Why do bromine radicals react in a highly specific manner with alkenes?

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Offline aysha

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Why does a Br• radical add to the alkene with characteristic regioselectivity, giving a primary alkyl bromide when the polar addition of HBr to an alkene would give a tertiary alkyl bromide? (1) attack at the unsubstituted end of the alkene is less sterically hindered; and (2) the tertiary radical thus formed is more stable than a primary radical.

In fact, of all the hydrogen halides, only HBr will add to alkenes in this fashion: HCl and HI will undergo only polar addition to give the tertiary alkyl halide.

But why?

« Last Edit: 11/08/2009 11:31:32 by chris »

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Offline Bored chemist

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Good question. Do you have any thoughts on the matter?
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