The Wurtz coupling uses sodium metal and two alkyl halides to make a new carbon-carbon bond. First, a metal-halogen exchange forms a carbanion that then attacks the second alkyl halide in SN2 fashion.
- Reagents: Sodium Metal, Solvent (THF, Et2O, Dioxane, Xylenes)
- Reactant: Alkyl Halide
- Product: Alkane
- Type of Reaction: Metal-Catalyzed Coupling Reaction
- Bond Formation: C-C
Lab Tips
- The classical reaction tends to be low yielding because of elimination and rearrangement side reactions. 1
- Better yields are achieved with finely dispersed sodium metal. 1
- Two identical alkyl halides result in a symmetrical alkane. 1
- Distinct alkyl halides result in a (low yield) mixture of both symmetrical and unsymmetrical product. 1
- The order of alkyl halide reactivity is I>>Br>>Cl. Primary alkyl iodides are the best substrates, while secondary alkyl halides should be avoided. 1
- Alkyl halides can also be coupled intramolecularly. 1
- Alkylated aromatic compounds made from alkyl and aryl halides is called the Wurtz-Fittig reaction. 1
- Other metals and various metal complexes have improved yields and suppressed side reactions, including use of Cu, Mn2(CO)10, Li metal/ultrasound, Na(Hg), Na-K alloy, etc. 1, 2, 3, 4, 5, 6
2. Meszaros, L., Soos, K., Sirokman, F. Reactivity of various metal powders and their applicability primarily in Wurtz syntheses. Acta Physica et Chemica 1970, 16, 51-55.
3. Ginah et al. Homocoupling of alkyl halides and cyclization of α,ω-dihaloalkanes via activated copper. J. Org. Chem. 1990, 55, 584-589.
4. Gilbert et al. Efficient radical coupling of organobromides using dimanganese decacarbonyl. Synth. Commun. 1999, 29, 2711-2718.
5. Lash, T. D., Berry, D. Promotion of organic reactions by ultrasound: coupling of alkyl and aryl halides in the presence of lithium metal and ultrasound. J. Chem. Educ. 1985, 62, 85.
6. Craig, A. D., MacDiarmid, A. G. Application of the Wurtz reaction to the synthesis of disilane and 1,2-dimethyldisilane. Journal of Inorganic and Nuclear Chemistry 1962, 24, 161-164.
Mechanism
Top Citations
Original Paper
Related Reactions
- Wurtz-Fittig Reaction
- Synthesis of Alkanes
