H acid → 2-Aminobenzenesulfonic acid

Participants

Reaction Steps

12.8 g of 1-amino-8-hydroxynaphthalene-3,6-disulphonic acid in 200 ml of water are subjected to a condensation reaction with 3.8 ml of cyanuric fluoride at pH 4.0-4.5 and at 0°-5° as described in Example 3. 7.0 g of 4-aminobenzenesulphonic acid are added to the resulting solution and the pH value in the reaction mixture is kept at 5.5-6.0. The mixture is subsequently stirred at 0°-5° for one hour. A diazonium salt suspension which has been obtained from 7.0 g of 2-aminobenzenesulphonic acid in 100 ml of water and 20 ml of concentrated hydrochloric acid with 20 ml of 2N sodium nitrite solution at 0°-5° is then allowed to run in and the pH value is kept at 7.0-7.5 and the temperature at 0°-10° for the coupling. Finally, the temperature is increased to 20° in the course of 1 hour. After the coupling has ended, the dyestuff is salted out by adding 100 g of sodium chloride, filtered off and washed with 20% strength sodium chloride solution until the runnings are almost colourless. The dyestuff, which, in the form of the free acid, corresponds to the formula ##STR25## is dried at 40° in vacuo.

Provenance & Evidence