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  • Wiley-Blackwell  (3)
  • 1975-1979  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1975), S. 442-447 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The mass spectrometric fragmentation of the 4-amino steroids has been studied and interpretations are proposed for the formation of the principal fragments. The loss of a primary radical in the principal fragmentations explains the low rate constant of these reactions, as shown by the occurrence of important intramolecular H-D scrambling in the case of the deuterated derivative in positions 3 and 5.
    Notes: La fragmentation des amino-4 stéroïdes en spectrométrie de masse est étudiée, et des interprétations proposées pour les principales fragmentations. La libération d'un radical primaire lors de la formation des principaux ions explique la relative lenteur de ces réaction attestée par l'existence d'importantes réactions d'éactions d'échangeH-D dans le cas du dérivé deutérié en 3 et 5.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dehydration of β-amino alcohols after chemical ionization with iso-butane as reagent gas is dependent upon the interfunctional distance. Relative protonation cross-sections of both functional groups appear to be essentially independent of their relative proton affinities.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 11 (1976), S. 964-974 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The three-step mechanism of formation of the important fragment ion of mass 84 from 3-dimethylaminosteroids under electron impact is accompanied by intramolecular hydrogen exchanges, as shown by the mass spectra of deuterium labelled derivatives. The hydrogen exchanges are shown to occur in the ring A opened molecular ion, i.e. after the initial C-3--C-4 bond rupture, and to compete with the final C-1--C-10 bond rupture. (The intensity of hydrogen-deuterium exchange reactions depends upon the activation energy of the final rupture.) The electron impact-induced-fragmentation of large alicyclic molecules bearing a strong charge stabilizing functional group, such as amines, appears to be the result of a series of displacements of the radical over different sites of the molecular ion through hydrogen (or carbon) rearrangements, with some of the radical sites being in the appropriate position to induce a final rupture.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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