Gattermann Reaction

The Gattermann reaction is as an organic chemical reaction in which Aromatic compounds are formylated by a mixture of hydrogen cyanide and hydrochloric acid(HCL) in the presence of a Lewis acid catalyst such as Alcl3

Formylation is a process where the formyl group(-CH=O) is attached to the compound.

It was named after a German chemist Ludwig Gattermann. It is also known as Gattermann formylation. It is a substitution reaction which is quite similar to the Friedel crafts reaction.


When Benzene or a derivative is treated with HCl and HCN in the presence of a Lewis acid catalyst (Alcl3), followed by hydrolysis gives benzaldehyde or substituted benzaldehyde.

Gattermann Reaction
Gattermann Reaction

Gattermann Reaction Mechanism 

Step 1: Formation of Formimino Chloride: HCN Reacts with HCl to form formimino chloride.

Formation of Formimino Chloride
Formation of Formimino Chloride

Step 2: Formation of Electrophile: Formimino chloride reacts with a lewis acid catalyst such as Alcl3 to form Formimino cation,

Formation of Electrophile
Formation of Electrophile

Step 3: Attack of Electrophile on Benzene Ring: The formimino Cation reacts with the  benzene ring to form Benzaldimine.

Attack of Electrophile on Benzene Ring
Attack of Electrophile on Benzene Ring

Step 4: Hydrolysis of Benzaldimine: Hydrolysis of benzaldimine takes place which results in the formation of benzaldehyde. 

Hydrolysis of Benzaldimine
Hydrolysis of Benzaldimine


This reaction is used for obtaining chlorobenzene or bromobenzene from benzenediazonium chloride by treating it with Cu/HCl or Cu/HBr respectively.

Gattermann Reaction Example


  • It is used in making aromatic halides such as Chlorobenzene and Bromobenzene.
  • It is used in making aromatic aldehydes such as benzaldehyde.
  • Products of this reaction are used in various fields such as pharmaceuticals, medicinal and Agriculture.


What is the catalyst used in the formation of benzaldehyde by Gattermann reaction?

Aluminium chloride(AlCl3).

What are the other names for the Gattermann reaction?

Gattermann formylation and Gattermann salicylaldehyde synthesis.

Gattermann reaction is similar to the ____?

Friedel craft’s reaction

More Organic Reactions

Swarts ReactionSandmeyer Reaction
Finkelstein ReactionReimer Tiemann Reaction
Stephen ReactionWurtz Reaction

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