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

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 .