Effect of Extraction Solvents on Extractability of Picrate with Potassium-18-Crown-6 Complex

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  • NOGUCHI Hideyuki
    Department of Applied Chemistry, Faculty of Science and Engineering, Saga University

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Other Title
  • カリウム-8-クラウン-6錯体によるピクリン酸イオンの抽出における溶媒効果

Abstract

The extraction of potassium picrate (Pic-) with 18?crown-6 (L) into 9 kinds of solvents has been studied at 25.0°C. The overall extraction equilibrium in all solvents used is shown by following equation; K++Lo+Pic-=KLPico, where subscript "o" and Pic- show organic phase and picrate ion, respectively. Extraction constants of ion-pairs KLPic (Kox=[KLPic]0/([KL+] [Pic-]), were calculated from stability constant between K+ and L in the aqueous phase, distribution coefficient of L (KdL, ) and overall extraction equilibrium constants. The values of log Kex are 4.95 (CH2Cl2), 4.85 (CHC13), 4.43 (CH2C1CH2C1), 3.39 (C6H5C1), 2.31(C6H5CH3), 1.91 (rn-(CH3)2C5H4), 1.51 (C6H5CH(CH3)2), 1.48 (CS2), and 1.04 (C2H5OC2H 5). It was found that there was a good linear relationship between log Kex and lo g Kd. L. Distribution coefficients of KLPic (log Kd) between water and benzene analogues were successfuly explained in terms of the regular solution theory. Solubility parameter and molar volume of KLPic were found to be 12.3 (cal. cm-3)1/2 and 280 cm3. mo1-1. Absorption spectra of KLPic in the extraction solvents show ed that KLPic would be considered to be solvated in solvents, CHC13, CH2C12, CH2CICH2C1, and C2H5OC2H5. Then, higher Kd value of these solvents than predicted one would be due to the solvation to KLPic in the organic phase. Linear relation ship between log Kex and log Kd, L, was theoretically explained by the regular solution theory, in which solvation of extraction solvent to KLPic and L was taken into account. The slope of the curve agreed well with the ratio of the molar volume of L calculated from X-ray data to that of KLPic determined here.

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1990 (9), 939-944, 1990-09-10

    The Chemical Society of Japan

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