ISOMERIZATION OF ALKYL PHOSPHOROTHIONATES INDUCED BY CARBOXYLIC ACID AMIDES

Alkyl phosphorothionates are isomerized to phosphorothiolates by the catalytic action of dimethylformamide. Methyl parathion (O, O-dimethyl O-p-nitrophenyl phosphorothionate) and sumithion (O, O-dimethyl O-3-methyl-4-nitrophenyl phosphorothionate) are more reactive than ethyl parathion (O, O-diethyl O-p-nitrophenyl phosphorothionate). Saligenin cyclic methyl phosphorothionate (salithion) decomposed to give a complicated pattern of products on thin layer chromatography. Besides S-methyl isomer, desmethyl sumithion (O-methyl O-3-methyl-4-nitrophenyl hydrogen phosphorothioate), 3-methyl-4-nitrophenol, methyl formate and dimethylamine were detected as reaction products from sumithion. Some other carboxylic amides including dimethylacetamide, acetamide and urea are also active. A reaction mechanism is proposed. © 1961 Taylor & Francis Group, LLC.