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I find this C-13 NMR Of phenol really weird.

enter image description here

It's weird because I would have expected that $a$ would be the most shifted, then $b$, then $c$ and finally $d$.

After all, d is the furthest from the electronegative element - thus it should be the most shielded from it's effects right?

Or am I missing something?

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    $\begingroup$ Mesomeric effects. $\endgroup$
    – Mithoron
    Jun 9 at 15:44
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    $\begingroup$ You are thinking only about inductive effect. Even in that regard, you got it revised. Mesomeric effect in aromatic ring is more prominent as Mithoron suggested. Also read about magnetic anisotropy (and its effect). $\endgroup$ Jun 9 at 17:07
  • $\begingroup$ Take a look at the resonance structures: commons.wikimedia.org/wiki/File:Phenol_resonance.svg $\endgroup$
    – Koba
    Jun 9 at 20:57
  • $\begingroup$ Sorry I've only done this up to a high school level. How do the resonance structures affect the NMR? $\endgroup$
    – John Hon
    Jun 10 at 14:50
  • $\begingroup$ In my opinion NMR spectroscopy is nothing for the high school level. Resonance in itself as a topic is often taught wrong at this level. Combining the two I think it's a disaster. However, I don't see why this question should be closed for this. I recommend a deep dive into both topics before carrying on though. $\endgroup$ Jun 14 at 22:35

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