Question

Cumene on reaction with oxygen followed by hydrolysis gives?
A) \[{\text{C}}{{\text{H}}_3}{\text{OH and }}{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{COC}}{{\text{H}}_3}\]
B) \[{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OH and }}{\left( {{\text{C}}{{\text{H}}_3}} \right)_2}{\text{O}}\]
C) \[{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OC}}{{\text{H}}_3}{\text{ and C}}{{\text{H}}_3}{\text{OH}}\]
D) \[{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OH and C}}{{\text{H}}_3}{\text{COC}}{{\text{H}}_3}\]

Answer 1

Hint: In this reaction a new bond is formed between oxygen atom and aromatic carbon atom. Also a bond between aliphatic carbon atom and the aromatic carbon atom is broken.

Complete answer:
Cumene is isopropyl benzene. Isopropyl group is \[{\left( {{\text{C}}{{\text{H}}_3}} \right)_2}{\text{CH}} - \] group. The Isopropyl group is directly attached to the phenyl ring. The chemical formula of cumene is \[{{\text{C}}_6}{{\text{H}}_5} - {\text{CH}}{\left( {{\text{C}}{{\text{H}}_3}} \right)_2}\].
Write the structure of cumene as shown below:

Cumene is oxidised in presence of oxygen to form cumenehydroperxide. Write the reaction for the oxidation of cumene to form cumene hydroperoxide.

In presence of dilute aqueous acids, cumene hydroperoxide undergoes hydrolysis to form a mixture of phenol and acetone. Write the reaction for the conversion of cumene hydroperoxide to phenol and acetone.

The end products of two step processes are phenol and acetone. The molecular formula of phenol and acetone are \[{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OH and C}}{{\text{H}}_3}{\text{COC}}{{\text{H}}_3}\] respectively.

Hence, the correct option is the option \[{\text{D ) }}{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{OH and C}}{{\text{H}}_3}{\text{COC}}{{\text{H}}_3}{\text{ }}\].

Additional Information Cumene is prepared by Friedel Crafts alkylation of benzene with n propyl benzene. The product is isopropyl benzene and not n propyl benzene because the intermediate carbocation undergoes rearrangement. This rearrangement occurs because secondary carbocation is more stable than primary carbocation.

Note: Air oxidation of cumene followed by acid hydrolysis to obtain phenol is an industrial method for the preparation of phenol. Phenol thus obtained also contains acetone by product. Hence, additional purification methods are necessary.