Chemistry - Carbonyl compounds Question with Solution | TestHub
Major form present in reaction mixture is :
Options:
Answer:
Solution:
Question Explanation:
The question asks which form will predominate when a strained β-hydroxy ketone is kept in a basic medium, considering reversibility and ring strain.
Concept :
This question is based on Aldol Addition, Retro-Aldol Reaction, Ring Strain, Thermodynamic Stability. Solution:
In the presence of base (OH- ), aldol reactions are reversible.
The given β-hydroxy ketone contains a 3-membered ring, which is highly unstable due to severe angle strain.
Under basic conditions:
1. The strained β-hydroxy ketone undergoes a retro-aldol reaction, breaking the C–C bond to form an open-chain dicarbonyl compound.
2. This intermediate then undergoes intramolecular aldol addition, cyclizing to form a 5-membered ring β-hydroxy ketone.
3. A 5-membered ring has much lower ring strain and is thermodynamically more stable than a 3 -membered ring. Therefore, equilibrium shifts toward formation of the more stable 5-membered cyclic β-hydroxy ketone.
