Question

Which reagent is used in the Reimer--Tiemann reaction to convert phenol to salicylaldehyde?

• A. \(CHCl_3\) and \(NaOH\)
• B. \(HNO_3\)
• C. \(KMnO_4\)
• D. \(HCl\)

Hint:

Remember: Reimer--Tiemann reaction = Phenol + \(CHCl_3\) + \(NaOH\) → Salicylaldehyde.

Answer 1

The Correct Option is A

Concept: The Reimer--Tiemann reaction introduces a formyl group \((-CHO)\) into phenol, producing salicylaldehyde. It uses:
• Chloroform \(CHCl_3\)
• Aqueous sodium hydroxide \(NaOH\)

Step 1: Reaction mechanism overview. In the presence of strong base, chloroform generates the reactive intermediate dichlorocarbene \((:CCl_2)\).

Step 2: Formation of salicylaldehyde. Phenol reacts with this intermediate and after hydrolysis forms: \[ \text{Salicylaldehyde (o-hydroxybenzaldehyde)} \]