7Li-NMR Determination of Stability Constants as a Function of Temperature for Lithium-Crown Ether Complexes in a Molten Salt Mixture

Autor:	Yo-Hsin Huang, Aaron M. Highley, Gabor Konya, Ben A. Garland, Sergio Petrucci, Rudi van Eldik, Edward M. Eyring, Achim Zahl, Daryl P. Cobranchi, Achim Gerhard
Rok vydání:	1994
Předmět:	chemistry.chemical_classification General Engineering chemistry.chemical_element Halide Resonance (chemistry) Chloride Ion Solvent chemistry medicine Physical chemistry Lithium Physical and Theoretical Chemistry Molten salt Crown ether medicine.drug
Zdroj:	The Journal of Physical Chemistry. 98:7923-7928
ISSN:	1541-5740 0022-3654
DOI:	10.1021/j100083a028
Popis:	The stability constants of several crown ethers with lithium ion were determined by [sup 7]Li-NMR measurements. A room temperature, basic molten salt of the composition of 55/45 mol % 1-methyl-3-ethyl-imidazolium chloride to aluminum (III) chloride was used as solvent. On the basis of a 1:1 complex formation the following order was found for the stability constants of the investigated crown ethers: 18-crown-6 < 12-crown-4 < benzo-15-crown-5 < 15-crown-5. A temperature dependence study for 12-crown-4, benzo-15-crown-5, and 15-crown-5 was undertaken for the range 5-84[degree]C. Values of [Delta]H and [Delta]S were calculated. At 5.5[degree]C the splitting of the single, fast exchange peak into two separate signals was observed for benzo-15-crown-5, providing further evidence for the formation of the 1:1 complex. 34 refs., 4 figs., 5 tabs.
Databáze:	OpenAIRE
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