%0 Journal Article
%T Protonation constants of hydroxybenzenes in hydrochloric acid
%A D. S. VESELINOVIC
%A M. V. OBRADOVIC
%A S. B. TOSIC
%J Journal of the Serbian Chemical Society
%D 1999
%I Serbian Chemical Society
%X The absorption spectra of monohydroxybenzene (Fen), 1,3-dihydroxybenzene (Rez), 1,4-dihydroxybenzene (Hi), 1,2,3-trihydroxybenzene (Pg) and 1,3,5-trihydroxybenzene (Fg) in aqueous solutions of hydrochloric acid with different values of the Hammett acidity function(H0) have two absorption bands in the region between 190-220 nm and 260-290 nm. This behavior is similar in another mineral acids (H2SO4, H3PO4, HClO4). The absorbance decreases with increasing of acidity (with decreasing of H0 values) because of O-protonation. The absorption maxima shift to longer wavelengths, and the graphic dependence of the absorption of the second band as a function of H0 gives characteristic S-curves. These curves show the different effect of the acid on the form the protonation of the investigated hydroxybenzenes. The potonation constants of the hydroxybenzenes were calculated: pKFen=-1.95; pKRez=-2.40; pKHi= -1.93; pKPg=-2.95; pKFg=-1.83.
%K hydroxybenzenes
%K Hammett acidity function
%K hydrochloric acid
%K protonation
%K UV spectra
%K S-curve
%K protonation constant
%U http://www.shd.org.yu/HtDocs/SHD/Vol64/No9-Pdf/V64-no9-05.zip