Extraction Equilibria between Benzene and Water of Uni- and Bivalent Metal Picrates with Lariat 16-Crown-5: Effect of the Side Arms onthe Extraction Ability and Selectivity

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• 作者：Katsuta ; Shoichi ; Kimura ; Tokutaro ; Kudo ; Yoshihiro ; Nakagawa ; Ryozo ; Takeda ; Yasuyuki ; Ouchi ; Mikio
• 关键词：solvent extraction ; constituent equilibria ; ion ; pair extraction constant ; lariat 16 ; crown ; 5 ; uni ; and bivalent metal picrates ; side ; arm effect
• 刊名：Journal of Inclusion Phenomena and Molecular Recognition inChemistry
• 出版时间：1998
• 出版年：1998
• 期刊代码：19_09230750
• 类别：soc
• 卷：31
• 期：2
• 页码：89-98
• 数据来源：sp

摘要

The overall extraction constants (K$\_ex$) of uni- andbivalent metal picrates with 15-(2,5-dioxahexyl)-15-methyl-16-crown-5(L16C5) were determined between benzene and water at 25°C. TheK$\_ex$ values were analyzed into the constituent equilibriumconstants, i.e., the extraction constant of picric acid, the distributionconstant of the crown ether, the stability constant of the metalion–crown ether complex in water, and the ion-pair extraction constantof the complex cation with the picrate anion. The K$\_ex$ valuedecreases in the orders Ag$^+$ > Na$^+$ >Tl$^+$ > K$^+$ > Li$^+$ andPb$^2+$ > Ba$^2+$ > Sr$^2+$ for theuni- and bivalent metals, respectively, which are the same as those observedfor 16C5. The extraction selectivity was found to be governed by theselectivity of the ion-pair extraction of the L16C5–metal picratecomplex rather than by that of the complex formation in water. Theextraction ability of L16C5 is smaller for all the metals than that of 16C5,which is mostly attributed to the higher lipophilicity of L16C5. Differencesin the extraction selectivity between L16C5 and 16C5 were observed for thebivalent metals but little for the univalent metals. The side-arm effect onthe extraction selectivity was interpreted on the basis of the negativecorrelation between the effect on the complex stability constant in waterand that on the ion-pair extraction constant.