Question

Benzene is passed through $$Na$$ in $$N{H}_3$$ solution then the major product was passed through ozone and $$Zn-H_{2}O$$ solution then the product of it was passed through $$Zn-Hg$$ in $$Conc.HCl$$ solution to give a product. What and how is the product formed?

Answer 1

Hint: Benzene is an aromatic compound and when reacted with sodium in ammonia undergo reduction to form $$1,4$$ cyclohexadiene. When this compound passes through ozone and $$Zn-H_{2}O$$ solution forms an aldehyde compound. When aldehyde is passed through $$Zn-Hg$$ in $$Conc.HCl$$ solution forms propane.

Complete answer:
Given that benzene is passed through $$Na$$ in $$N{H}_3$$ solution. The reaction is named as Birch reduction. Aromatic compound when passed through $$Na$$ in $$N{H}_3$$ solution undergoes reduction to form a $$1,4$$ cyclohexadiene.
The chemical reaction involved will be as follows-

When this $$1,4$$ cyclohexadiene is passed through ozone and $$Zn-H_{2}O$$ solution the double bond will converts into carbonyl group forms two molecules of dialdehyde compound named as $$1,3-propane-di-al$$. Two moles of dialdehyde compound form in this reaction.
The chemical reaction involved will be as follows-

Later, $$1,3-propane-di-al$$ passed through $$Zn-Hg$$ in $$Conc.HCl$$ solution undergoes clemmensen reduction to form alkanes. Carbonyl group converts into alkane in clemmensen reduction. Two molecules of $$1,3-propane-di-al$$ convert into two molecules of propane.
The chemical reaction involved will be as follows:

Thus, Benzene is passed through $$Na$$ in $$N{H}_3$$ solution then the major product was passed through ozone and $$Zn-H_{2}O$$ solution then the product of it was passed through $$Zn-Hg$$ in $$Conc.HCl$$ solution to give a product. The product is propane.

Note:
Birch reduction can occur in two types based on the group present on the aromatic ring. When there is a presence of an electron releasing group then the reduction takes place at $$2,5$$ positions. When there is a presence of an electron withdrawing group then the reduction takes place at $$1,4$$ positions.