UV study of the protonation of indole-2-carboxylic acid, 3-methylindole, 3-acetylindole and D-Tryptophan in perchloric acid solutions

摘要

Protonation of indole-2-carboxylic acid, 3-methylindole, 3-acetyl- indole and D-trypophan 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 pK_a's were de- Termined using Hammett's equation. Also, the dissociation con- Stants and solvent parameter m* were obtained by the Excess Aci- Dity Method. The position of additional protons in protonated com- Pounds was discussed.