4-(4,5-Dihydro-4-((5-hydroxy-3-methyl-1-(4-sulphophenyl)-1H-pyrazol-4-yl)methylene)-3-methyl-5-oxo-1H-pyrazol-1-yl)benzenesulphonic acid, compound with pyridine (1:2) 95008-99-4 EINECS 305-726-4