Question

Which of the followings is/are true regarding phenol?

• A. It turns pink an exposure to air
• B. It is less reactive than anisole in aromatic electrophilic substitution reaction
• C. It is more reactive than aniline in an aromatic electrophilic substitution reaction
• D. Acetylation of phenol decreases its reactivity in aromatic electrophilic substitution reaction

Answer 1

Answer: (A), (B), (D)

The correct options are
A It turns pink an exposure to air
B It is less reactive than anisole in aromatic electrophilic substitution reaction
D Acetylation of phenol decreases its reactivity in aromatic electrophilic substitution reaction

When phenol is exposed to air, a mixture of quinones is formed. This results in pink colour of phenol.
Acetylation of phenol results in formation of phenyl acetate. The acetate group reduces the electron density of aromatic nucleus through resonance and hence, decreases the reactivity towards electrophilic aromatic substitution reaction. Same is done by the oxygen atom in anisole.

For the similar reason, aniline is more reactive than phenol as nitrogen increases the electron density.