Question

Name the catalyst used in the commercial method of preparation of phenol.
(A) Silica
(B) Calcium phosphate
(C) Anhydrous aluminium chloride
(D) Cobalt naphthenate

Answer 1

As we know that catalyst is a substance which enables a chemical reaction to proceed at a faster rate or maybe under different conditions than otherwise possible such as at a lower temperature. These chemicals are not consumed during the catalyzed reaction but can act repeatedly. So here we have to talk about the catalyst which is used in the preparation of phenol.

Complete answer:
Let us discuss about catalyst as follows:-
Catalyst: These are the substances which enable a chemical reaction to proceed at a faster rate or maybe under different conditions than otherwise possible such as at a lower temperature. Generally very small amounts of catalyst are required during a chemical reaction. These chemicals are not consumed during the catalyzed reaction but can act repeatedly.
-Preparation of phenol: Phenol is prepared by various methods. One of the methods is aerial oxidation of cumene in the presence of a catalyst. The synthesis is shown below:-
(a) Use of Cobalt naphthenate:-

Cumene which is also known as isopropyl benzene is first oxidized in the presence of air to form cumene hydroperoxide. This is done with the help of Cobalt naphthenate at alkaline medium and at a temperature of 473 Kelvin.
-Reaction of cumene hydroperoxide with dilute sulphuric acid:-

Cumene hydroperoxide is now treated with dilute sulphuric acid and this is performed along with the supply of heat. It yields phenol along with acetone as by-products.
-Therefore the catalyst used in the commercial method of preparation of phenol is (D) Cobalt naphthenate.

Note:
-Remember that this synthesis of phenol from cumene yields acetone in very large amounts. Therefore phenol prepared by this method requires purification as well.
-Also cumene is generally obtained by Friedel-Crafts alkylation of benzene with propylene.