Identify the medium required for formation of p-Hydroxyazobenzene from benzene diazonium chloride and phenol.

Step-by-step solution

The electrophilic aromatic substitution between benzene diazonium chloride and phenol requires specific pH conditions. The diazonium cation C₆H₅N₂^+ acts as an electrophile, while phenol must be in its deprotonated phenoxide form C₆H₅O^- to serve as an effective nucleophile. A mild alkaline medium (typically pH 9 – 10 ) facilitates this deprotonation, enhancing nucleophilicity and enabling efficient coupling at the para position. Acidic conditions protonate the diazonium group or suppress phenol dissociation, while