Question

Topic: Hydrohalogenation and Carbocation Rearrangements Section: 9.3 Difficulty Level: Hard (29.) Select the expected major product(s) of the following reaction: HBr D) E) Ans: A and B A and C C Topic: Hydrohalogenation and Carbocation Rearrangements Section: 9.3 Difficulty Level: Hard 30. Identify the expected product(s) for the reaction shown below? I ) HB: + enantiomer Br B) Br "enantiomer + enantomer + enantiomer Ans: C

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Answer 1

Reaction of alkene with HBr involvesthe carbocation intermediate. So, rearrangement of carbocation is involved. (3° carbocation is more stable than 2 carbocation) Br HBr Br - Br 30 carbocation 20 carbocation С more stable Option C is the right answer. Reaction of alkene with HBr involvesthe carbocation intermediate. So, rearrangement of carbocation is involved. (3° carbocation is more stable than 2° carbocation) We know that carbocation is planar (sp2 hybridized). So, the Br- ion then attacks the carbocation from either side of the plane, results in the formation of racemic mixture, if a chiral center is formed Br HBr Br Br 2° carbocation attack from attack from 3° carbocation above below more stable Racemic mixture Option Cis the right answer.