The Wurtz reaction, named after French chemist Charles-Adolphe Wurtz, is a coupling reaction widely studied in organic and organometallic chemistry. It is also relevant to polymers of inorganic main group elements. The reaction involves two halogenated hydrocarbons reacting with sodium to produce new C-C bonds, synthesizing longer carbon chains：

Due to various limitations, the Wurtz reaction is rarely used in modern synthetic applications, especially when the target alkanes are easily obtainable from natural sources, such as crude oil, or derivable under mild conditions from fatty acids. However, Wurtz coupling proves particularly useful for forming small molecular rings, notably three-membered rings. For example, dicyclobutane can be synthesized from 1-bromo-3-chlorocyclobutane and sodium, achieving a high yield of 95%.

Additionally, other metals, including iron, silver, and zinc, have been found to participate in the reaction. Variants of the reaction can be catalyzed by indium, copper, manganese, or copper chloride. A related reaction, the Wurtz-Fittig reaction, is used to synthesize halogenated aromatic hydrocarbons. The reaction's chemoselectivity depends on the ease of reduction, with aryl halides being more easily reduced.

Reaction Mechanism

• Electron Transfer: One electron from sodium is transferred to the halogen, producing a sodium halide and an alkyl radical.
• Alkyl Anion Formation: The alkyl radical accepts another electron from sodium, forming a negatively charged alkyl anion, while sodium becomes a cation.
• SN2 Reaction: The alkyl anion displaces the halogen in an SN2 substitution reaction, creating a new C-C bond.

By-products:

The Wurtz reaction is limited to the synthesis of symmetric alkanes. When two different alkane halides react, a mixture of alkanes is produced, often making separation difficult. Side reactions can also generate alkenes, particularly when the reaction involves free radicals. These side reactions become significant when the haloalkane's carbon atoms are highly substituted, as the energy required for the SN2 reaction increases. In such cases, elimination reactions occur more readily.