Hypoiodous acid

Hypoiodous acid (HIO) is formed when mercury(II) oxide is shaken with aqueous iodine. It rapidly decomposes by disproportionation:
 * 5HIO → HIO3 + 2I2 + 2H2O

Reactive solutions of hypoiodites (salts of hypoiodous acid) can be prepared by reacting I2 with alkali hydroxides. . They rapidly disproportionate to form iodides and iodates.

In theory, HIO should be a powerful disinfectant as it is the iodine analogue to the hypochlorous acid formed when mixing chlorine with water. HIO is likely the active ingredient responsible for disinfection by iodine solutions used in the medical profession such as betadine or povidone iodine.