Effect of tetrabutylammoniumbromide(TBAB) on protonation equilibria of succinic acid and L-glutamine

Abstract

Effect of tetrabutylammoniumbromide(TBAB) on protonation equilibria of L-glutamine (Gln) and succinic acid (Suc) in varying concentrations (0.0-3.0%, w/v) of TBAB-water mixtures at an ionic strength of 0.16 mol dm-3 and temperature 303K has been made using a pH-meter. Various models for the species of these ligards are refined by using the computer programs SCPHD and MINIQUAD75. The active forms of the ligands are LH2 and LH- for succinic acid and LH2+ and LH for L-glutamine. The trend in the variation of protonation constants with dielectric constant is explained on the basis of electrostatic and non-electrostatic forces. The species distribution with pH at different solvent composition and the plausible equilibria for the formation of the species are also presented.

Keywords

• MINIQUAD75
• TBAB
• succinic acid
• L-glutamine
• speciation
• complex equilibria