Allylic Bromination

 

Allylic Bromination

Allylic bromination is the substitution of a C-H bond with a C-Br bond. The reaction will occur on an allylic carbon (a carbon next to the alkene). This can be useful to produce allylic bromides which can be used for future reactions. This reaction occurs in multiple steps.

Take Note

Pay attention to the number of bromine radicals formed throughout the reaction. A total of three bromine radicals are formed and three will be used throughout the reaction.

Overall Reaction:

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Step 1: Initiation

This step involves breaking down bromide using light or heat. This step will produce two bromine radicals.

Step 2: Propagation

This step involves removing one hydrogen from the allylic carbon. From this reaction, two radicals are formed as well as BrH.

After the formation of the carbon radical, one bromine radical will react with the carbon radical to form the final product. Since this molecule has a resonance structure, make sure to check which structure is more stable.

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Step 3: Termination

This step involves the recombination of two bromine radicals.

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