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KMID : 1059519880320010053
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Journal of the Korean Chemical Society
1988 Volume.32 No. 1 p.53 ~ p.59
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Formation Constants of 18-Crown-6 Complexes with Substituted Potassium Phenoxides
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Yoh Soo-Dong
Kim Soon-Kyoo
Han In-Sook
Park Jong-Hwan
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Abstract
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Recently, the formation of the complexes between macrocyclic polyethers and alkali metal salts have been determined by several methods. It has been suggested that the specificity of the complexation be due to the nature of the surrounding solvent molecules. The formation constant values (Kf) of K+ are shown to be the largest among the other alkali metal cations because the ionic diameter of K+ is approximately the same with the hole size of 18-crown-6. In this study the formation constants of the 1 : 1 complexes of 18-crown-6 with potassium p-substituted phenoxide are calculated by the conductance measurement in organic solvents. As a result, the Kf value series among organic solvents are given in the order of CH3OH > DMF > DMSO. It seems that the donor number of the solvent is a main factor in the formation of the complex between K+ metal ion and 18-crown-6 molecules. At the same time, the formation constants increase with increasing the electron-withdrawing power of substituents because the phenoxide ion is stabilized by the charge dispersion.
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