An Electrochemical Understanding of Extraction of Silver Picrate by Benzo-3<i>m</i>-Crown-<i>m</i> Ethers (<i>m</i> = 5, 6) into 1,2-Dichloroethane and Dichloromethane

Abstract

How to cite this paper: Kudo, Y., et al. (2014) − , into the two diluents were also determined with the determination of K ex . From comparison of these K D,Pic values with those standardized, interfacial potential differences (∆φ eq ) at extraction equilibria were evaluated. Then, using these ∆φ eq values, relations of the experimentally-determined logK ex± or logK ex values with their electrochemically-standardized ones were precisely discussed. Consequently, it was indicated that logK ex± should be expressed as a function of ∆φ eq .

On an Expression of Extraction Constants without the Interfacial Equilibrium-Potential Differences for the Extraction of Univalent and Divalent Metal Picrates by Crown Ethers into 1,2-Dichloroethane and Nitrobenzene

“…In the present paper, in order to solve the above two contradictions, namely the differences of K D,A caused by experimental conditions of extraction and the contradiction based on the thermodynamic cycles [3] [7], we proposed another expression without ∆φ eq of the extraction constants, K ex± and K ex2± . In course of clarifying this expression, some experimentally-determined constants [3] [7], such as K ex± , an individual distribution constant (K D,ML ) of the complex ion ML 2+ into the NB phase and that of AgL + into DCE, were also reproduced by calculation.…”

“…However, in spite of the limitation of the same K D,A definition and the same diluents, the thus-determined K D,Pic values have differed from each other. For example, the logK D,Pic values were −0.94 [2] for the PbPic 2 extraction with 18-crown-6 ether (18C6), −1.34 [7] for the SrPic 2 one with benzo-18C6 (B18C6) into NB, −2.4 6 [3] for the AgPic one with benzo-15-crown-5 ether, −1.89 [2] for the PbPic 2 one with 18C6 and −4.3 5 [6] for the CdPic 2 one with 18C6 into DCE. Thus, their values have changed over experimental errors with combinations of MPic z and L.…”

“…Similarly, the distribution constant of M z+ has been expressed with K D,M (see Equation (3) at 1 z = in the Section 2.1) [3]. Therefore, …”

“…In such high-polar diluents, an extracted ion-pair complex, MLPic z , dissociates ML z+ and zPic − [1]- [3] [6]. In introducing these component equilibria in an extraction model, an individual distribution constant (K D,A ) of Pic − (=A − ) into the diluents has been determined extraction-experimentally [1]- [3] [7]. However, in spite of the limitation of the same K D,A definition and the same diluents, the thus-determined K D,Pic values have differed from each other.…”

“…To clarify a reason for such differences, the authors have applied the idea [8] of an interfacial potential difference (∆φ eq ) at extraction equilibrium to an expression of log K D,A , namely On the other hand, from the thermodynamic points of view, these extraction constants are resolved into ( ) ( ) their expressions, because the constants are of homogeneous systems that all species relevant to the reaction are present in the single o phase [3] [7]; namely no interface is involved in these processes. Similarly, the distribution constant of M z+ has been expressed with K D,M (see Equation (3) at 1 z = in the Section 2.1) [3].…”