CHEMICAL PROPERTIES AND USES OF PHENOLS ASSIGNMENT

QUESTIONS

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

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

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

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

5. What will be the product ‘a’ for the given reaction?

a)
b)
c)
d)

6. What is the reagent which will react with cumene to give phenol?
a) Oxygen
b) Hydrogen
c) Nitrogen
d) Ozone

7. What will be the product ‘a’ in the given reation?

a) Enolate form
b) Benzene diazonium chloride
c) Benzene
d) Chlorobenzene

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

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

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

ANSWERS 

1. Answer: c
   Explanation: Upon warming with water, these diazonium salts finally hydrolyze to phenols.
2. Answer: a
   Explanation: Sodium benzene sulphonate reacts with NaOH and then on acidic hydrolysis, phenol.
3. 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.
4. 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. 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.
6. 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.
7. 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.
8. 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.
9. 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.
10. Answer: b
    Explanation: Upon warming with water, these diazonium salts finally hydrolyze to phenols.