Question

Reaction of phenol with chloroform in presence of dilute sodium hydroxide finally introduces which one of the following functional group ?

• A. ${ -CHCl2 }$
• B. ${ -CHO}$
• C. ${-CH2Cl }$
• D. ${-COOH }$

Answer 1

The Correct Option is B

The question involves understanding the reaction of phenol with chloroform in the presence of dilute sodium hydroxide. This reaction is commonly known as the Reimer-Tiemann reaction, which is used to form a new functional group on the aromatic nucleus.

Let's break it down step-by-step:

1. Reimer-Tiemann Reaction: This is an organic reaction used to convert phenols into ortho-hydroxy benzaldehydes. When phenol is treated with chloroform in basic medium (usually sodium hydroxide), a formylation reaction occurs.
2. Chemical Reaction Mechanism:
   • In the first step, chloroform (CHCl_3) reacts with the base (NaOH) to form the dichlorocarbene (:CCl_2).
   • The dichlorocarbene acts as an electrophile and reacts with the ortho position of phenol.
   • Following this, hydrolysis occurs, leading to the introduction of the formyl group (-CHO) at the ortho position.
3. Product Formation: The reaction results in the formation of salicylaldehyde, which contains the formyl group -CHO.
4. Conclusion: From the given options, the function group introduced is {-CHO}, which is a characteristic product of the Reimer-Tiemann reaction.

Therefore, the correct answer is the formyl group {-CHO}.