The dissociation constants of p-nitroaniline (B) (BH+ ⇔ B + H+) in methanol + water and propan-1-ol + water mixtures have been determined. Due to the presence of -NH2 and -NO2 groups in complimentary para positions, the dissociation constants for p-nitroaniline decrease with increase in percentage of organic co-solvents contrary to those observed in case of aniline, metanitroaniline etc.
A critical assessment of the solvent-sorting equilibrium method using p-nitroaniline as indicator has been made. The method is not suitable to determine the Gibbs energy of transfer of H+ from aqueous to aquo-rich organic solvents.
Print ISSN: 0942-9352
Volume: 215, 01/2001
Pages: 013