Transformation of DAEP (S-(2-acetylaminoethyl) dimethyl phosphorodithioate) under various oxidative conditions.

Abstract

14C-DAEP [S-(2-acetylaminoethyl) dimethyl phosphorodithioate] was subjected to four different oxidative conditions, and the products were identified. On peracid oxidation in dichloromethane, DAEP gave the oxon (1) predominantly, and 2-acetylaminoethyl dimethoxyphosphinyl disulfide (3), N-acetylcysteamine (10), its oxidized dimer (11) and a further oxidation product of compound 11. This indicates that an unstable phosphorus oxythionate was initially formed, which lost sulfur, was rearranged, and hydrolyzed to give these products. Under other conditions, phosphinyl disulfide 3 was not found. DAEP was metabolized in vitro with a rat liver microsome-NADPH system via oxidation. The aqueous reaction condition prevented the formation of compound 3 from the intermediate, which predominated as well as the oxon formation under anhydrous or close conditions. The formation of various products with sunlight irradiation on glass plates or on bean leaves could be interpreted by oxidation at P=S, C1 and C2 positions, demethylation, and deacetylation, followed by further transformation. The initial formation of phosphorus oxythionate seems to play an important role in the oxidation of the organothionophosphorus compound.