Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Organic Reaction Problem

  1. Feb 18, 2004 #1

    JDK

    User Avatar

    Hello,

    I came across this quetion...

    Complete and balance the following reactions:
    Code (Text):

                OH
                 |
    CH3-CH2-CH2-CH-CH3 ->
     
    Now, I don't know if I've gone crazy or something, but what's supposed to happen to that? Its a simple alcohol (2-pentanol) standing there all on its own. I don't have the foggiest what I'm supposed to do to it. I just finished a bunch of work on amides, amines, and polymers and suddenly there's these types of questions. Some are obvious and some... are not. Like this one for example. If anyone could shed some light upon this frustrated mind I'd be grateful. Thanks. [b(] :wink:
     
  2. jcsd
  3. Feb 18, 2004 #2

    FZ+

    User Avatar

    Does it give you any other clues at all? Like reagents? A final product? Is it part of a larger question?
     
  4. Feb 19, 2004 #3

    GCT

    User Avatar
    Science Advisor
    Homework Helper

    The alcohol can dehydrate if heat is applied.

    If the molecule was supposed to be an aldol then condensation could occur.

    Also think of what might happen if two of the alcohols reacted with each other.
     
  5. Feb 19, 2004 #4

    JDK

    User Avatar

    Thanks everyone. With your suggestions I eventually determined, in relation to what the assigned reading was for the Unit, that the reaction they were "implying" to happen was an elimination reaction like this...

    Code (Text):

                OH               H H H
                 |      acid     | | |
    CH3-CH2-CH2-CH-CH3  ---->  H-C-C-C-C=C-H
                                 | | | | |
                                 H H H H H

    2-pentanol                 1-pentene
     
    I do believe that is correct. But, please let me know if I'm wrong.
    :)
     
  6. Feb 19, 2004 #5

    GCT

    User Avatar
    Science Advisor
    Homework Helper

    Think markinakov reaction. You have an antimakinovkov product, which is incorrect. Forgot the spelling of his name.
     
  7. Feb 19, 2004 #6
    makinovkov
    I’m pretty sure it’s Markovnikov.
    Yap = will be on less substituted atom..
     
  8. Feb 20, 2004 #7

    FZ+

    User Avatar

    And since it asks you be balance the equation, you want to include the H2O product on the right hand side.
     
  9. Feb 24, 2004 #8
    I thought you are most likely to get the product with hydrogen to the carbon with the most hydrogen (Markovnikov's rule), i.e. most abundant, but the product GeneralChemTutor suggested the product was incorrect. Please correct me if I am wrong.

    Gary
     
  10. Feb 25, 2004 #9
    I think most acids can't trigger the above reaction. Concentrated sulphuric acid is one of those which can. Also, heat is required.
     
    Last edited: Feb 25, 2004
  11. Feb 25, 2004 #10
    what determines whether the acid can trigger the reaction or not?
     
  12. Feb 25, 2004 #11
    I may be wrong, but I think it is because concentrated sulphuric acid is a dehydrating agent, so it can eliminate H2O. I think the key point is whether it is a strong dehydrating agent or not.
     
  13. Feb 25, 2004 #12
    but how come a dehydrating agent can create a product not following Markovnikov's rule?
     
  14. Feb 25, 2004 #13

    GCT

    User Avatar
    Science Advisor
    Homework Helper

    The deyhydration product which is the most substituted will be the major product since it has the most electron donating groups to stabilize the intermediate carbocation.

    The reaction proceeds through a protonated alcohol, this converts the hydroxy group to a good leaving group.
     
  15. Feb 25, 2004 #14
    OK, so Markownikoff's (it's russian name, there is no 'proper' spelling in the english alphabet) Rule has to do with the addition of hydrogen halides to double bonds.

    We're dealing with elimination so we use Saytseff's or Hoffman's Rule. This is an E1 elimination, so we get the more substituted double bond due to hyperconjugation, it is also the more thermodynamically favored product.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Organic Reaction Problem
  1. Organic reactions (Replies: 2)

Loading...