In aqueous acid, what is the mechanism and major product for the reaction of 2-bromopentane?

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Multiple Choice

In aqueous acid, what is the mechanism and major product for the reaction of 2-bromopentane?

In polar protic, aqueous acid, a secondary alkyl bromide tends to do SN1 because the leaving group can depart to form a relatively stable secondary carbocation. Once the Br leaves, you get a planar carbocation at C-2. Water then, as a weak nucleophile, attacks this flat carbocation from either face, giving a protonated alcohol. Deprotonation yields 2-pentanol. Because the carbocation is planar, attack from the two faces occurs with equal probability, producing a racemic mixture of the two enantiomers of 2-pentanol. SN2 is unlikely here since water is a weak nucleophile and SN2 on a secondary center in aqueous acid is not favored, and forming a ketone would require a different pathway altogether.

In polar protic, aqueous acid, a secondary alkyl bromide tends to do SN1 because the leaving group can depart to form a relatively stable secondary carbocation. Once the Br leaves, you get a planar carbocation at C-2. Water then, as a weak nucleophile, attacks this flat carbocation from either face, giving a protonated alcohol. Deprotonation yields 2-pentanol. Because the carbocation is planar, attack from the two faces occurs with equal probability, producing a racemic mixture of the two enantiomers of 2-pentanol. SN2 is unlikely here since water is a weak nucleophile and SN2 on a secondary center in aqueous acid is not favored, and forming a ketone would require a different pathway altogether.

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