Q.62 How will you bling out the following conversion?


The active stated reaction is an example of electrophilic aromatic substitution. In an alkaline medium, phenol generates phenoxide ion which is more electron-rich than phenol and more reactive for the electrophilic attack.
The electrophile in this reaction is aryldiazonium cation. As we know, the stronger the electrophile faster is the reaction. pnitrophenyldiazonium cation is a stronger electrophile than p-toluene diazonium cation.
So, nitrophenyl diazonium chloride couples preferentially with phenol.