Magnesium iodide

Magnesium iodide
Names
	IUPAC name Magnesium iodide
Identifiers
CAS Number	10377-58-9 (anhydrous) ; 75535-11-4 (hexahydrate) ; 7790-31-0 (octahydrate) ;
3D model (JSmol)	Interactive image; Interactive image;
ChemSpider	59700 ;
ECHA InfoCard	100.030.738
EC Number	233-825-1;
PubChem CID	66322;
UNII	W74QE3H320 (anhydrous) ; 72I5H6SWMT (octahydrate) ;
CompTox Dashboard (EPA)	DTXSID6065056 ;
	InChI InChI=1S/2HI.Mg/h21H;/q;;+2/p-2 Key: BLQJIBCZHWBKSL-UHFFFAOYSA-L ; InChI=1/2HI.Mg/h21H;/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);
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); 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 (ΔfH⦵298)	−364 kJ/mol
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319
NFPA 704 (fire diamond)	3 1 1 COR
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). verify (what is ?) Infobox references

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[edit]

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

Preparation[edit]

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[edit]

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[edit]

^ 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.

[1] Perry, Dale L.; Phillips, Sidney L. (1995), Handbook of Inorganic Compounds, CRC Press, p. 240, ISBN 0-8493-8671-3, retrieved 2007-12-09

[alfa-2] Magnesium Iodide MSDS at AlfaAesar^{[permanent dead link]}

[3] Patnaik, Pradyot (2003), Handbook of Inorganic Chemicals, McGraw-Hill Professional, pp. 527–528, ISBN 0-07-049439-8, retrieved 2007-12-09

[4] 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.

[5] 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

[6] 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.

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