Syn Anti Addition

[busupshot83]

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I came across the following alkene halogenation problems:

alkene + Br2/CCl4 --> bromination via syn addition
alkene + Cl2/CCl4 --> chlorination via anti addition

Why do the halogens in each rxn add via different additions (syn and anti)? I was thinking both should be anti.

 

[Lonely Sol]

I came across the following alkene halogenation problems:

alkene + Br2/CCl4 --> bromination via syn addition
alkene + Cl2/CCl4 --> chlorination via anti addition

Why do the halogens in each rxn add via different additions (syn and anti)? I was thinking both should be anti.

Well wherever you got it from, does it say that Br2/ccl4- syn addition is a major product? If not, then thats correct

Because, whenever you brominate or chlorinate an alkene, you have will have a mixture of two prodcuts, cis or trans, but one (anti) overpopulates the other (syn). Hope this makes sense!

But if the book says syn is the major product, then I have to think about it!!