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What resonance forms stabilize deprotonated hydroquinone?

Deprotonated hydroquinone looks like this:

deprotonated hydroquinone

Possible resonance forms include:

resonance forms

1 and 2 look reasonable: they don't carry multiple charges. My question is: how much do these two structures contribute to the stability of deprotonated hydroquinone? I am thinking that they should be much higher energy than the structure on top, because the negative charge is on C, which is not nearly as electronegative as O.

Can this be quantified (by and for amateur chemists)?


Per Michael Lautman's suggestion, here are partial charges as calculated in Avogadro:

Avogadro 1

The pattern expected from the resonance forms above, with more negative charge on carbons 2, 4, and 6, is not there.

Why is C4 -0.20?

For comparison, deprotonated cyclohexane-1,4-diol:

Avogadro 2

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  • $\begingroup$ Resonance forms can be determined by following conjugation, which is the alternation of single bonds with p or pi electrons. Follow the conjugation. $\endgroup$ – Michael Lautman May 14 at 21:34
  • $\begingroup$ Yeah I know, thanks. I updated the question. $\endgroup$ – Martin May 21 at 8:11
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    $\begingroup$ You can use modeling software to quantify the partial charges on each atom. On windows, check out ArgusLab, or Avogodro for mac. $\endgroup$ – Michael Lautman May 21 at 12:34
  • $\begingroup$ @michael partial charges will not reproduce anything usable about the resonance, except an overall superposition. Avogadro only produces charges based on force fields, not the most reliable for an anion anyway. $\endgroup$ – Martin - マーチン Jun 12 at 12:51
  • $\begingroup$ @Martin, thanks. $\endgroup$ – Michael Lautman Jun 12 at 15:10

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