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1 Polish Journal of Chemistry

1 2001

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Effect of Partially Aqueous Solutions of Different pH's on the Hydrolisis Rate of Some Schiff Bases

El-Taher M., El-Haty M. T., Hussien T. M.

Polish Journal of Chemistry

2001

Vol. 75, nr 1

79-91

The mechanism of the hydrolysis of a series of Schiff bases derived from p-phenylenediamine and various aromatic aldehydes has been examined in aqueous media containing 40 wt% methanol, in the presence of NaOH. The base hydrolysis reaction of these compounds is strictly second-order kinetics, first-order with respect to the Schiff base and also to hydroxide ion, and the hydroxide ion attack on the free base becomes the rate-determining step under these basic conditions. The work is extended to include a systematic kinetic study on the hydrolysis reaction of the Schiff bases under investigation, in partially aqueous solutions of different pH's, in media containing 40 wt% methanol. Arate profile diagram of pH versus hydrolysis rate constant for all of the Schiff bases shows that the rate is minimal at alkaline region (pH > 8.96), and too rapid at strongly acidic media (pH < 3.53).