Question

Question: Draw the product(s) formed when each alkene is treated with either [1] HBr alone; or [2] HBr in the presence of peroxides.

a.

b.

c.

Short answer

Answer

a.

b.

c.

Step-by-step solution

Reaction of an alkene with HBr

The incorporation of HBr to alkene leads to the formation of alkyl bromide. A carbocation intermediate leads to the product in this reaction.

Reaction of an alkene with HBr and peroxide

Alkene combines with HBr in the presence of conditions like sunlight, heat, or peroxides resulting in the formation of alkyl bromides. This reaction proceeds through a radical intermediate.

Products obtained by the reaction of each alkene with HBr alone or in the presence of HBr and peroxide

a. The reaction of compound a with HBr results in the formation of 2-bromohexane. The reaction of compound a with HBr and peroxide leads to the formation of 1-bromohexane.

The addition of HBr in the absence of light takes place via the carbocation intermediate. The addition of HBr in the presence of light takes place via the radical intermediate. The reactions can be given as:

Reaction of compound a with HBr alone and in the presence of HBr and peroxide

b.The reaction of compound b with HBr leads to the formation of 1-bromo-1-methylcyclohexane. The reaction of compound b with HBr and peroxide leads to the formation of 1-bromo-2-methylcyclohexane. The reactions can be given as:

Reaction of compound b with HBr alone and in the presence of HBr and peroxide

c. The reaction of compound c with HBr alone or in the presence of HBr and peroxide leads to the formation of 2-bromohexane and 3-bromohexane. The reaction can be given as:

Reaction of compound c with HBr alone and in the presence of HBr and peroxide