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  • 1
    Electronic Resource
    Electronic Resource
    Gas-phase interaction of Me3Si+ ions withcis- andtrans-cyclohexanediols, their methyl ethers, and acetates (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1921-1924 
    Details
    ISSN: 1573-9171
    Keywords: mass spectrometry ; chemical ionization ; tetramethylsilane ; cyclohexanediols ; acetates ; methyl ethers ; stereochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The effect of stereochemistry on the mechanism of gas-phase fragmentation of [M+SiMe3]+ ions was studied usingcis- andtrans-1,2- and -1,4-cyclohexanediols, their methyl ethers, and acetates as model compounds. The higher stability of the [M+SiMe3]+ions is characteristic of cis-isomers of all the compounds examined, which is associated with chelation in the case ofcis-cyclohexanediols andcis-methoxycyclohexanols and with the higher reactivity oftrans-isomers due to anchimeric assistance of the methoxy and acetoxy groups. Dehydration is characteristic of the [M+SiMe3]+ ions formed from cyclohexanediols; both hydrogen atoms of the hydroxyl groups take part in the process, thus providing direct evidence of the chelation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01457777
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  • 2
    Electronic Resource
    Electronic Resource
    Specific features of the behavior of α- and β-glycosylfluoride tetraacetates during chemical ionization in isobutane and tetramethylsilane (1994)
    Springer
    Russian chemical bulletin 43 (1994), S. 578-582 
    Details
    ISSN: 1573-9171
    Keywords: mass-spectrometry ; chemical ionization ; tetramethylsilane ; glycosylfluorides ; anomeric effects ; fragmentation ; gas phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Reactions of α- and β-glycosylfluoride tetraacetates with trimethylsilicenium ion in the gas phase during chemical ionization have been studied. The [M+SiMe3]+ ions formed from the glycosylfluorides are more stable than the corresponding [M+H]+ ions. The cleavage of the weakest glycosidic bond leading to the generation of glycosidic ions is not dominant for the trimethylsilylated ions, as it has been observed in the corresponding protolytic reactions. The ratio of the intensities of the [M+SiMe3]+ and [M−F]+ ions characterizes the probability of the initial localization of the trimethylsilyl ion at the glycosidic center; the equatorial orientation of fluorine at C(1) makes it possible for the electrophile to bond with this substituent. Generation of the glycosidic ions is rather weakly affected by increasing temperature, whereas [M-AcO]+ formation is significantly intensified.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00699827
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    Paper (German National Licenses)
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