Question

multiple choice 1 point
why do tertiary alkyl halides generally react faster than primary alkyl halides in s_n1 reactions?
tertiary carbocations are more stable than primary carbocations.
primary carbocations are more stable than tertiary carbocations.
primary alkyl halides have better leaving groups.
tertiary alkyl halides have a higher bond dissociation energy.

Explanation:

In \(S_N1\) reactions, the rate - determining step is the formation of a carbocation. Tertiary carbocations are more stable than primary carbocations due to hyperconjugation and inductive effects. The more stable the carbocation intermediate, the faster the reaction. Primary carbocations are less stable. Also, the leaving group ability is not the main factor here as it is similar for similar halide leaving groups in alkyl halides. And higher bond dissociation energy would make the bond harder to break, which is not the case for faster reaction of tertiary alkyl halides. So, the stability of carbocation (tertiary carbocations being more stable) is the reason for tertiary alkyl halides reacting faster in \(S_N1\) reactions.

Answer:

Tertiary carbocations are more stable than primary carbocations.