Solvent effect on the dissociation of m- nitroanilinium ion in water-ethylene glycol media at 25°C

✍ Scribed by A.L. De

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 463 KB
• Volume: 28
• Category: Article
• ISSN: 0013-4686
• DOI: 10.1016/0013-4686(83)85229-3

✦ Synopsis

The dissociation constants (*K)aH + of m-nitroanilinium ion, have heen determined at 25°C in aqueous mixtures of IO, 30, 50, 70 and 90 wt. "/p of ethylene glycol from spectrophotometric measurements. The solvent effect on the dissociation behavtour of this acid: AGF(BH+ -B),,, = 2.303 RT [p(,K)g" + --p (,,.K)&+ 1 in these media results in a characteristic minimum with change in the solvent comnosition. The solvent effect has been discussed in terms of the free energies of transfer (AG!? from water to the aqueous glycol solvents, of the uncharged base (B) evaluated from measured s&udiiities, of the hydrochloride of the base (BHCI) computed from the corresponding values for HCI, and also of the individual ions assessed from the previous knowledge of Adp(Cl-< The corresponding data for the protonated Tris (hydroxymethyl) methylamine (Tris H*) and p-nitroanilinium ion in the same solvent mixtures obtained from the literature are also compared. Solvent effect on the dissociation of mnitroanilinium ion has been found to be nearly the same as that for the p-nitroanilinium ion with similar chemical composition but different from that observed in the case of Tris H+ of different chemical nature.