soil types).
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