Gabriel synthesis is used for the preparation of

Options

A. `1^@` amine
B. `2^@` amine
C. `3^@` amine
D. all can be prepared

Explanation

**Step-by-Step Solution:**

1. **Understanding Gabriel Synthesis**: Gabriel synthesis is a method used to prepare primary amines. It involves the use of phthalimide as the starting material.

2. **Starting Material**: The reaction begins with phthalimide, which has the structure:
\[ \text{C}_6\text{H}_4(\text{CO})_2\text{N} \]
(or more specifically, it can be represented as \( \text{C}_6\text{H}_4(\text{CO})_2\text{NH} \)).

3. **Reaction with Strong Base**: Phthalimide is treated with a strong base, such as sodium hydroxide (NaOH). The base deprotonates the nitrogen atom in phthalimide, forming a phthalimide anion:
\[ \text{Phthalimide} + \text{NaOH} \rightarrow \text{Phthalimide anion} + \text{H}_2\text{O} \]

4. **Alkyl Halide Reaction**: The phthalimide anion then reacts with an alkyl halide (R-X) through an SN2 mechanism. This step is crucial as it allows the introduction of an alkyl group to the nitrogen:
\[ \text{Phthalimide anion} + \text{R-X} \rightarrow \text{N-R} + \text{Phthalimide derivative} \]

5. **Hydrolysis**: The resulting product undergoes hydrolysis, where the phthalimide derivative is treated with water, leading to the formation of a primary amine:
\[ \text{N-R} + \text{H}_2\text{O} \rightarrow \text{Primary amine} + \text{Phthalic acid} \]

6. **Final Product**: The final product of Gabriel synthesis is a primary amine. This method is particularly useful because it selectively produces primary amines, avoiding the formation of secondary or tertiary amines.

**Conclusion**: Gabriel synthesis is primarily used for the preparation of primary amines.

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