If the hydroxl group on 4-aminophenol was protonated by a strong acid in aqueous solution, and the compound further to that dehydrated, could a rearrangement of the subsequent carbocation lead to formation of 2,5-cyclohexadien-1-imine and thus regenertion of the strong acid before SN1 was possible?

Is there a more common name for this sort of reaction (assuming it is possible)?

  • $\begingroup$ I'm afraid you didn't notice that there would be reduction needed there. $\endgroup$
    – Mithoron
    Aug 18, 2017 at 13:56
  • $\begingroup$ And it wouldn't work because hydride donor can't reduce in highly acidic solution. $\endgroup$
    – Mithoron
    Aug 18, 2017 at 14:10

1 Answer 1





As far as I understand, the reaction being suggested is as follows:

Suggested Reaction

The first thing one should notice is that 2,5-Cyclohexadien-1-imine is not going to stay as it is. It will tautomerise to the more stable and aromatic aniline. Tautomerisation to Aniline

Let us go back to the starting material - 4-aminophenol. Both the oxygen and the nitrogen are directly attached to the aromatic $\pi$-system. Both can donate a lone pair and cause a +R effect. Their electronegativities would result in a -I effect, which is very small, compared to the +R effects. The point is, the starting material is electron-rich, i.e. nucleophilic. It would not leave a carbocation (if it does form) alone.

Also, the thing about the lack of a hydride donor...

  • $\begingroup$ Thanks for your answer and comments! But what was that about the lack of a hydride donor?? $\endgroup$ Aug 18, 2017 at 17:24
  • $\begingroup$ See the difference in molecular formulae, for instance. The difference is not "$\ce{H_2O}$", but is "$\ce{OH}$". There needs to be something that provides that $\ce{H}$ $\endgroup$ Aug 18, 2017 at 17:26
  • $\begingroup$ Ah yes I see I may have overlooked that, my bad. Thanks anyway, an interesting discussion nonetheless. $\endgroup$ Aug 18, 2017 at 17:35

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