Specific hydrogen ion catalysed

Bronsted and Volqvartz (Z. physikal. Chem. 1928, 134, 97) had earlier used the specifically hydrogen-ion catalysed decomposition pf diazoacetic ester to determine the acidity constants of some aquo-cations, in particular Fe(H20)J+, Cr(H20)J, and several aquocobalt-ammine cations. 

The hydrolysis of 2-methoxymethoxybenzoic acid 3 was investigated in some detail [6]. Since this compound is an unsymmetrical acetal, two modes of bond fission are possible in the rate-determining step. It was shown by p.m.r. spectroscopy that methanolysis in CD3OD occurs with fission of the aryloxy-carbon bond and hence it seems probable that hydrolysis does also. The possibility that the fcj-term arose from a specific hydrogen ion catalysed reaction of the ionized form with the carboxylate group acting as an intramolecular nucleophilic catalyst as shown in equations 2 and 3 was excluded by... 

This leaves two reasonable explanations for the high value of ki. Either the reactive species is the ionized form 9 and the high rate arises from an electrostatic effect of the carboxylate group in a specific-hydrogen-ion catalysed reaction (equation 4) or it is the un-ionized... 

---