Studies in mixed aqueous media. II. Acidity Constants of Simple and Chloro-o-toluidinium Ions in the system dioxane–water

Acidity constants of 3-, 4- and 5-chloro-o-toluidinium ions have been measured at 25° in aqueous dioxane media containing 20, 45, 70 and 72 wt.% of 1.4-dioxane by pH metry. The necessary correction factors to convert pH meter readings into stoichiometric pH have been evaluated. The relation between the strength of anilinium ions and various solvent properties has been discussed. A HAMMETT type relation has been developed for correlating the acid strength of these disubstituted anilinium ions with HAMMETT 's structural parameters.