Permethrin

NOMENCLATURE
Common name: permethrin; thrine
IUPAC name: 3-phenoxybenzyl (1RS,3RS;1RS,3SR)-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate
Roth: 3-phenoxybenzyl (1RS)-cis-trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate
Chemical Abstracts name: (3-phenoxyphenyl)methyl 3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylate
CAS RN: [52645-53-1], (formerly [57608-04-5] and [63364-00-1])

PHYSICAL CHEMISTRY
Mol. wt.: 391.3, M.f.: C21H20Cl2O3; Form: Tech. is a yellow-brown to brown liquid, which sometimes tends to crystallise partly at room temperature. M.p.: 34-35 oC; cis- isomers 63-65 oC; trans- 44-47 oC. B.p.: 200 oC/0.1 mmHg; >290 oC/760 mmHg. V.p.: cis- 0.0025 mPa; trans- 0.0015 mPa (both 20 oC). KOW: logP = 6.1 (20 oC). S.g./density: 1.29 (20 oC). Solubility: In water 6x10-3 mg/l (pH 7, 20 oC). In xylene, hexane >1000, methanol 258 (all in g/kg, 25 oC). Stability: Stable to heat (2 y at 50 oC), more stable in acidic than alkaline media with optimum stability c. pH 4; DT50 50 d (pH 9), stable (pH 5, 7) (all 25 oC). Some photochemical degradation observed in laboratory studies, but field data indicate this does not adversely affect biological performance. F.p. >100 oC ('Perigen').

APPLICATIONS
Mode of action: Non-systemic insecticide with contact and stomach action, having a slight repellent effect.
Uses: A contact insecticide effective against a broad range of pests. It controls leaf- and fruit-eating Lepidoptera and Coleoptera in cotton, at 100-150 g a.i./ha, in fruit, at 25-50 g/ha, in tobacco, vines and other crops, at 50-200 g/ha, and in vegetables, at 40-70 g/ha. It has good residual activity on treated plants. It is effective against a wide range of animal ectoparasites, provides >60 d residual control of biting flies in.