Diiodomethane
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| Names | |||
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| IUPAC name
Diiodomethane
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| Other names
Methylene iodide, Methylene diiodide, Methyl diiodide
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| Identifiers | |||
3D model (JSmol)
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| ChemSpider | |||
| ECHA InfoCard | 100.000.765 | ||
| EC Number |
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PubChem CID
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| RTECS number |
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CompTox Dashboard (EPA)
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| Properties | |||
| CH2I2 | |||
| Molar mass | 267.84 g/mol | ||
| Appearance | Colorless liquid with chloroform-like odour | ||
| Density | 3.325 g/cm3 | ||
| Melting point | 6 °C (43 °F; 279 K) | ||
| Boiling point | 181 °C (358 °F) (decomp.) | ||
| 14 g/l at 20 °C | |||
| Hazards | |||
| NFPA 704 (fire diamond) | |||
| Flash point | 113 °C | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Diiodomethane or methylene iodide, commonly abbreviated "MI", is a liquid organoiodine compound. It is insoluble in water, but soluble in ether and alcohol. It has a relatively high refractive index of 1.741, and a surface tension of 0.0508 N·m−1 [1]. Diiodomethane is a colorless liquid, however, it decomposes upon exposure to light liberating iodine, which colours samples brownish.
With its high specific gravity, diiodomethane is used in the determination of the density of mineral and other solid samples. It is also used as a contact liquid for refractometers. Diiodomethane is a reagent in the Simmons-Smith reaction, serving as a source of methylene (CH2).[2]
Preparation
Although commercially available, it can be prepared by reducing iodoform with sodium arsenite:[3]
- CHI3 + Na3AsO3 + NaOH → CH2I2 + NaI + Na3AsO4
Diiodomethane can also be prepared from dichloromethane by the action of potassium iodide via the Finkelstein reaction:[3]
- CH2Cl2 + 2 KI → CH2I2 + 2 KCl
Safety
Alkyl iodides are alkylating agents and contact should be avoided.
References
- ^ Website of Krüss (8.10.2009)
- ^ Two cyclopropanation reactions: Smith, R. D.; Simmons, H. E. "Norcarane". Organic Syntheses
{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 5, p. 855., Ito, Y.; Fujii, S.; Nakatuska, M.; Kawamoto, F.; Saegusa, T. (1988). "One-Carbon Ring Expansion Of Cycloalkanones To Conjugated Cycloalkenones: 2-Cyclohepten-1-one". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 6, p. 327. - ^ a b Roger Adams, C. S. Marvel (1941). "Methylene Iodide". Organic Syntheses; Collected Volumes, vol. 1, p. 358.