Original scientific paper

UV Study of the Protonation of Indole-2-carboxylic Acid, 3-Methylindole, 3-Acetylindole and D-Tryptophan in Perchloric Acid Solutions

Blagoja S. Andonovski ; Institute of Chemistry, Faculty of Science, The Sv. Kiril i Metodij University, P. O. Box 162, 91001 Skopje, Republic of Macedonia

Abstract

Protonation of indole-2-carboxylic acid, 3-methylindole, 3-acetylindole and D-tryptophan in perchloric acid media was studied by UV spectroscopy methods in the 400–190 nm region. Absorbance values were measured at four selected wavelengths and the molar absorptivity was calculated. From these values, the pKa's were determined using Hammett's equation. Also, the dissociation constants and solvent parameter m* were obtained by the Excess Acidity Method. The position of additional protons in protonated compounds was discussed.

Keywords

UV spectra; protonation; indole-2-carboxylic acid; 3-methylindole; skatole; 3-acetylindole; D-tryptophan; dissociation constants; Hammett; acidity functions; excess acidity

Hrčak ID:

132271

URI

https://hrcak.srce.hr/132271

Publication date:

1.12.1999.

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