Arrange the following compounds in increasing order of reactivity towards Nucleophilic Substitution Reaction.

(A) Chlorobenzene
(B) 4-Nitrochlorobenzene
(C) 2,4-Dinitrochlorobenzene
(D) 2,4,6-Trinitrochloronitrobenzene

Choose the correct answer from the options given below:

(A), (B), (C), (D)

The correct answer is Option (1) → (A), (B), (C), (D)

Nucleophilic substitution in aromatic compounds is facilitated by electron withdrawing groups such as $-NO_2$ at ortho and para positions. More nitro groups increase reactivity by stabilizing the intermediate carbanion.

Explanation

Option A: Chlorobenzene

Chlorobenzene is least reactive towards nucleophilic substitution because the benzene ring stabilizes the C-Cl bond via resonance. There are no electron withdrawing groups to activate the ring.

Option B: 4-Nitrochlorobenzene

The presence of one nitro group at the para position withdraws electron density through -I and -R effects. This activates the ring for nucleophilic substitution by stabilizing the intermediate.

Option C: 2,4-Dinitrochlorobenzene

Two nitro groups at ortho and para positions increase electron withdrawal significantly. This enhances stabilization of the intermediate, increasing reactivity further.

Option D: 2,4,6-Trinitrochlorobenzene

Three nitro groups provide maximum electron withdrawal and maximum stabilization of the intermediate complex, making it the most reactive towards nucleophilic substitution.