Write Gatterman Koch reaction

Explanation

Chlorine or bremine can be introduced in the benzene ring by treating the diazonium salt solution with corresponding halogen acid in the presence of copper powder.
`ArN_(2)^(+)X^(-)overset("Cu/HCl")rarrArCl+N_(2)+CuX`
`ArN_(2)^(+)X^(-)overset("Cu/HBr")rarrArBr+N_(2)+CuX`
This reaction is called Gatterman reaction.