B Reactions involving retention of diazo group
coupling reactions
The azo products obtained have an extended conjugate system having
both the aromatic rings joined through the –N=N– bond These compounds
are often coloured and are used as dyes Benzene diazonium chloride
reacts with phenol in which the phenol molecule at its para position is
coupled with the diazonium salt to form p-hydroxyazobenzene