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  • 1
    Electronic Resource
    Electronic Resource
    Electron impact studies on some aryl heteryl ketoximes (1977)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 411-415 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of nine aryl heteryl ketoximes indicated that a gaseous phase Beckmann rearrangement occurs to a significant extent, as confirmed by the exact mass measurements of the resulting aroyl cation peaks. Loss of oxygen, hydroxyl radical and migration of the oxime hydrogen to the heterocycle is observed to take place in varying proportions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210120614
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  • 2
    Electronic Resource
    Electronic Resource
    Electron impact studies on oximes: Mass spectra of the condensation products of aniline, phenol and thiophenol with benzhydroximoyl chloride (1976)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 347-351 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The condensation products derived from aniline, phenol and thiophenol by treatment with benzhydroximoyl chloride, exhibited a stepwise (in the first two cases) or concerted (in the third case) loss of OH. and C6H5N from the corresponding skeletally rearranged molecular ions, affording [C6H5C≡X]+ ions (where X = NH or o or S) when subjected to electron impact. The process has been substantiated by deuterium labelling and exact mass measurements. The base peaks in all the spectra were due to the aniline, phenol and thiphenol radical ions as the case may be, obtained by a shift prior to fragmentation of the oxime hydrogen to the heteroatom contained in these ions.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210110403
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  • 3
    Electronic Resource
    Electronic Resource
    Electron impact studies on α,β-unsaturated carbonyl oximes (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 218-223 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Electron impact studies on eight α,β-unsaturated carbonyl oximes revealed many interesting hydrogen and skeletal rearrangements which were substantiated by deuterium labelling, exact mass measurements and metastable studies. Loss of H· and OH· as well as formation of the indenyl and fluorenyl cations and the [C9H6N]+ fragment proceed through cyclic intermediates. All the ionized oximes undergo a Beckmann rearrangement in the gaseous phase leading to intense aroyl cation peaks. Formation of the styrene radical ions and cleavage of the bond α to the oxime function have also been noticed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210130411
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  • 4
    Electronic Resource
    Electronic Resource
    Electron impact fragmentation of 2-arylhydrazonopropandioic acid derivatives (1979)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 14 (1979), S. 239-243 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Examination of the mass spectra of eleven 2-arylhydrazonopropandioic acid derivatives reveals that a radical ion which is tentatively formulated as a 1H-diazirine species is produced in each case (except for the diphenyl este) by more than one process. Formation of what is formally the aryl amine radical ion occurs by a novel hydrogen rearrangement. Simple cleavage of the bonds β to either the aromatic ring or the C=N moiety also produces abundant ions. The diphenyl ester behaves anomalously yielding the phenol ion instead of the amine. The proposed mechanisms were confirmed by metastable studies, deuterium labelling and exact mass measurements.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210140503
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  • 5
    Electronic Resource
    Electronic Resource
    Stereochemical applications of mass spectrometry: 1 - The utility of electron impact and chemical ionization mass spectrometry in the differentiation of stereoisomeric benzoin oximes and phenylhydrazones (1980)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1980), S. 249-256 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A study of the electron impact and chemical ionization (H2, CH4, and iso-C4H10) mass spectra of stereoisomeric benzoin oximes and phenylhydrazones indicates that while the former can be distinguished only by their chemical ionization mass spectra the latter are readily distinguishable by both their electron impact and chemical ionization mass spectra. The electron impact mass spectra of the isomeric oximes are practically identical; however, the chemical ionization spectra show that the E isomer forms more stable [MH]+ and [MH—H2O]+ ions than the Z isomer for which both the [MH]+ and [MH—H2O]+ ions are relatively unstable. In electron impact the Z-phenylhydrazone shows a lower [M]+· ion abundance and more facile loss of H2O than does the E isomer. This more facile H2O loss also is observed for the [MH]+ ion of the Z isomer under chemical ionization conditions.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210150508
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  • 6
    Electronic Resource
    Electronic Resource
    Chemical ionization mass spectra of mononitroarenes (1980)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1980), S. 284-288 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The H2 and CH4 chemical ionization mass spectra of a selection of substituted nitrobenzenes have been determined. It is shown that reduction of the nitro group to the amine is favoured by high source temperatures and the presence of water in the ion source. The H2 chemical ionization mass spectra are much more useful for distinguishing between isomeric compounds than the CH4 CI mass spectra because of the more extensive fragmentation. For ortho substituents bearing a labile hydrogen abundant [MH — H2O]+ fragments are observed. When the substituent is electron-releasing both ortho and para substituted nitrobenzenes show abundant [MH—OH]+ fragment ions while meta substituted compounds show abundant loss of NO and NO2 from [MH]+. The latter fragmentation is interpreted in terms of protonation para to the substituent or ortho to the vitro function, while the first two fragmentation routes arise from protonation at the nitro group. When the substituent is electron-attracting the chemical ionization mass spectra of isomers are very similar except for the H2O loss reaction for ortho compounds.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210150604
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  • 7
    Electronic Resource
    Electronic Resource
    Mass spectra of aliphatic dicarboxylic acids and their dimethyl esters: Cyclic structures for the [M - H2O]+· ions from the diacids and [M - MeOH]+· ions from the dimethyl esters (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1988), S. 723-728 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl 2-oxocycIoalkane carboxylate structures are proposed lor the [M - MeOH]+· ions from dimethyl adipate, pimelate, suberate and azelate. This proposal is based on a comparison of the metastable ion mass spectra and the kinetic energy releases for the major fragmentation reaction of these species with the same data for the molecular ions of authentic cyclic β-keto esters. The mass spectra of α,α,α′,α′-d4-pimelic acid and its dimethyl ester indicate that the α-hydrogens are involved only to a minor extent in the formation of [M - ROH]+· and [M - 2ROH]+· ions, while these α-hydrogens are involved almost exclusively in the loss of ROH from the [M - RO·]+ ions (R = H or CH3). The molecules XCO(CH2)7COOMe (X = OH, Cl) form abundant ions in their mass spectra with the same structure as the [M - 2MeOH]+· ions from dimethyl azelate.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210231009
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  • 8
    Electronic Resource
    Electronic Resource
    The mass spectrum of 2,4-dihydroxybenzophenone oxime (1977)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 536-538 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,4-Dihydroxybenzophenone Oxime is found to undergo loss of OH·, H2O, NHOH·; and PhCNO when subjected to electron impact, revealing novel hydrogen and skeletal migrations. The fragmentation mechanisms are found to differ considerably from those of benzophenone oxime and we confirmed these cleavages by exact mass measurements and deuterium labelling.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210120811
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  • 9
    Electronic Resource
    Electronic Resource
    Electron impact induced fragmentation of some 1,2,4-triazole derivatives (1977)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 307-312 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of eight 1,2,4-triazole derivaties have been recorded and found tao reveal extensive hydrogen and skeletal migrations. The structures of the fragments have been confirmed by deuterium labelling and exact mass measurement. The compounds revealed striking differences in their spectra depending on the nature of the substituents.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210120511
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  • 10
    Electronic Resource
    Electronic Resource
    Electron impact studies on 2-hydroxyimino-N-aryl acetamides (1978)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1978), S. 224-231 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of 13 2-hydroxyimino-N-aryl acetamides contain abundant arylamine, isocyanate and protonated benzimidazole ions, the mechanisms of formation of which were established by deuterium labelling and formulae by exact mass measurements. Loss of OH· and NO· were postulated to proceed through cyclic and acyclic intermediates respectively. Considerable hydrogen scrambling and rearrangement could be noticed in all the processes.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210130412
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