Question

Identify [A], [B], and [C], respectively in the following reaction sequence : 

• A.
• B.
• C.
• D.

Hint:

Recognize the reactions involved: diazotization, Sandmeyer reaction, and coupling reaction.

Answer 1

The Correct Option is C

Answer 2

To identify the compounds [A], [B], and [C] in the given reaction sequence, let's analyze each step of the reaction.

Step 1: The first reaction involves the treatment of [A] with \(\text{NaNO}_2\) and \(\text{HCl}\) at 273–278 K.

This is a typical diazotization reaction where an aromatic amine (aniline) is converted into a diazonium salt. Thus, [A] is aniline, \(\text{C}_6\text{H}_5\text{NH}_2\).

Step 2: The diazonium salt formed reacts with KI.

This is a Sandmeyer reaction where the diazonium group is replaced by iodide to form an iodobenzene compound. Hence, [B] is iodobenzene, \(\text{C}_6\text{H}_5\text{I}\).

Step 3: The compound undergoes a reaction with 2Na in dry ether.

This reaction is a typical Wurtz reaction where iodobenzene reacts with sodium to form biphenyl. Therefore, [C] is biphenyl, \(\text{C}_6\text{H}_5\text{-C}_6\text{H}_5\).

The complete reaction sequence can be summarized as follows:

From the given options, the correct identification of [A], [B], and [C] is as follows:

Thus, the correct answer is: Aniline ([A]) → Iodobenzene ([B]) → Biphenyl ([C]).