Free Radical Halogenation Practice Problems

Without any knowledge of the mechanism for following substitution reaction:

Predict the ratio of the products formed for the reaction (in whole numbers) based on random statistical distribution when iodine (I) replaces hydrogen (H) in isopentane (C₅H₁₂).

Determine the major product of the monohalogenation reaction of the alkane given below. State whether you believe the reaction is selective and explain why.

Reaction (a) shown below produces an unequal mixture of products while reaction (b) produces an equal (racemic) mixture of products. Explain why.

Draw the major product formed in the benzylic bromination reaction shown below.

In the following free radical halogenation reaction, one of the products is formed in excess. Identify which stereoisomer is the major product.

In the following free radical halogenation reaction, one of the products is formed in excess. Explain why this reaction yields an unequal mixture of products.

Predict the missing products in the free radical halogenation reaction shown below. Ignore stereoisomers.

Is it possible to make the following primary bromoalkane in good yield using the alkane halogenation reaction? Justify your answer.

Draw the major product obtained in the free radical halogenation reaction given below.

What would be the major product formed in the free radical bromination reaction given below?

Draw a suitable mechanism for the free radical bromination reaction given below.

Consider the following reaction and identify the weakest bond (a, b, or c) in the given molecule.

Determine why the marked bond in the following reaction is the weakest bond.

Draw a plausible mechanism for the following chlorination reaction. Hint: The movement of a single electron is represented using a fishhook arrow.

Predict the number of alkyl bromides expected from the monobromination of the alkane given below. Do not include stereoisomers. 

Determine the number of alkyl bromides expected from the monobromination of the alkane given below. Do not include stereoisomers.

How many monobrominated products are expected from the alkane given below? Do not include stereoisomers.

Determine the number of alkyl chlorides expected from the monochlorination of the alkane given below. Do not include stereoisomers.

Determine the number of alkyl chlorides expected from the monochlorination of the alkane given below. Do not include stereoisomers.

Determine the number of alkyl bromide expected from the monobromination of the alkane given below. Do not include stereoisomers.

Predict the number of alkyl halides expected from the monobromination of the alkane given below. Include stereoisomers.

Predict the number of alkyl bromides expected from the monobromination of the alkane given below. Include stereoisomers.

Determine the number of alkyl halides expected from the monobromination of the alkane given below. Include stereoisomers.

Determine the number of alkyl halides expected from the monobromination of the alkane given below. Include stereoisomers.

Determine the number of alkyl halides expected from the monochlorination of the alkane given below. Include stereoisomers.

Determine the number of alkyl bromides obtained from the monobromination of the alkane given below. Include stereoisomers.

Draw the product of the following reaction.

Draw the monochlorinated product obtained in the given reaction. Do not show stereochemistry.

Draw the product obtained from the given reaction. No need to show stereochemistry.

Draw the possible product(s) of the given monochlorination reaction. Do not show stereochemistry. 

What is the major monobrominated product formed when the following compound is heated with Br₂? Disregard stereoisomers.

Draw the major monochlorinated product obtained in the following reaction. Disregard stereoisomers.

What is the major product of the following reaction? No need to include stereoisomers.

What is the major product of the following reaction? Do not include stereoisomers.

Which isomer with formula C₇H₁₆ forms only three monobrominated products (one primary, one secondary, and one tertiary)? Two of these products are achiral and one is chiral.

Which isomer with formula C₇H₁₆ forms only three monobrominated products? All of these products are achiral.

Why does iodine not react with methane under ordinary conditions, even though I₂ is cleaved easily to form radicals?

Draw the major monobrominated product(s) obtained in the reaction given below. Include stereochemistry if applicable.

Write the mechanism of the monochlorination of cyclopentane, including initiation, propagation, and termination.

When propane is chlorinated, a mixture of products is obtained. Draw the structures of all the monochlorinated products present in this mixture.

Determine the ratio of monochlorinated products obtained by chlorination of butane. Assuming that all the hydrogen atoms can be substituted at the same rate.

Cyclopentene undergoes light-promoted bromination as shown below. Propose a mechanism for this reaction.

Draw all the possible monochlorinated products for each of the following alkanes.

a. 2-methylbutane
b. 2,2-dimethylpropane

Which monobrominated product would be produced in good yield by the free-radical bromination of the following alkanes?

a. 2-methylbutane
b. 2,2-dimethylpropane

Cyclopentane undergoes light-promoted chlorination as shown below. Propose a mechanism for this reaction and label the ­initiation and propagation steps.

When one mole of bromine is mixed with one mole of methane in the presence of light, then a mixture of di- tri- and tetrabromomethane is obtained along with some unreacted methane.
(a) Explain why a mixture of products is formed even if the reactants were in the same stoichiometric ratio.
(b) Show how these compounds are formed from bromomethane.

Hydrogen peroxide is often used as an initiator in free-radical chlorination reactions because the oxygen-oxygen bond undergoes homolytic cleavage easily compared to the chlorine-chlorine bond.

Propose a mechanism for the H₂O₂-initiated chlorination of cyclohexane.

Show how ethylbenzene can be converted to the product shown below using a single-step reaction.

3-Methylbut-1-ene gives two substitution products when treated with a low concentration of bromine under irradiation by a sunlamp.
Propose a mechanism to show the formation of these two products.

Propose a free-radical halogenation reaction to synthesize each of the compounds given below. Also, provide a reason why we get a single major product in each of these reactions.

a. 1-Chlorocyclopentane
b. 2-Bromo-2-methylpentane

Explain how would an industry control the ratio of methane and bromine.

a. To synthesize a good amount of CBr₄?
b. To synthesize a good amount of CH₃Br?

When pentane is reacted with chlorine in the presence of light, a poor yield of 1-chloropentane is obtained. However, cyclopentane can be converted to chlorocyclopentane with good yield by the same reaction.
a. Explain this difference.
b. What should be the ratio of reactants to get a good yield of chlorocyclopentane.