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  • Analytical Chemistry and Spectroscopy  (1)
  • Organic Chemistry  (1)
  • 2005-2009
  • 1985-1989  (1)
  • 1970-1974  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 548-552 
    ISSN: 0935-6304
    Keywords: Glass capillary gas chromatography ; Immobilization ; OV-240-OH cyanopropylpolysiloxane ; Isomer specificity ; Polychlorinated dibenzo-p-dioxins ; Polychlorinated dibenzofurans ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Glass capillaries were leached, dehydrated, persilylated with 1, 3-bis (3-cyanopropyl) tetramethyldisiloxane, and coated with OV-240-OH. After crosslinking and binding the phase to the glass surface the columns showed high separation efficiency, high temperature stability, and inertness comparable to persilylated apolar columns. Column performance is shown to be superior to liquid phase cyanopropyl columns such as SP 2330. The excellent separation capabilities together with the selectivity of the phase makes OV-240-OH coated columns a valuable tool for the determination of toxic isomers in complex mixtures of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). The order of elution of individual TCDD isomers was found to be similar to that described for SP 2330 or Silar 10c. The detection of PCDDs and PCDFs in a fly ash extract further illustrates the utility of OV-240-OH coated columns. The high temperature limit of these columns opens the way for the analysis of high boiling compounds such as mixed brominated/chlorinated dibenzo-p-dioxins and dibenzofurans.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 53 (1970), S. 964-973 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a search for a new and efficient synthesis of the compound 7, the cyclization of 5 (obtained by a Michael-reaction from 3 and 4) was studied. Treatment of 5 with strong acid furnished the known dienedione 8. Mild acidic conditions gave the bridged alcohol 9 and other, unidentified products, rather than the desired enone 6. Under basic conditions, 5 did not cyclize to 6, but underwent retro-Michael reaction. Attempts were then made to convert the dienedione 8 to the 14α-enone 19. However, both catalytic hydrogenation and lithium-ammonia reduction of 8 yielded mainly 14β-products. In some hydrogenation experiments, isomerization of the dienedione 8 to the phenols 13 (major) and 14 (minor) occurred. The stereochemistry of the new isomeric des-A-androst-9-en-5, 17-diones (16, 17 and 20) was determined by chemical and spectroscopic methods.
    Type of Medium: Electronic Resource
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