Gabriel synthesis is used for the preparation of primary amines. Phthalimide on treatment with ethanolic potassium hydroxide forms potassium salt of phthalimide which on heating with alkyl halide followed by alkaline hydrolysis produces the corresponding primary amine. Aromatic primary amines cannot be prepared by this method because aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.

Which of the following cannot be prepared by Gabriel Phthalimide reaction?

Aryl amine 

Gabriel Phthalimide reaction is not suitable for the preparation of aryl amines, because aryl halides are generally too inert to undergo nucleophilic substitution with the anion derived from phthalimide.