Protonation Constants of Valin in Different Aqueous Solutions of Dimethylsulfoxide

Subject Areas :

Masumeh Jabbari ¹ , Ali Shamel ² , Farrokh Ghari ³

1 - Chemistry Department, Islamic Azad University, Ardabil Branch, Ardabil, Iran,
2 - Chemistry Department, Islamic Azad University, Ardabil Branch, Ardabil, Iran
3 - Chemistry Department, Shahid Beheshti University, G. C., Tehran, Evin, Iran

Received: 2022-06-26 Accepted : 2022-06-26 Published : 2022-06-01

Keywords: Dimethylsulfoxide, solvent effect, valine, Tautomeric, Dissociation Constant,

Abstract :

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.