Chapter 17, Problem 35PP

Interpretation Introduction

Interpretation:

The structure of a conjugated diene yield a racemic mixture of 3-bromocyclohexene should be identified if the conjugated diene is treated with $\text{HBr}$.

Concept introduction:

• Conjugated Dienes undergoes addition reactions with $\text{HBr}$ as similar to simple alkenes addition with $\text{HBr}$.
  • The allylic carbocation is formed as an intermediate by the addition of proton in the $\text{HBr}$.
  • The ${\text{Br}}^{-}$(nucleophilic) can attacks in either of the two resonance stabilized carbocation’s in the in the allylic intermediate. 
• The butadiene produces two products for addition of $\text{HBr}$. Because it is forming 2-bromobutene (1,2 addition) and 4-bromobutene (1,4 addition).
• The simple cyclic dienes produces same products for addition of $\text{HBr}$, because the two formed cyclo-haloalkenes will have same names.

To draw: the structure of a conjugated diene yield a racemic mixture of 3-bromocyclohexene, if the conjugated diene is treated with $\text{HBr}$.