Gabriel phthalimide synthesis
Phthalimide is converted to its potassium salt, heated with an alkyl halide, and the N-alkylphthalimide is hydrolysed with alkali to give a primary amine.
BromoethaneCH₃CH₂BrHaloalkane - Step 1
potassium phthalimide, then NaOH(aq), heat
EthanamineCH₃CH₂NH₂Amine
How it works
- Ethanolic KOH forms potassium phthalimide.
- The phthalimide anion displaces the halide (SN₂) to give an N-alkylphthalimide.
- Alkaline hydrolysis releases the primary amine and sodium phthalate.
What it makes
Pure aliphatic primary amines.
Where it fails
Aromatic primary amines cannot be made because aryl halides do not undergo nucleophilic substitution under these conditions.
Class 12, Chapter 9 Amines
Gabriel phthalimide synthesis: quick answers
Why can aniline not be made by Gabriel synthesis?
Aryl halides do not react with the phthalimide anion by nucleophilic substitution.
What is the advantage over ammonolysis?
It gives only the primary amine, with no secondary or tertiary amine.
What is the by-product of hydrolysis?
Disodium phthalate.