The Gattermann-Koch reaction is a chemical reaction discovered in 1897 by German chemists Ludwig Gattermann and Julius Arnold Koch. It involves the formylation (addition of an aldehyde group) of aromatic compounds using a mixture of carbon monoxide, hydrogen chloride, and anhydrous aluminum chloride catalyst. The unstable formyl chloride intermediate reacts to add the formyl group to the aromatic ring, producing an aromatic aldehyde such as benzaldehyde from benzene.

1. GATTERMANN –
KOCH REACTION
By-
Manish Sahu
M.Sc. Chemistry (Final)
Sp.- Physical Chemistry

2.  Introduction
 Definition
 History
 Formylation
 Gattermann -Koch Formylation
 Mechanism
 Uses
 Conclusion
 Reference

3. The Gattermann-Koch reaction is a chemical reaction in
which aromatic compounds are formylated by a
mixture of CO and HCl in the presence of Anhydrous
AlCl3 .
This reaction is known as Gattermann-Koch
reaction .

4. A synthesis of an aldehyde from
an aromatic Hydrocarbon , Hydrogen , Carbon
monoxide , Hydrogen chloride , in the presence of
the catalyst Anhydrous Aluminium chloride .

5. The Gattermann-Koch
reaction , named after the
German Chemists LUDWIG
GATTERMANN and JULIUS
ARNOLD KOCH .
It was discovered in 1897 .
Ludwig Gatteramnn

6. Substitution of formyl group that
is , aldehyde group ( - CHO ) into aromatic
ring is known as formylaton .

7.  Formyl chloride is unstable. Hence the reaction takes place
under a high pressure with a mixture of CO , HCl in the
presence of a catalyst AlCl3.
 Product is Benzaldehyde.
+ HCl + CO
AlCl3
CHO
CuCl

8. The CO and HCl reacts to form an unstable formyl
chloride.
CO + HCl + AlCl3 → [ HC+ = O ↔ HC ≡ O+ ] AlCl-
4

9. The Mechanism of this reaction, the formyl
cation ( HC+ = O ) is the active electrophlic species .
The function of cuprous chloride is to co-ordinate
with CO to provide its higher local concentration .
Unlike the Gattermann reaction , this reaction
is not applicable to phenol and phenolic ether
substrates .

10.  It is the method of synthesizing aromatic aldehyde
by the action of a mixture of CO and HCl on aromatic
hydrocarbon .
 Use aluminium chloride as catalyst some time
Aluminium Bromide using a small amount of
monochloride of copper .

11. In Gattermann - Koch reaction , formylation of
benzene take place to form benzaldehyde . In this reaction ,
benzene is reacted with CO and HCl in presence of anhydrous
AlCl3. AlCl3 abstracts Cl- ion and initiates H+ ion , which
attack on carbon atom in CO. Due to this carbon aquires
positive charge , hence attack on benzene ring to form
arenium ion , which loses proton to form benzaldehyde .

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