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1.
The mass spectra of aluminum isopropoxide show that polymers, [Al(OC3H7)3]x where x = 1 to 7, can be present in the vapor and are, therefore, probably present in the bulk sample. The polymeric composition of the vapor depends on the previous history of the sample. Exact mass measurements on many of the ions along with data on a number of metastable peaks support the proposed fragmentation mechanisms. Loss of 102 mass units between intense peaks in the mass range above 500 a.m.u. leads to the suggestion that the higher polymers may be used as high mass marking substances. 相似文献
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Non-conjugated -dialkylated alkenes were oxidized to aldehydes in the presence of α,β-unsaturated carbonyl functional groups, providing a new synthesis of and a synthesis of that led to a revised structure for gastrolactone. 相似文献
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John S. Showell Henry M. Fales Edward A. Sokoloski 《Journal of mass spectrometry : JMS》1989,24(8):632-636
A series of mixtures of solid triglycerides and waxes are examined using 252Cf plasma desorption mass spectrometry. The relative abundances of diagnostic ions are found to vary with sample preparation, handling, and composition. It is proposed that the less efficiently packing, shorter chain, compounds are forced to the analysis site, i.e. the surface. This takes place at varying rates that reflect the bulk properties of the mixture as revealed by its phase diagram and thermal history. Mixtures that remain liquids during analysis show ion abundances correctly reflecting their composition. Mixtures of isotopomeric glycerides also show normal ion abundances. 相似文献
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Weisz A Andrzejewski D Fales HM Mandelbaum A 《Journal of mass spectrometry : JMS》2001,36(9):1024-1030
Positionally isomeric 2-(2-quinolinyl)-1H-indene-1,3(2H)-dione mono- and disulfonic acids give rise to similar electrospray ionization (ESI) and atmosphere pressure chemical ionization (APCI) mass spectra, which show very abundant MH(+) ions and negligible fragmentation. The MH(+) ions of these isomeric acids exhibit notably different behavior under collision-induced dissociation (CID) conditions. The acids with a sulfonic group at position 8' in the quinoline moiety, adjacent to the N-atom, exhibit highly abundant [MH - H(2)SO(3)](+) ions (m/z 272 for the mono- and m/z 352 for the disulfonic acids), which are of lower abundance in the CID spectra of isomers with the SO(3)H group at other positions, remote from the nitrogen atom. The latter isomers undergo efficient eliminations of SO(3) and HSO(3). The isomeric diacids with one SO(3)H group at position 4 of the indene-1,3(2H)-dione moiety, adjacent to one of the carbonyl groups, undergo highly efficient elimination of H(2)O. Mechanistic pathways, involving interactions between adjacent groups, are proposed for the above regiospecific fragmentations. Pronounced different behavior has been also observed in negative ion tandem mass spectrometric measurements of the sulfonic acids. The distinctive behavior of the isomeric acids was strongly pronounced when the measurements were performed with an ion trap mass spectrometer (LCQ), and much less so with a triple-stage quadrupole instrument (TSQ). 相似文献
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Lewis K. Panell Henry M. Fales John P. Scovill Daniel L. Klayman Douglas X. West Ramon L. Tate 《Transition Metal Chemistry》1985,10(4):141-147
Summary Californium-252 plasma desorption mass spectra were recorded for complexes of the anions of various thio-and seleno-semicarbazones of 3-acetylpyridines(1–4) with the transition metal ions iron(III) and cobalt(II). Positive ion spectra gave clear evidence of the cation present and fragmentation with loss of ligands or parts of ligands was straightforward. Negative ion spectra likewise provided evidence of the intact anion except with tetracoordinate metal halide systems [MX4]– which lost one or more halide atoms. Evidence of fragmentation of the ligand and recombination of the fragments with the metal ion was also observed in the negative ion mode. Spectra were used to revise the structure of a complex previously reported as [FeLCl2](1) to [FeL2]+[FeCl4]–. 相似文献
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B. Mears P. R. Pine H. W. Doughty B. Freeman J. Guzmán A. Rancano T. L. Kelley J. J. Melloy H. A. Fales T. Callan R. T. P. Jones B. Tougarinov H. Hölemann C. Frick H. Engemann A. Schleicher W. T. Schrenk Ph. H. Delano J. L. Merrill A. S. Russell S. W. Rowell K. S. Jackson N. H. Furman M. I. Schubin K Anderson H. Swett Ella M. Collin H. J. S. Sand L. F. Yntema und D. D. Peirce 《Fresenius' Journal of Analytical Chemistry》1932,87(5-6):214-224
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