Question

The decreasing order of the stabilities of the following alkenes is:

• A. $\left(i\right)>\left(ii\right)>\left(iii\right)>\left(iv\right)$
• B. $\left(iv\right)>\left(iii\right)>\left(ii\right)>\left(i\right)$
• C. $\left(i\right)>\left(ii\right)>\left(iv\right)>\left(iii\right)$
• D. $\left(i\right)>\left(iv\right)>\left(iii\right)>\left(ii\right)$

Answer 1

The correct option is B $\left(iv\right)>\left(iii\right)>\left(ii\right)>\left(i\right)$

Stability of alkenes $\propto$ Hyperconjugative structures $\propto$ Number of $\alpha -$Hydrogens

$\left(i\right)$

Number of $\alpha -$ Hydrogen = 0

$\left(ii\right)$

No of $\alpha -$Hydrogen = 6

$\left(iii\right)$

Number of $\alpha -$ Hydrogen = 9

$\left(iv\right)$

Number of $\alpha -$Hydrogen = 12
Therefore, the stability order will be
$\left(iv\right)>\left(iii\right)>\left(ii\right)>\left(i\right)$