Question

Identify A, B and C in following reaction when phenol is treated with chloroform in presence of NaOH?

• A.

  

• B.

  

• C.

  

• D.

  

Hint:

Phenol with chloroform and NaOH is the Reimer-Tiemann reaction, which adds a -CHO group at the ortho position.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
Phenol treated with chloroform and aqueous NaOH, followed by acid, is the Reimer-Tiemann reaction. It gives salicylaldehyde.

Step 2: Formation of A
NaOH forms dichlorocarbene from chloroform and converts phenol to phenoxide. The phenoxide ring attacks the carbene at the ortho position to give sodium o-(dichloromethyl)phenoxide (A).

Step 3: Formation of B
Alkaline hydrolysis of the -CHCl2 group gives a gem-diol that loses water to form -CHO. B is the sodium salt of salicylaldehyde.

Step 4: Formation of C
Acidification converts -ONa to -OH, so C is salicylaldehyde (2-hydroxybenzaldehyde).

Final Answer:
A is o-(dichloromethyl)sodium phenoxide, B is sodium salicylaldehyde and C is salicylaldehyde. \[ \boxed{\text{(A) }\text{o-(dichloromethyl)sodium phenoxide, sodium salicylaldehyde, salicylaldehyde}} \]