The Gabriel Synthesis is a highly efficient method for preparing pure Primary ($1^{\circ }$) Aliphatic Amines.

1. Phthalimide is treated with ethanolic $KOH$ to form potassium phthalimide.
2. This Reacts with an alkyl halide ($R-X$) via an $S_{N}2$ mechanims to form $N$-alkylphthalimide.
3. Alkaline hydrolysis or treatment with hydrazine yields the primary amine and phthalhydrazide.

• Note: Aromatic amines cannot be prepared this way because aryl halides do not undergo nucleophilic substitution ($S_{N}2$) with the phthalimide ion.