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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 6 (1992), S. 46-53 
    ISSN: 0951-4198
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Physik
    Notizen: Substituted cinnamic acids were dimerized, under fluorescent or UV light, as a glassy coating on a vial then subsequently analysed by GC/MS. Mass Spectrometric analysis of the dimers formed by each acid allowed the assignment of the dimer as a truxillic or truxinic structure since these structures had distinctive fragmentation patterns; the breakdown of the truxillic acids involves a McLafferty rearrangment before fragmentation occurs, whereas the truxinic acids, which have both carboxy groups on one side and both aromatic groups on the other, fragment asymmetrically to give characteristic stilbene and dicarboxylate fragments. It is apparent from the results of the dimerization of the lcinnamic acids that, under the conditions used here, if the monomeric acid had the capacity for hydrogen bonding using the ring substituent as well as the carboxy group, the dimerization products would be overshelmingly truxillic in structure. However, if only the carboxy group could hydrogen bond, the products would be almost exclusively traxinic in structure.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 23 (1994), S. 71-74 
    ISSN: 1052-9306
    Schlagwort(e): Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Using gas chromatography/mass spectrometry we have observed six peaks in the single ion chromatograph at m/z 674 of the alkaline extract of barley straw cell walls. The breakdown pattern of these ions suggests that they could all be isomers of 5,5′-bis-dehydroferulic acid. Since only the 5,5′ linkage is reported to be present in plants this tentatively suggests that these compounds exhibit stable orientational isomerism about this bond. Plausible breakdown mechanisms are presented which allow for the complete assignment of structure to all the isomers. These mechanisms suggest that the two pairs of breakdown ions at m/z 556 and 467, and 265 and 193 are representative of trans and cis double bonds, respectively.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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