Phenol ≠ alcohol
Direct attachment to the aromatic carbon changes the chemistry.
The oxygen lone pair interacts with the ring π system.
Molecular compound · aromatic hydroxy compound
Phenol
C₆H₆O
Phenol is C₆H₅OH: a hydroxyl group bonded directly to an aromatic benzene ring. That direct ring–OH connection changes both acidity and electron distribution compared with an ordinary aliphatic alcohol.
Classification rule: phenol is not simply “an alcohol with a benzene ring.” In chemical nomenclature and reactivity, phenols form their own important class.
Essentials
The hydroxyl group is attached directly to an aromatic ring.
That single connectivity fact distinguishes phenol from benzyl alcohol, where –CH₂OH is attached to the ring instead.
Detail
The reference skeletal structure preserves aromatic connectivity.
The O–H bond is polar, and the oxygen is electronically conjugated with the aromatic ring. This affects both substitution patterns and acidity.
Aromatic coupling
The ring and oxygen are electronically connected.
Phenol cannot be understood as benzene and water fragments merely placed next to one another.
Understand
Phenoxide is resonance-stabilized.
Removing the O–H proton gives phenoxide. Its negative charge can delocalize into the aromatic system, helping explain why phenol is more acidic than typical aliphatic alcohols.
Weak acid
More acidic than ethanol does not mean “strong acid.”
Phenol still ionizes only partially in ordinary aqueous conditions.
Reference identifiers
Names and identifiers that pin down the chemical identity.
| Formula | C₆H₆O / C₆H₅OH |
|---|---|
| CAS Registry Number | 108-95-2 |
| PubChem CID | 996 |
Advanced
Push past the first model without losing the simple picture.
Why is phenol more acidic than ethanol?
The conjugate base phenoxide is resonance-stabilized, whereas ethoxide lacks comparable aromatic delocalization.
Is phenol's oxygen lone pair fully delocalized?
The ring and oxygen interact by conjugation, but no single resonance drawing is the whole electron-density picture.
Is C₆H₆O enough to identify phenol?
No. Other isomers with the same formula exist; connectivity matters.
Constituent elements