Which of the following compounds possess more than one percent enol content?

enter image description here

I understood that stability of enols are dependent on the hydrogen bonding in the compounds. But here, what is the significance of more than one percent enol content?

  • 1
    $\begingroup$ I would like to express my disagreement with the assertion that the stability of enols would mainly be dependent on inter- and intra- molecular hydrogen bonding. $\endgroup$
    – user79161
    Commented Mar 26, 2021 at 9:15
  • $\begingroup$ @user79161 I mean that h-bonding is one of the factor that could be used for determining the stability of Enols. It need not be the primary factor. $\endgroup$ Commented Mar 26, 2021 at 9:53
  • 1
    $\begingroup$ Especially because of the nice representations of the formulae (for easier reading, consider to rotate labels, though [entry i]), a more useful question were the comparison of the entries by line to justify which ones are more likely to enolize, than others -- for example in the line of a to d. For some, $\log{}K$ may depend on the molecule's structure as well as (if there is) the solvent molecules. Or -- guessing -- are you literally looking for a tautomer database example? $\endgroup$
    – Buttonwood
    Commented Mar 26, 2021 at 9:57
  • 3
    $\begingroup$ chemistry.stackexchange.com/questions/18904/… This might help you;@Ron's answer was very extensive. Note that, as Buttonwood pointed out, a fruitful exercise would be to compare likelihood of enolization. To compare the respective percentages would need you to carry out an experiment and interpret that data. $\endgroup$
    – C_Lycoris
    Commented Mar 26, 2021 at 12:48

1 Answer 1


All the compounds that have a relation $\alpha-\beta$ between the carbonyl groups. The hydrogen between two $\ce{CO}$ is very acid because two electrowithdrawing remove electron density from the $\ce{C-O}$ bond. Therefore for this kind of compound the most stable for is the enol. In Organic Chemistry this is very useful in creating new carbon-carbon bonds in mild conditions like in aldoholic reactions, Michael reactions and so on. See the very good book of Marc Loudon, Organic Chemistry.


Not the answer you're looking for? Browse other questions tagged or ask your own question.