April 17, 2021, 10:50:32 PM
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Topic: Assigning carbon-13 NMR for ethyl 2-oxo-3,4-dihydrochromene-3-carboxylate.  (Read 172 times)

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Offline ae86

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Hi,

I have a molecule and an NMR spectrum, and I need to assign the NMR peaks to each of the carbons to the molecule.

I know that the 14.19 ppm and the 61.94 ppm correspond respectively to the carbon 12 and 11. However, I struggle for the other peaks especially between 116.76 and 148.51 ppm. I just know that it corresponds to the aromatic ring. Finally, I think that the 156.65 ppm and 155.15 ppm are respectively the carbon 9 and 10.

Thank you for your help.

Offline Babcock_Hall

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Re: Assigning carbon-13 NMR for ethyl 2-oxo-3,4-dihydrochromene-3-carboxylate.
« Reply #1 on: February 02, 2021, 07:53:34 PM »
I would use calculations of chemical shifts as well as the number of attached hydrogen atoms.

Offline kriggy

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Re: Assigning carbon-13 NMR for ethyl 2-oxo-3,4-dihydrochromene-3-carboxylate.
« Reply #2 on: February 17, 2021, 06:08:49 AM »
Exactly assigning all those signals is going to be impossible withtout further data comming from 2D experiments.

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