The bromination of allylic positions with N-bromosuccinimide (NBS) follows a radical pathway. Mechanism and Example of the Wohl-Ziegler Reaction.
Bromination of alkenes at the allylic or benzylic position on treatment with N-bromosuccinimide (NBS) in the presence of an initiator (e.g. peroxides or ALBN) or under photolysis is known as Wohl-Ziegler reaction.
[ALBN
= 2,2’-azobis-(2,4-dimethyl-4-methoxyvaleronitrile)]
Example
Mechanism of the Wohl-Ziegler Reaction
The reaction proceeds through a free-radical mechanism as depicted below.
References
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