Tebuthiuron

Tebuthiuron

丁噻隆

1-(5-tert-butyl-1,3,4-thiadiazol-2-yl)-1,3-dimethylurea

N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea

34014-18-1

C₉H₁₆N₄OS

Herbicides > Urea herbicides

Herbicide

Molecular weight:228.3; Physical form:Colourless, odourless solid. Melting point:161.5-164 °C (decomp.); Vapour pressure:0.27 mPa (25 °C); Henry constant:2.47 × 10-5 Pa m3 mol-1 ( calc.); Partition coefficient(n-octanol and water):logP = 1.79 ( pH 7, 25 °C); Solubility:In water 2.5 g/l (25 °C). In benzene 3.7, hexane 6.1, 2-methoxyethanol 60, acetonitrile 60, acetone 70, methanol 170, chloroform 250 (all in g/l, 25 °C).; Stability:Stable at 52 °C (highest storage temperature tested). Stable in aqueous media between pH 5 and 9. On hydrolysis, DT50 (25 °C) >64 d ( pH 3, 6 and 9).;

Oral:Acute oral LD₅₀ for mice 579, rats 644, rabbits 286, dogs >500, cats >200 mg/kg. Percutaneous:No skin irritation in rabbits when applied at 200 mg/kg; no eye irritation when applied at 71mg/kg. Phytotoxicity:Not to be applied near desirable trees or plants. ADI:0.15 mg/kg b.w.

Ecotoxicology: 
Algae: EC₅₀ for Anabaena 4.06, Navicula 0.081, Selenastrum 0.05, Skeletonema 0.05 ppm.Bees:LD₅₀ >100 µg/bee.Birds:Acute oral LD₅₀ for chickens, bobwhite quail, and mallard ducks >500 mg/kg. In 1 mo feeding trials, chickens receiving 1000 mg/kg showed no ill-effects.Daphnia: LC₅₀ 297 ppm.Fish: LC₅₀ (96 h) for rainbow trout 144, goldfish and fathead minnow >160, bluegill sunfish 112 mg/l.Other aquatic spp.: EC₅₀ for Lemna 0.135 ppm. 

Environmental fate: 
Animals:The major metabolites in mammals were formed by N-demethylation of the substituted urea side-chain (D. M. Morton & D. G. Hoffman, J. Toxicol. Environ. Health, 1976, 1, 757-768).Soil:Some microbial breakdown occurs in soil, but this is not the predominant mode of degradation. Loss due to photodecomposition and volatilisation is negligible. Half-life in soil is considerably greater in soils with low moisture content, and in high organiPlant:In plants, the principal metabolic pathways involve N-demethylation and hydroxylation of the tert-butyl side-chain.

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