Write a note on Sandmeyer's reaction

Explanation

Sandmeyer's reaction : When an aqueous solution of diazonium salt is warmed with cuprous chloride or bromide dissolved in corresponding halogen acid the diazonium group is replaced by chlorine or bromine
`C_(6) H_(5) N^(+) -= NX^(-) + HCI overset(CuCI)(to) C_(6)H_(5)CI + HX + N_(2)`
It has been observed in this reaction that it is the halogen of cuprous halide which enters the benzene ring and proceeds as follows:
`HCI + CuCI to CuCI_(2)^(-) + H^(+)`
`C_(6)H_(5)N^(+) -= N + CuCI_(2)^(-) to C_(6) H_(5) + CuCI_(2) + N_(2)`
`C_(6) H_(5) + CI - Cu - CI to C_(6) H_(5) CI + CuCI`