Question

A student obtained two products from the reaction of 1,3-cyclohexadiene with Br₂ (disregarding stereoisomers). His lab partner was surprised when he obtained only one product from the reaction of 1,3-cyclohexadiene with HBr (disregarding stereoisomers). Account for these results.

Short answer

The reaction of 1,3-cyclohexadiene with Br₂ forms a 1,2-addition product and 1,4 addition product but The reaction of 1,3-cyclohexadiene with HBr forms a product which is considered both 1,2-addition product and 1,4 addition product.

Step-by-step solution

Definition ofstereoisomers-

When molecules with the same molecular formula and pattern of bonded atoms (constitution) alter in the three-dimensional spatial orientations of their atoms, this is known as stereoisomerism, also known as spatial isomerism.

Step 2:

The reaction of 1,3-cyclohexadiene with Br₂ forms 3,4-dibromocyclohexane as 1,2-addition product and 3,6-dibromocyclohexane as 1,4 addition products.

Step 3:

The reaction of 1,3-cyclohexadiene with HBr forms 3-broomocyclohexadiene which is considered both 1,2-addition product and 1,4 addition product.