Question

Hydrolysis of which compound will give carbolic acid?

• A. Cumene
• B. Benzenediazonium chloride
• C. Benzal chloride
• D. Ethylene glycol ketal

Answer 1

The Correct Option is B

The question is asking which compound, upon hydrolysis, produces carbolic acid (phenol).

To answer this question, let's analyze the given options one by one:

1. Cumene:

Cumene itself does not directly hydrolyze to give carbolic acid. However, through a two-step process (oxidation to cumene hydroperoxide followed by acid-catalyzed decomposition), phenol can be produced. This is known as the cumene process, commonly used in industry. But cumene itself, without additional reactions, will not yield phenol by simple hydrolysis.

1. Benzenediazonium chloride:

This compound can directly hydrolyze to give phenol. When benzenediazonium chloride is treated with water, it forms phenol, nitrogen gas, and hydrochloric acid in a reaction mechanism that involves the replacement of the diazonium group with a hydroxyl group. The reaction is as follows:

\(\text{C}_6\text{H}_5\text{N}_2^+\text{Cl}^- + \text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_5\text{OH} + \text{N}_2 + \text{HCl}\)

This is the correct answer.

1. Benzal chloride:

Benzal chloride hydrolyzes to form benzaldehyde, not phenol. Benzal chloride contains two chlorine atoms on the same carbon, and when hydrolyzed, these are replaced by oxygen to form the carbonyl group of benzaldehyde.

1. Ethylene glycol ketal:

Ethylene glycol ketal, upon hydrolysis, splits into ethylene glycol and a ketone. This compound does not yield phenol through hydrolysis.

Conclusion: Among the given options, Benzenediazonium chloride is the only compound that hydrolyzes directly to yield phenol, which is commonly known as carbolic acid. Thus, the correct answer is Benzenediazonium chloride.

A good tip to remember is that diazonium salts can often produce phenols upon hydrolysis, a reaction frequently used in organic synthesis.