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  • Analytical Chemistry and Spectroscopy
  • Lunar and Planetary Science and Exploration
  • 1965-1969  (2)
  • 1
    Electronic Resource
    Electronic Resource
    ‘Mass spectrometry of vitamin B6: Different forms of the vitamin, its metabolites, antimetabolites, and analogs’ (1968)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 1 (1968), S. 151-166 
    Details
    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 different forms of vitamin B6, some metabolites and antimetabolites, and some analogs are reported. The free bases are suitable for study, but the 5-phosphates are not sufficiently volatile. The hydrochloride salts dissociate thermally in the inlet system into the free base and HCl and give the spectrum of the free base with the spectrum of HCL superimposed on it. The compounds studied are: pyridoxol, pyridoxamine and pyridoxal, which are different forms of vitamin B6; 4-pyridoxic acid and its lactone, 5-pyridoxic acid lactone, isopyridoxal, 5-formyl-3-hydroxy-2-methylpyridine-4-carboxylic acid, and 3-hydroxy-2-methylpyridine-4,5-dicarboxylic acid, which are vitamin B6 metabolites; α4-and α5-deoxypyridoxol, 3-deoxypyridoxol, and 4- and 5- norpyridoxol, which are antimetabolites and analogs of vitamin B6.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210010114
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Studies in nuclear magnetic resonance - IXFor Part VIII see Ref. 1.. Rotational barriers in substituted N,N-dimethylbenzamides (1969)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 1 (1969), S. 109-123 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The barriers to rotation about the C—N bond in eighteen substituted N,N-dimethylbenzamides have been determined by complete line shape analysis of the NMR spectra of the N,N-dimethyl protons. The barriers have been correlated with the substituent constants σ and σ+. It has been shown that polar solvents increase the barrier in N,N-dimethylbenzamide.Acid catalysis of rotation about the amide C—N bond in N-(p-N,N-dimethylcarboxamidobenzyl)-pyridinium bromide has been investigated. 18O exchange studies show that catalysis is due to N-protonation rather than the formation of a tetrahedral intermediate. The rate of rotation is a function of the Hammett acidity function, H0, and the water activity, and it is shown that proton exchange between the N- and O-protonated species involves the intermediacy of a water molecule.The differences in chemical shifts for the non-equivalent N, N-dimethyl groups of the benzamides are also a function of the substituents. Possible explanations of this phenomenon are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270010204
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