PHYSICAL CHEMISTRY    

Mol. wt. 218.1 M.f. C₉H₉Cl₂NO Form Colourless, odourless crystals; (tech. is a medium to dark grey, crystalline solid). M.p. 91.5 °C B.p. 351 °C V.p. 0.02 mPa (20 °C); 0.05 mPa (25 °C) Kow logP = 3.3 (20 °C) S.g./density 1.41 g/cm³ (22 °C) Solubility In water 130 mg/l (20 °C). In isopropanol, dichloromethane >200, toluene 50–100, hexane <1 (all in g/l, 20 °C). In benzene 7 × 10⁴, acetone 1.7 × 10⁶, ethanol 1.1 × 10⁶ (all in ppm, 25 °C).

APPLICATIONS    

Biochemistry Photosynthetic electron transport inhibitor at the photosystem II receptor site. Mode of action Selective contact herbicide with a short duration of activity.    

Uses Contact herbicide used post-emergence in rice, to control broad-leaved and grass weeds, including Amaranthus retroflexus, Digitaria spp., Echinochloa spp., Panicum spp. and Setaria spp. Also used, in mixture with MCPA, in wheat. A mixture with carbaryl is used in citrus crops grown in sod culture. Phytotoxicity Phytotoxic to many broad-leaved crops. Normally phytotoxic to crops which have been treated with organophosphate or carbamate insecticides.     

TOXICOLOGICAL & ENVIRONMENTAL REVIEWS    

Oral Acute oral LD₅₀ for rats >2500, mice c. 1800 mg/kg. Skin and eye Acute percutaneous LD₅₀ (24 h) for rats >5000 mg/kg. Not irritating to skin and eyes (rabbits). Not a skin sensitiser (guinea pigs). Inhalation LC50 (4 h) for rats >1.25 mg/l air (dust). NOEL (2 y) for rats 400, dogs 600 mg/kg diet. ADI/RfD (EPA) RfD 0.009 mg/kg b.w. [2006]. Toxicity Class  WHO (a.i.) III; EPA (formulation) III (EC) EC classification Xn; R22| N; R50| concn. dep.    

ECOTOXICOLOGY    

Birds Acute oral LD₅₀ for mallard ducks 375, bobwhite quail 196 mg/kg. Dietary LC₅₀ (5 d) for mallard ducks 5627, bobwhite quail 2861 ppm. Fish LC₅₀ (48 h) for carp 8–11 mg/l. Daphnia LC₅₀ (48 h) 4.8 mg/l.