Write short note on Sandmeyer reactions.

Explanation

When a diazonium salt solution is warmed with cuprous chloride `(Cu_(2)Cl_(2))` in HCl or cuprous bromide `(Cu_(2)Br_(2))` in HCl corresponding halide in formed.
`underset("Benzene diazonium chloride")(C_(6)H_(5)N_(2)Cl)overset(Cu_(2)Cl_(2)//HCl)rarrunderset("Chlorobenzene")(C_(6)H_(5)Cl)+N_(2)`
`underset("Benzene diazonium chloride")(C_(6)H_(5)N_(2)Cl)overset(Cu_(2)Br_(2)//HBr)rarrunderset("Bromobenzene")(C_(6)H_(5)Br)+N_(2)`
This reaction is known as Sandmeyer reaction.