Azo coupling

Aromatic azo compounds tend to be brightly colored due to their extended conjugated systems.

In this case, the diazonium ion is degraded by light, leaving a latent image in undegraded diazonium salt which is made to react with a phenol, producing a colored image: the blueprint.

Additionally, through the azo coupling reaction between the aromatic diazonium ion and aromatic amino acid residues, this reaction can also be used to form or to modify proteins such as tRNA synthetase.

[4] Illustrative is the reaction of phenol with benzenediazonium chloride to give a Solvent Yellow 7, a yellow-orange azo compound.

In alkaline media, diazonium salt can react with most primary and secondary amines, which exist as a free base to produce triazene.