Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub
For how many compounds keto form in more stable than enol form?
Answer:
Solution:
The four compounds where the keto form is more stable than the enol form are (iii), (vi), (vii), and (viii) based on the provided key.
(iii) The presence of the strong electron-withdrawing group destabilizes the enol (anthranol) form by withdrawing electron density from the aromatic system, leaving the keto form more stable.
(vi) In diethyl malonate (a 1,3-diester), the cross-resonance of the ester groups disrupts the stability of any potential enol form, making the keto form highly dominant.
(vii) This is a 1,4-diketone where the two carbonyl groups are isolated; since no conjugated or hydrogen-bonded system can form through enolization, the keto form remains much more stable.
(viii) For this highly sterically hindered aldehyde, the bulky groups favor the keto form to minimize geometric crowding compared to the planar enol structure.
