Distinction between acid and base hydrolyses of esters

4 Distinction between acid and base hydrolyses of esters 

There is a fundamental difference between the acid and base hydrolyses of esters. In the former the H30+ is a genuine catalyst, is incorporated in the activated complex and is regenerated after reaction. In base hydrolysis the OH- is also incorporated in the activated complex, but as a reactant, and cannot be regenerated after reaction. In this respect the common habit of referring to base hydrolysis as base catalysed hydrolysis is misleading. 

This can be contrasted with metal ion and anion catalyses, where the metal ion, or the anion, is incorporated into the activated complex, but is regenerated after the reaction. They are thus genuine catalysts for these hydrolyses, analogous to acid catalysis, and in direct contrast to the so-called base catalysed hydrolysis. These comments are pertinent to the following problem. 

Question. The acid hydrolysis of a positively charged ester HE+ (acetylcholine, (CH3)3N+CH2CH2OCOCH3) is first order in ester and first order in H30+. It is catalysed by SO] ions. A possible mechanism is 

Show that the following data, collected at constant ionic strength, is consistent with this mechanism, and find k1 and k2. Comment on the relative value of the two contributions to the rate. 

---