Strength of weak bases in aqueous acid by solvent extraction method

Abstract

<span style="font-size:12.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-ansi-language:="" en-in;mso-fareast-language:en-in;mso-bidi-language:ar-sa"="" lang="EN-IN">The protonation behaviour of N-arylsubstituted hydro xamic acids is investigated by the determination of their ionisation ratio measurements following the solvent extraction method. These reagents act as weak organic bases in strong acidic solutions. The values of protonation constants of the conjugate acids of these reagents are determined using three classical procedures, in order to rationalise the differences observed between <i style="mso-bidi-font-style: normal">pK</i>_BH⁺ values estimated by these methods. The first is based on the Bunnett-Olsen free energy relationship, developed for acid solutions and uses an ac idity function. The other is known as Excess Acidity Method. or X-function method . This method uses overlapping indicators but does not involve acidity function. The values of <i style="mso-bidi-font-style: normal">pK</i>_BH⁺ obtained by these two extrapolative procedures, both of which involve the use of activity coefficient ratios have been compared with the acidity constants obtained by old classical procedure, the Hammett Acidity Function Method.</span>