The Reimer-Tiemann reaction: Reaction and its Mechanism

Reimer-Tiemann Reaction

Phenols on reaction with chloroform in the presence of sodium hydroxide (or potassium hydroxide) solution give hydroxy aldehydes. The formyl group is directed to ortho-position unless one of the ortho-positions or both are occupied, in that case the attack is para. This formylation reaction is known as Reimer-Tiemann reaction.
Reimer Tiemann reaction

Reimer-Tiemann Reaction Mechanism

It involves the electrophilic substitution reaction and the electrophile in this reaction is dichlorocarbene which is produced by the reaction of chloroform with alkali. The attack of phenoxide anion on dichlorocarbene gives benzylidene dichloride, which is hydrolyzed to the corresponding hydroxy-aldehyde. The steps involved are shown below.
Reimer tiemann reaction mechanism

Reimer Tiemann reaction Examples
Reimer tiemann reaction Examples

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