• Azo?(or?diazonium)?compounds?are organic compounds that have an R₁-N=N-R₂?group
• They are often used as?dyes?and are formed in a?coupling reaction?between the?diazonium ion?and an?alkaline solution?of?phenol

Azo compounds are characterized by the presence of an?R₁-N=N-R₂?group

Coupling of benzenediazonium chloride with phenol in NaOH

• Azo compounds can be formed from the coupling reaction of a?benzenediazonium chloride salt?with?alkaline phenol
• Making an azo dye is a?multi-step process

Formation of azo compounds table

Reaction mechanism of the formation of azo compounds

• The?delocalised?electrons in the π bonding systems of the two benzene rings are?extended?through the -N=N- which acts as a?bridge?between the two rings
• As a result of the delocalisation of electrons throughout the compound, azo compounds are?very stable

Making other azo dyes

• Other dyes can be formed via a?similar route?as described above
• For example, the?yellow?dye?can be formed from the?coupling reaction?between?benzenediazonium chloride?and?C₆H₅N(CH₃)₂instead of phenol (C₆H₅OH)

The yellow azo dye is formed via a coupling reaction between benzenediazonium chloride and C₆H₅N(CH₃)₂