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Electron Ionization Mass Spectra (electron + ionization_mass_spectrum)
Selected AbstractsElectron ionization mass spectra of phosphorus-containing heterocycles.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 23 2006The 1,3,4,2-oxadiazaphosphinane 2-oxides differ not only in the relative configuration of the P atom (R* or S*), but also in many other ways such as the ring size, ring fusion, P substitution and bridgehead N atom whose effects on their fragmentations have been studied. Some fragmentations resembled those of 3,1,2-oxazaphosphinane 2-oxides and 1,3,2-diazaphosphinane-2-oxides, but new routes were also found, initiated by ionization at the bridgehead N atom. The relative abundances of the molecular ions and some fragment ions allowed the differentiation of cis-trans epimers. Compounds with n,=,2 and R,,N(CH2CH2Cl)2, and linearly or angularly isoquinoline-fused isomers in most cases, gave more numerous ions with lower relative abundances than the other compounds in this series. Only the isoquinoline derivatives provided fragments resulting from ionization of the aromatic part of the molecule. Copyright © 2006 John Wiley & Sons, Ltd. [source] Electron ionization mass spectra of phosphorus-containing heterocycles.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2006The electron ionization mass spectra of cis - and trans -fused 1,2,3,4,4a,5,6,7,8,8a-decahydro-1,3,2-benzodiazaphosphinine 2-oxides (1,17) were recorded, and the fragmentation pathways were established and compared with those of 1,4,4a,5,6,7,8,8a-octahydro-2H -3,1,2-benzoxazaphosphinine 2-oxides. In general, the mass spectral behaviors of the isomeric compounds were very similar and it was mostly impossible to differentiate them from each other on the basis of the relative abundances of their characteristic fragment ions. The compounds in which R2,=,Ph or OPh exhibited a series of common fragments, e.g. [R2H]+, R2PONHR1(3)+, [M,C3H7]+ and [M,C4H9]+, the latter two ions being present in the spectra of only two of the derivatives with an N(CH2CH2Cl)2 substituent on the P atom. When R2,=,Ph, numerous other alkyl radicals, alkenes and a cycloalkane were also ejected and these compounds also lost NH2, NH3, CH3N, CH4N or CH3NH2. The compounds with an N(CH2CH2Cl)2 substituent on the P atom most closely resembled their 3,1,2-O,N,P analogs in respect of the dominant role of this substituent. Copyright © 2006 John Wiley & Sons, Ltd. [source] Electron ionization mass spectra of phosphorus-containing heterocycles.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 3 2006The electron ionization mass spectra of 27 cis - and trans -annelated 1,4,4a,5,6,7,8,8a-octahydro-2H -3,1,2-benzoxazaphosphinine 2-oxides were recorded to clarify the effects of the ring heteroatom (O or N), ring annelation, the P configuration and the substituents attached to the ring or to the N and P atoms. For compounds 1,12 different alkyl radical and alkene losses and the cleavage of the P,heteroatom bonds, instead of the P,C bonds, were representative and dependent mainly on the substitution on the N and P atoms. The replacement of Ph and OPh by N(CH2CH2Cl)2 on the P atom had a dramatic influence on the fragmentation process: new fragment ions were obtained and very little M+. (1,3%) was formed. Only slight differences were found between some of the corresponding isomers, but interestingly the compounds formed clear groups on the basis of the differences in their fragmentation, depending on the ring-N and ring-P substituents. Copyright © 2006 John Wiley & Sons, Ltd. [source] Differentiation between isomeric 2-thionosparteine and 15-thionosparteine on the basis of electron ionization mass spectraJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 3 2003Renata Kolano [source] Electrospray ionization tandem mass spectral analysis of oxidation products of precursors of sulfur mustardsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2006Vijay Tak Electrospray ionization tandem mass spectral (ESI-MSn) analysis of thiodiglycol, bis(2-hydroxyethylthio)alkanes (BHETAs) and their mono-, di-, tri-, and tetraoxygenated compounds was carried out to obtain their characteristic spectra for ESI-MS analysis. These compounds are important markers of chemical warfare agents, namely sulfur mustards. ESI-MSn (n,,,3) analysis of a compound by collisionally induced dissociation in an ion trap gives rise to mass spectra that are somewhat similar to electron ionization mass spectra. These ESI-MSn spectra can be used for compound identification. Under ESI-MS and ESI-MS/MS the compounds mostly produced [M+NH4]+, [M+H]+ and [M+HH2O]+ ions. Fragmentations of these even-electron precursors in the ion trap gave rise to characteristic product ions via neutral loss of O2, H2O, C2H4, HCHO, C2H4O, C2H4S, HSC2H4OH and C2H4SO. Fragmentation routes of these compounds are proposed that rationalize the formation of product ions in ESI-MSn analysis. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||