Molecular Heteroconjugation Equilibria in ( n -Butylamine + Acetic Acid) Systems in Binary (Dimethyl Sulfoxide + 1,4-Dioxane) Solvent Mixtures

The acidity constants of molecular acid, Ka(HA), cationic acid, Ka(BH+ ), as well as the equilibrium constants of anionic homoconjugation, KAHA−, cationic homoconjugation, KBHB+, and molecular heteroconjugation, KAHB, have been determined in (n-butylamine+ acetic acid) systems without proton transfer in binary [dimethyl sulfoxide (DMSO)+1,4-dioxane (D)] solvent mixtures. The constants were determined by using the potentiometric titration method at a fixed ionic strength. It is concluded that the molecular heteroconjugation constants in the mixed solvent systems studied are linearly related to the 1,4-dioxane coIntent. Furthermore, in the (acid+base) systems without proton transfer, the direction of titration (direct B+HA or reverse HA+B) has been found to affect the precision of determination of reliable values of molecular heteroconjugation constants. Moreover, it has been found that the relative dielectric constants of the solvent mixtures studied change linearly as a function of solvent composition, as well as solvent components do not show iInteractions of solvent–solvent type.