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  • 1995-1999  (3)
  • 1940-1944
  • Organic Chemistry  (3)
  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 58-66 
    ISSN: 0899-0042
    Schlagwort(e): molecular mechanics ; HPLC ; chiral separation ; methylphenobarbitone ; hexobarbitone ; ibuprofen ; mandelic acid ; ephedrine ; pseudoephedrine ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: β-Cyclodextrin and its derivatives have been utilised to effect chiral separation in HPLC and CZE, both as stationary phases and mobile phase additives. The basis of the method is assumed to depend upon the formation of inclusion complexes of differing stabilities between enantiomeric analytes and the cyclodextrin, resulting in a differential dynamic distribution between chromatographic phases. In this study, force field calculations have been employed to model the inclusion complexes of enantiomeric brompheniramine, ephedrine, pseudoephedrine, ibuprofen, mandelic acid, methylphenobarbitone, and hexobarbitone with β-cyclodextrin. The resulting values for Δ(ΔH), the difference in enthalpy of complex formation between enantiomeric pairs has been compared with literature chromatographic data to explain the ability of the systems to achieve enantiomeric separations. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 0894-3230
    Schlagwort(e): Organic Chemistry ; Physical Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: An IR spectroscopic study of the hydrogen bonding of Bu3N+N-C≡N with 4-fluorophenol showed that the site of complexation is the nitrogen of the nitrile function. THe formation constant of the 1:1 complex in CCl4 indicates that this cyanamidate is a stronger hydrogen-bond base than is any nitrile, amine or pyridine. The Bu3N+-N- group increases the basicity of the nitrile group very efficiently because of the conjugation of two lone pairs on the anionic nitrogen with the π systems of the cyano group. This conjugation is also exemplified by the very low ν(C≡N) wavenumber (2104 cm-1).
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 449-451 
    ISSN: 0947-3440
    Schlagwort(e): Cyclophanes, multifunctionalized ; Auxiliaries, chiral ; Metalation, ortho-directed ; Fries rearrangement ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: For the preparation of the title compound, 4-hydroxy[2.2]paracyclophane (1) is first converted to the carbamate 2. Metalation of 2 with sec-butyllithium yields an ortho-anion which after trapping with dimethylformamide and acidic work-up provides 6 in 64% yield. Further application of the cyclophane anion include its capture by trimethylsilyl chloride to the trimethylsilyl derivative 3 (76%) and its Fries rearrangement to the phenol 4 (78%). The spectroscopic and analytical data of the new compounds are described in full detail.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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