Question

Identify the products [A] and [B] respectively in the following reaction:

• A.
• B.
• C.
• D.

Hint:

The high temperature and pressure conditions favor the nucleophilic substitution of chlorine in chlorobenzene, leading to phenol. Oxidation with Na$_2$Cr$_2$O$_7$ then converts phenol to benzoic acid.

Answer 1

The Correct Option is C

To determine the products [A] and [B] in the given reaction, let's analyze each step: 

The initial reactant is chlorobenzene (C₆H₅Cl). The reaction with \(\text{NaOH}\hspace{2pt} \text{at} \hspace{2pt} 623 \hspace{2pt} \text{K and} \hspace{2pt} 300 \hspace{2pt} \text{atm}\) is typical of a nucleophilic aromatic substitution. Under these harsh conditions, the chlorine atom is replaced by an OH group, forming phenol (C₆H₅OH).

Next, phenol (C₆H₅OH) is oxidized using \(\text{Na}_{2}\text{Cr}_{2}\text{O}_{7} \hspace{2pt} \text{in} \hspace{2pt} \text{H}_{2}\text{SO}_{4}\). This is a classic oxidation reaction where phenol is oxidized to benzoquinone.

So, the products are:

• [A] is phenol (C₆H₅OH)
• [B] is benzoquinone

The correct answer matches the provided option with products , which indicates phenol followed by oxidation to benzoquinone.

Answer 2

To identify the products [A] and [B] in the given chemical reaction, let's go through the reaction step-by-step.

1. The first step of the reaction involves the use of NaOH at high temperature (623K) and pressure (300 atm). This condition is typical for a nucleophilic aromatic substitution reaction known as the Dow process. In this process, chlorobenzene reacts with NaOH to form phenol.

   Thus, product [A] is phenol.

2. In the second step, phenol is oxidized using sodium dichromate (\( \text{Na}_2\text{Cr}_2\text{O}_7 \)) and sulfuric acid (\(\text{H}_2\text{SO}_4\)). This is a common oxidation reaction where phenol is converted to benzoquinone.

   Thus, product [B] is benzoquinone.

Let's confirm this by matching the products with the correct option from those provided.

The correct answer is that product [A] is phenol, and product [B] is benzoquinone, matching the given option.