Reimer-Tiemann Reaction

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.
Reimer-Tiemann Reaction
When CCl4 is used in place of chloroform, an acid (-COOH) group is introduced at ortho position of phenol.
Reimer-Tiemann Reaction with CCl4

Mechanism of Reimer-Tiemann Reaction

The possible mechanism is given below-
Mechanism of Reimer-Tiemann Reaction

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.
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.
Abnormal Reimer-Tiemann Reaction of Pyrrol

Reimer Tiemann Reaction of Indole

Indole also undergoes abnormal Riemer Tiemann reaction to give 3-chloroquinoline.
Abnormal Reimer-Tiemann Reaction of Indole

Examples of the Reimer-Tiemann Reaction

Examples of Reimer-Tiemann Reaction