Explain the mechanism of nucleophilic substitution reaction of ortho and para nitrohaloarenes.

(N/A) The presence of an electron-withdrawing group $(-NO_2)$ at the ortho or para position of haloarenes (like chlorobenzene) significantly increases the reactivity towards nucleophilic substitution.
This reaction proceeds via an addition-elimination mechanism,often referred to as nucleophilic aromatic substitution $(S_NAr)$.
$1$. In the first slow step,the nucleophile $(OH^-)$ attacks the carbon atom bearing the halogen,forming a resonance-stabilized carbanion intermediate (Meisenheimer complex).
$2$. The negative charge is delocalized onto the oxygen atoms of the $-NO_2$ group,which provides extra stability to the intermediate.
$3$. In the second fast step,the leaving group $(Cl^-)$ is eliminated,restoring the aromaticity of the ring to form the final product (nitrophenol).
This mechanism is facilitated by the $-NO_2$ group,which stabilizes the transition state and the intermediate carbanion through resonance.