NEET levelSingle correct optionDifficulty 1 of 3g2167
Phenol exists almost entirely in the enol form rather than as its keto tautomer, cyclohexa-2,4-dien-1-one. The main reason is that
Aphenol has no alpha hydrogen
Bthe enol form keeps the aromatic stabilisation of the benzene ring
Cthe keto form has an intramolecular hydrogen bond
Dthe C=O bond is always weaker than the C=C bond
Answer: B
Phenol is the enol of cyclohexa-2,4-dienone. The keto form would destroy the aromatic sextet, which costs about 150 kJ/mol of resonance energy. This outweighs the usual preference for the C=O form, so phenol is essentially all enol.