In order to convert Aniline into chlorobenzene, the reagents needed are:
(A) CuCl
(B) $N a N O_{2} / H C l$ and CuCl
(C) $C l_{2} / C C l_{4}$
(D) $C l_{2} / A l C l_{3}$

Answer

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Hint: This conversion can be brought by Sandmayer reaction. Here, we will also need to substitute the amino group from the ring by chlorine. So, whatever reagent we add during this reaction, should react with amino functional groups.

Complete Step-by-Step Solution:
- To convert Aniline into Chlorobenzene, we will need to remove the amino group and add chlorine atom to obtain chlorobenzene. There is only one reaction available that does this conversion.
- The name of this reaction is Sandmayer’s reaction. Let’s see the reaction to see the product obtained.

Sodium nitrite and hydrochloric acid react with aniline to form diazonium salt. Now, if this diazonium salt is allowed to react with CuCl, then it will replace the diazonium group on the aromatic ring and will give Chlorobenzene as a product.
- If we make aniline to react with just CuCl, then this reaction will not occur because diazonium salt will not be formed.
-

C l_{2} / C C l_{4}

is a reagent that substitutes chlorine atoms in place of hydrogen atoms of alkyl groups.
- If we will react

C l_{2} / A l C l_{3}

with aniline, then it will undergo Friedal-crafts reaction to give both amino and chlorine on the aromatic ring.
Hence, correct answer is (B)

N a N O_{2} / H C l

and CuCl

Additional Information:
- Many products can be obtained by reaction with diazonium salts. Below are some of them.
- If we add CuBr to diazonium salt then Bromobenzene will be the product.
- If CuCN is added then Cyanobenzene will be the product.
- If Water is added, then Phenol will be the product.
- If Hypophosphorous acid is added then, benzene will be the product.

Note: Remember that diazonium salt only gets converted to chlorobenzene when it is allowed to react with CuCl, so formation of diazonium salt is necessary. Do not get confused with