Identify the correct order of reactivity of the following compounds towards nucleophilic aromatic substitution ( S_NAr ): (i) (ii) (iii)

Step-by-step solution

Nucleophilic aromatic substitution ( S_NAr ) proceeds via an addition-elimination mechanism. The reactivity is highly enhanced by the presence of strong electron-withdrawing groups (EWGs) at the ortho and para positions relative to the leaving group, as they stabilize the intermediate carbanion (Meisenheimer complex) through both -M and -I effects. Furthermore, the rate of S_NAr depends on the electronegativity of the halogen leaving group. A more electronegative halogen makes the attached carbon more electrophilic