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Physical Properties
Molecular weight:288.3; Physical form:Off-white, fine to lumpy powder, with slight musty odour. Density:0.3 (20 °C); Composition:A mixture of m- and p- isomers. Melting point:113-153 °C; Flash point:>93 °C (closed cup); Vapour pressure:1.5 ×10-3 mPa (25 °C); Partition coefficient(n-octanol and water):logP = 1.54 (p- isomer), 1.82 (m- isomer); pKa:2.9 (23.5 °C); Solubility:In distilled water 1370 (m- isomer), 857 (p- isomer) mg/kg. Mixed isomers in acetone 230, dimethyl sulfoxide 216, isopropanol 183, methanol 309, toluene 45, n-heptane 0.6, n-hexane 0.4; Stability:Imazamethabenz-methyl is stable in storage at 25 °C for 24 months, at 37 °C for 12 months, or at 45 °C for 3 months. Hydrolysis is rapid at pH 9 but slow at pH 5 and pH 7.
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Toxicology
Oral:Acute oral LD50 for male and female rats >5000 mg/ kg. Percutaneous:Acute percutaneous LD50 for male and female rabbits >2000 mg/kg. Non-irritating to skin; reversible eye irritant (rabbits). Not a skin sensitiser in guinea pigs. Inhalation: LC50 for male and female rats >5.8 mg/l. Phytotoxicity:Cereals and sunflowers are highly tolerant to post-emergence applications. Sugar beet, beetroot, lentils, rape, mustard, tomatoes and broccoli should not be
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Environmental Profile
Ecotoxicology:
Bees: LD50 (contact) >100 μg/bee.Birds:Acute oral LD50 for bobwhite quail and mallard ducks >2150 mg/kg. Dietary LC50 (8 d) for bobwhite quail and mallard ducks >5000 mg/ kg diet.Daphnia: LC50 (48 h) >100 mg/l.Fish: LC50 (96 h) for bluegill sunfish and rainbow trout >100 mg/l.Worms:>123 ppm.
Environmental fate:
Animals:Rapidly excreted by animals (rats, goats, hens) after ingestion; low levels of residues found in blood and tissues of rats, in milk and tissues of lactating goats, and in the eggs and tissues of laying hens.Soil:Imazamethabenz-methyl is slowly degraded to corresponding free acids in sandy loam and clay loam soils under both aerobic and anaerobic conditions; DT50 25-45 d; hydrolysis increases with increasing pH. Subject to photolytic degPlant:In plants, the methyl group of the benzene moiety is oxidised to a hydroxymethyl group; glucoside conjugates have been identified as secondary metabolites.
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Transport Information
Signal Word:DANGER; Hazard Class:Ib(Highly hazardous)