Reassessment of the methyl derivatization reaction of carbamates with sodium hydride/dimethyl sulfoxide/methyl iodide for their determination by gas chromatography

• Published in: Journal of Chromatography A 2006-11, Vol.1132 (1), p.241-247
• Main Authors: Crespo-Corral, E., Santos-Delgado, M.J., Mª Polo-Díez, L., Sanz-Perucha, J.
• Format: Article
• Language: English
• Subjects: Alkyl derivatization reaction; Analytical chemistry; Carbamates; Carbamates - analysis; Carbamates - chemistry; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography, Gas - methods; Dimethyl Sulfoxide - chemistry; Exact sciences and technology; Gas chromatographic methods; Gas chromatography (GC); Hydrocarbons, Iodinated - chemistry; Molecular Structure; Reproducibility of Results
• ISSN: 0021-9673
• DOI: 10.1016/j.chroma.2006.07.056

A deep revision of the carbamate methyl derivatization reaction with sodium hydride/dimethyl sulfoxide/methyl iodide was carried out. Representative carbamates, R 1–NH–COO–R 2, mainly N-methyl and N-aryl ones, have been studied in order to clarify which carbamates undergo this reaction. Two possible reaction routes are proposed; the route depends on the carbamate substituent (–OR 2 group) more than on the methyl or aryl groups joined to the NH moiety as literature indicates. The classification of carbamates in N-methyl and N-aryl is not suitable to predict the methylation pathway. A laboratory-made closed reactor allows handling the reagents involved, minimizing hazards and simplifying the procedure for rapid analysis.