Question

Draw a stepwise mechanism for the following reaction.

Short answer

The cyclic amine reacts with a molecule of formaldehyde to undergo nucleophilic addition.

Nucleophilic addition

Step-by-step solution

Nucleophilic addition

The cyclic amine reacts with a molecule of formaldehyde to undergo nucleophilic addition.

Nucleophilic addition

Intramolecular proton transfer (IMPT)

The cation stabilizes via intramolecular proton transfer.

Intramolecular proton transfer

Dehydration

The lone pair of electrons on the oxygen atom of the hydroxyl group abstracts a proton followed by dehydration and ring closure.

Dehydration reaction

Resonance

The lone pair of electrons on the nitrogen atom delocalizes, which gives the corresponding resonating hybrids.

Resonance forms

Formation of product