Question

Identify the product formed in the following reaction sequence.

• A. 1
• B. 2
• C. 3
• D. 4

Hint:

Reaction of alkyl halides with KCN increases the carbon chain by one carbon atom: \[ R-X \rightarrow R-CN \] Reduction of nitriles gives primary amines: \[ R-CN \rightarrow R-CH_2NH_2 \] Thus, alkyl halide \(\rightarrow\) nitrile \(\rightarrow\) primary amine is a common method for chain extension.

Answer 1

The Correct Option is B

Step 1: Reaction of cyclopentyl chloride with ethanolic KCN.
Alkyl halides react with KCN through nucleophilic substitution.
The cyanide ion attacks through the carbon atom and forms a nitrile: \[ \text{Cyclopentyl chloride} \rightarrow \text{Cyclopentyl cyanide} \] \[ C_5H_9Cl + KCN \rightarrow C_5H_9CN + KCl \]

Step 2: Reduction of nitrile.
Nitriles on reduction with sodium amalgam in ethanol are converted into primary amines.
The nitrile group \[ -CN \] is reduced to \[ -CH_2NH_2 \] Therefore, \[ C_5H_9CN \rightarrow C_5H_9CH_2NH_2 \]

Step 3: Identify the product.
The product formed is Cyclopentylmethylamine which corresponds to a cyclopentane ring attached to \[ -CH_2NH_2 \] This is represented by option (2).

Step 4: Final conclusion.
Therefore, the final product is \[ \boxed{\text{Cyclopentylmethylamine}} \] Hence, the correct option is \[ \boxed{(2)} \]