Identify the amine which cannot be prepared by Gabriel phthalimide synthesis

Options

A.
B.
C.
D.

Answer

To solve the question of identifying the amine that cannot be prepared by Gabriel phthalimide synthesis, we will follow these steps:

### Step-by-Step Solution:

1. **Understand Gabriel Phthalimide Synthesis**:
- Gabriel phthalimide synthesis is a method used to prepare primary amines. It involves the use of phthalimide, which reacts with a base (like ethanolic KOH) to form potassium phthalimide. This intermediate can then react with an alkyl or aryl halide.

2. **Identify the Products**:
- The reaction of potassium phthalimide with an alkyl halide leads to the formation of an N-alkyl phthalimide. Upon hydrolysis (with dilute HCl or alkali), this N-alkyl phthalimide yields a primary amine and phthalic acid.

3. **Limitations of the Method**:
- The Gabriel synthesis is particularly useful for preparing aliphatic primary amines. However, it has limitations when it comes to aromatic primary amines. Specifically, aryl halides (like bromobenzene or chlorobenzene) do not undergo nucleophilic substitution reactions with potassium phthalimide under mild conditions.

4. **Conclusion on Aromatic Amines**:
- Since the question asks for an amine that cannot be prepared by this method, we conclude that aromatic primary amines (like aniline) cannot be synthesized using Gabriel phthalimide synthesis due to the inability of aryl halides to react with potassium phthalimide.

5. **Final Answer**:
- The amine that cannot be prepared by Gabriel phthalimide synthesis is **aniline** (or any other aromatic primary amine).