Question

What is formed when benzene diazonium chloride (BDC) reacts with phenol?

• A. Azo dye (p-hydroxyazobenzene)
• B. Benzoic acid
• C. Benzene
• D. Chlorobenzene

Hint:

Remember the important azo coupling reactions: \[ \boxed{ \begin{aligned} \text{BDC + Phenol} &\rightarrow \text{p-Hydroxyazobenzene}\\ \text{BDC + Aniline} &\rightarrow \text{p-Aminoazobenzene} \end{aligned} } \] The product always contains the characteristic azo linkage \[ \boxed{-N=N-.} \]

Answer 1

The Correct Option is A

Benzenediazonium chloride (BDC) acts as a weak electrophile and attacks the electron-rich phenol ring at the para position in an electrophilic aromatic substitution called a coupling reaction. The product is para-hydroxyazobenzene, an azo dye characterised by the $-N=N-$ linkage joining the two aromatic rings.