Reimer-Tiemann Reaction
Reimer-Tiemann Reaction
Formylation of phenol with chloroform in alkaline solution at about 60°C is known as Reimer-Tiemann Reaction. A mixture of ortho and para isomers are obtained but the ortho isomer predominates and para isomers predominates only when one of the ortho position is occupied.
When CCl
4 is used in place of chloroform, an acid (-COOH) group is introduced at ortho position of phenol.
Mechanism of Reimer-Tiemann Reaction
The possible mechanism is given below-
Abnormal Reimer Tiemann Reaction
Some certain molecules such as pyrrole, indene, indole undergo reaction with chloroform and bases (like NaOH, KOH etc.) to give rearrangement product instead of Riemer Tiemann product. This abnormal type of reaction is known as the abnormal Reimer Tiemann reaction.
Reimer Tiemann Reaction of Pyrrole
When pyrrole is heated with a mixture of chloroform and alkaline solution of NaOH, pyrrole is converted to 3-chloropyridine.
Reimer Tiemann Reaction of Indole
Indole also undergoes abnormal Riemer Tiemann reaction to give 3-chloroquinoline.
Examples of the Reimer-Tiemann Reaction
