Magnesium iodide explained

Magnesium iodide is an inorganic compound with the chemical formula . It forms various hydrates . Magnesium iodide is a salt of magnesium and hydrogen iodide. These salts are typical ionic halides, being highly soluble in water.

Uses

Magnesium iodide has few commercial uses, but can be used to prepare compounds for organic synthesis.

Preparation

Magnesium iodide can be prepared from magnesium oxide, magnesium hydroxide, and magnesium carbonate by treatment with hydroiodic acid:

Reactions

Magnesium iodide is stable at high heat under a hydrogen atmosphere, but decomposes in air at normal temperatures, turning brown from the release of elemental iodine. When heated in air, it decomposes completely to magnesium oxide.[1]

Another method to prepare is mixing powdered elemental iodine and magnesium metal. In order to obtain anhydrous, the reaction should be conducted in a strictly anhydrous atmosphere; dry-diethyl ether can be used as a solvent.

Usage of magnesium iodide in the Baylis-Hillman reaction tends to give (Z)-vinyl compounds.

Demethylation of certain aromatic methyl ethers can be afforded using magnesium iodide in diethyl ether.[2]

Hydrates

Two hydrates are known, the octahydrate and the nonahydrate, both verified by X-ray crystallography These hydrates feature [Mg(H<sub>2</sub>O)<sub>6</sub>]2+ ions.[3]

References

  1. N. T. M.. Wilsmore. 1891. Note on Magnesium Iodide. Report of the Third Meeting of the Australasian Association for the Advancement of Science. James Hector. The Association. Sydney. 116. 2007-12-09.
  2. Yamaguchi . Seiji . Nedachi . Masahiro . Yokoyama . Hajime . Hirai . Yoshiro . Regioselective demethylation of 2,6-dimethoxybenzaldehydes with magnesium iodide etherate . Tetrahedron Letters . October 1999 . 40 . 41 . 7363–7365 . 10.1016/S0040-4039(99)01411-2.
  3. 10.1107/S0108270113028138 . Crystal Structures of Hydrates of Simple Inorganic Salts. I. Water-Rich Magnesium Halide Hydrates MgCl2·8H2O, MgCl2·12H2O, MgBr2·6H2O, MgBr2·9H2O, MgI2·8H2O and MgI2·9H2O . 2013 . Hennings . Erik . Schmidt . Horst . Voigt . Wolfgang . Acta Crystallographica Section C Crystal Structure Communications . 69 . 11 . 1292–1300 . 24192174 .