Reassessment of the methyl derivatization reaction of carbamates with sodium hydride/dimethyl sulfoxide/methyl iodide for their determination by gas chromatography.
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.
Crespo-Corral
E
E
Department of Analytical Chemistry, Faculty of Chemistry, Complutense University of Madrid, 28040 Madrid, Spain. ecrespoc@quim.ucm.es <ecrespoc@quim.ucm.es>
Santos-Delgado
M J
MJ
M Polo-Díez
L
L
Sanz-Perucha
J
J
D002219:Carbamates / Q000032:analysis* / Q000737:chemistry; D002849:Chromatography, Gas / Q000379:methods*; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D006847:Hydrocarbons, Iodinated / Q000737:chemistry*; D015394:Molecular Structure; D015203:Reproducibility of Results
D002219:Carbamates; D006847:Hydrocarbons, Iodinated; C014055:methyl iodide; D004121:Dimethyl Sulfoxide