azobenzenes naphthols aromatic ether naphthalenesulfonic acid 4-hydroxy-3-[(2-methoxyphenyl)diazenyl]naphthalene-1-sulfonic acid 0 A naphthalenesulfonic acid that is naphthalene-1-sulfonic acid carrying additional hydroxy and (2-methoxyphenyl)diazenyl substituents at positions 4 and 3 respectively. The sodium salt is the biological stain 'acid red 4'. acid red 4 (free acid form) COc1ccccc1\N=N\c1cc(c2ccccc2c1O)S(O)(=O)=O 358.06234 JRLHFEXLBNGRJO-VHEBQXMUSA-N 4-hydroxy-3-[(2-methoxyphenyl)diazenyl]naphthalene-1-sulfonic acid chebi_ontology InChI=1S/C17H14N2O5S/c1-24-15-9-5-4-8-13(15)18-19-14-10-16(25(21,22)23)11-6-2-3-7-12(11)17(14)20/h2-10,20H,1H3,(H,21,22,23)/b19-18+ Reaxys:7348371 358.36800 C17H14N2O5S CHEBI:87098 4-hydroxy-3-[(2-methoxyphenyl)diazenyl]naphthalene-1-sulfonate