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.