Isocynide is prepared by:

Options

A. friedal - Crafts reaction
B. Wurtz reaction
C. Williamson synthesis
D. Carbylamine reaction

Explanation

To prepare isocyanide, we can utilize the Carbylamine reaction. Here’s a step-by-step breakdown of the process:

### Step-by-Step Solution:

1. **Identify the Reactants**:
- We need an aliphatic or aromatic primary amine (R-NH2).
- We also require chloroform (CHCl3) and a base, typically potassium hydroxide (KOH) in its ethanolic form.

2. **Set Up the Reaction**:
- Combine the primary amine (R-NH2) with chloroform (CHCl3) in the presence of ethanolic potassium hydroxide (KOH).
- The reaction should be performed under heating conditions to facilitate the reaction.

3. **Reaction Mechanism**:
- The base (KOH) deprotonates the amine to form an alkoxide ion (R-NH-).
- Chloroform reacts with the alkoxide ion, leading to the formation of an isocyanide (R-N≡C) through a series of steps that involve the formation of intermediate species.

4. **Formation of Isocyanide**:
- Upon heating, the reaction yields isocyanide (R-N≡C), along with byproducts such as potassium chloride (KCl) and water (H2O).
- The overall reaction can be summarized as:
\[ R-NH2 + CHCl3 + 3 KOH \rightarrow R-N≡C + 3 KCl + 3 H2O \]

5. **Conclusion**:
- The product formed, R-N≡C, is known as isocyanide or carbylamine, which is characterized by its foul smell.

### Final Answer:
The correct method for preparing isocyanide is through the **Carbylamine reaction**.

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