54(4), 2007, pp.1093-1097

Spectrophotometric Determination of Acidity Constants of 4-(2-Pyridylazo) Resorcinol in Various Micellar Media Solutions

Jahanbakhsh Ghasemi,* Hossein Peyman and Ali Niazi

Department of Chemistry, Faculty of Sciences, Razi University, Kermanshah, Iran

Abstract.     Dissociation equilibria of 4-(2-pyridylazo) resorcinol (PAR) in aqueous micellar solutions were determined spectrophotometrically at 25 °C and at the constant ionic strength I = 0.1 M KNO3. For this purpose, the effect of nonionic (Brij-35, Triton X-100, Triton X-114, Triton X-405), and anionic (SDS) surfactants on the absorption spectra of PAR at different pH values was studied. Results show that the pKa values and pure spectra of each species of PAR are influenced by percentages of a neutral and an anionic surfactant such as Brij-35, Triton X-100, Triton X-114, Triton X-405 and SDS, respectively, added to the solution of this reagent.

Keyword:  Acidity constant; PAR; Anionic surfactant; Neutral surfactant; DATAN; Spectrophotometric.