1: 2-amino-5-hydroxy-naphthalene-7-sulphonic acid With hydrogenchloride; sodium carbonate; sodium nitrite in water T=0 - 5°C; 1 h; 2: 2-amino-5-hydroxy-naphthalene-7-sulphonic acid in water T=0 - 5°C; pH=8 - 9; 2 h;