Preparation of O,S-dimethyl-thiolophosphoric acid amide

Abstract

A simplified process for preparing the known insecticide 0,S-dimethylthiolphosphoric acid amide of the formula ##STR1## inexpensively, in high purity and with minimum waste water and gas which would have to be specially treated to avoid environmental pollution, comprises (a) contacting 0,0 dimethyl-thiophosphoric acid amide of the formula ##STR2## in which Me is sodium or potassium, separating the aqueous phase, (b) optionally adding an organic solvent to the aqueous phase, and reacting the mass with methyl bromide or methyl chloride thereby to form the 0,S-dimethyl-thiolphosphoric acid amide, and either (c) extracting the amide with a sparingly water-miscible solvent thereby to dissolve the amide, or (d) concentrating the reaction mixture from the methylation step (b), by distillation, until the alkali metal halide formed has separated out, and filtering off the alkali metal halide.

Dependencies are inferred from the claim text.