Chemistry/Chapter 10: Hydroxy Compounds
10.4 Reactions of Phenol
The main idea is that the hydroxyl group (-OH)
Explanation level
In the previous section, we compared the acidity of phenol with water and ethanol. We learned that phenol is a stronger acid than both because its conjugate base (the phenoxide ion) is stabilized by resonance. This resonance stabilization also influences the reactivity of the benzene ring in phenol. In this section, we explore the key reactions of phenol, focusing on its reactions with sodium hydroxide, sodium metal, bromine water, nitric acid, and diazonium salts.
Main Idea
The main idea is that the hydroxyl group (-OH) on the benzene ring of phenol has a profound effect on its chemical reactivity. The lone pair of electrons on the oxygen atom can be delocalized into the aromatic ring through resonance, which increases the electron density of the ring, making it more reactive towards electrophilic substitution (especially at the ortho and para positions). Additionally, the -OH group is weakly acidic and can react with bases and active metals.
Core Concept
The core concept is that phenol exhibits the properties of both an alcohol (due to the -OH group) and an arene (due to the benzene ring). However, the interaction between the -OH group and the aromatic ring makes phenol more acidic than alcohols and more reactive than benzene towards electrophilic substitution. The resonance effect of the -OH group activates the ring towards electrophiles.
Detailed Explanation
The textbook describes several key reactions of phenol. These reactions demonstrate its acidic nature and its reactivity as an aromatic compound.
1. Reaction with Sodium Hydroxide (Acidic Nature)
Phenol is a weak acid and reacts with strong bases like sodium hydroxide to form a salt (sodium phenoxide) and water.
C_6H_5OH + NaOH \rightarrow C_6H_5ONa + H_2O
- Explanation: The acidic proton of the -OH group is neutralized by the hydroxide ion (OH^-), forming water. The phenoxide ion (C_6H_5O^-) is the conjugate base, which is stabilized by resonance.
- Significance: This reaction shows that phenol is more acidic than alcohols (which do not react with NaOH to any significant extent). It is used to distinguish phenol from alcohols.
2. Reaction with Sodium Metal (Formation of Phenoxide and Hydrogen Gas)
Like alcohols, phenol reacts with active metals like sodium to form a salt and release hydrogen gas.
2C_6H_5OH + 2Na \rightarrow 2C_6H_5ONa + H_2
- Observation: Effervescence (bubbles of hydrogen gas) is observed.
- Explanation: The sodium metal is oxidized to Na^+, and the acidic proton is reduced to hydrogen gas.
3. Reaction with Bromine Water (Electrophilic Substitution)
Phenol reacts rapidly with bromine water at room temperature to form a white precipitate of 2,4,6-tribromophenol. This is a classic test for phenol.
C_6H_5OH + 3Br_2 \rightarrow C_6H_2Br_3OH + 3HBr
- Observation: The brown colour of bromine water is decolorized, and a white precipitate forms.
- Explanation: The -OH group is strongly activating and ortho/para directing. The high electron density at the ortho and para positions makes phenol much more reactive than benzene towards electrophilic substitution. The reaction occurs without a catalyst, unlike the bromination of benzene.
- Product: 2,4,6-tribromophenol (the bromine atoms are at positions 2, 4, and 6 relative to the -OH group at position 1).
4. Reaction with Nitric Acid (Nitration)
Phenol reacts with dilute nitric acid at room temperature to form a mixture of ortho- and para-nitrophenol. With concentrated nitric acid, 2,4,6-trinitrophenol (picric acid) is formed.
Dilute Nitric Acid: C_6H_5OH + HNO_3 (dilute) \rightarrow C_6H_4(NO_2)OH + H_2O (Products: o-nitrophenol and p-nitrophenol)
Concentrated Nitric Acid: C_6H_5OH + 3HNO_3 (conc.) \rightarrow C_6H_2(NO_2)_3OH + 3H_2O (Product: 2,4,6-trinitrophenol, picric acid)
- Explanation: The -OH group activates the ring, making nitration much easier than for benzene. Nitration of benzene requires a mixture of concentrated nitric and sulfuric acids and heating, while phenol is nitrated even with dilute nitric acid at room temperature.
- Observation: The product, picric acid, is a yellow crystalline solid.
5. Reaction with Diazonium Salt (Coupling Reaction)
Phenol is dissolved in sodium hydroxide solution to give a solution of sodium phenoxide. When this solution is cooled in ice and a cold benzene diazonium chloride solution is added, a yellow-orange solution or precipitate is formed. The product is one of the simplest azo-compounds, which are used as azo dyes.
C_6H_5OH + NaOH \rightarrow C_6H_5ONa + H_2O \] \[ C_6H_5N_2^+Cl^- + C_6H_5ONa \rightarrow C_6H_5-N=N-C_6H_4OH + NaCl
- Explanation: The phenoxide ion (formed in the basic solution) is highly reactive towards the diazonium ion (an electrophile). The reaction is an electrophilic aromatic substitution, where the diazonium group couples with the phenoxide ring at the para position (or ortho if para is blocked).
- Product: A yellow-orange azo compound (an azo dye). Azo dyes are synthetic dyes that do not occur naturally. In azo-dyes, two benzene rings are linked by a nitrogen bridge (-N=N-).
Intermediate Level
The reactions of phenol are determined by the interaction between the -OH group and the benzene ring. The -OH group is weakly acidic, so phenol reacts with strong bases (like NaOH) to form phenoxide salts. It also reacts with sodium metal to release hydrogen gas. The -OH group is strongly activating and ortho/para directing, making the benzene ring much more reactive towards electrophilic substitution than benzene itself. For example, phenol reacts with bromine water without a catalyst to form 2,4,6-tribromophenol, and it can be nitrated with dilute nitric acid. Phenol also undergoes coupling reactions with diazonium salts to form azo compounds, which are used as dyes. The phenoxide ion is more reactive than phenol itself, which is why the coupling reaction is carried out in basic solution.
Important Points
- - Reaction with NaOH: Forms sodium phenoxide + water (acidic nature).
- - Reaction with Na: Forms sodium phenoxide + hydrogen gas.
- - Reaction with Bromine Water: Forms 2,4,6-tribromophenol (white precipitate). No catalyst needed.
- - Reaction with Nitric Acid: Dilute gives mono-nitrophenols; concentrated gives picric acid (2,4,6-trinitrophenol).
- - Reaction with Diazonium Salt: Forms azo dyes (yellow-orange precipitate).
- - -OH group: Activating, ortho/para-directing.
- - Phenoxide ion: More reactive than phenol itself.
Remember
- - Phenol + NaOH → Sodium phenoxide + water.
- - Phenol + Na → Sodium phenoxide + H_2.
- - Phenol + Br2 water → 2,4,6-tribromophenol (white precipitate).
- - Phenol + dilute HNO3 → o-/p-nitrophenol.
- - Phenol + conc. HNO3 → Picric acid.
- - Phenol + diazonium salt → Azo dye.
- - -OH is activating and ortho/para-directing.
- - Phenoxide ion is more reactive than phenol.
Common Mistakes
- - Thinking that phenol is a typical alcohol. It is more acidic than alcohols and reacts with NaOH.
- - Forgetting that the -OH group activates the ring. Phenol is much more reactive than benzene towards electrophilic substitution.
- - Assuming that bromination of phenol requires a catalyst. It does not; the ring is highly activated.
- - Not recognizing the difference between the reaction with dilute and concentrated nitric acid. Dilute acid gives mono-nitration; concentrated acid gives tri-nitration (picric acid).
- - Confusing the coupling reaction of phenol with diazonium salts. The product is an azo dye, not a simple diazonium salt.
Quick Revision
Phenol is a weak acid due to the -OH group on the benzene ring, and it reacts with NaOH to form sodium phenoxide and water. It also reacts with sodium metal to release hydrogen gas. The -OH group strongly activates the benzene ring towards electrophilic substitution. Phenol reacts rapidly with bromine water to form a white precipitate of 2,4,6-tribromophenol (a test for phenol), and with dilute nitric acid to form mono-nitrophenols. With concentrated nitric acid, it forms picric acid (2,4,6-trinitrophenol). Phenol also undergoes a coupling reaction with diazonium salts to form azo dyes, which are used as colorants. The reactions of phenol are a direct consequence of the interaction between the -OH group and the aromatic ring.
60-Second Revision
Phenol reacts with NaOH to form sodium phenoxide and water, demonstrating its acidic nature. With sodium metal, it releases hydrogen gas. The -OH group activates the benzene ring, making it highly reactive towards electrophiles. Phenol reacts with bromine water to form a white precipitate of 2,4,6-tribromophenol, and with nitric acid to form nitrophenols (or picric acid with concentrated acid). It also reacts with diazonium salts to form brightly coloured azo dyes.
Frequently Asked Questions (FAQs)
- Q1. What is the reaction of phenol with sodium hydroxide?
- Answer: Phenol reacts with sodium hydroxide to form sodium phenoxide (sodium benzoate) and water:
- C6H5OH + NaOH → C6H5ONa + H2O
- This reaction shows that phenol is acidic, unlike typical alcohols.
- Q2. What happens when phenol reacts with sodium metal?
- Answer: Phenol reacts with sodium metal to form sodium phenoxide and hydrogen gas:
- 2C6H5OH + 2Na → 2C6H5ONa + H2
- Bubbles of hydrogen gas are observed.
- Q3. Write the balanced chemical equation for the reaction of phenol with bromine water.
- Answer: Phenol reacts with bromine water to form 2,4,6-tribromophenol and hydrogen bromide:
- C6H5OH + 3Br2 → C6H2Br3OH + 3HBr
- A white precipitate of 2,4,6-tribromophenol is formed.
- Q4. What are the products of the reaction of phenol with dilute nitric acid?
- Answer: Phenol reacts with dilute nitric acid at room temperature to form a mixture of ortho-nitrophenol and para-nitrophenol:
- C6H5OH + HNO3 → C6H4(NO2)OH + H2O
- Q5. What is picric acid and how is it formed from phenol?
- Answer: Picric acid is 2,4,6-trinitrophenol. It is formed by the reaction of phenol with concentrated nitric acid:
- C6H5OH + 3HNO3 (conc.) → C6H2(NO2)3OH + 3H2O
- It is a yellow crystalline solid.
Q6. Describe the reaction of phenol with diazonium salts. Answer: Phenol reacts with benzene diazonium chloride in the presence of sodium hydroxide to form a yellow-orange azo compound (an azo dye). The reaction is an electrophilic aromatic substitution where the diazonium ion couples with the phenoxide ion at the para position (or ortho): C6H5N2+Cl- + C6H5ONa → C6H5-N=N-C6H4OH + NaCl
- Q7. What is the product of the reaction of phenol with bromine water?
- Answer: The product is 2,4,6-tribromophenol, which is a white precipitate. The reaction is used as a test for phenol.
Q8. Why is the -OH group in phenol considered an activating and ortho/para-directing group? Answer: The -OH group is activating because the lone pair on the oxygen atom can be delocalized into the aromatic ring through resonance. This increases the electron density of the ring, making it more reactive towards electrophiles. The resonance structures place the highest electron density at the ortho and para positions, so the incoming electrophile is directed to these positions.
- Q9. What is the reaction of phenol with sodium metal?
- Answer: Phenol reacts with sodium metal to form sodium phenoxide and hydrogen gas:
- 2C6H5OH + 2Na → 2C6H5ONa + H2
- This is similar to the reaction of alcohols with sodium.
- Q10. What is the reaction of phenol with sodium hydroxide?
- Answer: Phenol reacts with sodium hydroxide to form sodium phenoxide and water:
- C6H5OH + NaOH → C6H5ONa + H2O
- This reaction demonstrates the acidic nature of phenol.
Multiple Choice Questions (MCQs)
- Q1. What is the product of the reaction of phenol with sodium hydroxide?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium hydroxide
- Correct Answer: A
- Explanation: Phenol reacts with NaOH to form sodium phenoxide and water.
- Q2. What is the product of the reaction of phenol with sodium metal?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium
- Correct Answer: B
- Explanation: Phenol reacts with sodium metal to form sodium phenoxide and hydrogen gas.
- Q3. What is the observation when phenol reacts with bromine water?
- A. A white precipitate forms.
- B. A yellow precipitate forms.
- C. A gas is evolved.
- D. No visible change.
- Correct Answer: A
- Explanation: A white precipitate of 2,4,6-tribromophenol is formed.
- Q4. What is the product of the reaction of phenol with dilute nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: B
- Explanation: Dilute nitric acid gives a mixture of ortho- and para-nitrophenol.
- Q5. What is the product of the reaction of phenol with concentrated nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: A
- Explanation: Concentrated nitric acid gives 2,4,6-trinitrophenol (picric acid).
- Q6. What is the product of the reaction of phenol with benzene diazonium chloride?
- A. A yellow-orange azo dye
- B. A white precipitate
- C. A gas
- D. No reaction
- Correct Answer: A
- Explanation: A yellow-orange azo dye is formed.
- Q7. Which of the following reactions shows that phenol is acidic?
- A. Reaction with NaOH
- B. Reaction with Na
- C. Reaction with Br2 water
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with NaOH shows that phenol is acidic.
- Q8. Which of the following reactions is a test for phenol?
- A. Reaction with Br2 water
- B. Reaction with NaOH
- C. Reaction with Na
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The formation of a white precipitate with bromine water is a test for phenol.
- Q9. What is the chemical name for picric acid?
- A. 2,4,6-Trinitrophenol
- B. 2,4-Dinitrophenol
- C. 4-Nitrophenol
- D. Trinitrobenzene
- Correct Answer: A
- Explanation: Picric acid is 2,4,6-trinitrophenol.
- Q10. Which of the following is an azo dye?
- A. The product of phenol and diazonium salt.
- B. The product of phenol and bromine water.
- C. The product of phenol and nitric acid.
- D. The product of phenol and sodium hydroxide.
- Correct Answer: A
- Explanation: The product of phenol and diazonium salt is an azo dye.
Multiple Choice Questions (MCQs)
- Q1. What is the product of the reaction of phenol with sodium hydroxide?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium hydroxide
- Correct Answer: A
- Explanation: Phenol reacts with NaOH to form sodium phenoxide and water.
- Q2. What is the product of the reaction of phenol with sodium metal?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium
- Correct Answer: B
- Explanation: Phenol reacts with sodium to form sodium phenoxide and hydrogen.
- Q3. What is the observation when phenol reacts with bromine water?
- A. A white precipitate forms.
- B. A yellow precipitate forms.
- C. A gas is evolved.
- D. No visible change.
- Correct Answer: A
- Explanation: A white precipitate forms.
- Q4. What is the product of the reaction of phenol with dilute nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: B
- Explanation: Dilute nitric acid gives o- and p-nitrophenol.
- Q5. What is the product of the reaction of phenol with concentrated nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: A
- Explanation: Concentrated nitric acid gives picric acid.
- Q6. What is the product of the reaction of phenol with benzene diazonium chloride?
- A. A yellow-orange azo dye
- B. A white precipitate
- C. A gas
- D. No reaction
- Correct Answer: A
- Explanation: A yellow-orange azo dye is formed.
- Q7. Which of the following reactions shows that phenol is acidic?
- A. Reaction with NaOH
- B. Reaction with Na
- C. Reaction with Br2 water
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with NaOH shows that phenol is acidic.
- Q8. Which of the following reactions is a test for phenol?
- A. Reaction with Br2 water
- B. Reaction with NaOH
- C. Reaction with Na
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with bromine water is a test for phenol.
- Q9. What is the chemical name for picric acid?
- A. 2,4,6-Trinitrophenol
- B. 2,4-Dinitrophenol
- C. 4-Nitrophenol
- D. Trinitrobenzene
- Correct Answer: A
- Explanation: Picric acid is 2,4,6-trinitrophenol.
- Q10. Which of the following is an azo dye?
- A. The product of phenol and diazonium salt.
- B. The product of phenol and bromine water.
- C. The product of phenol and nitric acid.
- D. The product of phenol and sodium hydroxide.
- Correct Answer: A
- Explanation: The product of phenol and diazonium salt is an azo dye.
Multiple Choice Questions (MCQs)
- Q1. What is the product of the reaction of phenol with sodium hydroxide?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium hydroxide
- Correct Answer: A
- Explanation: Phenol reacts with NaOH to form sodium phenoxide and water.
- Q2. What is the product of the reaction of phenol with sodium metal?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium
- Correct Answer: B
- Explanation: Phenol reacts with sodium to form sodium phenoxide and hydrogen.
- Q3. What is the observation when phenol reacts with bromine water?
- A. A white precipitate forms.
- B. A yellow precipitate forms.
- C. A gas is evolved.
- D. No visible change.
- Correct Answer: A
- Explanation: A white precipitate forms.
- Q4. What is the product of the reaction of phenol with dilute nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: B
- Explanation: Dilute nitric acid gives o- and p-nitrophenol.
- Q5. What is the product of the reaction of phenol with concentrated nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: A
- Explanation: Concentrated nitric acid gives picric acid.
- Q6. What is the product of the reaction of phenol with benzene diazonium chloride?
- A. A yellow-orange azo dye
- B. A white precipitate
- C. A gas
- D. No reaction
- Correct Answer: A
- Explanation: A yellow-orange azo dye is formed.
- Q7. Which of the following reactions shows that phenol is acidic?
- A. Reaction with NaOH
- B. Reaction with Na
- C. Reaction with Br2 water
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with NaOH shows that phenol is acidic.
- Q8. Which of the following reactions is a test for phenol?
- A. Reaction with Br2 water
- B. Reaction with NaOH
- C. Reaction with Na
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with bromine water is a test for phenol.
- Q9. What is the chemical name for picric acid?
- A. 2,4,6-Trinitrophenol
- B. 2,4-Dinitrophenol
- C. 4-Nitrophenol
- D. Trinitrobenzene
- Correct Answer: A
- Explanation: Picric acid is 2,4,6-trinitrophenol.
- Q10. Which of the following is an azo dye?
- A. The product of phenol and diazonium salt.
- B. The product of phenol and bromine water.
- C. The product of phenol and nitric acid.
- D. The product of phenol and sodium hydroxide.
- Correct Answer: A
- Explanation: The product of phenol and diazonium salt is an azo dye.
Multiple Choice Questions (MCQs)
- Q1. What is the product of the reaction of phenol with sodium hydroxide?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium hydroxide
- Correct Answer: A
- Explanation: Phenol reacts with NaOH to form sodium phenoxide and water.
- Q2. What is the product of the reaction of phenol with sodium metal?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium
- Correct Answer: B
- Explanation: Phenol reacts with sodium to form sodium phenoxide and hydrogen.
- Q3. What is the observation when phenol reacts with bromine water?
- A. A white precipitate forms.
- B. A yellow precipitate forms.
- C. A gas is evolved.
- D. No visible change.
- Correct Answer: A
- Explanation: A white precipitate forms.
- Q4. What is the product of the reaction of phenol with dilute nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: B
- Explanation: Dilute nitric acid gives o- and p-nitrophenol.
- Q5. What is the product of the reaction of phenol with concentrated nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: A
- Explanation: Concentrated nitric acid gives picric acid.
- Q6. What is the product of the reaction of phenol with benzene diazonium chloride?
- A. A yellow-orange azo dye
- B. A white precipitate
- C. A gas
- D. No reaction
- Correct Answer: A
- Explanation: A yellow-orange azo dye is formed.
- Q7. Which of the following reactions shows that phenol is acidic?
- A. Reaction with NaOH
- B. Reaction with Na
- C. Reaction with Br2 water
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with NaOH shows that phenol is acidic.
- Q8. Which of the following reactions is a test for phenol?
- A. Reaction with Br2 water
- B. Reaction with NaOH
- C. Reaction with Na
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with bromine water is a test for phenol.
- Q9. What is the chemical name for picric acid?
- A. 2,4,6-Trinitrophenol
- B. 2,4-Dinitrophenol
- C. 4-Nitrophenol
- D. Trinitrobenzene
- Correct Answer: A
- Explanation: Picric acid is 2,4,6-trinitrophenol.
- Q10. Which of the following is an azo dye?
- A. The product of phenol and diazonium salt.
- B. The product of phenol and bromine water.
- C. The product of phenol and nitric acid.
- D. The product of phenol and sodium hydroxide.
- Correct Answer: A
- Explanation: The product of phenol and diazonium salt is an azo dye.
Multiple Choice Questions (MCQs)
- Q1. What is the product of the reaction of phenol with sodium hydroxide?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium hydroxide
- Correct Answer: A
- Explanation: Phenol reacts with NaOH to form sodium phenoxide and water.
- Q2. What is the product of the reaction of phenol with sodium metal?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium
- Correct Answer: B
- Explanation: Phenol reacts with sodium to form sodium phenoxide and hydrogen.
- Q3. What is the observation when phenol reacts with bromine water?
- A. A white precipitate forms.
- B. A yellow precipitate forms.
- C. A gas is evolved.
- D. No visible change.
- Correct Answer: A
- Explanation: A white precipitate forms.
- Q4. What is the product of the reaction of phenol with dilute nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: B
- Explanation: Dilute nitric acid gives o- and p-nitrophenol.
- Q5. What is the product of the reaction of phenol with concentrated nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: A
- Explanation: Concentrated nitric acid gives picric acid.
- Q6. What is the product of the reaction of phenol with benzene diazonium chloride?
- A. A yellow-orange azo dye
- B. A white precipitate
- C. A gas
- D. No reaction
- Correct Answer: A
- Explanation: A yellow-orange azo dye is formed.
- Q7. Which of the following reactions shows that phenol is acidic?
- A. Reaction with NaOH
- B. Reaction with Na
- C. Reaction with Br2 water
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with NaOH shows that phenol is acidic.
- Q8. Which of the following reactions is a test for phenol?
- A. Reaction with Br2 water
- B. Reaction with NaOH
- C. Reaction with Na
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with bromine water is a test for phenol.
- Q9. What is the chemical name for picric acid?
- A. 2,4,6-Trinitrophenol
- B. 2,4-Dinitrophenol
- C. 4-Nitrophenol
- D. Trinitrobenzene
- Correct Answer: A
- Explanation: Picric acid is 2,4,6-trinitrophenol.
- Q10. Which of the following is an azo dye?
- A. The product of phenol and diazonium salt.
- B. The product of phenol and bromine water.
- C. The product of phenol and nitric acid.
- D. The product of phenol and sodium hydroxide.
- Correct Answer: A
- Explanation: The product of phenol and diazonium salt is an azo dye.
Multiple Choice Questions (MCQs)
- Q1. What is the product of the reaction of phenol with sodium hydroxide?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium hydroxide
- Correct Answer: A
- Explanation: Phenol reacts with NaOH to form sodium phenoxide and water.
- Q2. What is the product of the reaction of phenol with sodium metal?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium
- Correct Answer: B
- Explanation: Phenol reacts with sodium to form sodium phenoxide and hydrogen.
- Q3. What is the observation when phenol reacts with bromine water?
- A. A white precipitate forms.
- B. A yellow precipitate forms.
- C. A gas is evolved.
- D. No visible change.
- Correct Answer: A
- Explanation: A white precipitate forms.
- Q4. What is the product of the reaction of phenol with dilute nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: B
- Explanation: Dilute nitric acid gives o- and p-nitrophenol.
- Q5. What is the product of the reaction of phenol with concentrated nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: A
- Explanation: Concentrated nitric acid gives picric acid.
- Q6. What is the product of the reaction of phenol with benzene diazonium chloride?
- A. A yellow-orange azo dye
- B. A white precipitate
- C. A gas
- D. No reaction
- Correct Answer: A
- Explanation: A yellow-orange azo dye is formed.
- Q7. Which of the following reactions shows that phenol is acidic?
- A. Reaction with NaOH
- B. Reaction with Na
- C. Reaction with Br2 water
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with NaOH shows that phenol is acidic.
- Q8. Which of the following reactions is a test for phenol?
- A. Reaction with Br2 water
- B. Reaction with NaOH
- C. Reaction with Na
- D. Reaction with HNO3
- Correct Answer: A
- Explanation: The reaction with bromine water is a test for phenol.
- Q9. What is the chemical name for picric acid?
- A. 2,4,6-Trinitrophenol
- B. 2,4-Dinitrophenol
- C. 4-Nitrophenol
- D. Trinitrobenzene
- Correct Answer: A
- Explanation: Picric acid is 2,4,6-trinitrophenol.
- Q10. Which of the following is an azo dye?
- A. The product of phenol and diazonium salt.
- B. The product of phenol and bromine water.
- C. The product of phenol and nitric acid.
- D. The product of phenol and sodium hydroxide.
- Correct Answer: A
- Explanation: The product of phenol and diazonium salt is an azo dye.
Multiple Choice Questions (MCQs)
- Q1. What is the product of the reaction of phenol with sodium hydroxide?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium hydroxide
- Correct Answer: A
- Explanation: Phenol reacts with NaOH to form sodium phenoxide and water.
- Q2. What is the product of the reaction of phenol with sodium metal?
- A. Sodium phenoxide + water
- B. Sodium phenoxide + hydrogen
- C. Phenoxide + carbon dioxide
- D. Benzene + sodium
- Correct Answer: B
- Explanation: Phenol reacts with sodium to form sodium phenoxide and hydrogen.
- Q3. What is the observation when phenol reacts with bromine water?
- A. A white precipitate forms.
- B. A yellow precipitate forms.
- C. A gas is evolved.
- D. No visible change.
- Correct Answer: A
- Explanation: A white precipitate forms.
- Q4. What is the product of the reaction of phenol with dilute nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: B
- Explanation: Dilute nitric acid gives o- and p-nitrophenol.
- Q5. What is the product of the reaction of phenol with concentrated nitric acid?
- A. Picric acid
- B. o-Nitrophenol and p-nitrophenol
- C. Nitrobenzene
- D. Benzoic acid
- Correct Answer: A
- Explanation: Concentrated nitric acid gives picric acid.
Q6. What is the product of the reaction of phenol with
Did you understand this topic?
Your answer is saved with your learning record. It does not mark the topic as mastered.
Quick revision
Revision Zone
10.4 Reactions of Phenol
Sticky Notes · Quick Revision
Key Point 1
- Phenol + NaOH → Sodium phenoxide + water.
Key Point 2
- Phenol + Na → Sodium phenoxide + H_2.
Key Point 3
- Phenol + Br2 water → 2,4,6-tribromophenol (white precipitate).
Key Point 4
- Phenol + dilute HNO3 → o-/p-nitrophenol.
Key Point 5
- Phenol + conc. HNO3 → Picric acid (2,4,6-trinitrophenol).
Key Point 6
- Phenol + diazonium salt → Azo dye (yellow-orange).
Key Point 7
- -OH is activating, ortho/para-directing.
Key Point 8
- Phenoxide ion is more reactive than phenol.
Same supplied content as this Notes page (shared canonical source).