4-((4,7,7-Trimethyl-3-oxo-bicyclo(2.2.2)hept-2-ylidene)methyl)benzenesulfonic acid 4-((4,7,7-Trimethyl-3-oxobicyclo(2.2.1)hept-2-ylidene)methyl)benzenesulfonic acid 56039-58-8 Benzenesulfonic acid, 4-((4,7,7-trimethyl-3-oxobicyclo(2.2.1)hept-2-ylidene)methyl)-