The effect of leaving group variation on reactivity in the dissociative hydrolysis of aryl 3,5-dimethyl-4-hydroxybenzenesulfonates

The hydrolysis of aryl esters of 3,5-dimethyl-4-hydroxybenzenesulfonic acid in moderately to strongly alkaline aqueous solution follows a dissociative pathway with the participation of a sulfoquinone (thioquinone dioxide) intermediate, Bronsted-type correlation between log k(app) and pK(LG) and inspection of the effective charge changes involved in the reaction further support the ElcB mechanism. From this and previous studies it appears that aryl esters of hydroxyarenesulfonic acids seem to be more inclined to hydrolyse through dissociative pathways than the corresponding hydroxyarenecarboxylic acids esters.