Phenol, upon treatment with concentrated sulfuric acid, yields a compound (X), which upon reaction with concentrated nitric acid forms (Z). Identify compound (Z).
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 2,4,6-Trinitrophenol.
Phenol is very reactive, and direct treatment with concentrated nitric acid oxidises much of it, giving a poor yield. So picric acid is made in two steps:
Sulphonation: phenol with concentrated sulphuric acid gives phenol-2,4-disulphonic acid (X). The –\( \ce{SO3H} \) groups deactivate the ring and protect it from oxidation.
\( \displaystyle \ce{C6H5OH + 2H2SO4} \xrightarrow{\text{conc.}} \ce{C6H3(OH)(SO3H)2 + 2H2O} \)
Nitration: with concentrated nitric acid, both –\( \ce{SO3H} \) groups are replaced by –\( \ce{NO2} \) groups and a third –\( \ce{NO2} \) enters the other ortho position, giving 2,4,6-trinitrophenol (picric acid, Z).
\( \displaystyle \ce{C6H3(OH)(SO3H)2 + 3HNO3} \xrightarrow{\text{conc.}} \ce{C6H2(OH)(NO2)3 + 2H2SO4 + H2O} \)
So compound Z is 2,4,6-trinitrophenol.
NCERT (2026-27 edition):
Nitration – …
