Gomberg–Bachmann–Hey_reaction
Gomberg–Bachmann reaction
Aryl-aryl coupling reaction via a diazonium salt
The Gomberg–Bachmann reaction, named for the Russian-American chemist Moses Gomberg and the American chemist Werner Emmanuel Bachmann, is an aryl-aryl coupling reaction via a diazonium salt.[1][2][3]
The arene compound (here benzene) is reacted with a diazonium salt in the presence of a base to provide the biaryl through an intermediate aryl radical. For example, p-bromobiphenyl may be prepared from 4-bromoaniline and benzene:[4]
- BrC6H4NH2 + C6H6 → BrC6H4−C6H5
The reaction offers a wide scope for both diazonium component and arene component but yields are generally low following the original procedure (less than 40%), given the many side-reactions of diazonium salts. Several improvements have been suggested. One possibility is to employ diazonium tetrafluoroborates in arene solvent together with a phase-transfer catalyst,[5] another is to use 1-aryl-3,3-dialkyltriazenes.[6]