(RS)-α-cyano-3-phenoxybenzyl (1RS,3RS)-3-[(Z)-2-chloro-3,3,3-trifluoropropenyl]-2,2-dimethylcyclopropanecarboxylate or (RS)-α-cyano-3-phenoxybenzyl (1RS)-cis-3-[(Z)-2-chloro-3,3,3-trifluoropropenyl]-2,2-dimethylcyclopropanecarboxylate
Molecular weight:449.9; Physical form:Yellow to brown viscous oil ( tech.). Density:1.25 (25 °C); Composition:Tech. grade cyhalothrin has purity 90% m/m, of which 95% is cis- isomers. Flash point:204 °C ( tech., Pensky-Martens closed cup); Vapour pressure:0.001 mPa (20 °C, est.); Partition coefficient(n-octanol and water):logP = 6.9 (20 °C); pKa:>9 (hydrolysis prevents measurement); Solubility:In water 0.005 mg/l ( pH 6.5, 20 °C). In acetone, dichloromethane, methanol, diethyl ether, ethyl acetate, hexane, toluene, all >500 g/l (20 °C).; Stability:Stable to decomposition and cis/trans isomerisation for at least 4 years in the dark at 50 °C. Stable to light; loss on storage in the light is <10% in 20 months. Decomposes at 275 °C. Slowly hydrolysed by water in sunlight.
Toxicology
Oral:Acute oral LD50 for male rats 166, female rats 114, guinea pigs >5000, rabbits >1000 mg/kg. Percutaneous:Acute percutaneous LD50 for male rats 1000-2500, female rats 200-2500, rabbits >2500 mg/kg. Moderate eye irritant; not a skin irritant (rabbits). Moderate skin sensitiser (guinea pigs). Inhalation: LC50 (4 h) for rats >0.086 mg/l.
Environmental Profile
Ecotoxicology:
Birds:Acute oral LD50 for mallard ducks >5000 mg/kg.Daphnia: LC50 (48 h) 0.38 μg/l.Fish: LC50 (96 h) for rainbow trout 0.00054 mg/l.
Environmental fate:
Animals:In rats, following oral administration, cyhalothrin is rapidly eliminated in urine and faeces. The ester group is hydrolysed, both moieties forming polar conjugates.Soil:In soil, DT50c. 4-12 weeks. Leaching of cyhalothrin and its degradation products through a range of soil types is negligible.