Thermodynamics of Solvation of 18-Crown-6 and Its Alkali-Metal Complexes in Various Solvents |
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| Authors: | Kumiko Ohtsu Kazuhiko Ozutsumi |
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| Affiliation: | (1) Laboratory of Analytical Chemistry, Department of Chemistry, University of Tsukuba, Tsukuba, 305-8571, Japan;(2) Department of Applied Chemistry, Faculty of Science and Engineering, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, 525-8577, Japan |
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| Abstract: | Heats of solution of 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) in acetonitrile, 1,2-dichloroethane, N,N-dimethylformamide, dimethyl sulfoxide, nitromethane, propylene carbonate, pyridine and water were measured at 25 °C and the enthalpies of the transfer of 18-crown-6 from waterto the aprotic solvents were derived. The thermodynamic quantities,  G1°, H1° and T S1°, for the formation of the[M(18-crown-6)]+ (M+ = Na+, K+, Rb+, Cs+, NH4+) complexeswere determined by titration calorimetry in dimethyl sulfoxide containing0.1 mol dm-3 (C2H5)4NClO4 as a constant ionic medium at 25 °C. These thermodynamic quantities suggest that the complexationof 18-crown-6 with the alkali-metal ions mainly reflects the different solvationof 18-crown-6 and also the different degree of solvent structure. |
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| Keywords: | alkali-metal complexes aprotic solvents 18-crown-6 enthalpies of transfer solvent effect on complexation water |
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