Looking at the HSQC of my unknown compound, there is a carbon signal that correlates to two different H signals. How can I tell which H signal is the hydrogen on the carbon?
Well, you probably have to anisochronous protons (e.i. of different chemical shifts) connected to the same carbon, for example in a H2C=CH-X group. Kind regards.
To add to Ludger Ernst 's answer above: if the carbon should only have one proton attached to it, perhaps you have two carbons resonating at the same frequency. In which case you'll have to use other experiments and connectivities, maybe NOESY, to separate the signals based on other information you have. Would need to know more about the specific of the problem to give a more specific answer.
Dear Eli,
- What are the integrals of the two 1H signals in 1D 1H? Is each signal one (diastereotope CH2 likely) or two hydrogens (13C chemical shift degeneration likely). Do the two hydrogens show geminal coupling in 1D 1H - again diastereotope CH2 likely?
- The sign of the signal in a multiplicity edited HSQC (normally available at any NMR machine) will tell you whether you have anisochronous (diasterotope) CH2.
- Do you have a 13C 1D - this will tell you if you have two nearly degenerate carbons....optionally you can acquire the HSQC with high resolution
I hope this helps!
Kind regards
Alfred
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