10346. Pyroxsulam

Nomenclature

CAS number: 422556-08-9
N-(5,7-Dimethoxy[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)-2-methoxy-4-(trifluoromethyl)-3-pyridinesulfonamide; XDE-742; Admitt (Dow AgroSci.); Powerflex (Dow AgroSci.).
C14H13F3N6O5S; mol wt 434.35.
C 38.71%, H 3.02%, F 13.12%, N 19.35%, O 18.42%, S 7.38%.

Description and references

Post-emergent herbicide for control of weeds in wheat and other cereal crops. Acetolactate synthase (ALS) inhibitor. Prepn: T. C. Johnson et al., WO 0236595; eidem, US 6559101 (2002, 2003 both to Dow AgroSci.); B. M. Bell et al., Org. Process Res. Dev. 10, 1167 (2006) DOI. Large scale process: M. A. Gonzalez et al., ibid. 12, 301 (2008) DOI. Review of activity and environmental fate: J. Becker et al., J. Plant Dis. Protect. XXI, 623-628 (2008). Comprehensive description: Pyroxsulam Pesticide Fact Sheet (U.S. EPA, February, 2008) 55 pp.

Chemical structure

Properties

White needles from methanol/acetonitrile. mp 208.3°. d20 1.62. pKa 4.7. Vapor pressure (20°): <7.5 × 1010 Pa. Log P (octanol/water): 1.08 (pH 4); 1.01 (pH 7). uv max: 297 nm (ε 8000). Soly at 20° (mg/l): 1,2-dichloromethane 39400; acetone 27900; ethyl acetate 21700; methanol 10100; xylene 352; octanol 730; heptane <10. Soly in water at 20° (g/l): 0.0164 (pH 4); 3.20 (pH 7). LD50 in rats (mg/kg): >2000 orally; >2000 dermally; LC50 in rainbow trout: >87 mg/l (Becker). LC50 in rats (mg/l): >5.12 (U.S. EPA).

Use

Herbicide.