Question

When phenol is distilled with Zn dust, the main product is:
(A) Biphenyl
(B) Benzene
(C) Benzaldehyde
(D) Phenolphthalein

Answer 1

Hint: Zinc dust acts as a reducing agent. Phenol undergoes reduction reaction in presence of zinc dust. Reduction reaction means the addition of electrons or removal of oxygen or addition of hydrogen.

Complete step by step answer:
-We have to find the product when phenol is distilled with Zinc dust.
-Phenol undergoes a reduction reaction when heated with Zinc dust and forms benzene.
-It is one of the vital methods to prepare benzene.

-In the above reaction, initially phenoxide ion is going to form by losing hydrogen.
-The hydrogen ion formed accepts electrons from zinc and converts into hydrogen radical.

-Later the bond between carbon and oxygen breaks and generates phenyl radical, which combines with hydrogen radical and forms Benzene.
-The representation of the above discussion is as follows.

-Therefore when phenol is distilled with Zn dust, the main product is Benzene and zinc oxide also formed as a sub-product.
-Though the yield of benzene in this reaction is very less.

So, the correct option is B.

Additional information:
-Benzene is used as a solvent for different reactions in industries.
-Benzene is a carcinogenic solvent.

Note: Zinc dust at high temperatures acts as an excellent reducing agent. Zinc dust can be used as a reducing agent for the reduction of all aromatic compounds. The oxygen in the ketone functional group also can be replaced with hydrogen by using Zinc.