Specification :

Pyrazosulfuron-Ethyl

pyrazosulfuron-ethyl
Common name: pyrazosulfuron-ethyl
IUPAC name: ethyl 5-( 4, 6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl) -1-methylpyrazole-4-carboxy late
Chemical Abstracts name: ethyl 5-[ [ [ [ ( 4, 6-dimethoxy-2-pyrimidinyl) amino] carbonyl] amino] sulfonyl] -1-methyl-1 H-pyrazole-4-carboxylate
CAS RN: [ 93697-74-6]

pyrazosulfuron
Common name: pyrazosulfuron
IUPAC name: 5-( 4, 6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl) -1-methylpyrazole-4-carboxy lic acid
Chemical Abstracts name: 5-[ [ [ [ ( 4, 6-dimethoxy-2-pyrimidinyl) amino] carbonyl] amino] sulfonyl] -1-methyl-1 H-pyrazole-4-carboxylic acid
CAS RN: [ 98389-04-9]

PHYSICAL CHEMISTRY
pyrazosulfuron-ethyl
Mol. wt.: 414.4; M.f.: C14H18N6O7S; Form: Colourless crystals. M.p.: 177.8-179.5 ° C. V.p.: 4.2x10-5 mPa ( 25 º C) . KOW: logP = 1.3 ( unstated pH) . S.g./ density: 1.46 ( 20 º C) . Solubility: In water 9.96 mg/ l ( 20 º C) . In methanol 4.32, hexane 0.0185, benzene 15.6, chloroform 200, acetone 33.7 ( all in g/ l, 20 º C) . Stability: Stable at 50 º C for 6 months. Relatively stable at pH 7. Unstable in acidic or alkaline media. pKa: 3.7

pyrazosulfuron
Mol. wt.: 386.3; M.f.: C12H14N6O7S

APPLICATIONS
pyrazosulfuron-ethyl
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.
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
pyrazosulfuron-ethyl
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
pyrazosulfuron-ethyl
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 ug/ bee.

ENVIRONMENTAL FATE
pyrazosulfuron-ethyl
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