TRIFLUOROACETYLATION OF PESTICIDES AND METABOLITES CONTAINING A SULFOXIDE MOIETY FOR QUANTITATION BY GAS-CHROMATOGRAPHY AND CHEMICAL CONFIRMATORY PURPOSES

The Pummerer reaction was evaluated as a means of derivatizing pesticides and their metabolites, which contain a S→0 moiety for analysis by gas chromatography. Dasanit, dasanit oxon, and the sulfoxides of Mesurol, Nemacur, and aldicarb all readily reacted with trifluoroacetic anhydride at RT/15 min to give trifluoroacetoxymethyl sulfide analogues. For compounds possessing an NH moiety, more vigorous reaction conditions were required in order to form the di-trifluoroacetyl derivative as a single product in high yield. Oxydemeton-methyl, oxycarboxin, Counter, and phorate sulfoxides also reacted with trifluoroacetic anhydride, but gave anomalous products. The secondary trifluoracetoxy moiety of oxydemeton-methyl thermally decomposed on-column to give cis- and trarcs-dehydrooxydemeton-methyl. Oxycarboxin underwent both an additive and transannular Pummerer reaction, depending on the reaction conditions, while phorate and Counter sulfoxides were transformed to their respective oxons. © 1978, American Chemical Society. All rights reserved.