Question

Arrange the following carbanions in order of stability.

• A. $\left(I\right)>\left(III\right)>\left(II\right)$
• B. $\left(II\right)>\left(III\right)>\left(I\right)$
• C. $\left(I\right)>\left(II\right)>\left(III\right)$
• D. $\left(III\right)>\left(II\right)>\left(I\right)$

Answer 1

Answer: (A)

$\left(I\right)>\left(III\right)>\left(II\right)$

Carbocations are highly stable when there are electron-donating groups attached to it, that is, $+R,+I$ groups.

So, in picture (1) the carbanion is stabilised by $+R$ effect andin picture (2) the carbanion is stabilised by $+I$ effect.

(3) $Ph-\stackrel{\oplus }{C{H}_2}>C{H}_3-\stackrel{\oplus }{CH}-C{H}_3>C{H}_3-{\stackrel{\oplus }{CH}}_2$

Therefore, the correct order is shown in picture (3).