Question

Which of the following is the major product in the electrophilic addition of HCl to (3S)-2,3-dimethylpent-1-ene?

a. (3S)-3-chloro-2,3-dimethylpentane exclusively

b. (3R)-2-chloro-2,3-dimethylpentane exclusively

c. 2-chloro-2,3-dimethylpentane racemic mixture of two enantiomers

d. (3S)-2-chloro-2,3-dimethylpentane exclusively

e. (2R,3S)-1-chloro-2,3-dimethylpentane exclusively

Answer 1

Answer:

(3S)-2-chloro-2,3-dimethylpentane is produced exclusively.

Explanation:

Electrophilic addition to (3S)-2,3-dimethylpent-1-ene proceeds through a carbocationic intermediate.

In the first step, $H^{+}$ adds onto double bond to produce more stable tertiary carbocation. (protonation)

In the second step, $Cl^{-}$ adds onto carbocation to produce (3S)-2-chloro-2,3-dimethylpentane exclusively.(nucleophilic addition)

So, option (d) is correct.