When benzene diazonium chloride reacts with phenol, it results in the formation of an orange colored compound (X); and when benzene diazonium chloride reacts with aniline, it results in the formation of a yellow colored compound (Y). What are X and Y?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → X: p-Hydroxyazobenzene; Y: p-Aminoazobenzene
In a coupling reaction the benzenediazonium ion, \( \ce{C6H5N2+} \), acts as a weak electrophile and attacks a strongly activated benzene ring, such as that of phenol or aniline. The attack takes place at the para position, which is activated by the –OH or –\( \ce{NH2} \) group and is less hindered than the ortho positions.
With phenol (in mildly alkaline solution) the product X is p-hydroxyazobenzene, an orange dye; with aniline (in mildly acidic solution) the product Y is p-aminoazobenzene, a yellow dye.
Why the other options are incorrect
Option (2) X: p-Hydroxybenzene; Y: p-Aminobenzene — Incorrect. These names have no azo (–N=N–) group; in coupling the nitrogen atoms of the diazonium ion are kept, linking the two rings.
Option (3) X: o-Hydroxyazobenzene; Y: o-Aminoazobenzene — Incorrect. Coupling occurs at the para position, not the ortho position.
Option (4) X: p-Hydroxyazobenzene; Y: o-Aminoazobenzene — Incorrect. X is right, but aniline also couples at its para position.
NCERT (2026-27 edition):
Reactions Involving Retention of Diazo Group
