Tsurko, Elena N. and Neueder, Roland and Kunz, Werner (2008) Activity of water and osmotic coefficients of histidine derivatives in aqueous solutions at 310.15 K. JOURNAL OF SOLUTION CHEMISTRY, 37 (3). pp. 421-431. ISSN 0095-9782,
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From the data of vapor pressure osmometry the activity of water, osmotic coefficients, and the values of activity coefficients of two derivatives of histidine: N-Boc-L-histidine (Boc-His-OH, m=0.005-0.14 mol.kg(-1)) and N-Boc-L-histidine-methyl ether (Boc-His-OMe, m=0.005-0.05 mol.kg(-1)) are obtained in aqueous solutions at 310.15 K. From the comparison of water activity and osmotic coefficient values it follows that Boc-His-OMe shows a more pronounced deviation from ideality than Boc-His-OH. Both components exhibit a stronger non-ideality than histidine and a weaker one than His center dot HCl. By means of potentiometric titration the acid-base properties of Boc-His-OMe are investigated and the ionization constant at 298.15 K is determined. The pK value related to the acid-base equilibrium of the nitrogen atom in the imido group of the imidazole ring is higher (6.47) than the corresponding value of histidine (6.00).
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CHANNELS; vapor pressure osmometry; Emf; activity of water; activity coefficients; osmotic coefficients; N-Boc-L-histidine; N-Boc-L-histidine methyl ether; zwitterions; ionic form of amino acid; dissociation constant |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > Prof. Dr. Werner Kunz |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 09 Nov 2020 05:47 |
| Last Modified: | 09 Nov 2020 05:47 |
| URI: | https://pred.uni-regensburg.de/id/eprint/31287 |
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