Question

Which of the following carbanion has the highest stability?

• A. $I$
• B. $II$
• C. $III$
• D. $IV$

Answer 1

The correct option is A $I$

The stability order of the carbanions can be determined using the $-M$ effect of the substituents present at the para position. Higher the $-M$ power of the substituents, higher will be the stability of the carbanion.

The order of $-M$ power of the substituents is:
$-N{O}_2>-CN$
$-C{H}_3\&-OC{H}_3$ shows $+M$ effect which makes the carbanion less stable as compared to the carbanions where $-M$ group is attached
Therefore, carbanion $I$ is the most stable