Magnesium iodide
Magnesium iodide is the name for the chemical compounds with the formulas MgI2 and its various hydrates MgI2(H2O)x. These salts are typical ionic halides, being highly soluble in water.
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Names | |||
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IUPAC name
Magnesium iodide | |||
Identifiers | |||
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3D model (JSmol) |
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ChemSpider | |||
ECHA InfoCard | 100.030.738 | ||
EC Number |
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PubChem CID |
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UNII | |||
CompTox Dashboard (EPA) |
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Properties | |||
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) | ||
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 | ||
−111.0·10−6 cm3/mol | |||
Structure | |||
Hexagonal (anhydrous) Monoclinic (hexahydrate) Orthorhombic (octahydrate) | |||
Thermochemistry | |||
Heat capacity (C) |
74 J/mol K | ||
Std molar entropy (S |
134 J/mol K | ||
Std enthalpy of formation (ΔfH⦵298) |
-364 kJ/mol | ||
Hazards | |||
GHS pictograms | |||
GHS Signal word | Warning | ||
GHS hazard statements |
H315, H319 | ||
NFPA 704 (fire diamond) | |||
Related compounds | |||
Other anions |
Magnesium fluoride Magnesium bromide Magnesium chloride | ||
Other cations |
beryllium iodide calcium iodide strontium iodide barium iodide | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
Infobox references | |||
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]
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]
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
- 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, Wiley-VCH, p. 59, ISBN 3-527-29060-5, retrieved 2007-12-09