Question

Phenol can be converted to \(o\)-hydroxybenzaldehyde by

• A. Riemer-Tiemann reaction
• B. Tischenko reaction
• C. Sandmeyer reaction
• D. Wurtz reaction

Hint:

Phenol to salicylaldehyde is done by Reimer-Tiemann reaction using \(CHCl_3/NaOH\).

Answer 1

The Correct Option is A

Concept:
The Reimer-Tiemann reaction is used to introduce an aldehyde group \(-CHO\) at the ortho position of phenol. The product formed is: \[ o\text{-hydroxybenzaldehyde} \] It is also called: \[ \text{salicylaldehyde} \]

Step 1: Write the starting compound.
Starting compound is phenol: \[ C_6H_5OH \] Phenol has an \(-OH\) group attached to benzene ring. The \(-OH\) group is ortho-para directing.

Step 2: Understand Reimer-Tiemann reaction.
Phenol reacts with chloroform and alkali: \[ CHCl_3/NaOH \] This introduces an aldehyde group mainly at the ortho position. \[ C_6H_5OH \xrightarrow{CHCl_3/NaOH} o\text{-hydroxybenzaldehyde} \]

Step 3: Identify product.
The product: \[ o\text{-hydroxybenzaldehyde} \] is salicylaldehyde.

Step 4: Check the options.
Option (A) Reimer-Tiemann reaction is correct.
Option (B) Tischenko reaction involves aldehydes forming esters.
Option (C) Sandmeyer reaction involves diazonium salts.
Option (D) Wurtz reaction is used for coupling alkyl halides. Hence, the correct answer is: \[ \boxed{(A)\ \text{Riemer-Tiemann reaction}} \]