3-Aminobenzenesulfonic acid → 2-Amino-1,5-naphthalenedisulfonic acid

Participants

Reaction Steps

31.9 g of 2-amino-5-hydroxynaphthalene-1,7-disulphonic acid are dissolved in 400 ml of water under neutral conditions. 300 g of ice are then added, and 8.8 ml of trifluorotriazine are run in while maintaining a pH of 4.0 to 4.5 with 15% strength sodium carbonate solution. Stirring is continued for 5 minutes, and a neutral solution of 17.3 g of m-sulphanilic acid is then added while maintaining a pH of 5.0 to 5.5 with 15% strength sodium carbonate solution. During acylation, the temperature is allowed to rise to 15° to 20°. A diazo compound obtained in the usual manner by diazotisation of 30.3 g of 2-aminonaphthalene-1,5-disulphonic acid is added to the resulting solution of the reaction product of the formula ##STR15## at 5° to 10°, while simultaneously maintaining the pH at 7.0 to 7.5 by sprinkling in sodium bicarbonate. After coupling is complete, the dyestuff of the formula ##STR16## is salted out, filtered off with suction, dried and milled.

Provenance & Evidence