Question

The correct order of stability of given carbanions is:

• A. $\text{a}>\text{b}>\text{c}>\text{d}>\text{e}$
• B. $\text{b}>\text{e}>\text{d}>\text{c}>\text{a}$
• C. $\text{b}>\text{a}>\text{c}>\text{d}$
• D. $\text{d}>\text{e}>\text{c}>\text{a}>\text{b}$

Hint:

For benzyl carbanions, groups at the $p$-position stabilize via resonance/induction (EWG) or destabilize (EDG). The $\text{CHO}$ group provides the greatest stabilization through resonance.

Answer 1

The Correct Option is D

Stability of carbanions is increased by Electron Withdrawing Groups ($\text{EWG}$) and decreased by Electron Donating Groups ($\text{EDG}$).
(e) $\text{CHO}$: Strong $\text{EWG}$ ($\text{M}$ effect). Highly stabilizing.
(d) $\text{Br}$: Weak $\text{EWG}$ ($\text{I}$ effect). Stabilizing.
(a) $\text{H}$: Reference.
(c) $\text{CH}_3$: Weak $\text{EDG}$ ($+\text{H}$). Destabilizing.
(b) $\text{OCH}_3$: Strong $\text{EDG}$ ($+\text{M}$). Highly destabilizing.
Expected Stability Order: $\text{e}>\text{d}>\text{a}>\text{c}>\text{b}$.