Solvent extraction of Li + , H 3 O + and NH 4 + into nitrobenzene by using sodium dicarbollylcobaltate and calix[4]arene
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Solvent extraction of Li+, H3O+ and NH4+ into nitrobenzene by using sodium dicarbollylcobaltate and calix[4]arene-bis(t-octylbenzo-18-crown-6) E. Makrlı´k • P. Selucky´ • P. Vanˇura B. A. Moyer
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Received: 4 September 2012 / Published online: 26 September 2012 Ó Akade´miai Kiado´, Budapest, Hungary 2012
Abstract From extraction experiments and c-activity measurements, the exchange extraction constants corresponding to the general equilibrium M? (aq) ? NaL? (nb) , ML? (nb) ? Na? (aq) taking place in the two–phase water–nitrobenzene system (M?= Li?, H3O?, NH4?; L = calix[4]arenebis(t-octylbenzo-18-crown-6); aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the ML? complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following cation order: H3O? \ Li? \ NH4?. Keywords Univalent cations Calix[4]arenebis(t-octylbenzo-18-crown-6) Complexation Water– nitrobenzene system Extraction and stability constants
Introduction Calixarenes are macrocyclic compounds which are not only easily available on a large scale, but also offer nearly E. Makrlı´k (&) Faculty of Environmental Sciences, Czech University of Life Sciences, Prague, Kamy´cka´ 129, 165 21 Prague 6, Czech Republic e-mail: [email protected] P. Selucky´ ˇ ezˇ, Czech Republic Nuclear Research Institute, 250 68 R P. Vanˇura Department of Analytical Chemistry, Institute of Chemical Technology, Prague, Technicka´ 5, 166 28 Prague 6, Czech Republic B. A. Moyer Oak Ridge National Laboratory, Chemical Sciences Division, P. O. Box 2008, Oak Ridge, TN 37831-6119, USA
boundless possibilities for chemical modification [1]. This makes them highly attractive as building blocks for more sophisticated and elaborate host molecules. Among the numerous ‘‘tailor made’’ ligands for a large variety of metal cations, crown ether derivatives of calixarenes (calixcrowns) represent not only some of the earliest complexes [2], but also elegantly demonstrate the potential of these compounds [3]. Calixarenes find applications as selective binders and carriers, as analytical sensors, as catalysts and model structures for biomimetic studies [4]. New cesium—selective extractants especially from the calix[4]arene-crown-6 and calix[4]arene-bis(crown-6) families have been introduced [5–11] The corresponding crystal structures of model complexes with cesium salts have demonstrated a significant p-interaction between the facing aromatic rings and the Cs? guest cation [5–7] Besides, the calix[4]arene-crown-6 family of the mentioned compounds gives Cs?/Na? separation factors exceeding ten thousand [6]. The dicarbollylcobaltate anion (DCC-) [12] and some of its halogen derivatives are very useful reagents for the extraction of various metal cations (especially Cs?, Sr2?, Ba2?, Eu3? and Am3?) from aqueous solutions into a polar organic phase, both under laboratory conditions for purely theoretical or analytical purposes [13–20], and on the technological scale for the separation of some high-activity iso
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