Strecker synthesis template

Ammonia and acetaldehyde give an iminium ion, cyanide adds to give the aminonitrile, and hydrolysis gives alanine.

Mechanism step by step

Aldehyde + ammonia + cyanide: an α-aminonitrile, then an α-amino acid

1. Ammonia adds – Attack on the C=O
2. Proton transfer – A hemiaminal
3. Protonation – NH₄⁺ protonates the OH
4. Iminium ion – Water leaves
5. Cyanide adds – The α-aminonitrile

Key points

• Hot aqueous acid then hydrolyses C≡N to CO₂H (via the amide).
• The product is racemic: cyanide adds to either face of the flat iminium ion.
• Strecker’s 1850 alanine was the first laboratory amino-acid synthesis.
• Chiral catalysts or amines give single enantiomers.

Drawn with 55 atoms, 16 arrows, 7 shapes – every one editable in MolDraw.

Sources

• Strecker, Justus Liebigs Ann. Chem. 1850, 75, 27 Original paper
• Kürti & Czakó, Strategic Applications of Named Reactions in Organic Synthesis, Elsevier 2005 Textbook
• Clayden, Greeves & Warren, Organic Chemistry, 2nd ed., OUP 2012 Textbook