Reaction of sulfur and iodine The first attempt and claim to produce a sulfur iodide were made in 1813 by
Bernard Courtois when exploring the properties of his newly discovered element, iodine. He reacted to sulfur and iodine, claiming they had made a compound. However, this production was doubted by
Gay-Lussac. Between 1827 and 1896, more attempts were made to make sulfur iodide by combining the elements; however, all were inconclusive on the existence of the compound or failed. Later, when
thermal analysis was developed, it was shown that when the elements were combined, it only resulted in a mixture, not a compound.
Production by double replacement When attempts to produce sulfur iodide by the direct combination of the elements failed to overcome the low thermodynamic stability of the compound, production by double replacement was attempted between 1833 and 1886. Some reactions that were attempted was the reaction of
disulfur dichloride and
hydroiodic acid:
Isolation Disulfur diiodide was first isolated by the reaction of disulfur dichloride and potassium iodide,
sodium iodide, or hydrogen iodide in
pentane at −90 °C, and verified by
infrared spectroscopy. ==Properties==