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ochem problem from topscore test#1

Discussion in 'DAT Discussions' started by allstardentist, Aug 7, 2006.

  1. allstardentist

    allstardentist All-Star
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    In aldol condensation, in order to remove the OH group from the beta-hydroxyaldehyde, don't we need to add heat? However, according to #76 in topscore #1 test, there's no heat required to remove the OH group and form a C-C double bond.
     
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  2. dat_student

    dat_student Junior Member
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    my chem books also don't say anything about the heat requirement.
     
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  3. OP
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    allstardentist

    allstardentist All-Star
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    look at princeton review page 556
     
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  4. dat_student

    dat_student Junior Member
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    I just did. It may be needed. Apparently some books show it; some don't :)
     
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  5. DonExodus

    DonExodus Dentist in Virgin Islands
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    Aye, all my books show it, including the textbook. It shows the condensation product as C=O and -OH. Once you add heat, you get the C=O and C=C .

    If the C=O and -OH product is not listed, and neither is heat, I would just assume the answer is C=O and C=C.
     
  6. dhollings0

    dhollings0 Junior Member
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    aldol condensation can be accomplished:
    1) Thermally (heat)
    2) Acid catalyst
    3) Base catalyst

    Source:
    http://www.organic-chemistry.org/namedreactions/aldol-condensation.shtm

    "In some cases, the adducts obtained from the Aldol Addition can easily be converted (in situ) to α,β-unsaturated carbonyl compounds, either thermally or under acidic or basic catalysis."

    So I guess heat is not always required. My McMurry textbook discusses condensation using the acid/base catalyst, but does not mention heat; however, Kaplan says heat is required, but does not mention a catalyst.

    Hope that helps
     
  7. DonExodus

    DonExodus Dentist in Virgin Islands
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    In the link you provided, it also shows the elimination reaction as needing heat.
     
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    allstardentist

    allstardentist All-Star
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    The thing is one of the choices was none of the above, so i put that and got it wrong.
     
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  9. DonExodus

    DonExodus Dentist in Virgin Islands
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    Oh thats just ****ed up...
     
  10. slayerdeus

    slayerdeus Member
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    From what I can recall aldol condensation can come about a number of ways. Most notably from Claisen condensation (2 equiv. of ether + strong base -> enolate attacks ether + aq. acid -> aldol) is the one that you should be most familiar with I think.
     

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