Temperature Dependence of Enantioselectivity in Complexations of Optically Active Phenolic Crown Ethers with Chiral Amines in Solution

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The association constants (K) of complexes of chiral neutral amines with optically active crown ethers ((S,S)-1, (S,S)-2, (S,S)-4 and (S,S)-5) which contain the phenyl chiral barriers and the phenol moiety bearing an additional para-substituent were determined at various temperatures by the 1H n.m.r. spectroscopic method in CDCl3. The thermodynamic parameters for complexation, which were determined from the van't Hoff plots of the K values, suggested that the acidity of the phenolic crown ethers markedly affected the enthalpy and entropy changes upon complexation with neutral amines. The crown ethers ((S,S)-2, (S,S)-4 and (S,S)-5) having higher acidity showed more negative ΔH and ΔS values and a larger slope in the enthalpy-entropy compensation plot than crown ether (S,S)-1 having a lower acidity. The temperature-dependent enantioselectivity in complexation of chiral neutral amines with (S,S,S,S)-6 containing phenyl substituents and the cyclohexane moieties as chiral barriers together with the p-(2,4-dinitrophenylazo)phenol moiety was also examined, demonstrating that steric interactions between the bulky steric barriers and the amine induced larger conformational changes of the host and guest molecules upon complexation. The data of the temperature-dependent enantioselectivity demonstrate a reversal of the relative merits of the enantioselectivity depending upon the temperature. A linear relatioship between the TΔR,SΔS values and the ΔR,SΔH values (TΔR,SΔS=0.812ΔR,SΔH-0.342, R=0.983) shows that the ΔR,SΔH and ΔR,SΔS values compensate each other. Therefore, complexation having a larger ΔR,SΔH value does not always show a higher degree of the enantioselectivity at any temperature than that having a smaller ΔR,SΔH value.

収録刊行物

  • Analytical sciences : the international journal of the Japan Society for Analytical Chemistry  

    Analytical sciences : the international journal of the Japan Society for Analytical Chemistry 14(1), 175-182, 1998-02-10 

    社団法人 日本分析化学会

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各種コード

  • NII論文ID(NAID)
    10002414573
  • NII書誌ID(NCID)
    AA10500785
  • 本文言語コード
    ENG
  • 資料種別
    ART
  • ISSN
    09106340
  • NDL 記事登録ID
    4406441
  • NDL 雑誌分類
    ZP4(科学技術--化学・化学工業--分析化学)
  • NDL 請求記号
    Z54-F482
  • データ提供元
    CJP書誌  NDL  J-STAGE 
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