JEE PYQ: Aldehydes And Ketones Question 1
Question 1 - 2021 (16 Mar Shift 1)
Assertion A: Enol form of acetone $[\text{CH}_3\text{COCH}_3]$ exists in $< 0.1%$ quantity. However, the enol form of acetyl acetone $[\text{CH}_3\text{COCH}_2\text{OCCH}_3]$ exists in approximately 15% quantity.
Reason R: Enol form of acetyl acetone is stabilized by intramolecular hydrogen bonding, which is not possible in enol form of acetone.
Choose the correct statement:
(1). ($A$ is false but $R$ is true)
(2). (Both A and R are true and R is the correct explanation of A)
(3). (Both $A$ and $R$ are true but $R$ is not the correct explanation of A)
(4). (A is true but R is false)
Show Answer
Answer: (2)
Solution
Keto-enol tautomerism of acetone gives very little enol ($< 0.1%$). In acetylacetone, the enol form is stabilized by intramolecular H-bonding between the enol OH and the adjacent C=O, giving much higher enol content (>50%). Both A and R are true, and R correctly explains A.
BETA
