Question

Explain why hydroxide ion catalyzes the reaction of piperidine with 2,4-dinitroanisole but has no effect on the reaction of piperidine with 1-chloro-2,4-dinitrobenzene.

Short answer

Hydroxide ion catalyzes the reaction of piperidine with 2,4-dinitroanisole because a methoxy group is a poorer leaving group than the ammonium group. In contrast, hydroxide ion catalyzes no effect on the reaction of piperidine with 1-chloro-2,4-dinitrobenzene as chlorine is a better leaving group than the ammonium group.

Step-by-step solution

Leaving group

Leaving group

Leaving the group is the atom or group of atoms that get replaced/removed during the chemical reaction; good leaving groups are preferred for the chemical reaction to be favorable.

A good leaving group is removed in the form of a stable ion or molecule.

Step 2: Hydroxide ion catalyzes the reaction

Hydroxide ion catalyzes the reaction of piperidine with 2,4-dinitroanisole because a methoxy group is a poorer leaving group than the ammonium group, so the ammonium group is eliminated reforming the starting material.

The addition of hydroxide ion to the solution hydroxide ion converts the ammonium group into ab amino group. Since the amino group is a poorer leaving group than the methoxy group, the methoxy group will be eliminated.

Hydroxide ion catalyzes the reaction of piperidine with 2,4-dinitroanisole is shown as follows:

Hydroxide ion catalyzes no effect on the reaction of piperidine with 1-chloro-2,4-dinitrobenzene as chlorine is a better leaving group than the ammonium group, so the product is formed without hydroxide ion catalysis shown as follows: