* In Wurtz reaction, two alkyl halide molecules are coupled in presence of sodium metal in anhydrous ether or tetrahydrofuran to form a new carbon carbon bond and thus by giving a symmetrical alkane.
| Dry Ether | |
| R-X + 2Na + X-R | -----------------> | R-R + 2NaX |
| | |
Where X = halogen
* The Wurtz reaction must be performed under anhydrous conditions because the alkyl free radical formed (see the mechanism) during the reaction is strongly basic and can abstract proton from water.
* In case of alkyl and aryl fluorides as well as aryl chlorides, tetrahydrofuran is used as solvent instead of ether.
* The Wurtz reaction is limited to synthesis of symmetrical alkanes with even number of carbon atoms only. The number of carbons in the alkane is double that of alkyl halide (n ---> 2n type reaction)
* If dissimilar alky halides are used, a mixture of alkanes is formed. It is usually difficult to separate the mixture and hence wurtz reaction not a suitable method to synthesize unsymmetrical alkanes.
E.g. The Wurtz reaction between R-X and R'-X yields not only R-R' but also R-R and R'-R'. This mixture cannot be separated easily.
* Methane cannot be prepared by this method.
* A modification of this reaction involving alkyl and aryl halides is called
Wurtz-Fittig reaction. If only aryl halides are subjected to coupling, the reaction is called as
Fittig reaction.
