Question

Question: Use the Hammond postulate to explain why ${\left(C{H}_3\right)}_{\mathbf{2}}\mathit{C}\mathbf{=}\mathit{C}{\mathit{H}}_{\mathbf{2}}$reacts faster than $\mathit{C}{\mathit{H}}_{\mathbf{3}}\mathit{C}\mathit{H}\mathbf{=}\mathit{C}{\mathit{H}}_{\mathbf{2}}$ in electrophilic addition of HX.

Short answer

Answer

${\left(C{H}_3\right)}_{2}C=C{H}_2$generates a $3°$ carbocation and imparts greater stability. Hence, ${\left(C{H}_3\right)}_{2}C=C{H}_2$ reacts faster.

Step-by-step solution

Hammond postulate

The HX is added to that carbon in the $\mathit{C}\mathbf{=}\mathit{C}$ bond of the alkene which is less substituted.

Reaction rates

The more substituted and stable carbocation leads to a faster reaction.

Products of the given reactions