Gomberg–Bachmann reaction

Gomberg–Bachmann reaction is a notable chemical reaction named after the chemists Moses Gomberg and Werner Bachmann, who first reported it in 1924. This reaction involves the arylation of aryl diazonium salts with aryl halides in the presence of a base. It is a pivotal method for the synthesis of biaryl compounds, which are a fundamental structural unit in many pharmaceuticals, natural products, and advanced materials.

Mechanism

The Gomberg–Bachmann reaction proceeds through a radical mechanism. Initially, the aryl diazonium salt reacts with the base to form a diazo compound, which decomposes to generate an aryl radical. This radical then attacks the aryl halide, forming a new carbon-carbon bond and yielding a radical halide. Finally, the radical halide abstracts a hydrogen atom from another molecule, regenerating the base and forming the biaryl product.

Scope and Limitations

The scope of the Gomberg–Bachmann reaction is broad, encompassing various aryl halides and diazonium salts. However, the reaction conditions need to be carefully optimized for each specific substrate to achieve high yields and selectivities. The major limitation of this reaction is its tendency to produce mixtures of products due to the high reactivity of the aryl radicals, which can lead to side reactions such as homocoupling.

Applications

The Gomberg–Bachmann reaction has been widely applied in the synthesis of complex organic molecules, including natural products, pharmaceuticals, and polymers. Its ability to form carbon-carbon bonds efficiently and selectively makes it a valuable tool in the field of organic synthesis.

Related Reactions

• Ullmann reaction
• Suzuki coupling
• Heck reaction

See Also

• Biaryl
• Radical (chemistry)
• Aryl halide
• Diazonium compound