Question

Identify Z in the following series of reactions:
\text{CH}_3\text{-CH}_2\text{-CH}_2\text{-Cl} + \text{KOH(alco.)} \rightarrow X \quad \text{Y} + \text{HBr (peroxide)} \quad \text{Z} \quad \text{KCN (alcohol)} \rightarrow Z

• A. CH\(_3\)-CH\(_2\)-CH\(_2\)-CN
• B. CH\(_3\)-CH\(_2\)-CH\(_2\)-Br
• C. CH\(_3\)-CH\(_2\)-CH\(_3\)-CN
• D. CH\(_3\)-CH\(_2\)=CH\(_2\)

Hint:

In reactions with KCN, halides are often replaced with cyanide ions to form nitriles, which is the key reaction in this question.

Answer 1

The Correct Option is A

Step 1: Understanding the reactions.
- The first reaction involves the substitution of chlorine with a hydroxyl group in an alcohol, forming a primary alcohol.
- The second reaction with HBr (in the presence of peroxide) leads to a radical halogenation that gives an alkyl halide.
- The final reaction with KCN in alcohol results in the formation of a nitrile group by nucleophilic substitution of the halide with the cyanide ion.
Step 2: Analyzing the options.
(A) CH\(_3\)-CH\(_2\)-CH\(_2\)-CN: This is the correct answer. The final product is a nitrile (CN) group attached to a three-carbon chain.
(B) CH\(_3\)-CH\(_2\)-CH\(_2\)-Br: This is incorrect, as the final product should contain a nitrile group, not a bromine atom.
(C) CH\(_3\)-CH\(_2\)-CH\(_3\)-CN: This is incorrect, as the structure shown is not consistent with the reactions described.
(D) CH\(_3\)-CH\(_2\)=CH\(_2\): This is incorrect. The final product is not an alkene, but a nitrile.
Step 3: Conclusion.
The correct answer is (A) CH\(_3\)-CH\(_2\)-CH\(_2\)-CN, which is the nitrile product formed.