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Thermodynamics of cesium complexes formation with 18-crown-6 in ionic liquids |
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| Authors: | A G Vendilo H Rönkkömäki M Hannu-Kuure M Lajunen J Asikkala V G Krasovsky E A Chernikova P Oksman L H J Lajunen T Tuomi K I Popov |
| Institution: | 1. State Research Institute of Reagents and High Purity Substances (IREA), Bogorodskii val 3, 107258, Moscow, Russia 2. Finnish Institute of Occupational Health, Aapistie 1, 90220, Oulu, Finland 3. Department of Chemistry, University of Oulu, P.O. Box 3000, 90014, Oulu, Finland 4. Zelinsky Institute of Organic Chemistry RAS, Leninsky pr. 47, 119991, Moscow, Russia 5. Finnish Institute of Occupational Health, Arinatie 3, 00370, Helsinki, Finland 6. Department of Physical and Colloid Chemistry, Moscow State University of Food Technologies, Volokolamskoye Sh.11, 125080, Moscow, Russia |
| Abstract: | Thermodynamic data for cesium complexes formation with 18-crown-6 (18C6, L) Cs(18C6)]+ in N-butyl-4-methyl-pyridinium tetrafluoroborate (BMPy]BF4], I), in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM]BF4], II) and in 1-butyl-3-methylimidazolium dicyanamide (BMIM]N(CN)2], III) were measured with NMR 133Cs technique at 23–50 °C. The stability of cesium complex in RTILs is estimated to be in the range between water and DMFA. Stability constants for Cs(18C6)]+ are found to decrease as temperature is increasing. The following values for lgK(Cs+L) and ΔH(Cs+L) at 23 °C are determined: 2.6 (0.3), ?47(1) kJ/mol (RTIL I); 2.8(0.3), ?80(3) kJ/mol (RTIL II) and 3.03 (0.08), ?47(2) kJ/mol (RTIL III). It is demonstrated that enthalpy change promotes complex formation while the corresponding change of entropy is negative and provides decomposition of Cs(18C6)]+. |
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