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Would this be proper resonance structures? I know there's a lone pair on the top carbon. Having a carboanion isn't favorable as opposed to a negative formal charge on the more electronegative carbon so I flipped a bonding pair to oxygen's valence. I then proceeded to move the pi electrons inside the ring as well. This seems to satisfy all octet requirements.

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For the second resonance diagram I saw the negative charge on the oxygen and decided to take one of its lone pairs and make it a bonding pair so that oxygen has 0 formal charge. This in turn necessitates pushing around a few pi electron pairs inside the ring. Same thing for the third one; I tried giving nitrogen a positive formal charge.

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Yes, they are all valid resonance structures. In the first series, there is a third resonance structure you could draw with the negative charge alpha to the carbonyl carbon. In the second series, the phenoxide anion, you can draw two more structures. One with the negative charge in the other ortho position and one with the negative charge in the para position. This significant resonance stabilization of the phenoxide anion explains why phenol is such a strong acid. In your third series there is also a third structure with the positive charge situated alpha to the nitrogen.

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  • $\begingroup$ Yep! I noticed that the second is the conjugate base of phenol. The delocalization of negative charge in the conjugate base of phenol provides the conjugate base stability and this is what allows phenol to be an unusually strong acid as far as hydrocarbons go. $\endgroup$ – Dissenter May 21 '14 at 20:51
  • $\begingroup$ Phenol can cause severe burns. It is also rapidly absorbed through the skin leading to a host of other problems, including death. $\endgroup$ – ron May 21 '14 at 20:54
  • $\begingroup$ Sounds like hydrofluoric acid, which isn't a strong acid per se, but dissociates to a significant extent so that skin contact can cause significant absorption of fluoride ion (which has a pretty high electron affinity) and can cause heart attacks. $\endgroup$ – Dissenter May 21 '14 at 21:05

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