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Consider ethanedioic acid:

enter image description here

Could it form intramolecular hydrogen bonds (between the C=O and HO)?

enter image description here

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  • $\begingroup$ It's theoretically possible, but I'm not sure if it's observed in practice $\endgroup$ – Mithoron Apr 18 '15 at 14:18
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    $\begingroup$ To add to @Mithoron 's comment, here is a link to a paper where calculations suggest that intramolecular hydrogen bonding (like what you've drawn) occurs in oxalic acid. Here is a link to another reference that discusses this result. $\endgroup$ – ron Apr 18 '15 at 16:55
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No, this would not happen the way your second drawing depicts because the hydrogens do not orient themselves that way. Intramolecular hydrogen bonding would be no more feasible in ethandioic acid than any other monocarboxylic acid. See picture below:oxalic acid

Source: http://commons.wikimedia.org/wiki/File:Oxalic-acid-3D-balls-B.png

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    $\begingroup$ I'm afraid It's not a proof. $\endgroup$ – Mithoron Apr 18 '15 at 14:19
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    $\begingroup$ Why do you believe that the hydrogens "do not orient themselves that way"? See my comment above, calculations suggest that a conformation with intramolecular hydrogen bonds is the most stable conformation. $\endgroup$ – ron Apr 18 '15 at 16:59
  • $\begingroup$ It would be a large concentration of charge in a relatively small region of space. It is my understanding that the electron clouds and atoms orient themselves in a molecule so as to reduce this repulsion between the substituent atoms. $\endgroup$ – ringo Apr 18 '15 at 17:30

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