Question

Illustrate the following reactions giving suitable example in each case 

Coupling reaction

Answer 1

 Coupling reaction: The reaction of joining two aromatic rings through the −N=N−bond is known as the coupling reaction. Arenediazonium salts, such as benzenediazonium salts, react with phenol or aromatic amines to form coloured azo compounds.

For example, the reaction of benzenediazonium chloride with phenol yields p-hydroxyazobenzene (orange dye).

$${C_6{H}_5-N^{+}\equiv N{Cl}^{-}}_{Benzenediazoniumchloride}+{C_6{H}_5-OH}_{Phenol}{\to }^{{OH}^{-}}{C_6{H}_5-N^{+}=N-C_6{H}_5-OH}_{p-Hydroxyazobenzene}+{Cl}^{-}+H_{2}O$$