Hamamcı C, Hoşgören H, Erdoğan S
Department of Analytical Chemistry, Faculty of Science, University of Dicle, TR-21280 Diyarbakir, Turkey.
Talanta. 1998 Sep;47(1):229-36.
Extraction of alkali metal picrates with N,N'-dibenzyl-18-crown-6 was carried out, with dichloromethane as water-immiscible solvent, as a function [ligand]/[metal cation]. The extractability of metal picrates (Li(+), Na(+), K(+), Rb(+), Cs(+)) was evaluated as a function of [L]/[M(+)]. The extractability of complex cation-picrate ion pairs decreases in this sequence: Li(+)>Rb(+)>Cs(+)>K(+)>Na(+). The overall extraction equilibrium constants (K(ex)) for complexes of N,N'-dibenzyl-18-crown-6 with alkali metal picrates between dichloromethane and water have been determined at 25 degrees C. The values of the extraction constants (logK(ex)) were determined to be 10.05, 6.83, 7.12, 7.83, 6.73 for Li(+), Na(+), K(+), Rb(+) and Cs(+) compounds, respectively. DB186 shows almost 2-fold extractability against Li(+) compared to the other metal picrates, whereas it shows no obvious extractability difference amongst the other metal cations when [L]/[M(+)] is 0.2-1. However, an increasing extractability is observed for Cs(+) when [L]/[M(+)] [1].
以二氯甲烷作为与水不混溶的溶剂，研究了用N,N'-二苄基-18-冠-6萃取碱金属苦味酸盐的过程，该过程是[配体]/[金属阳离子]的函数。评估了金属苦味酸盐（Li⁺、Na⁺、K⁺、Rb⁺、Cs⁺）的萃取率与[L]/[M⁺]的关系。复合阳离子-苦味酸根离子对的萃取率按以下顺序降低：Li⁺>Rb⁺>Cs⁺>K⁺>Na⁺。已在25℃下测定了N,N'-二苄基-18-冠-6与碱金属苦味酸盐在二氯甲烷和水之间形成的配合物的总萃取平衡常数（K(ex)）。Li⁺、Na⁺、K⁺、Rb⁺和Cs⁺化合物的萃取常数（logK(ex)）值分别确定为10.05、6.83、7.12、7.83和6.73。与其他金属苦味酸盐相比，DB186对Li⁺的萃取率几乎高出2倍，而当[L]/[M⁺]为0.2 - 1时，它在其他金属阳离子之间未显示出明显的萃取率差异。然而，当[L]/[M⁺]>1时，观察到Cs⁺的萃取率增加。
