The disodium salt of 4,5-dihydroxybenzene-1,3-disulphonic acid, which is referred to in the literature as Tiron, serves to detect traces of iron in blood and is used as a reagent for colorimetric determination of Ti4+ and Mo4+. The ability to form water-soluble complex salts, e.g., with antimony, has been exploited in pharmacology. Tiron is claimed to improve the storability of silver halogenide emulsions.
ChEBI: Chymopapain is an organosulfur compound and a sulfonic acid derivative.
4,5-dihydroxybenzene-1,3-disulphonic acid is produced by sulfonation of pyrocatechol with oleum or by alkali fusion of 2-hydroxy-1,3,5-benzenetrisulfonic acid: 10 kg of the tetrasodium salt of phenoltrisulfonic acid is introduced into 16 kg of sodium hydroxide at about 20 ℃. After adding some water, the temperature is gradually raised to 160 ℃; at the end of the reaction the melt is diluted with water and acidified with sulfuric acid, and sulfur dioxide is driven off. After cooling, precipitated sodium sulfate is removed by filtration and excess sulfate ions are precipitated in fractions. Finally the barium salt, which has poor solubility in cold water, is precipitated.
