The influence of the nature of acidic medium on the kinetics and the mechanism of the hydrolysis of pyrrolidenc bcnzoylhydrazone (PBH) and thiophenylidene benzoylhydrazone (TBH) has been studied.

The observed rate constants, activation energy and thermodynamic parameters for the hydrolysis of PBH and TBH in tetraoxalate buffer solutions at 35°C have been measured. These results were compared with that reported for furfurylidene benzoylhydrazone FBH and the effect of heteroatom on the hydrolysis has been investigated.

In presence of tetraoxalate buffer as a hydrolysis medium for TBH, the catalytic rate constants with respect to H+. F{C204 and H2C204 were calculated. An equation relating the observed rate constant to the concentration of all species in the buffer mixture has been constructed.