Baddeley isomerization

What is Baddeley isomerization?

The Baddeley reaction, first reported in the 1930s by Baddeley, involves the migration of alkyl groups in polyalkylbenzenes or polynuclear aromatic compounds in the presence of anhydrous aluminum chloride, AlCl3, or a mixture of protonic acid and Lewis acid. During one of Baddeley’s experiments, 1,3,4-tri-n-propylbenzene was heated with AlCl3 at 100 °C, resulting in the formation of 1,3,5-tri-n-propylbenzene, along with lower and higher alkylated benzenes.

Baddeley Isomerization - AlCl3 aluminum chloride
Baddeley isomerization (1,2,4-tri-n-propylbenzene into

Further studies revealed that the amount of α-isomer could be decreased by adding various substances, such as nitrobenzene and excess acid chloride, to the reaction mixture that strongly complex with aluminum chloride. Moreover, carrying out the reaction in nitrobenzene has been found to result in less α-isomer formation. Additionally, if hindered aromatic ketones are melted with an excess amount of aluminum chloride AlCl3 and sodium chloride NaCl, isomerization occurs.