Protonierungs- und Deprotonierungskinetik des Systems Azulen-Azuleniumkation,ein Beitrag zur Kenntnis der Hammett'schen Ho-Aciditätsfunktion

Using a flashphotolysis-method to evaluate the rates of the protonation of azulene and the deprotonation of azuleniumcation as a function of H₀ the validity of the Hammett H₀-function was examined. Using this technique it was possible to obtain information on the behaviour of the activity coefficients and to show that the H_c-acidityfunction of Reagan [1] is a better measure of the hydrogen activity than the H₀-function. The dependence of the deprotonation rate on H₀ is explained as a consequence of the different behaviour of the activity coefficients of Hammett-indicators and azulene/azuleniumcation, respectively.