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Topic: Halogenations question  (Read 3236 times)

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zephy

  • Guest
Halogenations question
« on: November 17, 2004, 02:45:58 AM »
Hi. I'm having trouble figuring out the allowable reactions for halogenating an alkene.

If I want to do a Markovnikov addition with one halogen, there seems to be a basic ionic addition, where an H and Br is added. Does this apply to the rest of the halogens, like HCl and HI? If I wanted to add anti-Markovnikov, there is free radical addition, which only applies to HBr because only Br has the correct energy to do it. What about the other halogens - how would I add them anti-markovnikov?

If I wanted to do an anti-addition of two halogens (like Br2) then I would use addition of halogens, where one Br forms that triangle thing (I forgot what it's called), then the other Br attacks from behind, to give anti. Is this correct, and does it apply to the rest of the halogens? Also, is there a reaction to give a syn addition? I couldn't seem to find one in my textbook. For removal of one halogen, I could do an E2 reaction, correct? And to remove 2 halogens which are anti to each other, I could use a reaction called Dehalogenation of Vicinal halogens, I think. Is this also correct?

Thanks.

bg1047

  • Guest
Re:Halogenations question
« Reply #1 on: November 18, 2004, 10:12:37 PM »
Mark. addition can occur with Cl and I. The only one you can not include in Mark Addition is HF. When wanting to do a anti-mark addition I am not sure. What are you wanting to add and to what. Because to do anti mark addition of Cl you would do free radical chlorination and add the Cl to the molecule. Yes the formation of a bromonium ion formed will cause anti mark addition and the same will happen when the addition of ozone you would form your ozonide intermediate. I have some reactions that I can show you to help you out if you want to email me at bg1047@txstate.edu. Organic is a tough subject and you need to understand it really well to move on. If you have questions feel free to email me and I will try to answer them BECAUSE I loved organic. :albert:

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