# FAQs on Reimer Tiemann Reaction in JEE

Reimer Tiemann reaction is one of the most important reactions in organic chemistry included in JEE syllabus. It is one of the few reactions in JEE Syllabus involving the carbene mechanism. Some Frequently Asked Questions related to Reimer Tiemann reaction are:

## Reimer Tiemann reaction:

When phenols are treated with chloroform in the presence of sodium hydroxide, an aldehyde group (-CHO) is introduced at the ortho position of benzene ring leading to the formation of o-hydroxybenzaldehyde. This reaction is popularly known as Reimer Tiemann reaction.

What is the general mechanism of Reimer Tiemann reaction?

Reimer Tiemann reaction is one of the few reactions included in JEE syllabus which involves carbene mechanism. This mechanism of the reaction can be explained in eight major steps:

• Generation of chloroform carbanion by deprotonation of chloroform with a strong base.

$CHCl_3~+~OH^-~ ightleftharpoons~H_2O~+~:overset{ominus}CCl_3$

• The chloroform carbanion generated, quickly undergoes alpha elimination to yield dichlorocarbene.

$:overset{ominus}CCl_3~ ightleftharpoons~Cl^-~+~:CCl_2$

• The phenol atom also undergoes deprotonation in the presence of a strong base like KOH or NaOH to yield a negatively charged phenoxide ion.
• The negative charge on phenoxide ion is delocalized into the aromatic ring. This increases the nucleophilicity of phenoxide ion.
• Phenoxide ion attacks on the dichlorocarbene from the ortho position to produce an intermediate dichloromethyl substituted phenol.

• Finally, a strong base is made to attack the intermediate produced. This leads to the formation of 2-hydroxybenzaldehyde.

Which reference books can one follow for Reimer Tiemann reaction?

A brisk walk through reactions of phenols from NCERT Chemistry Textbook for class 12th (Part II) will give you a sound idea of this reaction. Apart from this you can follow a reference book to understand the detailed mechanism of this reaction. Some authentic books for understanding the detailed mechanism of Reimer Tiemann reaction include books from authors like Solomons & Fryhle, Morrison & Boyd. Once you have developed concepts on this topic, you can practice questions from the books of authors like M. S. Chauhan, etc.

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