Magnesium iodide

Names

IUPAC name

Magnesium iodide

Identifiers

CAS Number

10377-58-9 (anhydrous)^Y
75535-11-4 (hexahydrate)^N
7790-31-0 (octahydrate)^Y

3D model (JSmol)

Interactive image
Interactive image

ChemSpider

59700^N

ECHA InfoCard

100.030.738

EC Number

233-825-1

PubChem CID

66322

UNII

W74QE3H320 (anhydrous)^Y
72I5H6SWMT (octahydrate)^Y

CompTox Dashboard (EPA)

DTXSID6065056

InChI

InChI=1S/2HI.Mg/h2*1H;/q;;+2/p-2^N
Key: BLQJIBCZHWBKSL-UHFFFAOYSA-L^N
InChI=1/2HI.Mg/h2*1H;/q;;+2/p-2
Key: BLQJIBCZHWBKSL-NUQVWONBAV

SMILES

I[Mg]I
[Mg+2].[I-].[I-]

Properties

Chemical formula

MgI₂ (anhydrous)
MgI₂·6H₂O (hexahydrate)
MgI₂·8H₂O (octahydrate)^[1]

Molar mass

278.1139 g/mol (anhydrous)
386.2005 g/mol (hexahydrate)
422.236 g/mol (octahydrate)

Appearance

white crystalline solid

Odor

odorless

Density

4.43 g/cm³ (anhydrous solid)
2.353 g/cm³ (hexahydrate solid)
2.098 g/cm³ (octahydrate solid)

Melting point

637 °C (1,179 °F; 910 K) (anhydrous, decomposes)
41 °C (octahydrate, decomposes)

Solubility in water

54.7 g/(100 cm³) (anhydrous, 0 °C)
148 g/(100 cm³) (anhydrous, 18 °C)^[2]
81 g/(100 cm³) (octahydrate, 20 °C)

Solubility

soluble in ether, alcohol and ammonia

Magnetic susceptibility (χ)

−111.0·10⁻⁶ cm³/mol

Structure

Crystal structure

Hexagonal (anhydrous)
Monoclinic (hexahydrate)
Orthorhombic (octahydrate)

Thermochemistry

Heat capacity (C)

74 J/(mol·K)

Std molar
entropy (S^⦵₂₉₈)

134 J/(mol·K)

Std enthalpy of
formation (Δ_fH^⦵₂₉₈)

−364 kJ/mol

Hazards

GHS labelling:

Pictograms

Signal word

Warning

Hazard statements

H315, H319

NFPA 704 (fire diamond)

COR

Related compounds

Other anions

Other cations

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

N verify (what is ^YN ?)

Infobox references

Chemical compound

Magnesium iodide is an inorganic compound with the chemical formula Mg I₂. It forms various hydrates MgI₂·xH₂O. 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:^[3]

MgO + 2 HI → MgI₂ + H₂O

Mg(OH)₂ + 2 HI → MgI₂ + 2 H₂O

MgCO₃ + 2 HI → MgI₂ + CO₂ + H₂O

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.^[4]

Another method to prepare MgI₂ is mixing powdered elemental iodine and magnesium metal. In order to obtain anhydrous MgI₂, 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.^[5]

Demethylation of certain aromatic methyl ethers can be afforded using magnesium iodide in diethyl ether.^[6]

References

^ Perry, Dale L.; Phillips, Sidney L. (1995), Handbook of Inorganic Compounds, CRC Press, p. 240, ISBN 0-8493-8671-3, retrieved 2007-12-09
^ Magnesium Iodide MSDS at AlfaAesar^{[permanent dead link]}
^ Patnaik, Pradyot (2003), Handbook of Inorganic Chemicals, McGraw-Hill Professional, pp. 527–528, ISBN 0-07-049439-8, retrieved 2007-12-09
^ Wilsmore, N. T. M. (1891). "Note on Magnesium Iodide". In James Hector (ed.). Report of the Third Meeting of the Australasian Association for the Advancement of Science. Sydney: The Association. p. 116. Retrieved 2007-12-09.
^ Tietze, Lutz-Friedjan; Brasche, Gordon; Gericke, Kersten (2006), "Domino Reactions in Organic Synthesis", Chemical Reviews, 96 (1), Wiley-VCH: 115–136, doi:10.1021/cr950027e, ISBN 3-527-29060-5, PMID 11848746, retrieved 2007-12-09
^ Yamaguchi, Seiji; Nedachi, Masahiro; Yokoyama, Hajime; Hirai, Yoshiro (October 1999). "Regioselective demethylation of 2,6-dimethoxybenzaldehydes with magnesium iodide etherate". Tetrahedron Letters. 40 (41): 7363–7365. doi:10.1016/S0040-4039(99)01411-2.