Acidium ions
Acidium ions are cations of the general formula R – C (OH) 2 + . In formal terms, they represent a violation of Erlenmeyer's rule . However, since there is mesomerism stabilization (the positive charge can migrate between the oxygen atoms or the carboxyl carbon in the boundary formulas ), there are no two hydroxyl functions . Since acidium ions are protonated carboxylic acids , i.e. substances that deprotonate themselves in an aqueous medium, they can only exist in an anhydrous medium. Acidium ions can form when strong mineral acids (e.g. perchloric acid ) or sulfonic acids are dissolved in anhydrous carboxylic acids (e.g. glacial acetic acid ). In this example, Acetacidium ions would then be formed:
