JEE Main · 2026 · 24 Jan 2026 · Shift 1 · General Organic Chemistry

A benzylic carbanion is stabilised by electron-withdrawing para substituents that disperse the negative charge and destabilised by electron-donating ones. The $-\mathrm{CHO}$ group in IV ($-M$ and $-I$) is the strongest acceptor and gives the most stable carbanion, followed by the weakly withdrawing $-\mathrm{Br}$ in I and then the unsubstituted benzyl carbanion II. The $p\text{-}\mathrm{C}{\mathrm{H}}_3$ in V is a weak donor and destabilises slightly, while the $p\text{-}\mathrm{OC}{\mathrm{H}}_3$ in III is a strong $+M$ donor and destabilises most. The decreasing order of stability is $\mathrm{IV}>\mathrm{I}>\mathrm{II}>\mathrm{V}>\mathrm{III}$.