Question

What will be the product of the following reaction:
 $ 2{\text{ }}{{\text{C}}_6}{{\text{H}}_5} - X{\text{ + 2 Na }}\xrightarrow{{dry{\text{ ether}}}}{\text{ A + 2 NaX}} $
 $ (i){\text{ }}{{\text{C}}_6}{{\text{H}}_5} - Cl $
 $ (ii){\text{ }}{{\text{C}}_{12}}{{\text{H}}_{10}} $
 $ (iii){\text{ }}{{\text{C}}_6}{{\text{H}}_5} - {C_6}{H_5} $
 $ (iv){\text{ }}{{\text{C}}_6}{{\text{H}}_5} - Na $

Answer 1

Hint: When two moles of an alkyl halide are made to react with sodium metal in the presence of dry ether then the product formed is the coupled product of the alkyl. We get the dimer for this reaction.The dry ether is used as solvent for the reaction.

Complete answer:
Whenever an alkyl halide is made to react with the sodium metal in the presence of the dry ether then the coupling of the alkyl halide takes place. This reaction is also an example of the Wurtz reaction. The reaction proceeds by the mechanism of free radical chain reaction. Since aryl halide is used , this is known as the Wurtz fittig reaction. The reaction takes place in two steps. In the first step formation of free radicals takes place. In the second step these free radicals combine with each other to form a product which is dimer of aryl.
 $ 2{\text{ }}{{\text{C}}_6}{{\text{H}}_5} - X{\text{ + 2 Na }}\xrightarrow{{dry{\text{ ether}}}}{\text{ }}{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{ - }}{{\text{C}}_{\text{6}}}{{\text{H}}_{\text{5}}}{\text{ + 2 NaX}} $
Thus the product A will be the dimer of phenyl which is known as bi-phenyl. There can be coupling of aryl with alkyl also. The necessary condition is that the halide must be the same. It is one of the oldest name reactions which is still in use for making coupled products.
Therefore, option (C) is correct.

Note:
The metal which is used in the above reaction can be silver, indium and even iron can also be used for this coupling reaction. The solvent must be a dry ether. This is because it is an aprotic solvent. If we use protic solvent then it will donate hydrogen ions which will interfere in the reaction and the coupled product may not be formed.