Organic Question

[robg]

Does anyone have defiitive rules as to when to add halides following markovnikov's rule or anti-markovniov?

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[DDS4tehwin]

if you see peroxide (h202) it is always anti-mark

 

[ashleybeans]

Whenever peroxides are present it is always anti-Markovnikov (b/c it proceeds by a radical intermediate, not carbocation).

 

[Saber tooth]

if you see peroxide (h202) it is always anti-mark

thats true, you simply look at the solvent to see how the reagents will react

 

[s0chon02]

Whenever peroxides are present it is always anti-Markovnikov (b/c it proceeds by a radical intermediate, not carbocation).

I thought it's anti only with HBR/Peroxide. For example, HCl with Peroxide will still yield Markovnikov.. Anybody?!

 

[denticus]

I thought it's anti only with HBR/Peroxide. For example, HCl with Peroxide will still yield Markovnikov.. Anybody?!

Everyone here is wrong except for s0chon02. Don't be fooled into thinking that peroxides will ALWAYS yield anti-markonikov addition of halides. In your ochem text I'm sure that you will see that early experiments showed that anti-markonikov addition of halide"s" really only worked for HBr but for other halides such as HCl and HI, they will always add markonikov. There are exceptions however. But with regards to peroxides it is only HBr that is anti.

 

[robg]

So Anti-mark is only HBr in peroxide for the most part, right?

 

[denticus]

right