1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Organic Chemistry IR and NMR problem solving

  1. Jan 16, 2015 #1
    NMR.png 1. The problem statement, all variables and given/known data
    I am trying to help my daughter determine the structure of this carbon compound. It has seven carbons, 14 hydrogens and one oxygen. The oxygen must be in a ketone group. Also each carbon is different (as indicated by the carbon 13 NMR).

    2. Relevant equations


    3. The attempt at a solution
    We think that the correct interpertation of the NMR shown is that there are 4 hydrogens with 3 neighboring hydrogens, 2 hydrogens with 4 nieghboring hydrogens, 2 hydrogens with 5 neighboring hydrogens, 3 hydrogens with 2 neighboring hydrogens and 3 hydrogens with 2 neighboring hydrogens.


    Are we correct so far? Any suggestions?
     

    Attached Files:

    Last edited: Jan 16, 2015
  2. jcsd
  3. Jan 16, 2015 #2

    Bystander

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Looks reasonable. What do the NMR shifts tell you about relative distances from the carbonyl functional group?
     
  4. Jan 16, 2015 #3
    The 4 hydrogens will be closest to the carbonyl and the 3 hydrogens will be farthest from the carbonyl. And one of the groups of 3 hydrogens will be closer than the other group of three hydrogens.
     
  5. Jan 16, 2015 #4

    Bystander

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Might as well call these two methyl groups.
    Next, the four most shifted hydrogens: possibility of superposition of triplets?
     
  6. Jan 16, 2015 #5
    By triplets do you mean the four most shifted hydrogens having three (hydrogen) neighbors? That is the premise we have been working with but we must be missing something obvious.
     
  7. Jan 16, 2015 #6

    Bystander

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    I was wondering if the "quartet" might actually be a pair of triplets sitting almost on top of each other. Haven't got Silverstein and Basler handy, and I'm winging it right now on that part. If it is, the whole thing becomes "trivial." Hah, hah --- sure.
     
  8. Jan 16, 2015 #7
    Arrgh! Taking a break. Then we will play with it some more. Thanks for the suggestion.
     
  9. Jan 19, 2015 #8

    Borek

    User Avatar

    Staff: Mentor

    Asymmetry baffles me.
     
  10. Jan 19, 2015 #9
    As it turns out, the data is bad.

    Scratch the 4 hydrogens with 3 neighbors. So it becomes 7 carbon atoms in a line with the third having a double bond with oxygen.

    Thanks for looking at it!
     
  11. Jan 19, 2015 #10

    Bystander

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    And this was a teaching exercise for your daughter? I would demand my money back.
     
  12. Jan 19, 2015 #11
    Full scholarship...

    I guess you really do get what you pay for.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Organic Chemistry IR and NMR problem solving
Loading...