Why is Br2 an electrophile?

1 Answer
Apr 15, 2016

Because the BrBr bond is polarizable.

Explanation:

The halogen molecules have a large, polarizable electron cloud that (so we assume) can be distorted. δ+XXδ representations are very common, and these explain the reaction of the halogens with electron rich olefin species.

Interhalogen species, say IBr can also undergo electrophilic substitution. The iodine end of the molecule is more polarizable. The bromine is more electronegative. With an unsymmetrical alkene, say propylene, that reacts with 1 equiv IBr, which alkyl halides would you predict you would get?