Question

The deuterium kinetic isotope effect for the hydrolysis of aspirin is 2.2. What does this tell you about the kind of catalysis exerted by the o- carboxyl substituent?

Short answer

The answer is,

General- base catalyst

Step-by-step solution

Catalysis

In order to carry out a reaction with a faster rate, substances called catalyst. This will increase the rate of a reaction by decreasing the activation energy of the reactant compound or by forming a stable transition state.

Explanation

The o-carboxylate ion is acting as a general- base catalyst, the kinetic isotope effect will be greater than 1.0, because an OH is broken in the slow step of the reaction and an OD bond is stronger than an OH bond and therefore is harder to break.

If the o- carboxylate ion is acting as a nucleophile catalyst, the kinetic isotope effect will be about 1.0, because an OH or OD bond is not broken in the slow step of the reaction.