B. S. Andonovski* and G. M. Stojković
Institute of Chemistry, “St. Cyril and Methodius University, P.O. Box 162, 91001 Skopje, Macedonia
Protonation of indole and 3-acetylindole in phosphoric and hydrochloric acid solutions was studied by UV spectroscopy. We present pKa values obtained by the CVA (Characteristic Vector Analysis) method. From the data, pKa values for protonation were obtained by using the Hammett's equation: pKa = H0 + log[c(BH+)/c(B)]. The dissociation constants and solvent parameter m* were obtained by application of the Excess Acidity Method. The position of protonation is discussed.
Key words: UV spectra, indole, 3-acetylindole, protonation, dissociation
constants, Hammett Acidity Function Method, Excess Acidity Method, Characteristic