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  • Chemistry  (4)
  • 1965-1969  (4)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 2 (1969), S. 1039-1039 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 2 (1969), S. 829-833 
    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 structure of the [M  -  1] ions of thioxanthene (I) and xanthene (II) is investigated by means of the 9,9-dideuteroderivatives (Ia and Ia). The formation of an [M  -  1]ion from Ia and IIa shows that beside a simple dissociation reaction a rearrangement to a tropylium ion is involved. A further rearrangements of this type occurs in the frgmentation of thioxanthene-S,S-dioxide (III).
    Notes: Die struktur der [M  -  1]-Ionen von Thioxanthen (I) und Xanthen (II) wird mit Hilfe der 9,9-Dideuteroderivate (Ia und IIa) untersucht. Das Auftreten eines [M  -  1]-Ions auch bei Ia und IIa zeigt, daß neben einer einfachen Abspaltungsreaktion eine Umlagerung zu einem Troppyliumkation beteilligt ist. Eine wietere derartige Umlagerungsreaktion tritt auch bei der Fragmentierung von Thioxanthen-S,S-dioxid (III) auf.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 2 (1969), S. 819-828 
    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 some sulphur containing dibenzo-heterocycles and their S-oxides is investigated by exact mass measurements. The stability of the molecular ions and their fragmentation strongly depends upon the nature of the bridging atom groups in the central six-membered ring. Two mechanisms are discussed for the elimination of ketene from the N-acetylic derivatives of phenothiazine and its S-oxides.
    Notes: Das massenspektrometrische Fragmentierungsverhalten schwefelhaltiger Dibenzoheterocyclen und deren S-oxide wird mit Hilfe exakter Massenmessungen untersucht. Die Stabilität der Molekülionen und der Zerfall hängen stark von der Art der Zweiten Atomgruppe im zentralen Sechsring ab. Für die Ketenabspalutung aus den N-Acetylderivaten von Phenothiazin und dessen S-Oxiden werden Mechanismen diskutiert.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Besides o-benzoquinones and o-naphthoquinones, p-quinones and stilbene quinones also exhibit [M + 2]+·-peaks. These are mainly produced by the residual moisture in the mass spectrometer and are more dependent on the partial pressure of the compounds and of the present water respectively, than on the temperature. The spectra of the [M + 2]+·-ions correspond to those of the ionized quinols. There exists a parallelism between the redox potential and the intensity of the [M + 2]+·-peak of p-quinonoid systems. The electron-impact induced fragmentations of 2,6-ditert.-butyl-benzoquinone-(1,4) and 3,5-di-tert.-butylbenzoquinone-(1,2) are discussed.
    Notes: Außber den o-Benzochinonen und o-Naphthochinonen zeigen auch p-Chinone, sowie Diphenochinone und Stilbenchinone [M + 2]+·-Peaks. Diese beruhenim wesentlichen auf der Restfeuchtigkeit mi Massenspektrometer und hängen stärker vom Partialdruck dersubstanzen bzw. des Wassers als von der Temperatur ab. Die Spektren der [M + 2]+·-Ionen entsprechen denjenigen der zugehörigen ionisierten Hydrochinone. Zwischen dem Redoxpotential und der Instensität des [M + 2]+·-Peaks p-chinoider Systeme besteht ein Zusammenhang. Die elektronenstoßinduzierte Fragmentierung von 2.6-Di-tert.-butyl-benzochinon-(1.4) und 3.5-Di-tert.-butylbenzochinon-(1.2) wird diskutiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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