SN1 Reaction and Halides

SN1 (Substitution Nucleophilic Unimolecular) is a type of reaction mechanism that involves two steps. The first step is the formation of a carbocation intermediate, and the second step is the attack of the nucleophile on the carbocation. Halides are commonly used substrates in SN1 reactions.

Reactivity of Halides in SN1 Reaction

The reactivity of halides in SN1 reactions depends on several factors, including the stability of the carbocation intermediate that is formed in the first step of the reaction. The stability of the carbocation intermediate is influenced by the nature of the alkyl group attached to the halogen atom.

The Most Reactive Halide in SN1 Reaction

Among the given options, the most reactive halide towards SN1 reaction is tert-Butyl chloride (c). This is because the tert-butyl group is highly bulky, and it stabilizes the carbocation intermediate by preventing the nucleophile from attacking it. The bulky tert-butyl group also hinders the solvent molecules from approaching the carbocation, which reduces the chances of solvation and stabilizes the carbocation intermediate.

On the other hand, n-Butyl chloride (a) and sec-Butyl chloride (b) have less bulky alkyl groups, which makes the carbocation intermediate less stable. Allyl chloride (d) has a resonance-stabilized allylic carbocation intermediate, which is more stable than a primary or secondary carbocation intermediate. However, it is still less stable than the carbocation intermediate formed from tert-Butyl chloride.

Conclusion

In conclusion, the most reactive halide towards SN1 reaction among the given options is tert-Butyl chloride (c). The bulky tert-butyl group stabilizes the carbocation intermediate, making it less likely to undergo solvation or attack by the nucleophile.