Which of the following compounds can be prepared in good yield by Gabriel phthalimide synthesis?

To determine which compound can be synthesized using the Gabriel phthalimide synthesis, we must consider the scope and limitations of this reaction.

The Gabriel phthalimide synthesis is a well-known method used for the preparation of pure primary aliphatic and benzylic amines. In this method, phthalimide is first converted into potassium phthalimide by treatment with $$KOH$$. The resulting nucleophile undergoes an $$S_N2$$ substitution with an alkyl halide to form an $$N$$-alkylphthalimide, which upon hydrolysis yields the corresponding primary amine.

The overall sequence can be represented as

$$\text{Phthalimide} \xrightarrow{KOH} \text{Potassium phthalimide} \xrightarrow{R-X} N\text{-alkylphthalimide} \xrightarrow{\text{Hydrolysis}} RNH_2.$$

The reaction has two important limitations:

• It produces only primary amines, since the phthalimide nitrogen can accommodate only one alkyl group.
• It cannot be used to prepare primary aromatic amines, because aryl halides do not undergo $$S_N2$$ substitution due to the partial double-bond character of the carbon-halogen bond and the $$sp^2$$ hybridization of the aromatic carbon.

Considering the given compounds:

• (A) Benzylamine $$\left(C_6H_5CH_2NH_2\right)$$ is a primary benzylic amine. It can be prepared from benzyl halides, which readily undergo $$S_N2$$ substitution. Hence, it can be synthesized by the Gabriel phthalimide method.
• (B) N-Methylethylamine $$\left(CH_3CH_2NHCH_3\right)$$ is a secondary amine. Since Gabriel synthesis produces only primary amines, this compound cannot be prepared.
• (C) 2-Phenylacetamide $$\left(C_6H_5CH_2CONH_2\right)$$ is an amide, whereas Gabriel synthesis is a method for preparing amines. Therefore, it cannot be synthesized by this route.
• (D) p-Aminobenzylamine $$\left(H_2N-C_6H_4-CH_2NH_2\right)$$ contains both an aromatic amino group and a benzylic amino group. Although the benzylic amino group could be introduced through Gabriel synthesis, the aromatic amino group cannot be obtained because aryl halides do not undergo $$S_N2$$ substitution.

Therefore, the only compound that can be synthesized using the Gabriel phthalimide synthesis is benzylamine.

Hence, the correct answer is

$$\boxed{\text{(A) Benzylamine}}.$$