Which one of the following alkenes will react faster with $\mathrm{H}_2$ under catalytic hydrogenation…
Which one of the following alkenes will react faster with $\mathrm{H}_2$ under catalytic hydrogenation conditions?
Solution
Due to steric hinderence, hyperconjugation and heat of hydrogenation, reactivity of alkenes can be shown as:
$\begin{aligned}
& \mathrm{H}_2 \mathrm{C}=\mathrm{CH}_2 > \mathrm{R}-\mathrm{CH}=\mathrm{CH}_2 > \\
& \mathrm{R}-\mathrm{CH}=\mathrm{CH}-\mathrm{R} > \mathrm{R}_2 \mathrm{C}=\mathrm{CH}_2 > \\
& \mathrm{R}_2 \mathrm{C}=\mathrm{CHR} > \mathrm{R}_2 \mathrm{C}=\mathrm{CR}_2 .
\end{aligned}$
Related Theory
The relative rates of hydrogenation decrease with the increase of steric hindrance. In order of stability of alkene, most stable the alkene slowly it gives the product.
