Degradation of Sulfosulfuron, a Sulfonylurea Herbicide, As Influenced by Abiotic Factors

A laboratory experiment was conducted to study the stability of sulfosulfuron [1-(2-ethylsulfonylimidazo[1,2-a]pyridin-3-ylsulfonyl)-3-(4,6-dimethoxypyrimidin-2yl) urea] in a controlled environment of pH, temperature, solvent, and surface. In another experiment the photostability of sulfosulfuron was studied after irradiation under sunlight. Under alkaline condition, it yielded 1-(2-ethylsulfonylimidazo[1,2-a]pyridin-3-yl-3-(4,6-dimethoxypyrimidin-2-yl) amine, and under acidic condition it degraded to 1-(2-ethylsulfonylimidazo[1,2-a] pyridin)-3-sulfonamide and 4,6-dimethoxy-2-aminopyrimidine. Photodegradation included breaking of a sulfonylurea bridge, as in the case of acidic hydrolysis and contraction of the sulfonylurea bridge was the major pathway of alkaline hydrolysis.