Chemical Properties
Methoxsulam, also known as amidosulfanilamide, is a colorless crystal in pure form with a melting point of 208℃ (decomposition). Vapor pressure＜1×10-4mPa(20℃). Relative density 1.618(20℃), KowlgP:1.08(pH 4), -1.01(pH 7), -1.60(pH 9), Henry's constant <1.36×10-8Pa -m3/mol(pH 7,20℃). Solubility in water (20℃, g/L): distilled water 0.0626, buffer solution 0.0164 (pH 4), 3.20 (pH 7), 13.7 (pH 9); Solubility in other solvents (g/L, 20℃): methanol 1.01, acetone 2.79, ethyl acetate 2.17, 1,2-dichloroethane 3.94, octanol 0.0730, xylenol 0.0352, n-heptane ≤ 0.001. pH 5, 7 and 9 are stable in water at 25℃, photolysis in water DT503.2d. pKa 4.67.
Uses
Pyroxsulam is a herbicide containing auxin hormone and two acetolactate synthase inhibitors for controlling weeds.
Mechanism of action
Very broad-spectrum having both foliar and soil activity, translocates and inhibits acetolactate synthase
Synthesis
Example 5 Preparation of N-(5,7-dimethoxy[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)-2-methoxy-4-(trifluoromethyl)pyridine-3-sulfonamide: 2-Amino-5,7-dimethoxy[1,2,4]triazolo[1,5-a]pyrimidine (59 g, 0.30 mol) was mixed with 2-methoxy-4-(trifluoromethyl)pyridine- 3-sulfonyl chloride (86 g, 0.31 mol, 1.03 eq.) were mixed in acetonitrile (210 mL) and 3,5-dimethylpyridine (120 g, 93% technical grade). DMSO (1.3 g, 0.017 mol) was added and the reaction mixture was stirred at room temperature for 12 hours. Subsequently, the reaction mixture was treated with 4N HCl (310 mL) and continued to be stirred at 25 °C for 2 hours and then cooled to 10 °C. The solid product was collected by filtration, washed sequentially with a 2:1 v/v water-acetonitrile mixture (160 mL) and 95% ethanol (2 x 80 mL), and finally dried under vacuum at 100 °C to afford 112 g of the target product, which was determined to have a purity of 98 wt% (84% yield calculated as 2-amino-5,7-dimethoxy[1,2,4]triazolo[1,5-a]pyrimidine (the yield calculated as 2-methoxy-4-(trifluoromethyl)pyridine-3-sulfonyl chloride was 82%).
References
[1] Patent: US2005/215570, 2005, A1. Location in patent: Page/Page column 5
Pesticide Type
Herbicide; Graminicide
![2-Amino-5,7-dimethoxy-1,2,4-triazolo[1,5-a]pyrimidine](/CAS/GIF/13223-43-3.gif)
