Question

Which of the following carbanion expected to be most stable?

• A. $p$-$NO_{2}C_{6}H_{4} \overset{-}{C}H_{2}$
• B. $o$-$NO_{2}C_{6}H_{4} \overset{-}{C}H_{2}$
• C. $o$-$CHOC_{6}H_{4} \overset{-}{C}H_{2}$
• D. $p$-$CHOC_{6}H_{4} \overset{-}{C}H_{2}$

Answer 1

Answer: (B)

$o$-$NO_{2}C_{6}H_{4} \overset{-}{C}H_{2}$

Answer 2

Carbanions are stabilised by electron withdrawing groups. - $NO_{2}$ is stronger electron withdrawing group as compared to - $CHO$. At ortho-position, the effect is more pronounced.