[ling87]

13C NMR - Peak allocation to Structure?
Compound:
<img src="http://img85.imageshack.us/img85/1756/compound5.jpg">

There are 13C NMR peaks at
- 190 ppm
- 163 ppm
- 152 ppm
- 131 ppm
- 126 ppm
- 114 ppm
- 55 ppm

Which ones can you identify definitively? I know the theory behind NMR but I'm still not very certain on how to distinguish between certain peaks.

For example, I am unsure whether C=O or C-O (branch directly off the aromatic ring) would be the peak(s) at 190 and 163ppm.

I am assuming at the peak(s) at 55ppm and 114ppm are the CHs that are on the -CH2=CH2-CHO branch, but which peak should be assigned to which CH2?

Knowing this, it shouldn't be hard to assign the rest of the peaks to the aromatic carbons.

Thanks in advance!

[AC Prabakar]

Can you please give me the structure clearly...
Is only Oxygen(or some other like ester,ether,H) attached directly to aromatic?

[ling87]

yes, it's only oxygen attached to the aromatic. this is the entire structure.

[Dan]

So it's a radical? Odd question.

Either the 55 ppm peak is a typo and should be 155 ppm, or there is a methyl group on the phenolic oxygen. If the latter is the case then there should be another peak >100 though - I count 7 signals for your radical and I'd be very surprised if it has any peaks below 100 ppm.

Are you absolutely sure the structure/peak list is complete?

[Med90]

every peaks except at 55 looks fine...I guess ppm 55 peak is for O-CH3. Could you please check your structure once?