 Numerous sulfonic acid derivatives of 2-naphthylamine are used in commerce, such as precursors to dyes.Owing to the carcinogenicity of the amine, these derivatives are mainly prepared by amination of the corresponding naphthols.Of them, the δ-acid and Bronner's acid are of more value technically, since they combine with "ortho"-tetrazoditolyl to produce fine red dye-stuffs.