Question

The solvent used in Wurtz reaction is:
a) \[{{C}_{2}}{{H}_{5}}OH\]
b) \[C{{H}_{3}}COOH\]
c) \[{{H}_{2}}O\]
d) \[{{C}_{2}}{{H}_{5}}O{{C}_{2}}{{H}_{5}}\,(dry)\]

Answer 1

Hint: Wurtz reaction is named after Alsatian French chemist Charles Adolphe Wurtz. It is a coupling reaction having its uses in organic chemistry, organometallic chemistry and recently inorganic main group polymers.

Complete step by step answer:
An organic chemical coupling reaction where alkyl halides on treatment with sodium metal in dry ethereal (free from moisture) solution give higher alkanes. This reaction is known as Wurtz reaction and is used for the preparation of higher alkanes containing even numbers of carbon atoms. Let’s see the mechanism of this reaction.

First, transfer of single-electron from Na to the halogen atom occurs which leads to the formation of an alkyl radical R and sodium halide.
\[\text{R-X + Na }\to \text{ R}^{\bullet} \text{ + N}{{\text{a}}^{+}}{{\text{X}}^{-}}\]

Now, the alkyl radical forms acts as an electron acceptor from another Na atom and results in formation of a highly nucleophilic intermediate.
\[\text{R}^{\bullet} \text{ + Na }\to \text{ R-N}{{\text{a}}^{+}}\]

Finally, a \[S{{N}^{2}}\] reaction takes place, this alkyl sodium intermediate reacts with another alkyl halide in the aliphatic nucleophilic substitution:
\[\text{R-N}{{\text{a}}^{+}}\text{ + R-X }\to \text{ R-R + N}{{\text{a}}^{+}}{{\text{X}}^{-}}\]

Since, sodium is used in the reaction, which is a highly reactive metal, selection of the solvent is done in such a way that the sodium metal does not react with the solvent and dry ether is a very good poly aprotic solvent. Hence, it is used in the Wurtz-Fittig reaction.

So, the correct option is (d).

Note: There is another variation of this reaction called the Wurtz-Fittig reaction. It is a modification in the Wurtz reaction that involves alkyl and aryl halides.