Kinetic studies of the effect of substituents on the strength of the internal hydrogen bond in salicylate ions

Abstract

Kinetic and equilibrium results have been obtained for removal of the hydrogen-bonded proton from substituted salicylate ions by hydroxide ion and buffer bases in 50%(v/v) Me2SO–H2O. From the values of the rate coefficients for proton removal it is concluded that the hydrogen bond is strengthened by electron-releasing substituents and by the change from aqueous solution to 50%(v/v) Me2SO–H2O. Curvature in the plots of rate against hydroxide ion concentration is observed above 0.02 mol dm–3 and this may mean that opening of the hydrogen bond is partially rate-limiting under these conditions.