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NOMENCLATURE Common name: bispyribac-sodium
Classification: herbicide
IUPAC name :sodium 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoate
Chemical name :sodium 2,6-bis[(4,6-dimethoxy-2-pyrimidinyl)oxy]benzoate
CAS RN [125401-75-4] for acid; [125401-92-5] for sodium salt
PHYSICAL CHEMISTRY Composition Tech. is >93%. Mol. wt. 452.4 M.f. C19H17N4NaO8; C19H18N4O8 for the acid Form White powder. M.p. 223-224 °C V.p. 5.05 ´ 10-6 mPa (25 ºC) KOW logP = -1.03 (23 °C) Henry 3.12 ´ 10-11 Pa m3 mol-1 (calc.) S.g./density Bulk density 0.0737 (20 °C, CIPAC MT 3) Solubility In water 73.3 g/l (25 ºC). In methanol 26.3, acetone 0.043 g/l (25 °C). Stability Stable in water; DT50 >1 y (pH 7 & 9), 448 h (pH 4). Stable to light. Not decomposed after 14 d at 55 °C. pKa 3.05
APPLICATIONS Biochemistry Branched chain amino acid synthesis (ALS or AHAS) inhibitor. Mode of action Selective, systemic post-emergence herbicide, absorbed by foliage and roots. Uses Control of grasses, sedges and broad-leaved weeds, especially Echinochloa spp., in direct-seeded rice, at rates of 15-45 g/ha. Also used to stunt growth of weeds in non-crop situations. Formulation types SC; water-soluble liquid.
MAMMALIAN TOXICOLOGY Oral Acute oral LD50 for male rats 4111, female rats 2635, male and female mice 3524 mg/kg. Skin and eye Acute percutaneous LD50 for rats >2000 mg/kg. Non-irritating to skin; slightly irritating to eyes (rabbits). Inhalation LC50 (4 h) for rats >4.48 mg/l. NOEL (2 y) for male rats 20 mg/kg diet (1.1 mg/kg b.w. daily), female rats 20 mg/kg diet (1.4 mg/kg b.w. daily), male mice 14.1 mg/kg daily, female mice 1.7 mg/kg b.w. daily. ADI 0.011 mg/kg. Other Non-mutagenic in the Ames test, and non-teratogenic to rats and rabbits. Toxicity class WHO (a.i.) III (Table 5)
ECOTOXICOLOGY Birds Acute oral LD50 for bobwhite quail >2250 mg/kg. Dietary LC50 (5 d) for bobwhite quail and mallard ducks >5620 mg/kg diet. Fish Acute LC50 (96 h) for rainbow trout and bluegill sunfish >100 ppm. Daphnia LC50 (48 h) >100 ppm. Algae EC50 (120 h) for Selenastrum capricornutum 3.4 mg/l, NOEC 0.625 mg/l. Bees LD50 (oral) >200 mg/bee; LC50 (contact) >7000 mg/l spray. Worms NOEL (14 d) for Eisenia foetida >1000 mg/kg soil.
ENVIRONMENTAL FATE Animals >95% of dose applied to rats was excreted in urine and faeces within 7 d. Plants Following application to foliage and soil at 5-leaf stage of rice plants, c. 10% of carbon label was distributed between straw and roots at harvest. Soil/Environment In soil, DT50 <10 d (flooded and upland conditions).
bispyribac-sodium herbicide 10%SC in Herbicide