Allylic Bromination Practice Problems

What brominated product(s) are formed in the allylic bromination reaction given below? (Do not include stereoisomers)

What brominated product(s) are formed in the allylic bromination reaction shown below?

Draw a mechanism for the following allylic bromination reaction.

Which two different alkenes would undergo allylic bromination with NBS to produce the following product?

What reagent is required for the bromination of cyclopentene at the allylic position?

Identify the position in the given radical where the new C—Br bond is most likely to form during the second propagation step of the free radical bromination using NBS.

Identify the position in the given radical where the new C—Br bond is most likely to form during the second propagation step of the allylic bromination using NBS.

What product(s) would be formed in the allylic bromination reaction shown below?

What product(s) would be formed in the allylic bromination reaction given below?

Provide a suitable mechanism to show the formation of the product shown below.

Determine the number of allylic bromoalkenes formed in the following reaction. Include stereoisomers.

Draw the major product(s) of the reaction given below. Do not include stereoisomers.

Draw a suitable mechanism for the following reaction.

Predict the product of the reaction given below. Include stereochemistry where applicable.

Determine the number of allylic bromoalkenes obtained in the following reaction. Include stereoisomers.

Predict the product of the reaction given below. Include stereochemistry where applicable.

Predict the product of the reaction given below. Include stereochemistry where applicable.

Show how you can synthesize 3-bromo-2-methylbut-1-ene using 2-methylbut-1-ene as starting material. If the product contains a stereocenter, assume that the final product is part of a racemic mixture.

The reaction of 1,2-dimethylcyclohexene with NBS under UV light produces a mixture of two products.

However, the reaction of cyclopentene with NBS only produces one product despite the generation of a resonance-stabilized radical. Explain why this reaction does not yield a second product.

Draw the structures of all expected products of the following reaction:

Ignore stereochemistry.

The reaction of 1,2-dimethylcyclohexene with NBS under UV light produces a mixture of two products.

Draw a mechanism for this reaction that accounts for the formation of these products.

The reaction of methylenecyclohexane with NBS in presence of sunlight produces a mixture of two products. Draw the structures of these two products and write a mechanism for the reaction.

Draw only the major product of the reaction shown below.

Draw the major product/s when the following organic compound undergoes allylic bromination.

When methylenecyclopentane reacts with NBS, two products are formed. Show the mechanism of this reaction. [Note: Ignore stereoisomers.]

For the reactions of 1-isobutylcyclohex-1-ene with the following reagents, draw the major product(s). [Note: Ignore stereoisomers.]

(i) NBS/∆/peroxide

(ii) Br₂/CH₂Cl₂

For the given reaction, draw the major products. Ignore stereoisomers.

For the following reaction, draw the major products. Ignore stereoisomers.

Determine the number of products, including stereoisomers, formed from the reaction of cyclobutene with NBS.

Identify the number of products formed, including stereoisomers, from the reaction of 3-ethylcyclobut-1-ene with NBS.

Propose a mechanism (initiation and propagation) to rationalize the formation of the mixture of products in the reaction below.

Suggest a mechanism (initiation and propagation) to rationalize the formation of the following products:

Predict the product/s of the reaction of the following compound with NBS in the presence of light.

A student reacted NBS with 1-methylcyclopent-1-ene under a sunlamp.

(i) Draw all resonance forms of the three possible allylic free radical intermediates of the reaction

(ii) Label the three intermediates 1 through 3 (1 is the most stable; 3 is the least stable)

(iii) Draw the products that could be obtained from the reaction

The following light-promoted reaction has been observed in the presence of a small amount of bromine:

Why is only one type of hydrogen substituted, unlike the other hydrogen atoms in the starting material?

Show the initiation and propagation steps to explain the formation of the products in the given reaction.

Draw the products that would form when the following compounds react with NBS in the presence of light. Do not include stereoisomers.

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

What product/s would form in the allylic bromination reaction shown? (Note: Ignore stereochemistry.)

Determine the carbon in the given radical where the new C-Br bond is most likely to form in the second propagation step of the free radical bromination using NBS. [Ignore stereochemistry.]

The reaction below proceeds in the presence of light and a small amount of bromine.

Why does cyclopentene react with bromine much faster than cyclopentane, which requires heat to react?

The following light-promoted reaction occurs in the presence of a small amount of bromine:

What is the mechanism for the reaction showing the formation of both products? (Note: Observe which hydrogen atom has been removed in both products. There is no need to show the termination step.)

The product of the allylic halogenation is under thermodynamic control and the second propagation step of these reactions is reversible. Draw an arrow-pushing mechanism for the given second propagation step resulting in the formation of a more stable alkene.