Phase transfer catalyzed method to prepare symmetrical azobenzenes from anilines

Article abstract of DOI:10.1002/jccs.199900134

Using free radical 4-hydroxy-2,2,6,6-tetramethyl-l-piperidinyolxyl as catalyst, the phase transfer catalyzed method of oxidation of anilines to symmetrical azobenzenes with a saturated solution of potassium ferricyanide in 2N aqueous potassium hydroxide and dichloromethane is described for the first time. The reaction has an intimate relation with Hammett substituent constants. This report offers an efficient and rapid method to prepare azobenzenes, and a possible mechanism is also suggested.