What is the action of following reagents on chlorobenzene? (i) conc. HNO3 (ii) fuming H2SO4

Answer: (i) Nitration gives 1-chloro-4-nitrobenzene (major) and 1-chloro-2-nitrobenzene (minor). (ii) Sulfonation gives 4-chlorobenzenesulfonic acid (major) and 2-chlorobenzenesulfonic acid (minor).

–Cl is deactivating but ortho/para directing, so substitution takes place at the ortho and para positions; the para product is major because of less steric hindrance.

(i) Nitration (conc. HNO₃ + conc. H₂SO₄, heat):

C₆H₅Cl + HNO₃ → o-ClC₆H₄NO₂ (minor) + p-ClC₆H₄NO₂ (major) + H₂O

(ii) Sulfonation (fuming H₂SO₄, heat):

C₆H₅Cl + H₂SO₄ → o-ClC₆H₄SO₃H (minor) + p-ClC₆H₄SO₃H (major) + H₂O