Process for the preparation of 2-aminobenzene-1,4-disulphonic acids and the new compound 6-chloro-2-aminobenzene-1,4-disulphonic acid

A Process for the preparation of an 2-aminobenzene-1,4-disulphonic acid of the formula (I) ##STR5## in which X represents hydrogen or chlorine,

• in which a 4-chloro-3-nitrobenzene-sulphonic acid of the formula (II) ##STR6## in which X represents hydrogen or chlorine,
• is reacted with sodium sulphite in an aqueous alkaline medium and then reduced with iron, in which process the reaction with sodium sulphite is carried out at 40.degree. to 90.degree. C., no intermediate isolation is carried out before the reduction with iron and the 2-aminobenzene-1,4-disulphonic acid of the formula (I) is isolated after filtering off the iron oxide, after a pH of <1 has been established in the filtrate at 70.degree. to 90.degree. C. using mineral acid and after the filtrate has been cooled.