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  • 1995-1999  (3)
  • 1965-1969
  • 1880-1889
  • 1998  (3)
  • Key words Artesunate  (1)
  • Physical Chemistry  (1)
  • fluorine-modified alumina  (1)
  • monomolecular reaction  (1)
Materialart
Erscheinungszeitraum
  • 1995-1999  (3)
  • 1965-1969
  • 1880-1889
Jahr
Schlagwörter
  • 1
    ISSN: 1572-879X
    Schlagwort(e): 1-butene ; skeletal isomerization ; fluorine-modified alumina ; acid site concentration ; monomolecular reaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract γ-alumina catalysts modified with different weight loadings of fluorine have been used for skeletal isomerization of 1-butene in order to investigate the effects of the fluorine loading level on the conversion of 1-butene and the selectivity to isobutene formation. Increasing the actual loading of fluorine up to 0.012 wt% led to an increase in conversion of 1-butene over fluorine-modified γ-alumina catalysts, while the high selectivity to isobutene remains almost unchanged. On the other hand, a clear trend of increasing 1-butene conversion with a decreasing selectivity to isobutene is observed for the γ-alumina catalysts with higher loadings of fluorine. An analysis of the results from the thermal analysis, NH3 temperature-programmed desorption, infrared and the 1-butene sorption measurments clearly indicates that the number of strong acid sites in the modified γ-alumina catalysts is greatly enhanced at fluorine loadings higher than 0.012 wt%, leading to the acceleration of 1-butene oligomerization followed by cracking to light hydrocarbons. Therefore, the 1-butene isomerization selectivity from fluorine-modified γ-alumina catalysts can be understood in terms of a competition between the monomolecular and bimolecular reaction pathways, which highly depend on the concentration of strong acid sites.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 53 (1998), S. 375-376 
    ISSN: 1432-1041
    Schlagwort(e): Key words Artesunate ; Dihydroartemisinin ; Pharmacokinetics ; Bioequivalence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 0538-8066
    Schlagwort(e): Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Vacuum line kinetic studies of the reaction of p-toluenesulfonyl chloride and benzene or toluene, using aluminum chloride as the catalyst and dichloromethane as the solvent were determined at 25°C by means of gas chromatography. The reaction is first-order in arene, tosyl chloride, and in AlCl3 as catalyst. Noncompetitive results are kT/kB=22±7 with a product sulfone isomer distribution: ortho, 14±1%; meta, 4.3±0.2%; and para 82±1%. With hexadeuteriobenzene kH/kD was determined to be 1.8±0.1. Rate constant ratios and product isomer distributions were also determined competitively: with AlCl3, kT/kB=30±2; % ortho, 13±1; % meta, 4.0±0.5; % para, 84±3; with SbCl5, kT/kB=40±4; % ortho 10.3±0.4; % meta, 4.7±0.2; and % para, 85.0±0.5. The kT/kB ratio for AlCl3 and the meta sulfone product percentages for both AlCl3 and SbCl5 are considerably higher than those reported in the literature. NMR and Raman studies suggest a molecular complex between p-tosyl chloride and AlCl3, with coordination through oxygen as the dominant species and the probable electrophile in CH2Cl2. A reaction mechanism consistent with the kinetic and spectroscopic results is proposed. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 367-372,1998
    Zusätzliches Material: 5 Tab.
    Materialart: Digitale Medien
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