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

Yoshihiro Kudo, Marina Ogihara, Shoichi Katsuta, Yasuyuki Takeda

Graduate School of Science, Chiba University, Chiba, Japan.

DOI: 10.4236/ajac.2014.57052                

Abstract

Two extraction constants (K_ex± and K_ex) for extraction of silver picrate (Ag^﹢Pic^﹣) by benzo-15-crown-5 ether (B15C5) and benzo-18-crown-6 one (B18C6) into 1,2-dichloroethane (DCE) and dichloromethane (DCM) were determined at 298 K and given values of ionic strength. Here, K_ex± and K_ex were expressed as [AgL^﹢]_o[Pic^﹣]_o/[Ag^﹢][L]_o[Pic^﹣] and [AgLPic]_o/[Ag^﹢][L]_o[Pic^﹣], respectively: L symbolizes B15C5 or B18C6 and the subscript “o” denotes the organic phase composed of DCE or DCM. Individual distribution constants (K_D,Pic) of picrate ion, Pic^﹣, 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 () at extraction equilibria were evaluated. Then, using these 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 .

Keywords

Individual Distribution Constants, Interfacial Potential Differences, Standardized Extraction Constants, Silver Picrate, Benzo Crown Ethers, Dihaloalkanes

Conflicts of Interest

The authors declare no conflicts of interest.

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