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Data misinterpretation based on personal bias happens more often than an elucidator likes to admit. The purpose of this puzzle is to examine a potential pitfall while interpreting data from a 2D NMR spectrum.
For an unknown compound, the 1H -13C HMQC spectrum below shows two correlations both of which are assigned to the same carbon shift at 126 ppm. The 1H integral information shows the correlations to be 1 Hydrogen atom each. Is the 13C at 126 ppm a CH2?
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What is the distance, in Hz, between the two protons in the F2 dimension?
Posted by: Rodri | March 09, 2011 at 06:54 AM
Hello Rodri,
I added the instrument frequency to the image.
Regards,
Arvin
Posted by: Arvin | March 09, 2011 at 10:26 AM
For this situation you must be correlate with DEPTH-135 to 13-carbon and confirm that whether it belongs to CH or CH2.
Regards
Rajdip Vansadiya
NMR and Mass Scientist
Posted by: Rajdip Vansadiya | March 09, 2011 at 02:50 PM
Thanks for the info on the spectrometer frequency.
With that info, it seems to me that the two protons cannot be attached to the same carbon. Typically, a geminal J1(H-H) coupling is a large negative value, but not as large as the splitting we can see in this case (> 50 Hz?)
Cheers,
Rodri
Posted by: Rodri | March 09, 2011 at 05:06 PM