Fenchlorazole

Common name: fenchlorazole
IUPAC name: ethyl 1-(2,4-dichlorophenyl)-5-trichloromethyl-1H-1,2,4-triazole-3-carboxylate
Chemical Abstracts name: ethyl 1-(2,4-dichlorophenyl)-5-(trichloromethyl)-1H-1,2,4-triazole-3-carboxylate
CAS RN: [103112-35-2]; [103112-36-3] (acid)

PHYSICAL CHEMISTRY
Mol. wt.: 403.5; (acid 375.4). M.f.: C12H8Cl5N3O2; (acid C10H4Cl5N3O2). Form: White, practically odourless solid. M.p.: 108-112 ºC. V.p.: 8.9x10-4 mPa (20 ºC) (OECD 104). S.g./density: 1.7 (20 ºC). Solubility: In water 0.9 mg/l (pH 4.5, 20 ºC). In n-hexane 2.5, methanol 27, toluene 270, acetone 360, dichloromethane >500 (all in g/l, 20 ºC). Stability: Aqueous hydrolysis DT50 115 d (pH 5), 5.5 d (pH 7), 0.079 d (pH 9).

APPLICATIONS
Biochemistry: Fenchlorazole-ethyl synergises the activity of fenoxaprop-ethyl in susceptible species by enhancing de-esterification to the acid, which is the active form. It also enhances the tolerance of wheat by accelerating the metabolic breakdown of fenoxaprop, leading to the formation of non-phytotoxic degradation products.
Mode of action: Applied to the foliage of wheat in combination with the grass herbicide fenoxaprop-ethyl or fenoxaprop-P-ethyl, it prevents growth retardation, leaf discolouration, and chlorosis of the crop.
Uses: Used as a safener for fenoxaprop-ethyl or fenoxaprop-P-ethyl in post-emergence control of grass weeds in wheat, durum wheat, rye, and triticale.

MAMMALIAN TOXICOLOGY
Oral: Acute oral LD50 for rats >5000, mice >2000 mg/kg.
Skin and eye: Acute percutaneous LD50 for rats and rabbits >2000 mg/kg. Non-irritating to eyes and skin (rabbits). Non-sensitising to skin (guinea pigs).
Inhalation: LC50 (4 h) >1.52 mg/l.
NOEL: (90 d) for rats 1280, male mice 80, female mice 320, dogs 80 mg/kg diet; (1 y) for dogs 80 mg/kg diet.
Toxicity class: WHO (a.i.) III (Table 5)

ECOTOXICOLOGY
Birds: Acute oral LD50 for mallard ducks >2400 mg/kg.
Fish: LC50 (96 h) for rainbow trout 0.08 mg/l.
Daphnia: LC50 (48 h) 1.8 mg/l.
Bees: Not harmful to bees: LC50 (48 h) >300 ug/bee.