NMR Diastereotopic Proton Splitting

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SUMMARY

In NMR spectroscopy, diastereotopic protons can exhibit different splitting patterns due to their distinct spatial environments. For example, in a CH2R group, one diastereotopic proton may appear as a doublet while the other appears as a triplet. This phenomenon occurs because the bonding relationship to neighboring nuclei remains the same, but spatial location and through-space coupling can influence the observed splitting. Ultimately, the equivalency of protons is determined by their interactions with neighboring equivalent protons, not by the non-equivalence of diastereotopic protons.

PREREQUISITES
  • NMR spectroscopy fundamentals
  • Understanding of diastereotopic protons
  • Knowledge of splitting patterns in NMR
  • Familiarity with CH2R group behavior in NMR
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  • Study the principles of NMR spectroscopy
  • Research diastereotopic vs. enantiotopic protons
  • Learn about through-space coupling in NMR
  • Explore splitting patterns in complex organic molecules
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Chemists, NMR spectroscopists, and students studying organic chemistry who seek to deepen their understanding of proton splitting and diastereotopic behavior in NMR analysis.

echandler
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This is one of those questions that probably has a very simple answer, but I can't find it anywhere, and as much as I think about it, the more confused I get.

Can diastererotopic protons have different number of split peaks in their overall signal like on a CH2R group, for example, one proton splits as a doublet and the other splits as a triplet?

My mind keeps bouncing back and forth between "No because their bonding relationship to other nuclei is the same" and "Yes, because their spatial location is different, and then through space coupling may have an effect," which is usually followed by "that would result in a furthing splitting of the first multiplet, not change the number of the multiplet." I think I'm too deep in it to think clearly.

Thanks in advance.
 
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To get a triplet, you need two neighbouring equivalent protons. The equivalency of the protons does not depend on the non-equivalency of the two diastereotopic protons you are considering.
 

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