How is 2,2'-Disulfanediyldianiline (CAS: 1141-88-4) typically synthesized?

2,2'-Disulfanediyldianiline (CAS: 1141-88-4) is typically synthesized through the reaction of aniline with sulfur dioxide in the presence of a catalyst, such as aluminum chloride or aluminum sulfate. The reaction involves the sulfonation of aniline followed by coupling, leading to the formation of the disulfide aniline derivative. The yield and selectivity can be improved by optimizing reaction conditions, such as temperature, concentration, and catalyst choice.