O,O-dimethyl-dithiophosphoryl-acetic acid N-monomethylamide - obtd from O,O-dimethyldithiophosphate, reaction with methyl-2-chloroacetate, then monomethylamine

摘要

O,O-dimethyl-dithiophosphoryl acetic acid N-mono-methylamide (I) is prepd. by reacting phosphorosulphides with methanol in toluene to give O,O-dimethyl-dithiophosphoric acid (II) which is reacted with aq. alkali metal hydroxides or -carbonates to form the salts. The soln. is then reacted with 2- chloroacetic acid methyl ester (III) at pH 5.5-7 and 80-100 degrees for 10-15 min. and the product is purified by steam-distn. at 60-65 degrees at a reduced pressure of 140-150 mm Hg, the vol. ratio steam : ester being (0-25:1). The methylester obtained (IV) is reacted with aq. methylamine at 0-10 degrees C in the presence of a surface-active agent whereby a part of the slurry contg. (I) is refluxed back to the reactor. (I) is a known cpd. with insecticidal activity. The process may be continuous giving high yields of very high purity.