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Topic: Strange peak on NMR  (Read 2482 times)

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Offline Spartacus

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Strange peak on NMR
« on: November 21, 2010, 12:48:07 PM »
Hi all, brand new to this forum so please forgive the slightly noob-ish style. :)

As part of my degree course I have a section on spectroscopy. We are given a series of spectra for several molecules and tasked to identify their structures.

I have assigned all but one of these molecules, and am having some real trouble with it. However I think the key to understanding it is one particular peak on the proton-NMR spectrum.

  • It is a singlet at 9.1 ppm, with integration of 1.
  • This suggests it is an aldehyde, but my DEPT_90 for 13C NMR reveals no CH nuclei in the aldehyde region. The highest chemical shift for the CH's in the molecule is in fact 130, which is the aromatic part of the molecule.
  • The molecule definitely contains carbonyl (or multiple carbonyls) somewhere as the Infrared is pretty conclusive on that.

I am not seeking help with the entire molecule as part of the challenge with this is to find the resources myself. However just a little helping hand with this mysterious peak on NMR would probably help me along the road very nicely. I have shown it to the housemates (who are all also chemists) and none of us can work it out. Plus a brief scan of the literature does not reveal much in the way of helpful information.

Just for ease of analysis, the spectra show a reaction product of benzil (this: http://en.wikipedia.org/wiki/Benzil) in some reaction. I do not know the reaction; that is part of the challenge. But this spectrum is of one possible compound which can be gained from reacting benzil in some way.

Thank you very much. :)

Will.
« Last Edit: November 21, 2010, 01:23:05 PM by Spartacus »

Offline Nicolas88

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Re: Strange peak on NMR
« Reply #1 on: November 21, 2010, 01:59:27 PM »
maybe this site will offer you the help your seeking :
http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi

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