Question

Phenols are more acidic than alcohol. Explain why?

Answer 1

Acidic nature of Alcohol:

• In the case of alcohol, the alkyl group$(-{\mathrm{CH}}_3)$ attached to the alcohol is of electron-donating nature which decreases the electronegativity of the Oxygen atom and makes it less polar and more stable.
• In the case of lower electronegativity due to the alkyl group, it cannot donate the ${\mathrm{H}}^{+}$ ion more readily.
• Even if the alcohol donates the ${\mathrm{H}}^{+}$ ion, the remaining alkoxide ion is highly unstable, so it accepts ${\mathrm{H}}^{+}$ ion and converts it back to alcohol.

Acidic nature of Phenol:

• In the case of phenol, the phenyl group $(-\mathrm{OH})$ attached to the Benzene ring is of electron-withdrawing nature.
• This increases the electronegativity of the Oxygen atom and hence its tendency to release ${\mathrm{H}}^{+}$ion.

• Also after releasing ${\mathrm{H}}^{+}$ ion the remaining phenoxide ion is more stable because of charge delocalization due to the resonance.

Hence, Phenol is more acidic than alcohol.