ISSN:
0030-493X
Schlagwort(e):
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The field desorption mass spectral behavior of several hydroxyammoniocarboxylates was studied at both low and high emitter heating currents. The molecular weights of these thermally unstable compounds can be determined directly from the low emitter current (〈10 mA) field desorption mass spectra, which are dominated by [xM+H]+ and [xM+H—CO2]+ ions (1≥x≥4). At higher emitter currents (∼20 mA), pyrolytic processes become important. These include intermolecular transfer of a single alkyl group yielding [M+alkyl]+ ions, intermolecular isomerization producing a hydroxyaminoester as the rearranged form of the molecule, and elimination of alcohol from the rearranged molecule, producing γ or δ lactones. The distribution of pyrolysis products does not depend significantly on the length of the carboxylate chain, but does appear to depend upon the chain length of the alkyl substituent on nitrogen. The spectra of molecules containing a long alkyl substituent (e.g. C14H29, C22H45) exhibit relatively high levels of [M+alkyl]+ ions, unlike the spectra of compounds which contain only methyl or ethyl substituents on the quaternary nitrogen. These latter compounds exhibit a relatively greater tendency toward lactone formation.
Zusätzliches Material:
3 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/oms.1210150708
