The kinetics and mechanism of the hydrolysis of 2,3-(phenylmethylenedioxy)benzoic acid (OO′-benzylidene-2,3-dihydroxybenzoic acid)

Abstract

The hydrolysis of OO′-benzylidene-2,3-dihydroxybenzoic acid is considerably faster than that of OO′-benzylidene-3,4-dihydroxybenzoic acid and OO′-benzylidenecatechol. The pH-rate profile is of the form: k_obs=k₁/(1 +K_a/10^–pH). The high rate is associated with the k₁-term which probably arises from intramolecular general-acid catalysis. This kinetic parameters of this reaction are compared with those for the formally analogous inter-molecularly general-acid catalysed hydrolysis of benzylidenecatechol. OO′-Benzylidene-2,3-dihydroxybenzoic acid is not intramolecularly hydrogen bonded in dilute solutions in carbon tetrachloride.