How is the "correct" answer not a redox reaction?

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Isn't the "correct" choice a textbook example of an organic redox reaction? After all, we are breaking a C-C bond and replacing that with a C-O bond. If that's not redox I don't know what is redox.

Or am I missing something fundamental here?


The reaction in question involves the addition of water across a double bond. The proton from the water is added to one carbon in the double bond - this carbon is reduced. The hydroxyl group is added to the other end of the double bond - this carbon is oxidized. Even though the oxidation number of one olefinic carbon (the one that winds up with 2 hydrogens attached) changes from-1 to -2, and the other from -1 to 0, overall, for the entire molecule, there is no net oxidation or reduction.

  • $\begingroup$ seems like it was a semantics question then! $\endgroup$ – Dissenter Sep 24 '14 at 2:42
  • $\begingroup$ Perhaps, I don't know how he defined redox reactions in the lecture. I think it could be argued either way, so it comes back to the definition he put forward in class. Was this an exam question? Maybe discussing this point with him would be worthwhile. $\endgroup$ – ron Sep 24 '14 at 2:47
  • $\begingroup$ redox was defined as the loss/gain of electrons. No nuance regarding "net" oxidation or reduction was made. This is a practice question. I might raise it with the prof but I don't think it'll be a worthwhile endeavor considering that the also stated that bond breaking was exergonic. (I knew that what meant was that subsequent hydration combined with the bond breaking step was overall exergonic but still ...) @ron $\endgroup$ – Dissenter Sep 24 '14 at 2:50
  • $\begingroup$ The correct term I was looking for above is exothermic. Not exergonic. $\endgroup$ – Dissenter Sep 24 '14 at 6:05

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