Protonation Constants of Valin in Different Aqueous Solutions of Dimethylsulfoxide
الموضوعات : International Journal of Heterocyclic Chemistry
Masumeh Jabbari
1
(Chemistry Department, Islamic Azad University, Ardabil Branch, Ardabil, Iran,)
Ali Shamel
2
(Chemistry Department, Islamic Azad University, Ardabil Branch, Ardabil, Iran)
Farrokh Ghari
3
(Chemistry Department, Shahid Beheshti University, G. C., Tehran, Evin, Iran)
الکلمات المفتاحية: Dimethylsulfoxide, solvent effect, valine, Tautomeric, Dissociation Constant,
ملخص المقالة :
The protonation constants of valin (K1 and K2) was determined in binary mixtures of water with dimethylsulfoxide containing (0, 10, 20, 30, 40, and 50) % (v/v) using a combination of potentiometric method at 25 °C and constant ionic strength (0.1mol ·dm-3 sodium perchlorate). The protonation constants were analyzed using the normalized polarityparameter (ETN) and Kamlet, Abboud, and Taft (KAT) parameters. A very good linear correlation of log K versus the normalized polarity parameter was obtained. Dual-parameter correlation of log K versus π*(dipolarity/polarizability) and R (hydrogen-bond donor acidity) as well as π* and (hydrogen-bond acceptor basicity) also gives good results in various aqueous organic solvent mixtures. Finally, the results are discussed in terms of the effect of the solvent on the protonation constants.
