Question

The order of stability of the alkenes $\underset{I}{R_{2}C=C{R}_2},\underset{II}{R_{2}C=CHR},\underset{III}{R_{2}C=C{H}_2},\underset{IV}{RCH=CHR}$, and $\underset{V}{RCH=C{H}_2}$ is:

• A. I > II > III > IV > V
• B. I = II > III > IV > V
• C. II > I > IV > III > V
• D. V > IV > III > I > II

Answer 1

The correct option is A I > II > III > IV > V

The order of stability of alkenes is as follows:

$R_{2}C=C{R}_2\left(I\right)>R_{2}C=CHR\left(II\right)>R_{2}C=C{H}_2\left(III\right)>RCH=CHR\left(IV\right)>RCH=C{H}_2\left(V\right)$

This order of stability is due to hyper conjugation.

Hyper conjugation: The stabilizing interaction that results from the interaction of the electrons in a σ-bond (usually $C-H$ or $C-C$) with an adjacent empty or partially filled p-orbital or a π-orbital to give an extended molecular orbital that increases the stability of the system.

So answer is A.