Question

Identify 'B' in the following reaction
Ethyl cyanide \(\overset{\text{H}_2\text{O}\,}{\rightarrow }\text{A}\overset{\text{H}_2\text{O / dil HCl}\,}{\rightarrow }\text{B}+\text{NH}_3\)

• A. Ethanoic acid
• B. Ethanamide
• C. Propanoic acid
• D. Propanamide

Hint:

Nitrile partly hydrolyses to an amide (A). Further hydrolysis gives the acid (B) and ammonia.

Answer 1

The Correct Option is C

Step 1: Track the carbons:
Ethyl cyanide has $\text{C}_2\text{H}_5$ plus the nitrile carbon, three carbons in all. So B must be a three-carbon compound, ruling out ethanoic acid and ethanamide.

Step 2: Track the stages:
First stage adds one water to give the amide A: propanamide. The question says the second stage gives B plus $\text{NH}_3$. An amide loses ammonia only when it is hydrolysed to the acid.

Step 3: Conclusion:
So B is $\text{CH}_3\text{CH}_2\text{COOH}$, propanoic acid. Propanamide is A, not B.

Final Answer:
Option (C). \[ \boxed{\text{Propanoic acid (C)}} \]