Organic Chemistry Questions and Answers – Preparation of Phenols

This set of Organic Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “Preparation of Phenols”.

1. On heating aqueous solution of benzene diazonium chloride, which of the following is formed?
a) benzene
b) chlorobenzene
c) phenol
d) aniline
View Answer

Answer: c
Explanation: Upon warming with water, these diazonium salts finally hydrolyze to phenols.
Following formed is phenol on heating aqueous solution of benzene diazonium chloride

2. Sodium benzene sulphonate reacts with NaOH and then on acidic hydrolysis, it gives which of the following compound?
a) Phenol
b) Benzoic acid
c) Benzene
d) Disodium benzaldehyde
View Answer

Answer: a
Explanation: Sodium benzene sulphonate reacts with NaOH and then on acidic hydrolysis, phenol.
Following is Phenol for sodium benzene sulphonate reacts with NaOH & acidic hydrolysis

3. What is the commercial method of preparation of phenol?
a) Dows process
b) From diazonium salt
c) By decarboxylation of salicylic acid
d) Hock method
View Answer

Answer: d
Explanation: The Hock process (cumene-phenol process, cumene process) is an industrial process for developing phenol and acetone from benzene and propylene. The term stems from cumene (isopropyl benzene), the intermediate material during the process.
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4. Reaction of aqueous sodium hydroxide on chlorobenzene gives which of the following products?
a) o-chlorophenol
b) o-chlorophenol
c) phenol
d) no reaction
View Answer

Answer: c
Explanation: Chlorobenzene does not undergo hydrolysis under normal conditions. However, it undergoes hydrolysis when heated in an aqueous sodium hydroxide solution at a temperature of 623 K and a pressure of 300 atm to form phenol.

5. What will be the product ‘a’ for the given reaction?
Find the product ‘a’ for the given reaction ethers
a)The product ‘a’ for the given reaction ethers - option a
b) The product ‘a’ for the given reaction ethers - option b
c) The product ‘a’ for the given reaction ethers - option c
d) The product ‘a’ for the given reaction ethers - option d
View Answer

Answer: c
Explanation: When ethers are treated with strong acid in the presence of a nucleophile, they can be cleaved to give alcohols and alkyl halides.
When ethers are treated with acid in presence of nucleophile cleaved to give alcohols
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6. What is the reagent which will react with cumene to give phenol?
a) Oxygen
b) Hydrogen
c) Nitrogen
d) Ozone
View Answer

Answer: a
Explanation: Upon oxidation of cumene (isopropylbenzene) in presence of air (oxygen), cumene hydroperoxide is obtained. Upon further treatment of cumene hydroperoxide with dilute acid phenols are obtained.The treatment of cumene hydroperoxide with dilute acid phenols are obtained

7. What will be the product ‘a’ in the given reation?
The product ‘a’ in the given reation is Benzene diazonium chloride
a) Enolate form
b) Benzene diazonium chloride
c) Benzene
d) Chlorobenzene
View Answer

Answer: b
Explanation: When an aromatic primary amine is treated with nitrous (NaNO2 + HCl) acid at 273 – 278 K, diazonium salts are obtained. Upon warming with water, these diazonium salts finally hydrolyze to phenols.
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8. What is the reactant ‘x’ and ‘y’ that will react with benzene to give phenol?
a) X is Oleum and y is molten sodium hydroxide followed by H+
b) X is Oleum and y is HCl
c) X is Oleum and y is NH3
d) X is Oleum and y is water
View Answer

Answer: a
Explanation: Benzenesulphonic acid can be obtained from benzene by reacting it with oleum. Benzenesulphonic acid thus formed is treated with molten sodium hydroxide at high temperature which leads to the formation of sodium phenoxide. Finally, sodium phenoxide on acidification gives phenols.
Reactant ‘x’ & ‘y’ react with benzene to give phenol is Oleum & sodium hydroxide

9. Which of the following is not a method for preparation of phenol?
a) Dows process
b) From diazonium salt
c) By decarboxylation of salicylic acid
d) By the decarboxylation of sodium benzoate
View Answer

Answer: d
Explanation: The decarboxylation of sodium benzoate is not the method of preparation of phenol, this method is used for the preparation of benezene.
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10. Phenol is obtained by heating aqueous solution of which of the following?
a) Aniline
b) Benzene diazonium chloride
c) Benzoic acid
d) Benzyl alcohol
View Answer

Answer: b
Explanation: Upon warming with water, these diazonium salts finally hydrolyze to phenols.
Phenol is obtained by heating aqueous solution is Benzene diazonium chloride

Sanfoundry Global Education & Learning Series – Organic Chemistry.

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If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]

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