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Homework Help: Alkene reactions

  1. Nov 15, 2009 #1
    Hey i'm studying for my chem exam & im having difficulty solving some problems.

    1. 1,3cyclohexadiene + Br2= ?
    Here,should i treat it like a conjugated diene? Meaning that the Br molecules will have 1,2 and 1,4 additions on the diene and 2 products will be there?

    2. 1,4cyclohexadiene + Br2 = ?
    Here should i t eat it like an isolated diene? & if so..where should the Br add? On which bond? Or will there be 2 products? With Br adding on the 1 double bond in the first & 4 double bond in the second?

    3. When propylene is treated with bromine in methanol (CH3OH),two products are formed C3H6Br2 & C4H9BrO.Explain meachanistically how each are formed.
    Here,the first product is simple..its obtained by halogenation of alkenes..simple addition of the Br molecules on the pi-bond.But i wasn't able to determine how the second product is obtained? Obviously methanol has something to do with it..But what kind of reaction is it? We studied hyrohalogenation but nothing about alcohols & halogens together.

    4. 1,2-dimethylcyclopentene + BH3 + H2O2/NaOH =
    This gives us the same product as direct hydrolysis since the alkene is symmetrical,correct?

    Any help in these questions would be greatly appreciated.They are just doubts that need clarifying :) & my exam is tomorrow.
  2. jcsd
  3. Nov 15, 2009 #2
    Anyone,please? :(
  4. Nov 17, 2009 #3


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    I guess I'm too late to help you for your exam. How did you do on the test? You were right about some of these.
  5. Nov 18, 2009 #4
    1) Probably condition dependent. I have seen both 1,4 and 1,2 addition in similar cases.

    2) Try drawing the mechanism, and see if you can get addition to both double bonds with one equivalent.

    3) What is the intermediate in halogenation?

    4) As per your previous thread, if we assume the lack of locant for the ene means it's a 1-ene. I'm not sure you get hydrolysis.
  6. Dec 20, 2009 #5
    86,highest grade :P I went early the next day & asked my prof about them hehe.
    Thanx tho :D
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