Hofmeister Anion Effects on Thermodynamics of Caffeine Partitioning between Aqueous and Cyclohexane Phases
| Autor: | Yanjie Zhang, Tye S. Thompson, Bradley A. Rogers |
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| Rok vydání: | 2016 |
| Předmět: |
Aqueous solution
Cyclohexane Inorganic chemistry Enthalpy Aqueous two-phase system Thermodynamics 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Surfaces Coatings and Films Gibbs free energy Ion symbols.namesake chemistry.chemical_compound chemistry Materials Chemistry symbols Molecule Physical and Theoretical Chemistry 0210 nano-technology Caffeine |
| Zdroj: | The Journal of Physical Chemistry B. 120:12596-12603 |
| ISSN: | 1520-5207 1520-6106 |
| Popis: | Specific anion effects on the thermodynamics of caffeine partitioning between aqueous and cyclohexane phases were studied in the presence of 11 sodium salts by utilizing UV–vis spectroscopy. It is observed that weakly hydrated anions such as ClO4–, SCN–, and I– salt caffeine into the aqueous phase and increase the standard Gibbs free energy for caffeine transfer. On the other hand, well-hydrated anions such as CO32– and SO42– salt caffeine molecules out of the aqueous solution and promote the transfer process. Results suggest that weakly hydrated anions associate with the hydrophobic patches of caffeine including three methyl groups and a flat heteroatomic ring to solvate caffeine molecules. Well-hydrated anions are excluded from the caffeine surface to salt caffeine molecules out of aqueous solution. Moreover, the enthalpy and entropy of caffeine transfer were obtained by measuring the standard Gibbs free energy for caffeine transfer at varied temperatures. The transfer of caffeine from the aqueous to cy... |
| Databáze: | OpenAIRE |
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