Question

The reaction of an aromatic halogen compound with an alkyl halide in presence of sodium and ether is called:
A. Wurtz reaction
B. Sandmeyer’s reaction
C. Wurtz-Fittig reaction
D. Kolbe reaction

Answer 1

Hint: It is one of the important methods that can be employed for the laboratory preparation of substituted aromatic compounds. The product formed is an alkane.

Complete Step by Step Solution:
Many of the substitution reactions which do occur when organometallic reagents are used as nucleophiles proceed with only moderate yields. The coupling of haloalkanes in the presence of an active metal is known as the Wurtz reaction. The reaction is usually accomplished by adding sodium metal to an organohalogen compound in an inert solvent. The organosodium compound which forms combines with an unreacted haloalkane.

The general equation of Wurtz reaction is as shown below:
\[{\rm{R}} - {\rm{X}} + 2{\rm{Na}} + {\rm{X}} - {\rm{R}} \xrightarrow[ether]{dry} {\rm{R}} - {\rm{R}} + {\rm{2NaX}}\];
where \[{\rm{R}}\]= alkyl group
\[{\rm{X}}\]= halogen atom
Hence, option (A) is incorrect.

In Sandmeyer’s reaction, benzene diazonium chloride is treated with cuprous halide \[{\rm{(C}}{{\rm{u}}_{\rm{2}}}{\rm{C}}{{\rm{l}}_{\rm{2}}}\,\,{\rm{or}}\,\,{\rm{C}}{{\rm{u}}_{\rm{2}}}{\rm{B}}{{\rm{r}}_{\rm{2}}}{\rm{)}}\]. Iodobenzene is obtained by treating it with potassium iodide \[{\rm{(KI)}}\]. Hence, option (B) is incorrect.
In the Wurtz-Fittig reaction, an alkyl halide and a solution of an aryl halide (aromatic halogen) in ether is made to react with sodium.

Image: reaction of an aromatic halogen (chlorobenzene) with alkyl halide (chloromethane) in presence of sodium and ether.
Hence, option (C) is correct.

In Kolbe’s reaction, sodium phenoxide on heating to \[{\rm{400}}\,\,{\rm{K}}\]with \[{\rm{C}}{{\rm{O}}_2}\]under pressure \[{\rm{(6 - 7}}\,\,{\rm{atm)}}\]yields sodium salicylate. This acidification gives salicylic acid. Hence, option (D) is incorrect.
Hence, the two alkyl halides are 2-chloropropane and chloromethane.
Therefore, option C is correct.

Note: Wurtz-Fittig reaction is named after Wilhelm Rudolph Fittig and Charles Adolphe Wurtz. Wurtz-Fittig reaction is used in the laboratory for the preparation of organosilicon compounds and many substituted aromatic compounds.