Photodegradation of herbicide triasulfuron

Triasulfuron was degraded in aqueous solution by ultraviolet irradiation to yield 2-chloroethoxybenzene and (4-methoxy-6-methyl-1,3,5-triazin-2-yl)ure a. The reaction followed first-order kinetics. In sunlight, the reaction wa s slower and afforded these two photoproducts together with 2-amino-4-metho xy-6-methyltriazine and 2-(2-chloroethoxy)benzenesulfonamide. The latter co mpounds arise from hydrolytic cleavage of the sulfonylurea bridge of triasu lfuron because of the acidity of the reaction medium due to the loss of sul fur dioxide. A mechanism which accounts for the formation of the photoprodu cts is proposed. (C) 1999 Society of Chemical Industry.