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Logic Puzzle #14: No Bias this Time Please

March 8, 2011

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?


4 Replies to “Logic Puzzle #14: No Bias this Time Please”

  1. For this situation you must be correlate with DEPTH-135 to 13-carbon and confirm that whether it belongs to CH or CH2.
    Rajdip Vansadiya
    NMR and Mass Scientist

  2. 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?)


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