Rank the following substrates from most to least reactive in an S_N1 reaction.

Question

Quizplus · Accepted Answer

The S_N1 reaction is a substitution reaction where the substrate undergoes unimolecular dissociation. The rate-determining step of this reaction is the breaking of the bond between the leaving group and the substrate to form a carbocation intermediate. Therefore, the more stable the carbocation intermediate, the more reactive the substrate. In substrate A, the carbocation intermediate is stabilized by resonance with the adjacent phenyl ring, making it the most reactive substrate. Substrate B also has a stabilizing phenyl group, but it is farther away from the reaction center, so it is less reactive than substrate A. Substrate C has no stabilizing groups, making it less reactive than substrate A and B. Finally, substrate D has an electron-donating group (methyl) which destabilizes the carbocation intermediate, making it the least reactive substrate. Therefore, the correct answer is choice A, A>B>C>D.

Rank the Following Substrates from Most to Least Reactive in an SN1

Rank the Following Substrates from Most to Least Reactive in an S_N1