Determination of Distribution Equilibrium-Potential Differences Based on Extraction with Several Crown Ethers by Nitrobenzene, 1,2-Dichloroethane and Dichloromethane

Yoshihiro Kudo,Satoshi Ikeda,Tomohiro Amano

doi:10.5539/ijc.v9n4p110

Abstract

Extraction constants (Kex± & Kex) were determined at 298 K for the extraction of sodium picrate (NaPic) by nitrobenzene (NB), 1,2-dichloroethane (DCE) and dichloromethane using 3m-crown-m ethers and their benzo-derivatives (m = 5, 6; abbreviated as L) together with the determination of conditional distribution constants (KD,Pic) of picrate ion, Pic-, into these diluents. The K1,org (= [NaLPic]org/[NaL+]org[Pic-]org) values at the organic (org) phases, such as NB & DCE, were calculated from the relation Kex/Kex± = K1,org. Distribution equilibrium-potential differences (Dfeq) at extraction equilibria were evaluated from the equation Dfeq = -0.05916´(log KD,Pic - constant) at 298 K. Correlations of the above equilibrium constants, particularly Kex±, with Dfeq were examined. Furthermore, the standard formal potentials for Na+ transfers across the interfaces were briefly evaluated from calculated Dfeq, [Na+] and [Pic-]org. The above extraction systems were characterized by K1,org and the complex formation constants of Na+ with L in the org phases.

Highlights

IntroductionIn our previous papers (Kudo & Takeuchi, 2014; Kudo & Katsuta, 2015), distribution equilibrium-potential difference (dep, Δφeq as a symbol) has been reported through studies of extraction of some metal picrates {AgPic & MPic with M = Ca(II), Sr(II) & Ba(II)} by several diluents, such as 1,2-dichloroethane (DCE) and nitrobenzene (NB), using crown ethers (L), such as 18-crown-6 ether (18C6) and benzo-18C6 (B18C6)
In our previous papers (Kudo & Takeuchi, 2014; Kudo & Katsuta, 2015), distribution equilibrium-potential difference has been reported through studies of extraction of some metal picrates {AgPic & MPic2 with M = Ca(II), Sr(II) & Ba(II)} by several diluents, such as 1,2-dichloroethane (DCE) and nitrobenzene (NB), using crown ethers (L), such as 18-crown-6 ether (18C6) and benzo-18C6 (B18C6)
Distribution equilibrium-potential differences (Δφeq) at extraction equilibria were evaluated from the equation Δφeq = −0.05916×(log KD,Pic − constant) at 298 K

Summary

Introduction

In our previous papers (Kudo & Takeuchi, 2014; Kudo & Katsuta, 2015), distribution equilibrium-potential difference (dep, Δφeq as a symbol) has been reported through studies of extraction of some metal picrates {AgPic & MPic with M = Ca(II), Sr(II) & Ba(II)} by several diluents, such as 1,2-dichloroethane (DCE) and nitrobenzene (NB), using crown ethers (L), such as 18-crown-6 ether (18C6) and benzo-18C6 (B18C6) In these studies, the dep values have been experimentally determined using the equation log KD,A=−{Δφeq−(standard formal potential)}/0.05916 at 298 K, where KD,A is a conditional distribution constant of A− into an organic (org) phase under the condition of Δφeq ≠ 0 V (Kudo & Takeuchi, 2014; Kudo et al, 2014; Kudo et al, 2015).

Methods

Results

Conclusion