Question

predict the major product.
br2
h2o
a. br + en
ho
c. ho + en
br
b. ho + en
br
d. ho + en
br

Explanation:

Step1: Formation of bromonium ion

The alkene attacks \(Br_2\) to form a bromonium ion intermediate. This is a cyclic, positively - charged intermediate with a three - membered ring containing a bromine atom.

Step2: Nucleophilic attack by water

Water (\(H_2O\)) acts as a nucleophile. In the bromonium ion, the carbon - bromine bond has some partial positive charge on the carbon. The nucleophile (\(H_2O\)) attacks the more substituted carbon (due to greater partial positive charge on the more substituted carbon in the bromonium ion, following the concept of inductive effect). When \(H_2O\) attacks, it forms a bond with the carbon, and the bromine atom remains attached. Then, after deprotonation (loss of \(H^+\)), the product is formed. The bromine atom and the hydroxyl group (\(OH\)) have an anti - stereochemistry (opposite sides) with respect to each other.

Answer:

A.