Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub

Compound (b) has the higher enol content. The enol of (a), cyclohexane-1,3,5-trione, is phloroglucinol (aromatic), and that of (b), 3-hydroxycyclohex-2-en-1-one, is resorcinol (also aromatic). The difference : phloroglucinol readily reverts to its triketo form (the triketone is known and a trioxime can be made), so compound (a) keeps a measurable keto fraction and its enol content is well short of 100%. Resorcinol does not form its diketo tautomer at all, so compound (b) exists essentially completely as the enol. Hence enol content of (b) is higher than that of (a).