Protonierungs‐ und Deprotonierungskinetik des Systems Azulen‐Azuleniumkation, ein Beitrag zur Kenntnis der Hammett 'schen H o ‐Aciditätsfunktion

Using a flashphotolysis‐method to evaluate the rates of the protonation of azulene and the deprotonation of azuleniumcation as a function of H 0 the validity of the Hammett H 0 ‐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 H 0 ‐function. The dependence of the deprotonation rate on H 0 is explained as a consequence of the different behaviour of the activity coefficients of Hammett ‐indicators and azulene/azuleniumcation, respectively.