Synthesis and spectroscopic characterization of acetyl-Clx (x = 0,1,2 or 3) and nitroso derivatives of carbaryl and three possible metabolites.

Acetyl-Clx (x = 0,1,2 or 3) and nitroso derivatives of carbaryl, 1-naphthol. 5-hydroxycarbaryl, and 1,5-naphthalenediol were synthesized. Compounds were characterized by infrared, mass, and nuclear magnetic resonance spectroscopy. N-chloroacetylation (Cl = 0,1,2, or 3) of carbaryl was readily accomplished through the pyridine-catalyzed reaction of carbaryl with the appropriate acid chlorides. Trichloroacetylation was also possible through the pyridine-catalyzed reaction with the anhydride. N-nitrosation could also be done readily. N-nitroso- and N-trichloroacetyl carbaryl underwent decomposition to carbaryl on exposure to atmosphere moisture and could be maintained in the pure state only with difficulty. The other derivatives were stable under normal storage conditions.

Gas chromatographic evaluation of some N-derivatives of intact carbaryl.

Gas chromatographic (GLC) detection of aryl N-methylcarbamates as the N-acetyl-Clx or N-nitroso derivatives of the intact molecule was explored using carbaryl as the model compound. These derivatives were designed for use with the microcoulometric detector for chlorine and the solution conductivity detector for nitrogen but response to the electron capture detector was also studied. GLC characteristics of the derivatives were evaluated in terms of thermal stability and detector response. N-Trichloracetyl and N-nitroso carbaryl underwent extensive decomposition in the GLC system. Although the N-monochloroacetyl derivatives were also subject to thermal decomposition, they gave sufficient linearity and sensitivity with the microcoulometric detector for analysis at the residue level. N-Acetyl carbaryl was thermally stable and the response of electrolytic conductivity and the electron capture detectors were adequate for residue analysis.