Organic Chemistry IR and NMR problem solving

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NMR.png

Homework Statement


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).

Homework Equations




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. [/B]

Are we correct so far? Any suggestions?
 

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Answers and Replies

  • #2
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Looks reasonable. What do the NMR shifts tell you about relative distances from the carbonyl functional group?
 
  • #3
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Looks reasonable. What do the NMR shifts tell you about relative distances from the carbonyl functional group?
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.
 
  • #4
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group of three hydrogens.
Might as well call these two methyl groups.
Next, the four most shifted hydrogens: possibility of superposition of triplets?
 
  • #5
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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.
 
  • #6
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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.
 
  • #7
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Arrgh! Taking a break. Then we will play with it some more. Thanks for the suggestion.
 
  • #8
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Asymmetry baffles me.
 
  • #9
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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!
 
  • #10
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As it turns out, the data is bad.
And this was a teaching exercise for your daughter? I would demand my money back.
 
  • #11
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I would demand my money back.
Full scholarship...

I guess you really do get what you pay for.
 

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