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Alcohols are defined as organic compounds containing one or more than one hydroxyl group attached to a sp3 hybridized carbon atom.

And it is mentioned in the book I am referring to [errorless chemistry] that compounds in which hydroxyl group is attached directly to sp2 hybridized carbon are known as enols or phenols (aromatic compounds).

Does this mean that -OH group is never attached to triple bonded carbon?

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    $\begingroup$ Look up “ynol”. . . $\endgroup$
    – Andrew
    Jun 8 at 17:57
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    $\begingroup$ It seems an OH directly attached to a triple bond is unstable with respect to a ketene H2C=C=O. I think I can see why, The OH would be relatively acidic and the carbonyl double bond more stable. This is an interesting question something that I never thought of before. Too bad your text didn't even hint about this. [or maybe they did by omission congrats on picking up on it.] $\endgroup$
    – jimchmst
    Jun 8 at 19:36
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    $\begingroup$ The keto-enol tautomerism is in most cases favoured for the ketone. It does actually show that both forms are stable. The same is likely to be true for the ynol and ketene equilibrium, just even more favoured. $\endgroup$ Jun 8 at 19:54
  • $\begingroup$ There is a reasonable mechanism for keto-enol isomerization the alpha protons are acidic. The vinyl protons in the ketene are much less acidic so in spite of the law of Microscopic reversibility this looks like a one way street. Some reactions such as some radical combinations just don't reverse unless a lot of energy is involved. Also the mechanism must be very elementary. $\endgroup$
    – jimchmst
    Jun 9 at 2:39
  • $\begingroup$ @jimchmst Thanks,I get it now. Its just that the definition does not make sense to me. I'd like to classify ynol as alcohol too $\endgroup$ Jun 9 at 5:46

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