The Basicities of Tropone and Tropolone

Abstract
The ultraviolet absorption spectra of tropone (I) and tropolone (II) were measured with sulfuric acid solutions of various acidities. The accurate pKa values, as determined by the proposed method, were −1.02 and −0.86 for I and II respectively. The Raman spectra of II were measured with sulfuric acid solutions of various acid concentrations. The bands in the 6 and 15 μ regions change sharply when the solvent acidity changes from 5 to 25%, corresponding well to the ultraviolet absorption change. The infrared absorption spectra of II were measured with the concentrated deuterosulfuric acid solution in the 6 μ region. The vibrationals mode of the protonated tropolone were discussed.