Reaction with secondary amines to form enamines

Most aldehydes and ketones react with 2º-amines to give products known as enamines. It should be noted that, like acetal formation, these are acid-catalyzed reversible reactions in which water is lost. Consequently, enamines are easily converted back to their carbonyl precursors by acid-catalyzed hydrolysis.

Mechanism

1) Nucleophilic addition

2) Proton transfer

3)  Protonation of OH

4)  Removal of water (nucleophile elimination)

5)  Deprotonation