H2 C=CHCH2 Cl is solvolyzed faster than (CH3)2 CHCl. Explain. Solvolyses go by an SN 1 mechanism

step 1 In SN2 reactions, some molecules react better than others. For example, we have this molecule an

H2 C=CHCH2 Cl is solvolyzed faster than (CH3)2 CHCl....

$\mathrm{H}_2 \mathrm{C}=\mathrm{CHCH}_2 \mathrm{Cl}$ is solvolyzed faster than $\left(\mathrm{CH}_3\right)_2 \mathrm{CHCl}$. Explain. Solvolyses go by an $\mathrm{S}_{\mathrm{N}} 1$ mechanism. Relative rates of different reactants in $\mathrm{S}_{\mathrm{N}} 1$ reactions depend on the stabilities of intermediate carbocations. $\mathrm{H}_2 \mathrm{C}=\mathrm{CHCH}_2 \mathrm{Cl}$ is more reactive because $$ \left[\mathrm{H}_2 \mathrm{C}=\mathrm{CH}=\mathrm{CH}_2\right]^{+} $$ is more stable than $\left(\mathrm{CH}_3\right)_2 \mathrm{CH}^{+}$. See Problem 6.35 for a corresponding explanation of stability of an allyl radical.)

$\mathrm{H}_2 \mathrm{C}=\mathrm{CHCH}_2 \mathrm{Cl}$ is solvolyzed faster than $\left(\mathrm{CH}_3\right)_2 \mathrm{CHCl}$. Explain.
Solvolyses go by an $\mathrm{S}_{\mathrm{N}} 1$ mechanism. Relative rates of different reactants in $\mathrm{S}_{\mathrm{N}} 1$ reactions depend on the stabilities of intermediate carbocations. $\mathrm{H}_2 \mathrm{C}=\mathrm{CHCH}_2 \mathrm{Cl}$ is more reactive because
$$
\left[\mathrm{H}_2 \mathrm{C}=\mathrm{CH}=\mathrm{CH}_2\right]^{+}
$$
is more stable than $\left(\mathrm{CH}_3\right)_2 \mathrm{CH}^{+}$. See Problem 6.35 for a corresponding explanation of stability of an allyl radical.)

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Key Concepts

SN1 Mechanism

The SN1 reaction mechanism involves a two-step process where the first and rate-determining step is the formation of a carbocation intermediate by the departure of the leaving group. The overall reaction rate is governed by the stability and formation of this carbocation, making the nature of the intermediate pivotal in determining the reaction's speed.

Carbocation Stability

Carbocation stability is a critical factor in SN1 reactions because a more stable carbocation forms more readily, leading to faster reaction rates. Stability is influenced by factors such as the inductive effect, hyperconjugation, and resonance stabilization, all of which can delocalize and mitigate the positive charge on the carbocation.

Allylic Resonance Stabilization

In an allylic system, the positive charge of the carbocation can be delocalized over adjacent pi bonds, a phenomenon known as resonance stabilization. This delocalization distributes the positive charge over multiple atoms, significantly enhancing the stability of the carbocation compared to non-resonance stabilized carbocations, thereby accelerating the solvolysis reaction.

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