Abnormal Strength of 2:6-Dihydroxybenzoic Acids

Abstract

THE work of W. Ostwald1 showed that the electrolytic dissociation constants of the hydroxybenzoic acids vary greatly with the positions of the hydroxyl groups. Thus the dissociation constants of benzoic acid, and of those mono-, di- and tri-hydroxybenzoic acids, which do not possess a hydroxyl group in the ortho-position to the carboxyl group, have dissociation constants all less than 1 × 104; the dissociation constants of the various hydroxybenzoic acids containing an ortho-hydroxyl group are all of the order of 1 × 103, and 2:6-dihydroxybenzoic acid has a dissociation constant of 5.0 × 102 (see Table 1).