Chapter 12, Problem 12.5P

Interpretation Introduction

Interpretation:

The products of the given reaction are to be predicted, and it is to be explained if the product mixture would be optically active or inactive.

Concept introduction:

Alkene reacts with molecular bromine $\left({\text{Br}}_{\text{2}}\right)$ in carbon tetrachloride ${\text{(CCl}}_{\text{4}}\text{)}$ to yield a mixture of dibromoalkanes. Molecular bromine undergoes anti addition across a carbon-carbon double bond. To account for the stereochemistry of the reaction, the mechanism must proceed through a cyclic halonium ion intermediate. If the mixture of products is diastereomers, then the mixture would be optically active. If the products are either enantiomers or a meso compound, then the mixture is optically inactive. A symmetrically substituted alkene may yield a meso compound, which would be optically inactive.