Diiodosyl sulfate explained

Diiodosyl sulfate is an inorganic compound, a basic salt of iodine and sulfuric acid with the formula (IO)₂SO₄. It forms yellow crystals.^[1]

Synthesis

Reaction of iodic and sulfuric acids :

2 HIO₃ + H₂SO₄ → (IO)₂SO₄ + O₂ + 2 H₂O

Passing ozonized oxygen through a solution of iodine in sulfuric acid:

I₂ + 3 O₃ + H₂SO₄ → (IO)₂SO₄ + 3 O₂ + H₂O

Physical properties

Diiodosyl sulfate forms yellow hygroscopic crystals and is poorly soluble in cold water.^[2]

It dissolves in and can be recrystallized from concentrated sulfuric acid.

Chemical properties

Under the influence of atmospheric moisture, diiodosyl sulfate hydrolyzes with the release of iodine, iodic and sulfuric acids.

It decomposes when heated:^[3]

4(IO) ₂ SO ₄ → 2I₂O₅ + 2I₂ + 4SO₃ + O₂

It reacts with sulfur(VI) oxide:^[4]

(IO)₂SO₄ + 2SO₃ → I₂(SO₄)₃

With concentrated sulfuric acid, it forms an acidic salt:

(IO)₂SO₄ + H₂SO₄ → 2 IOHSO₄

Notes and References

1. Cations and Oxy Cations of Iodine. II. Solutions of Iodosyl Sulfate, Iodine Dioxide, and Iodic Acid-Iodine Mixtures in Sulfuric Acid and Dilute Oleum. R. J.. Gillespie. J. B.. Senior. July 5, 1964. Inorganic Chemistry. 3. 7. 972–977. CrossRef. 10.1021/ic50017a010.
2. Chemistry of inorganic sulfonates and sulfates of polyvalent iodine. Russian Chemical Reviews 66. 1997.
3. 670. Iodine oxygen compounds. Part II. Iodosyl and related compounds. W. E.. Dasent. T. C.. Waddington. January 1, 1960. Journal of the Chemical Society (Resumed). 3350–3356. pubs.rsc.org. 10.1039/JR9600003350.
4. Argument . Cyril . 1944 . The iodous sulphates . Durham theses. Durham University . p. 22.