Our interpretation is further reinforced by a comprehensive high-throughput study of the solubility of quinone derivatives . Under strongly acidic conditions, various quinone derivatives were nearly insoluble because of their pK a > pH. These derivatives remain unaffected by chemical reactions and equilibrate with the solvent in their unionized forms. However, their solubility increases dramatically in a strong basic medium, where the -OH and -SO 3 H functional groups undergo deprotonation reactions, resulting in the formation of -O -and -SO - 3 , respectively. In addition to pH and pK a , information regarding supporting electrolytes is another critical property that is currently missing from existing data banks. The presence of additional ions from the supporting electrolyte alters the concentration of free ions with opposite charges and shields interactions between solute ions, which can lead to modifications in solubil-ity . For example, the solubility of 2,2,6,6-tetramethyl-1piperidinyloxy has increased from 0.8 M to 4.8 M through the use of different salts.