Determination of Pka Values of Some Vic-Dioximes in Non-Aqueous Media

Mehmet Tun

¹Faculty of Education, University of Nigde - 51100, Nigde (Turkey) ²Department of Chemistry, Faculty of Science and Arts, University of Nigde-51100, Nigde (Turkey)

A potentiometric titration method in non-aqueous media is proposed for the determination of some vic-dioxime compounds. Potentiometric titration of vic-dioxime ligands was carried out in 2-propanol solvent using tetra-n-butylammonium hydroxide (TBAH) as titrant at 25°C and under nitrogen atmosphere. The hydroxide protons of vic-dioximes were titrated to have clear information about their acidic characterization. There are two main effects to acidity of vic-dioximes, respectively, molecular structure and solvent effect. PKa values and half neutralization potentials of these compounds were determined using the potentiometric titration curves. A comparison of the pK1 values of vic-dioximes reveals that the chlorophenyl ring is more acidic than the phenyl and naphthalene ring. PKa values of the naphthalene ring were determined that more acidic then phenylene ring. The standard errors and signum values of the potentiometric titration datas were calculated with linear regulation method.

Potentiometry; non-aqueous media; inductive effect; vic-dioximes