Norflurazon

Norflurazon

氟草敏

4-chloro-5-methylamino-2-(α,α,α-trifluoro-m-tolyl)pyridazin-3(2H)-one

4-chloro-5-(methylamino)-2-[3-(trifluoromethyl)phenyl]-3(2H)-pyridazinone

27314-13-2

C₁₂H₉ClF₃N₃O

Herbicides > Pyridazinone herbicides

Herbicide

Molecular weight:303.7g/mol; Physical form:White to greyish brown, crystalline powder. Melting point:174-180 ℃; Vapour pressure:3.857 × 10-3 mPa (25 ℃); Henry constant:3.5 × 10-5 Pa m3 mol-1 (calc.); Partition coefficient(n-octanol and water):logP = 2.45 (pH 6.5, 25℃); pKa:No dissociation in range pH 1 to 12 (25℃); Solubility:In water 34 mg/l (25 ℃). In ethanol 142, acetone 50, xylene 2.5 (all in g/l, 25℃). Sparingly soluble in hydrocarbons.; Stability:Stable in aqueous solution (<8% loss after 24 d at 50 ℃). Stable under alkaline and acidic conditions. Shelf-life at 20℃ is 4 y. Rapidly degraded by sunlight.

(Rat): Oral LD₅₀ >8000 mg/kg. (Rabbit): Dermal LD₅₀ >20,000 mg/kg. In 90-day feeding tests, the "no-effect" level was 50 mg/kg/day (rat); 12.5 mg/kg/day (dog).Non-irritating to skin and eyes; not a skin sensitiser.

Ecotoxicology:
Algae: EC₅₀ (5 d) for Selenastrum capricornutum 0.0176 mg/l.Bees:Non-toxic to bees at 0.235 mg/bee.Birds:Acute oral LD₅₀ for mallard ducks >2510 mg/ kg.Daphnia: LC₅₀ (96 h) >15 mg/l.Fish: LC₅₀ (96 h) for rainbow trout 8.1, bluegill sunfish 16.3 mg/l.Worms: LC₅₀ (14 d) >1000 mg/ kg soil.Other aquatic spp.: EC₅₀ (14 d) for Lemna gibba 0.0875 mg/l.

Environmental fate:
Animals:In rats, norflurazon undergoes demethylation, followed principally by conversion to a sulfoxide (J. Agric. Food Chem., 1989, 37, 1413).Soil:Dissipated in soil by photodegradation and volatilisation. DT₅₀ in soil (US field) c. 6-9 mo. K_oc 218-635 ml/g.Plant:In plants, norflurazon undergoes N-demethylation to desmethylnorflurazon, and this is further hydrolytically dechlorinated.

Signal Word:CAUTION; Hazard Class:III(Slightly hazardous)