SEARCH Articles Figures Tables 4- Pyridine sulfonic acid Organic Compounds Pyridine 1-oxide sulfonation Pyridine-2-sulfonic acid metal complexes Pyridine-3-sulfonic acid Pyridine-4-sulfonic acid, sodium salt Pyridine-sulfonic anhydride, adduct Pyridines pyridyl-2-sulfonates Pyridines, acylation sulfonation Pyridine—continued sulfonation Sulfonation of pyridines