IDENTIFICATION
Common name: Pretilachlor
Other name: pretilachlor (BSI, E- ISO); pretilachlore ((m) F-ISO)
Iupac name: 2-chloro-2`,6`-diethyl-N-(2-propoxyethyl)acetanilide
Chemical abstracts name: 2-chloro-N-(2,6- diethylphenyt)-N-(2-propoxyethyl)acetamide
Type: Herbicide
CAS RN: [51218 49 6]
M.F.: C17H26ClNO2
Mol Wt: 311.9
PHYSICAL CHEMISTRY
Form (appearance): Colourless liquid.
B.P.: 135℃/0.001 mmHg
V.P.: 0.133 mPa (20℃)
F.P.: 129℃ (EEC A.9)
S.G.: 1.076 (20℃)
Solubility.: In water 50 mg/l (20℃). Very soluble in benzene, hexane, methanol and dichloromethane.
Stability: Relatively stable to hydrolysis; DT50 (catc.) (20℃) >200 d (pH 1-9), 14 d (pH 13).
Henry: 8.1 × 10-4 Pa m3 mol-1
KowlogP: 4.08 (shake flask)
APPLICATION
Formulation types: EC; GR.
Biochemistry: Cell division inhibitor.
Mode of action: Selective herbicide. It is taken up readily by the hypocotyls, mesocotyls and coleoptites, and, to a lesser extent, by the roots of germinating weeds.
Uses: Herbicide effective against main annual grasses, broad leaved weeds and sedges in transplanted and seeded rice, at 1-1.25 kg/ha.
Phytotoxicity: Applied alone, pretilachlor will cause iniury to direct-seeded rice.
MAMMALIAN TOXICOLOGY
Oral: Acute oral LD50 for rats 6099 mg/kg.
Skin and eye: Acute percutaneous LD50 for rats >3100 mg/kg. Moderate irritant to skin; non irritant to eyes (rabbits).
Inhalation: LC50 (4 h) for rats >2.8 mg/l air.
Noel: (2 y) for rats 30, mice 300 ppm; (0.5 y) for dogs 300 ppm.
ADI: 0.018 mg/kg.
Toxicity: WHO (a.i.) 111 (Table 5)
EC hazard: (R38, R43)
ECOTOXICOLOGY
Birds: Non-toxic to birds; LD50 for Japanese quail >10000 mg/kg. LC50 for Japanese quail >1000 ppm.
Fish: LC50 (96 h) for rainbow trout 0.9, catfish 2.7, crucian carp 2.3 mg/l.
Daphnia: LC50 13 mg/l.
Algae: EC50 for Selenastrum capricornutum 0.002 mg/l.
Worms: Bees LD50 (contact) 93 μg/bee.
ENVIRONMENTAL FATE
Plant: Substitution of the chlorine atom to form a conjugate. Cleavage of the ether bond to yield an ethyl alcohol derivative. Hydrolytic and reductive removal of the chlorine atom.
Animals: Substitution of the chlorine atom for glutathione to form a conjugate. Cleavage of the ether bond to yield an ethyl alcohol derivative. Both metabolites are susceptible to further degradation.
Soil/Environment: Applied to paddy water, pretilachlor disappeared from the water by adsorption to the soil, where it is rapidly degraded under practical conditions, median DT50 (lab.) 30 d. Due to strong soil adsorption, unlikely to leach.
|
