Gabriel phthalimide synthesis is specifically used for the preparation of pure primary aliphatic amines. Phthalimide on reaction with ethanolic $\text{KOH}$ forms potassium phthalimide, which on alkylation with primary alkyl halide followed by alkaline hydrolysis yields pure primary aliphatic amine (aromatic primary amines cannot be prepared by this method because aryl halides do not undergo nucleophilic substitution with phthalimide anion).