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  • 1970-1974  (2)
  • 1955-1959  (5)
  • Organic Chemistry  (7)
  • General Chemistry
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  • Organic Chemistry  (7)
  • General Chemistry
  • Chemistry  (7)
  • 1
    Electronic Resource
    Electronic Resource
    Studien in der Lumiflavin-Reihe V. Spezifische Reaktivität 8-ständiger Substituenten am Isoalloxazin-Kern Flavin-Dimere (1959)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 42 (1959), S. 2164-2177 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 8-methyl group of riboflavin and lumiflavin is shown to be activated, in agreement with B. & A. Pullman's LCAO-MO-model. Chemical evidence for this is given by reactions of 8-chloro-7,10-dimethyl-flavin with nucleophilic agents, of 8-methylflavins with NO and CO groups, and by the base-catalysed dimerisation of 8-methylflavins giving rise to a new class of flavin-like pigments. The particular redox-behaviour of these “biflavins” is described and their possible biochemical importance is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19590420645
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesen in der Lumiflavinreihe II (1957)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 40 (1957), S. 180-186 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Starting from lumiflavine and its 2-thio-analogue, the leukoflavine nucleus was obtained and stabilized by reductive acylation. The acyl-leuko-compounds seem to exhibit the possibility of substitution reactions in 2- and 4-positions. Several new lumiflavines were obtained, e. g. 4-thiolumiflavine and 2-desoxylumiflavine. The latter shows rather peculiar oxido-reductive properties which are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19570400120
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  • 3
    Electronic Resource
    Electronic Resource
    Synthesen in der Lumiflavinreihe IVIII: P. HEMMERICH, Helv. 41, 514 (1958). (1959)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 42 (1959), S. 1604-1611 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2,4-Substituted flavins (isoalloxazines) bearing an NH2-group in 8-position were found to be stable and easily accessible. In particular the 2- and 4-imino-, resp. 2,4-diimino-compounds are similar to riboflavin in colour and fluorescence, but readily water-soluble. The chemical behaviour of this new class of flavins is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19590420522
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  • 4
    Electronic Resource
    Electronic Resource
    Pyridyl-1,3,4-thiadiazole; eine neue Variante der Thiadiazol-Synthese (1958)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 41 (1958), S. 2058-2065 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thiosemicarbazones of aromatic aldehydes react with acetic anhydride to give well-defined N4,S-diacetyl derivatives, which readily undergo oxidative cyclisation to 2-aryl-4-acetamido-1,3,4-thiadiazoles. From these intermediates, aryl-thiadiazoles - especially 2-(2′-pyridyl)-1,3,4-thiadiazole, inaccessible by the common methods - can be obtained by acidic deacetylation, SANDMEYER substitution and catalytic dehalogenation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19580410714
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  • 5
    Electronic Resource
    Electronic Resource
    Zur Stabilität und Struktur der CuI-Komplexe des Imidazols und Histamins. Chemie des einwertigen Kupfers in homogener, polarer Lösung. 1. Mitteilung (1970)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 53 (1970), S. 177-185 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Univalent copper is stabilized in aqueous medium by the non-protophilic ligand CH3CN, allowing ligand displacement reactions to be investigated as if a stable CuI-hydrate did exist. Under these conditions the formation of CuI-complexes with imidazole and its derivatives has been studied in polar solution in the absence of CuII. Imidazole (ImH) acts upon CuI as a bidentate ligand forming polynuclear chains according to the equation Histamine reacts in the same way, i. e. the coordination number of CuI does not exceed 2; by comparison of the complexes of CuI with histamine and its N-methyl-derivatives it is shown that no six-membered chelate - which sterically would be possible - is built up. Trigonal as well as tetrahedral coordination of CuI - i. e. chelate formation - in dilute polar solutions are confined to π- or d-acceptor ligands, e. g. bipyridine or methionine. Conclusions are drawn from this on the requirements for redox-active copper in proteins.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19700530125
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  • 6
    Electronic Resource
    Electronic Resource
    Studien in der Flavin-Reihe. XIX. Mitteilung.VIII Mitt. : [1]. Anomale Reduktion des Flavinkerns: Pteridine aus (Iso)alloxazinenVorläufige Mitt.: [2].Prof. Dr. M. Viscontini zum 60. Geburtstag gewidmet (1973)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 56 (1973), S. 1908-1920 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The catalytic hydrogenation of isoalloxazines in aqueous solutions proceeds non stoichiometrically.This is explained by a reaction side path, which is competitive with the normal reversible 1,5-dihydrogenation and leads to the irreversible reduction of the ‘o-xyloquinoid’ (rather than benzenoid) subnucleus in the (iso)alloxazine system. In trifluoroacetic acid, this irreversible side reaction is found to be complete within several hours, while 8 H-equivalents are absorbed per flavin molecule. The products are shown to be cyclohexano-[g]-pteridine-2,4-diones in the normal 5,6,7,8-tetrahydro state, which are oxidized to yield, subsequently, 7,8-dihydro- and ‘fully oxidized’ pteridines (= 6,7,8,9-tetrahydrofavins).The spectral characteristics, tautomeric structures and pK-values are discussed in context with recent data on 6,7,8-trialkylpteridine-2,4-diones [3].
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19730560611
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  • 7
    Electronic Resource
    Electronic Resource
    Synthesen in der Lumiflavinreihe (1956)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 39 (1956), S. 1242-1252 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A short way for the synthesis of lumiflavin and derivatives is developed, leading to the new structural analogues 2-thiolumiflavine and 2-lumiflavimine, which exhibit interesting oxido-reductive and metal chelating properties and may be riboflavin antirnetabolites.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19560390511
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