1, 4-phenylenediamine-2, 5-disulphonic acid - prodn

摘要

acid, which is a valuable intermediate for the production of reactive azo dyestuffs, is produced by treating p-phenylene-diamine sulphate with steam until two sulphonic acid groups are introduced. The reaction mixture is then cooled, poured into ice water, and the product is separated by filtration, washed with water and dried.