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  • 2000-2004  (1)
  • 1975-1979  (1)
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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 44 (1979), S. 0 
    ISSN: 1750-3841
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: A fractionation procedure, based on extraction with acidified ethanol, was developed for the separation of betalaine pigments in beet juice powder. Extraction of lyophilized fresh beet juice with boiling 95% ethanol and subsequent chilling of the extract to −25°C yielded two fractions: an orange precipitate containing betaxanthines and a yellow pigment obtained from the filtrate. Three additional extractions of the beet juice powder residue were carried out at room temperature with 95% ethanol containing 1.0, 0.6 and 0.4% HCl, respectively, and the resulting fractions were combined. This extract contained mainly the betacyanines. This procedure achieved rapid and satisfactory separation of the principal constituents of betalaine, comparable to other more complex methods. Fractions were analyzed by thin-layer chromatography (TLC) on cellulose-coated plates developed sequentially with solvent mixtures consisting of ethanol, isopropanol, water and HCl.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1434-1948
    Schlagwort(e): Thiacalixarene ; Trimetallic sandwich ; Cobalt ; Zinc ; Divergent receptors ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Reaction between deprotonated p-tert-butyltetrathiacalix[4]arene and CoII or ZnII under strictly defined conditions leads to the formation of sandwich species in which a trimetallic unit is held between two opposed, divergently oriented, staggered O- and S-bound calixarene ligands in the cone conformation. Despite the isomorphous nature of the crystalline compounds, there is a subtle difference in the coordination of CoII and ZnII, presumably related to the differences in metal radius and electron configuration combined with structural restrictions imposed by the calixarene framework, in that whereas all three Co atoms may be considered six-coordinate (and approximately octahedral), only two of the Zn atoms appear so, the third being five-coordinate and more nearly trigonal bipyramidal in its coordination geometry.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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