Best Terbutryn Supplier
Common name: terbutryn; terbutryne
IUPAC name: N2-tert-butyl-N4-ethyl-6-methylthio-1,3,5-triazine-2,4-diamine
Chemical Abstracts name: N-(1,1-dimethylethyl)-N'-ethyl-6-(methylthio)-1,3,5-triazine-2,4-
Composition: Tech. is 98%.
Mol. wt.: 241.4;
Form: White powder.
B.p.: 274C/101 kPa.
V.p.: 0.225 mPa (25C) (OECD 104).
KOW: logP = 3.65 (25 oC, unionised).
Henry: 1.5x10-3 Pa m3 mol-1 (calc.)
S.g./density: 1.12 (20C).
Solubility: In water 22 mg/l (22C). In acetone 220, hexane 9, n-octanol 130, methanol 220, toluene 45 (all in g/l, 20C). Also readily soluble in dioxane, diethyl ether, xylene, chloroform,
carbon tetrachloride, dimethylformamide. Slightly soluble in petroleumether.Stability:
Stable under normal conditions. The methylthio group is hydrolysed in the presence of
strong acids or alkalis. At 70C, no significant hydrolysisCcurs at pH 5, 7, or 9. pKa:
4.3, weak base.
Biochemistry: Photosynthetic electron transport inhibitor at the photosystem II receptor
Mode of action: Selective herbicide, absorbed by the roots and foliage, with translocation
acropetally through the xylem, and accumulation in the apical meristems.
Uses: Used pre-emergence in winter cereals, at 1-2 kg a.i./ha, to control blackgrass and annual meadow grass. Among the autumn-germinating broad-leaved weeds controlled are chickweed, mayweed, poppies and speedwell, but cleavers are rather resistant. Other pre-emergence uses are on sugar cane and sunflowers; and, in mixture with terbuthylazine, on beans, peas and potatoes. In mixture with metolachlor, used in cotton and peanuts. Also used post-emergence (0.2-0.4 kg/ha) in cereals, (1-3 kg/ha) in sugar cane, and as a directed spray in maize. As 'Clarosan', it is used to control algae and submerged vascular plants in waterways, reservoirs and fish ponds.
Phytotoxicity: Not safe for post-emergence use in cereals which are under stress.
Formulation types: FW; GR; MG; SC; WP.
Oral: Acute oral LD50 for rats 2500, mice 500 mg/kg.
Skin and eye: Acute percutaneous LD50 for rats >2000, rabbits >20 000 mg/kg. Not a skin or eye irritant (rabbits). Not a skin sensitiser (guinea pigs).
Inhalation: LC50 (4 h) for rats >2200 mg/m3 air.
NOEL: (2 y) for rats 300 ppm, for mice 3000 ppm; (1 y) for dogs 100 mg/kg diet daily.
ADI: 0.027 mg/kg b.w.
Toxicity class: WHO (a.i.) III (Table 5); EPA (formulation) III
Birds: Dietary LC50 (5 d) for bobwhite quail 5000, mallard ducks >4640 mg/kg b.w.
Fish: LC50 (96 h) for rainbow trout 1.1, bluegill sunfish 1.3, carp 1.4.
Daphnia: LC50 (48 h) 2.66 mg/l.
Algae: EC50 (7 d) for Selenastrum capricornutum 0.013 mg/l.
Other aquatic spp.: EC50 (48 h) for Quahog clam 5.6 mg/l.
Bees: Not toxic to bees. LD50 (oral) >225 ug/bee; (contact) >100 ug/bee.
Worms: LC50 for Eisenia foetida 170 mg/kg.
Animals: In mammals, following oral administration, 73-85% is eliminated as the dealkylated hydroxy metabolite in the faeces within 24 hours.
Plants: In plants, terbutryn is degraded in a manner similar to other methylthio-s-
triazines, viz. by oxidation of the methylthio group to hydroxy metabolites, and by
dealkylation of the side-chains. Conjugates are also formed.
Soil/Environment: Soil micro-organisms play an important role in the degradation of
terbutryn. Residual activity in soil is 3-10 weeks, depending upon rate of application,
soil type, and weather. DT50 in soil 14-50 d. Koc 2000, indicating a low leaching
potential. Degradation in aquatic systems is caused by microbial processes; photolysis also contributes. Considerable amounts of terbutryn are removed from the water by adsorption to the sediment.