2050-34-2 4-((2,4-Dihydroxyphenyl)azo)benzenesulphonic acid AI3-08837 Benzenesulfonic acid, 4-((2,4-dihydroxyphenyl)azo)- Benzenesulfonic acid, 4-[(2,4-dihydroxyphenyl)azo]- EINECS 218-087-0