Electron ionization mass spectra of monosaccharide O-methyloxime trifluoroacetates

Abstract

Electron ionization mass spectra for trifluoroacetate (TFA) derivatives of aldose, ketose, and deoxyaldose O-methyloximes are reported. Typical fragmentation patterns include loss of F, CH 3O, CF 3CO, or CF 3CO 2 fragments from the generally observable parent ion, as well as cleavage between each of the sugar CC chain bonds. The most intense ions result from loss of trifluoroacetic acid and/or trifluoroacetic anhydride from these primary fragments. Suitable high-mass and fragmentation ions are present to make this technique a useful structural probe. During the preparation of fructose TFA O-alkyloximes, partial conversion to 1-chloro-1-deoxyfructose derivatives is observed due to displacement of an O-trifluoroacetyl group by chloride ions present in the reaction mixture.