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uv Study of the Protonation of Indole and 3-Substituted Indoles in Perchloric Acid Media

R. Andonovski ; Institut za kemija, PMF, Univerzitet "Sv. Kiril i Metodij«, P.O. Box 162, 91001 Skopje, Macedonia
I. Spirevska ; Institut za kemija, PMF, Univerzitet "Sv. Kiril i Metodij«, P.O. Box 162, 91001 Skopje, Macedonia
A. Nikolovski ; Institut za kemija, PMF, Univerzitet "Sv. Kiril i Metodij«, P.O. Box 162, 91001 Skopje, Macedonia

Sažetak

The protonation of indole, indolyl-3-acetic acid, indolyl-3-propionic
acid and indolyl-3-butyric acid in perchloric acid media was studied
by the methods of ultraviolet spectroscopyin the 320-190 nm region.
The absorbance values were meas ured at several selected wavelengths and the molar absorptivity was calculated. From these values, using the Hammett's equation: pKa = H + 10g[c(BH+)/c(B)]
where H is Ha or Hi (i.e. Hammett's acidity function or its corrected
value), the pKa values for the reaction of protonation were obtained.
The Hammett's postulate (the slopes of the plots log
[c(BH+)/c(B)]vs. H should be equal to 1) was tested. Also, the dissociation constants and the solvent parameter m were obtained by
application of the Excess Acidity Method. The position of the additional
protons in the protonated compounds was discussed.

Ključne riječi

Hrčak ID:

177139

URI

https://hrcak.srce.hr/177139

Datum izdavanja:

1.11.1996.

Posjeta: 1.365 *