Relations structure-réactivité grandeurs thermodynamiques de protonation d'h'et'erocycles saturés et non saturés

Proton ionisation thermodynamical quantities ot two series of heterocyclic compounds were determined at 25°C, in an aqueous medium of constant ionic strength 0.5M KNO₃.

The first series consists of some saturated molecules, e.g., imides (pyrrolidine, thiazolidine, 2,4-thiazolidinedione, hydantoin, thiohydantoin, succinimide, parabanic acid, barbituric acid), the second one of azoles (imidazole, benzimidazole, pyrazole, thiazole, 1,2,4-triazole, benzotriazole).

The influence of the structure of these molecules on their reactivity towards the hydrogen ion was discussed, on the basis of the related ΔH° and ΔS° functions.