Question 1

Why is phenol a strongly activating ortho/para director?

Accepted Answer

The -OH group donates electron density into the aromatic ring through its +R effect. This raises electron density especially at the two ortho positions and the para position, allowing electrophiles to react there readily.

Question 2

What happens when phenol reacts with bromine water?

Accepted Answer

Phenol reacts rapidly with bromine water without a catalyst. Bromination at C-2, C-4 and C-6 produces 2,4,6-tribromophenol, observed as a white precipitate.

Question 3

How do ortho and para products form during nitration of phenol?

Accepted Answer

Dilute nitric acid electrophilic substitution gives a mixture of ortho-nitrophenol and para-nitrophenol. The nitro group occupies C-2 or C-4 relative to the OH-bearing carbon at C-1.

Question 4

How does temperature affect sulphonation of phenol?

Accepted Answer

Concentrated sulfuric acid is used for sulphonation. At 293 K, the ortho-phenolsulphonic acid isomer is major, while raising the temperature to 373 K favors the para isomer.

Question 5

What is the major product of the Reimer–Tiemann reaction?

Accepted Answer

When phenol is treated with chloroform and aqueous NaOH and then acidified, the major product is o-hydroxybenzaldehyde, also called salicylaldehyde. The -CHO group is ortho to the phenolic -OH group.

Phenol Electrophilic Attack — EAS and Reimer–Tiemann

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