Question

Compound having the highest enol content will be?

Answer 1

The methyl group in acetone does stabilize the carbon-carbon double bond in the enol form for the reasons you suggest. However the methyl group also stabilizes the carbonyl double bond in the keto form (see here for example, this is why a carbonyl in a ketone is slightly stronger than a carbonyl in an aldehyde). In fact, in simple carbonyl compounds, the methyl group stabilizes the carbonyl double bond a bit more than it stabilizes the enolic carbon-carbon double bond. As a result, simple aldehydes generally have a higher enol content than simple ketones. Hence, the enol content in acetaldehyde is greater than the enol content in acetone.

carbonyl↽−−⇀enolcarbonyl↽−−⇀enol

Keq=[enol][carbonyl]Keq=[enol][carbonyl]

compoundacetaldehydeacetoneKeq6×10−75×10−9compoundKeqacetaldehyde6×10−7acetone5×10−9

The two ββ-dicarbonyl compounds have a higher enol content than the two monocarbonyl compound because hydrogen bonding and conjugation stabilize their enols. The enol content in C (a mono aldehyde) is higher than D because of the reasons outlined above.

Therefore, the overall order of increasing enol content is C > D >> A > B.

Unless you've studied this before, you might not know that a "methyl group stabilizes the carbonyl double bond a bit more than it stabilizes the enolic carbon-carbon double bond". So a general rulethat might come in handy in these situations is that the enol content increases with the acidity of the enolic hydrogen. A more acidic αα-hydrogen implies a weaker C−HC−H bond. Since the position of a keto-enol equilibrium is dependent on the relative stabilities of the keto and enol forms (the compound with the highest bond strengths overall will be more stable and will predominate at equilibrium) a weak C−HC−H (lower pKapKa) generally implies a higher enol content.

HOPE THIS WILL HELP U

Answer 2

Answer:

Compound having the highest enol content will be acetyl acetone.

Explanation:

Enol is a double bond that is conjugated with an alcohol group.

To form alcohol, a hydrogen atom migrates to the carbonyl oxygen, and the hydrogen-deficient carbon forms a double bond. Automerization occurs during this process, and the enol product is a tautomer of the carbonyl reactant. The following are the structures of the compounds: The enol content of a compound refers to how much of it is present in its enol form in a pure solution of the compound. If the reaction favors the enol product, the enol content is high, implying that enol is more stable than the carbonyl group. In simple monocarboxylic compounds such as acetone, acetophenone, and ethanoic acid, the ketonic form predominates. This is because the C=O bond in keto form is stronger than the C=C bond in enol form. The enolic form is found in $1$,$3$-dicarbamoyl compounds such as acetyl acetone. Because of the stability of the enol product, acetyl acetone will have the highest enol content of the options presented.