Nitrate phenol to 2- and 4-nitrophenol
Use dilute aqueous nitric acid at room temperature to form a mixture of 2-nitrophenol and 4-nitrophenol.
A Level; Cambridge International Chemistry 9701, 2028–2030 syllabus, Topic 32. Distinguish phenol (–OH directly on an aromatic ring) from an alcohol (–OH on an aliphatic carbon). Use the specified reagents, temperatures and products; phenol reactions are limited to those listed in the syllabus. Written practice is self-checked
Before you begin
- Recognise alcohols and phenols, aromatic substitution, acids and bases, and diazonium ions from the preceding organic topics.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
What acid conditions nitrate phenol in the syllabus?
What you will learn
- Recall the nitration conditions for phenol
- Identify the 2- and 4-nitrophenol products
- Explain why the conditions are milder than benzene nitration
Phenol nitrates under milder conditions
Phenol reacts with dilute aqueous HNO₃ at room temperature to give a mixture of 2-nitrophenol and 4-nitrophenol. Position 2 is ortho to –OH; position 4 is para.
The –OH group donates electron density into the aromatic ring and activates it toward electrophilic substitution. Therefore phenol reacts with dilute nitric acid at room temperature, while benzene nitration uses concentrated HNO₃/H₂SO₄ at 25–60°C.
Compare the reagents without swapping products
For phenol, state dilute HNO₃(aq), room temperature and the 2-/4- product mixture. For benzene, state concentrated HNO₃ plus concentrated H₂SO₄ and 25–60°C.
Do not use the benzene nitration mixture as the phenol condition. The more electron-rich phenol ring does not need the same strongly activating mixture and higher temperature.
Pause and explain
Which pair of products forms from phenol nitration?
Worked example
State the products and conditions for nitrating phenol.
Show the worked solution
- Use dilute aqueous HNO₃.
- Keep the reaction at room temperature.
- The –OH group directs substitution to positions 2 and 4.
Answer A mixture of 2-nitrophenol and 4-nitrophenol forms with dilute HNO₃(aq) at room temperature.
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Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Write the conditions and product mixture for phenol nitration.
Give me a hint
Include the dilute aqueous acid, temperature and two positions.
Compare my reasoning
- Use dilute HNO₃(aq).
- React at room temperature.
- Show nitro substitution at positions 2 and 4 relative to –OH.
Dilute HNO₃(aq), room temperature → a mixture of 2-nitrophenol and 4-nitrophenol.
Look for these in your work
- Acid concentration stated
- Temperature stated
- Both products named
Compare phenol and benzene nitration conditions and give the electronic reason for the difference.
Give me a hint
Relate –OH donation to ring activation.
Compare my reasoning
- Phenol uses dilute HNO₃(aq) at room temperature.
- Benzene uses concentrated HNO₃/H₂SO₄ at 25–60°C.
- Phenol's –OH donates electron density and makes the ring more reactive.
Phenol nitrates with dilute aqueous HNO₃ at room temperature because –OH activates the ring; benzene needs concentrated HNO₃/H₂SO₄ at 25–60°C.
Look for these in your work
- Both conditions compared
- Temperature contrast stated
- Activation explained
A learner predicts 3-nitrophenol as the only product because they treat –OH like –NO₂. Correct the directing logic.
Give me a hint
Use the directing effect of –OH, not the effect of nitro.
Compare my reasoning
- Phenolic –OH directs to positions 2, 4 and 6.
- In a monosubstituted ring, positions 2 and 6 are equivalent.
- The syllabus product mixture is 2- and 4-nitrophenol.
–OH is ortho/para directing, so the products are 2-nitrophenol and 4-nitrophenol, not 3-nitrophenol alone.
Look for these in your work
- Correct director applied
- Equivalent position noted
- Product mixture corrected
Common mistakes
- Using concentrated nitric and sulfuric acids as the phenol condition
- Predicting only nitrobenzene
- Putting –NO₂ at position 3 without considering –OH direction
- Forgetting phenol gives a mixture of two ring-position isomers
What can you explain now?
What acid conditions nitrate phenol in the syllabus?
Compare with the explanation
Dilute HNO₃(aq) at room temperature
Phenol is activated and reacts under these milder conditions.
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Make it stick
Why does phenol nitrate more readily than benzene, and where does –NO₂ enter?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.