Coupling reaction between benzene diazonium chlorides with aniline in acidic medium takes place to give yellow colour. In this reaction the nitrogen N2 in the diazonium ion is lost and forms the bridge between two benzene rings forming an electrophilic substitution reaction.

Fluoro benzene is prepared by treating benzene diazonium chloride with fluoro boric acid. This reaction produces diazonium fluoroborate which on heating produces fluorobenzene. This reaction is called Balz-Schiemann reaction.

Gattermann reaction is used for obtaining chlorobenzene from benzenediazonium chloride by treating it with Cu/HCl respectively.

Similarly, Benzene diazonium chloride solution on reaction with cuprous cyanide and potassium cyanide gives benzonitrile. This reaction is known as Sandmeyer's reaction.

s reacted with reagents in List I to form products in List II



