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  • Analytical Chemistry and Spectroscopy  (13)
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  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 3 (1970), S. 777-788 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of steroidal model compounds specifically designed to allow maximal as well as minimal charge localization at certain functional groups was subjected to mass spectrometric analysis. The results indicate that electron deficiency at the potentially reactive site is a prequisite for any fragmentation reaction to occur to an appreciable extent. The amount of charge density required at such a site seems to vary substantially for different types of fragmentation processes.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 351-369 
    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 spectra of the catenanes functionalized in one ring by β-phenylethylaza-, aza-, acetylaza-, trideuteroacetylaza- and trifluoroacetylaza groups respectively, are compared with the spectra of correspondingly substituted macrocyclic and long chain compounds. The mass spectra of most of the catenanes investigated are distinguished by a dominant fragmentation process, which isinitiated by the interannular transfer of ahydrogen atom to the functional group. Fragmentations caused by initial rupture of one of the macrocycles are much less favoured. Apart from H-transfer, no interannular reactions could be detected. In the presence of a β-phenylethylaza substituent, the loss of the benzyl radical is so fast, however, that no fragmentation initiated by H-transfer can be detected. The comparison of the spectra of the open chain compounds with the macrocyclic and catenane compounds suggests that significant solvation of these functional groups by long aliphatic chains does not exist.
    Notes: Die Massenspektren der Catenane, die in einem der beiden Ringe durch β-Phenyläthylaza-, Aza-, Acetylaza-, Trideuterioacetylaza- oder Trifluoracetylaza-Gruppen funktionalisiert sind, werden mit den Spektren entsprechend funktionalisierter makrocyclischer und langkettiger Moleküle verglichen. Die Massenspektren der meisten untersuchten Catenane zeichnen sich durch eine dominierende Fragmentierung aus, die durch eine interannulare H-Übertragung auf die funktionelle Gruppe eingeleitet wird. Fragmentierungen, die durch Ringbrüche eingeleitet werden, treten dagegen zurück. Abgesehen von H-Übertragungen sind keine interannularen Reaktionen nachweisbar. Bei Anwesenheif, einer β-Phenyläthylaza-Gruppe erfolgt der Verlust der Benzylgruppe so rasch, daβ keine bedeutende H-Übertragungsreaktion zustande kommt. Der Vergleich der Massenspektren der offenkettigen Verbindungen einerseits mit den makrocyclischen und catenan-artigen andererseits legt die Annahme nahe, daß eine bedeutende Solvatisierung der untersuchten funktionellen Gruppen durch lange Ketten nicht vorliegt.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 2 (1969), S. 781-790 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: While heterolysis of oxonium ions generated upon electron-impact in the mass spectrometer is a well documented phenomenon in the fragmentation of aliphatic ethers, little analogy exists for structurally comparable immonium ions. Exceptions are ions of the latter class in which dissociation is facilitated by the presence of proper substituents in position allowing satabilization of daughter ions. Two main types of subtitution were explored providing(1) resonance stabilization of the product ions by aryl substituents in benzylic,heterolysis,and (2) aryl neighboring group participation in homobenzylic heterolysis, possibly yielding phenonium ions (or isometric ions via further rearrangement) as stable products in the gas phase. In the discussion emphasis will be placed on Case 2.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 16 (1981), S. 118-122 
    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 the nicotinates of two methyl branched and one unsaturated long chain alcohol were compared with the mass spectra of the underivatized alcohols and of their trimethylsilyl ethers. It is shown that the structure of the chain is much more clearly shown by the spectra of the nicotinates than in the other spectra.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 21 (1986), S. 85-89 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron impact mass spectra of the pyrrolidides of both the cis- and trans-octylcyclohexanecarboxylic acids show the structure of the aliphatic chain, despite the steric hindrance of a direct H transfer from the chain to the functional group.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 20 (1985), S. 266-267 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1988), S. 566-572 
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triazolopyridine is proposed as a new derivative for the location of branches and double bonds in fatty acids. It is compared with previously used derivatives and found to be clearly superior to the pyrrolidide and slightly superior to the β-picolinyl ester with regard to the structure-specific fragmentation pattern. It is prepared by reacting the activated acid with 2-hydrazinopyridine followed by cyclization.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 643-646 
    ISSN: 0935-6304
    Keywords: Gas chromatography/Mass spectrometry ; Chiral GC ; Deuterium-labeled compounds ; Hexachlorocyclohexane ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Perdeuterated α-1,2,3,4,5,6-hexachlorocyclohexane (α-PDHCH) was synthesized and isolated in pure form. α-PDHCH was baseline separated from unlabeled α-HCH by high resolution gas chromatography on different stationary phases. α-PDHCH was also resolved into its enantiomeric forms by application of a chiral GC phase. Furthermore, chiral chromatography of a mixture of labeled α-PDHDH and unlabeled α-HCH resulted in four peaks. Standard solutions of α-PDHCH are recommended both as recovery standard for sample clean-up and as internal standard for the quantitation of chlorinated hydrocarbons with GC/MS or GC/ECD in environmental samples.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1040-7685
    Keywords: capillary gas chromatography ; capillary supercritical fluid chromatography ; enantiomeric alcohols ; diastereomeric esters ; Trolox methyl ether ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomers of aliphatic alcohols are transformed by a new chiral reagent (S)-Trolox methyl ether to their diastereomeric esters which are separated by capillary GC or SFC on achiral columns. The applicability of this reagent and its superiority to the hitherto known reagents are demonstrated by selected examples.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1994), S. 379-379 
    ISSN: 1052-9306
    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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