Question

Choose the correct statement regarding the given alkenes:

• A. $I$ has more $\alpha$-hydrogens than $II$.
• B. Stability of $I$ is more than stability of $II$.
• C. Stability of $I$ is less than stability of $II$.
• D. Both $I$ and $II$ are equally stable.

Answer 1

The correct option is C Stability of $I$ is less than stability of $II$.

Both the structures have 5$\alpha$-hydrogens.
In case of structure $I$ :


Here, after hyperconjugation $2^{\circ }$ carbanion is formed.
In case of structure $II$:

Here , after hyperconjugation $1^{\circ }$ carbanion is formed.

Comparing the stability of carbanions, more the number of alkyl groups attached to carbanion, lesser is the stability. This is because alkyl group shows $+I$ effect and further increases the electron density on carbanion, thus making it unstable.
Since, in case of structure $II$, more stable carbanion is formed .
So, Stability of $I$ is less than stability of $II$