3-Aminobenzenesulfonic acid → 2-Amino-5-methoxybenzenesulfonic acid

Beteiligte Stoffe

Reaktionsschritte

31.9 g of 2-amino-5-hydroxy-naphthalene-1,7-disulphonic acid are dissolved in 400 ml of water to give a neutral solution. 300 g of ice are then added, and 8.8 ml of trifluorotriazine are allowed to run in, a pH of 4.0-4.5 being maintained with 15% strength sodium carbonate solution. The mixture is subsequently stirred for 5 minutes, a neutral solution of 17.3 g of m-sulphanilic acid is then added, and a pH of 5.0-5.5 is maintained with 15% strength sodium carbonate solution. During the acylation, the temperature is allowed to rise to 15°-20°. A diazo compound obtained by the customary route by diazotisation of 20.3 g of 1-amino-4-methoxy-benzene-2-sulphonic acid is added to the resulting solution of the reaction product of the formula ##STR17## at 5°-10°, the pH simultaneously being kept at pH 7.0-7.5 by sprinkling in sodium bicarbonate. When the coupling has ended, the dyestuff of the formula ##STR18## is salted out, filtered off with suction, dried and ground. The red dyestuff powder dissolves readily in water and dyes cotton a clear scarlet (colour code number 6) by a process customary for reactive dyestuffs.

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