Nuclear Magnetic Resonance Identification of New Sulfonic Acid Metabolites of Chloroacetanilide Herbicides

The detection of the sulfonic acid metabolites of the chloroacetanilide herbicides acetochlor, alachlor, butachlor, propachlor, and, more recently, metolachlor in surface and ground water suggests that a common mechanism for dechlorination exists via the glutathione conjugation pathway. The identification of these herbicides and their metabolites is important due to growing public awareness and concern about pesticide levels in drinking water. Although these herbicides are regulated, little is known about the fate of their metabolites in soil. The sulfonic acid metabolites were synthesized by reaction of the parent compounds with an excess of sodium sulfite. Acetochlor, alachlor, butachlor, metolachlor, and propachlor and their sulfonic acid metabolites were studied by nuclear magnetic resonance spectroscopy and fast atom bombardment mass spectrometry. This paper provides a direct method for the preparation and characterization of these compounds that will be useful in the analysis and study of chloracetanilide herbicides and their metabolites.