Arrange the following aryl halides in decreasing order of reactivity towards Aromatic Nucleophilic S — Reaction Mechanism Chemistry Question

💡 Solution & Explanation

The rate of the $S_NAr$ mechanism (Addition-Elimination) depends on the electron-withdrawing inductive effect ($-I$) of the halogen, which stabilizes the intermediate carbanion (Meisenheimer complex) during the rate-determining attack of the nucleophile. Because Fluorine is the most electronegative, $Ar-F$ is the most reactive. The leaving group ability is not the deciding factor in the slow step. The correct order is $Ar-F > Ar-Cl > Ar-Br > Ar-I$.