Substituent effects on the hydrolysis of m-substituted benzonitriles in sulfuric acid solutions at 25.0 ± 0.1 oC

Abstract EN

The rate constants (kobs) for acid hydrolysis of m-substituted benzonitriles have been measured spectrophotometric ally in sulfuric acid solutions (10.0 M to 18.2 M) at 25.1 ± 0.1oC.

The logarithms kobs were correlated with different substituent constants (inductive and resonance).

The results indicate in 10.0 M sulfuric acid that the rate constants are enhanced by electron-releasing (inductive effect) and the protonation of m-substituted benzonitriles was most probably slower than the nucleophilic addition.

In 18.2 M sulfuric acid, the rate-determining step for the hydrolysis of benzonitriles was the addition of nucleophile which is enhanced by electron-withdrawing (inductive effect).

A combination of the Two mechanisms were most likely occurred in 13.0 to 17.0 M sulfuric acid solutions.