Question

Which of the following method gives better yield of p-nitrophenol?

• A. Phenol [20^∘ C]dil. HNO₃ p-nitrophenol
• B. Phenol NaNO₂ + H₂SO₄(8^∘ C) p-nitrophenol
• C. Phenol NaOH → conc. HNO₃
• D. None of the three

Hint:

Use sulphonation as a blocking strategy to control orientation.

Answer 1

The Correct Option is B

Step 1: Direct nitration gives mixture of ortho and para products.
Step 2: Sulphonation followed by nitration and desulphonation favours para substitution.
Step 3: Hence method (B) gives better yield of p-nitrophenol.