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alkene + X2 + ???

Discussion in 'DAT Discussions' started by joonkimdds, Dec 25, 2008.

  1. joonkimdds

    joonkimdds Senior Member
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    Alkene + X2 when X is halogen breaks C=C and adds X to each C in anti manner.

    I learned that adding Br2 to alkene is same as adding Br2 with CH2Br2,

    adding Cl2 is same as adding CCl4.

    my question is
    1) why do I need CH2Br2 and CCl4 if having them absent still brings the same product?

    2) adding X2 with H2O will add OH and X. Which one attaches to more substituted C?

    3) X2 with hv swaps H with one X.
    Br2 with methanol adds Br to less substituted, OCH3 to more substituted C.

    What other X2 +??? reaction type do I need to know besides what I posted above and aromatic substitution? I learned about Br2 with methanol recently from Destroyer and didn't learn it from my OCHEm class so I am worried that there are reactions that I haven't seen before can show up on DAT.
     
  2. sciencegod

    sciencegod Super Member
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    1. ccl4 is solvent. probly always needed just not writen.
    2. OH goest to more substitueded carbon.
    3.the br2 with methabol is same mech as br2 with OH. look at mech and you'll understand.
     
  3. doc3232

    7+ Year Member

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    exactly, but for #2 just to clarify. The Br makes the 3 membered ring then H2O attacks (Anything can attack really, methanol, ethanol). The methanol attacking is nothing new.
     
  4. Panther85

    2+ Year Member

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    highly unlikely... if u've taken a year long semester course dont get caught up in memorizing everything. if u have destroyer, just know the road map. most likely u wont see anything other than important reagents.

    also make sure u know stereochemistry and naming cold. that is free points on the exam bc those are the easiest questions
     

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