pyrazosulfuron-ethyl 10%WP in rice herbicide

Specifications

pyrazosulfuron-ethyl 98%TC and 10%WP
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NOMENCLATURE
Common name :pyrazosulfuron-ethyl

 

Classification: rice herbicide

IUPAC name: ethyl 5-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-1-methylpyrazole-4-carboxylate 

Chemical  name :ethyl 5-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]-1-methyl-1H-pyrazole-4-carboxylate 

CAS RN: [93697-74-6]     Development codes :NC-311 (Nissan)  

 

PHYSICAL CHEMISTRY
Mol. wt. 414.4     M.f. C14H18N6O7S  Form Colourless crystals.  M.p. 177.8-179.5 °C  V.p. 4.2 ´ 10-5 mPa (25 ºC)  KOW logP = 1.3 (unstated pH)  S.g./density 1.46 (20 ºC)  Solubility In water 9.96 mg/l (20 ºC). In methanol 4.32, hexane 0.0185, benzene 15.6, chloroform 200, acetone 33.7 (all in g/l, 20 ºC).  Stability Stable at 50 ºC for 6 months. Relatively stable at pH 7. Unstable in acidic or alkaline media.  pKa 3.7 

 

APPLICATIONS
Biochemistry Branched chain amino acid synthesis (ALS or AHAS) inhibitor. Acts by inhibiting biosynthesis of the essential amino acids valine and isoleucine, hence stopping cell division and plant growth. Selectivity derives from rapid metabolism (demethylation of methoxy group) in the crop. Metabolic basis of selectivity in sulfonylureas reviewed (M. K. Koeppe & H. M. Brown, Agro-Food-Industry, 6, 9-14 (1995)).  Mode of action Systemic herbicide, absorbed by roots and/or leaves and translocated to the meristems.  Uses Control of annual and perennial broad-leaved weeds and sedges, pre- or post-emergence in wet-sown and transplanted rice crops, at 15-30 g/ha.  Formulation types GR; SC; WG; WP.   

 

MAMMALIAN TOXICOLOGY
Oral Acute oral LD50 for rats and mice >5000 mg/kg.  Skin and eye Acute percutaneous LD50 for rats >2000 mg/kg. Non-irritating to skin and eyes (rabbits). Non-sensitising to skin (guinea pigs).  Inhalation LC50 for rats >3.9 mg/l air.  NOEL (78 w) for mice 4.3 mg/kg daily.  ADI 0.043 mg/kg.  Other Non-mutagenic in the Ames test. Non-teratogenic in rats and rabbits.  Toxicity class WHO (a.i.) III (Table 5) 

 

ECOTOXICOLOGY
Birds Acute oral LD50 for bobwhite quail >2250 mg/kg.  Fish LC50 (96 h) for rainbow trout and bluegill sunfish >180 mg/l; (48 h) for carp >30 mg/l.  Daphnia TLm (3 h) >40 ppm.  Algae I50 for green algae (Scenedesmus acutus) 1 ppm.  Bees LD50 (contact) >100 mg/bee. 

 

ENVIRONMENTAL FATE
Animals In rats, after 48 h, 80% of applied pyrazosulfuron-ethyl is excreted in urine and faeces. The major metabolic reaction is demethylation of the methoxy group.  Soil/Environment In soil, DT50 <15 d. In water, DT50 in buffer solution (pH 7), paddy fields or river water are c. 28 d.