Title: SYNTHESIS OF (ETHYL-D10) DEUTERATED COUMAPHOS AND RELATED COMPOUNDS
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 13, 2000
Publication Date: N/A
Interpretive Summary: The honey bee is an important beneficial insect, both for its production of honey and wax and for its pollinataing activities, but it has been threatened by introduced parasites, particularly the Vattoa mite. Coumaphos is an insecticide that has recently received an emergency registration for use as a control of Varroa mites infesting honey bee hives, but no residues in hive products are allowed. Improved methods of analysis are desirable. To facilitate coumaphos residue analyses, an isotope-labeled coumaphos was prepared. It will enable better measurement of losses during isolation of trace amounts of coumaphos in honey and beeswax. This development is important to scientists and regulators concerned with residues of coumaphos in agricultural products. Since the synthesis can be easily extended to many other labeled organophosphate insecticides, other residue analyses shoud become more accurate.
Two deuterated insecticides were prepared for use as internal standards for GC/mass spectrometric analyses. Diethly chlorothiophospate-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 refluxing acetone gave labeled coumaphos. An analogous reaction with 4-methyl-7-hydroxycoumarin gave labeled potasan, and the technique can be used for synthesis of labeled forms of most dialkyl thiophosphate insecticides.