Synthesis of (diethyl-d10) coumaphos and related compounds

Two deuterated insecticides were prepared for use as internal standards for gas−liquid chromatographic−mass spectrometric analyses. Diethyl chlorothiophosphate-d10 was prepared by reaction of ethanol-d6 with P2S5 to give labeled diethyldithiophosphoric acid, followed by chlorination. Treatment of the acid chloride with 3-chloro-4-methyl-7-hydroxycoumarin and potassium carbonate in acetone at reflux gave labeled coumaphos. An analogous reaction with 4-methyl-7-hydroxycoumarin gave labeled potasan, and the technique should be usable for synthesis of labeled forms of other dialkyl thiophosphate insecticides. Keywords: Coumaphos-d10; potasan-d10; deuterated pesticides; labeled pesticides