Arrange the following compounds in decreasing order of reactivity towards nucleophilic aromatic subs — Aromatic Hydrocarbons Chemistry Question

💡 Solution & Explanation

The rate of $S_NAr$ depends on the stabilization of the carbanion intermediate (Meisenheimer complex). Electron-withdrawing groups (like $-NO_2$) at the ortho and para positions strongly stabilize the intermediate by withdrawing electron density via $-M$ and $-I$ effects. The greater the number of such groups, the lower the activation energy and the faster the reaction. Thus, 2,4,6-trinitrochlorobenzene (picryl chloride) is the most reactive.