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Question
Why cannot aromatic primary amines be prepared by Gabriel phthalimide synthesis?
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Solution
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.
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