The total number of amines among the following which can be synthesized by Gabriel synthesis is ______.

• (A) Isobutylamine: This is a primary aliphatic amine. Its corresponding alkyl halide (isobutyl halide) can successfully undergo the required $$S_N2$$ reaction.
• (B) Ethylamine: This is a simple primary aliphatic amine. Ethyl halides are excellent substrates for $$S_N2$$ reactions, making this highly suitable.
• (C) Benzylamine: While it contains a benzene ring, the amine group is attached to a $$CH_2$$ carbon, making it a primary aliphatic amine. The corresponding benzyl halide is actually highly reactive towards $$S_N2$$ nucleophilic attack, so this works perfectly.

Amines that CANNOT be synthesized:

• (D) Aniline: This is a primary aromatic amine, meaning the nitrogen is attached directly to the benzene ring. It cannot be synthesized using this method.

Reasoning: The Gabriel synthesis is a classic and highly specific method used exclusively for preparing primary aliphatic amines. Thus ,it cannot be used to prepare aniline.