A reaction in which a primary or secondary amine reacts with methanal (formaldehyde) and a carbonyl compound to produce an amino-carbonyl compound. It takes place in two stages. First the amine reacts with methanol to form a Schiff base:R2N+H2CO → R2N +=CH2. This then reacts with the carbonyl compound:R2N +=CH2+R 1R 2CHCOR 3 → R2N-CH2–C(R 1R 2)COR 3. The reaction was first reported by Carl Mannich in 1912.
R2N+H2CO → R2N +=CH2.
R2N +=CH2+R 1R 2CHCOR 3