Gattermann reaction
Chlorine or bromine is introduced into the benzene ring by treating the diazonium salt with copper powder and the halogen acid.
Benzene diazonium chlorideC₆H₅N₂⁺Cl⁻Diazonium salt - Step 1
Cu powder, HCl
ChlorobenzeneC₆H₅ClHaloarene
How it works
- Aniline is diazotised with NaNO₂ and HCl at 273 to 278 K.
- Copper powder with HCl or HBr replaces the diazonium group by Cl or Br.
- Nitrogen is evolved.
What it makes
Chlorobenzene and bromobenzene from aniline.
Where it fails
Yields are lower than with the Sandmeyer reaction. Do not confuse it with the Gattermann-Koch reaction.
Class 12, Chapter 9 Amines
Gattermann reaction: quick answers
Is the Gattermann reaction the same as Gattermann-Koch?
No. Gattermann replaces a diazonium group with Cl or Br using copper. Gattermann-Koch puts a CHO group on benzene using CO and HCl.
What is the reagent in the Gattermann reaction?
Copper powder with HCl (for chlorobenzene) or HBr (for bromobenzene).
Which gives better yield, Sandmeyer or Gattermann?
The Sandmeyer reaction.