Organic chemistry

Reimer Tiemann reaction – Crack Chemistry

Reimer Tiemann reaction | Organic Reaction Mechanism | Crack Chemistry

This is one of the very very important naming reaction in organic chemistry especially for students pursuing Higher Secondary and Bachelor’s Degree in Chemistry Subject.
This reaction is about Ortho-Formylation in aromatic alcohols.
Simply we can say, Reimer Tiemann Reaction is used to conversation of Phenol into Salicylaldehyde.
This reaction is important because it contains most important Reaction intermediate. That is Carbene.
 
Lets See…,

Reaction Mechanism :-

Reimer Tiemann Reaction :-

General Reaction :-

  When the Phenol and Chloroform is reacted in presence of strong base like Potassium Hydroxide is forms Salicylaldehyde.
The general reaction is given below in image
Phenol to Salicyaldehyde, Reimer Tiemann Reaction,carbene, Salicyaldehyde, crackchemistry ,crack Chemistry
General Reaction

Formation of Carbene :-

 
First of all, the carbene is formed by the reaction of KOH ( Potassium Hydroxide ) with Chloroform, it forms trichloromethyl carbanion.
Reimer Tiemann Reaction, crackchemistry, organic chemistry, reaction mechanisms
Chloroform reacting With KOH

Then the formed trichloromethyl carbanion will Converted into Carbene ( dichloromethylene )

Reimer Tiemann Reaction, crackchemistry, organic chemistry, reaction mechanisms
Carbene

Formation of Phenoxide ion :-

The Phenol is reacted with KOH and the base will obstruct the proton from the Phenol and it ends up in formation of Phenoxide ion.
Reimer Tiemann Reaction, crackchemistry, organic chemistry, reaction mechanisms,phenoxide ion
Convertion of Phenol to Phenoxide ion

Reaction of Carbene and Phenoxide ion :-

 
In this part, Phenoxide ion is reacted with Carbene intermediate in presence of KOH (Strong base).
Finally it forms Salicylaldehyde.

Reimer Tiemann Reaction, crackchemistry, organic chemistry, reaction mechanisms
Reaction between Carbene & Phenoxide ion
Reimer Tiemann Reaction, crackchemistry, organic chemistry, reaction mechanisms
KCl – Elimination

After Adding the KOH base in the above process, KCl (Potassium Chloride) will eliminated. It forms -OH in the respective chain.

Reimer Tiemann Reaction, crackchemistry, organic chemistry, reaction mechanisms, Salicyaldehyde,phenol
Proton Transfer

In this above step,

The proton transfer is takes place. That is Proton of one Alcohol group is shifted to the another group.
So Conversion of Phenol ( any aromatic alcohol ) into Salicylaldehyde is known as Reimer Tiemann Reaction.

Key Notes :-

This reaction is also get done in Aromatic alcohols with Heteroatom’s like Thiolate etc..,
• The intermediate formed in this reaction is very short living Species called as Carbene
• The temperature of the reaction is carried out in 60°C.
• It is position specific reaction ( Ortho – Formylation )
• The IUPAC name of product formed in this reaction is 2-hydroxy Benzaldehyde.

Frequently Asked Questions :-

Here i give 5 frequently asked questions in this above reaction. Try to answer it.

Crack Chemistry – Do follow
All the images of the post is created by Crack Chemistry

Leave a Reply

Back to top button