Identify Major Product in Organic Reaction Sequence Starting from Propanoic Acid

To determine the final major product $(X)$ of the given organic reaction sequence, we analyze each reaction step-by-step:

Step 1: Reaction of Propanoic Acid with $\text{NH}_3 / \Delta$

Propanoic acid ($\text{CH}_3\text{CH}_2\text{COOH}$) reacts with ammonia ($\text{NH}_3$) upon heating to form an ammonium salt which, on thermal dehydration, yields propanamide: $\text{CH}_3\text{CH}_2\text{COOH} \xrightarrow{\text{NH}_3, \Delta} \text{CH}_3\text{CH}_2\text{CONH}_2 + \text{H}_2\text{O}$

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Step 2: Hofmann Bromamide Degradation ($\text{NaOH}/\text{Br}_2$)

Propanamide ($\text{CH}_3\text{CH}_2\text{CONH}_2$) undergoes the Hofmann bromamide reaction on treatment with $\text{Br}_2$ and aqueous $\text{NaOH}$, resulting in the loss of the carbonyl carbon to produce a primary amine with one carbon less, which is ethylamine (ethanamine): $\text{CH}_3\text{CH}_2\text{CONH}_2 + \text{Br}_2 + 4\text{NaOH} \rightarrow \text{CH}_3\text{CH}_2\text{NH}_2 + \text{Na}_2\text{CO}_3 + 2\text{NaBr} + 2\text{H}_2\text{O}$

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Step 3: Reaction with Nitrous Acid ($\text{HNO}_2/\text{H}_2\text{O}, 0^\circ\text{C}$)

When ethylamine ($\text{CH}_3\text{CH}_2\text{NH}_2$) reacts with nitrous acid ($\text{HNO}_2$) at $0^\circ\text{C}$, an unstable aliphatic diazonium salt ($\text{CH}_3\text{CH}_2\text{N}_2^+\text{Cl}^-$) is formed. This salt rapidly decomposes in aqueous medium with the release of $\text{N}_2$ gas to form ethanol: $\text{CH}_3\text{CH}_2\text{NH}_2 \xrightarrow{\text{HNO}_2 / \text{H}_2\text{O}, 0^\circ\text{C}} \text{CH}_3\text{CH}_2\text{OH} + \text{N}_2\uparrow + \text{HCl}$

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Step 4: Reaction with Benzenediazonium Chloride ($\text{C}_6\text{H}_5\text{N}_2\text{Cl}, 0^\circ\text{C}$)

Ethanol ($\text{CH}_3\text{CH}_2\text{OH}$) acts as a mild reducing agent. When treated with benzenediazonium chloride ($\text{C}_6\text{H}_5\text{N}_2\text{Cl}$), ethanol reduces the diazonium group to form benzene ($\text{C}_6\text{H}_6$), while ethanol itself gets oxidized to ethanal ($\text{CH}_3\text{CHO}$): $\text{C}_6\text{H}_5\text{N}_2\text{Cl} + \text{CH}_3\text{CH}_2\text{OH} \rightarrow \text{C}_6\text{H}_6 + \text{N}_2\uparrow + \text{HCl} + \text{CH}_3\text{CHO}$

Thus, the final major product $(X)$ is Benzene.

Correct Option: A (Benzene)