“…For example, KLPic dissociates into KL + and picrate ion (Pic ) in dichloromethane (Frensdorff, 1971) and water (Takeda, 2002) at L = dibenzo-18-crown-6 ether (DB18C6) and n = 1 and in 1,2-dichloroethane (DCE) at L = 18-crown-6 ether, 18C6, and n = 1 (Kolthoff & Chantooni, 1993); CaLA 2 dissociates into CaLA + and A at L = dicyclohexyl-18C6, A = dipicrylaminate ion, and n = 2 (Jawaid & Ingman, 1978). In solvent extraction, the presence of such equilibria means at least the presence (Kudo, Harashima, Katsuta, & Takeda, 2011;Kudo, Katsuta, & Takeda, 2012;Kudo, Horiuchi, Katsuta, & Takeda, 2013) of the individual distribution of A (or MLA + ) into the organic phase under the condition that the free A (or MLA + ) is detected in the aqueous phase. Furthermore, this distribution is related to an ion transfer of A across a liquid/liquid interface, such as nitrobenzene/aqueous and DCE/aqueous ones, and then its distribution data have been connect with electrochemical properties of A at the interface (Osakai & Ebina, 1998;Kudo & Takeuchi, 2013).…”