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  • Gas-solid chromatography  (2)
  • Organic Chemistry  (2)
  • 1
    ISSN: 1612-1112
    Keywords: Gas-liquid chromatography ; Gas-solid chromatography ; Retention index data ; Cycloalkanes ; Cycloalkenes ; Cycloalkadienes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention indices of cycloalkenes and cycloalkadienes with C6–C13 rings are determined by gas-liquid chromatography (GLC) on glass capillary columns coated with OV-1 and Ucon LB 550X and by gas-solid chromatography (GSC) on a microcolumn packed with uncoated graphitized thermal carbon black (GTCB). Structure — retention correlations are derived on using index differences such as HOV, HGTCB and ΔI values, considering the differences in the stereochemistry of these compounds. It is shown that the combined application of index increments obtained in GLC and GSC provides more detailed structure informations. The value of the retention index units agree with the most stable conformations of the alicyclic compounds. The high value for the energy equivalent to an index unit (ΔGI.U.=4.18kJ/mol) confirmes that graphitized thermal carbon black causes much stronger dispersive interactions than any nonpolar liquid phase.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Gas-solid chromatography ; Graphitized thermal carbon black ; Hydrocarbon analysis ; Micropacked columns ; Separation of structural and spatial isomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The adsorption of moelcules on the nonspecific and nonporous adsorbent graphitized thermal carbon black (GTCB) is mainly determined by their intermolecular dispersion interaction with the flat graphite surface. Since the retention values strongly depend on the geometrical configuration and shape of the investigated molecules and their arrangement on the graphite plane, it is possible to separate compounds with only small differences in their molecular shape on short columns packed with particles of pure or modified GTCB. The outstanding shape-selectivity of GTCB toward isomeric hydrocarbons is demonstrated by some examples. In most cases the elution sequences of isomeric compounds differ from that obtained in GLC using nonpolar stationary liquids. Moreover, the well defined relationship between retention data and molecular structure by adsorption on a flat and homogeneous surface give useful information for the identification of separated compounds or for the investigation of the molecular structure.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A Simple Method for Quantitative Determination of Silanol GroupsDie Bestimmung der Konzentration von Hydroxylgruppen auf Kieselgeloberflächen ist von großem analytischen Interesse, da diese die chromatografischen oder katalytischen Eigenschaften des Kieselgelmaterials maßgeblich beeinflussen. Dazu wurden bisher sowohl spektroskopische als auch chemische Bestimmungsmethoden angewendet [1-7], die uns jedoch aufgrund des apparativen Aufwandes bzw. der benötigten Zeit für Routineuntersuchungen als ungeeignet erschienen. Die von GALLEI [3]vorgeschlagene, gut reproduzierbare aber apparativ anspruchsvolle Variante der chemischen Umsetzung der Silanolgruppen mit Lithiummethyl und anschließender gaschromatografischer Bestimmung des gebildeten Methans wurde von uns wesentlich vereinfacht, wobei die Bestimmung der gebildeten Methanmenge volumetrisch erfolgte.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Separation of Diastereomeric Methoxybutanes by Preparative High Performance Liquid Chromatography Using Several Detection Methods
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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