Diiodomethane
| Diiodomethane | |
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Diiodomethane[1] |
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Other names
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| Identifiers | |
| CAS number | 75-11-6  |
| PubChem | 6346 |
| ChemSpider | 6106 |
| EC number | 200-841-5 |
| MeSH | methylene+iodide |
| RTECS number | PA8575000 |
| Beilstein Reference | 1696892 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | CH2I2 |
| Molar mass | 267.84 g mol−1 |
| Exact mass | 267.824586904 g mol−1 |
| Appearance | Colorless, transparent liquid |
| Density | 3.325 g mL−1 |
| Melting point |
5-6 °C, 278.5-279.3 K, 42-43 °F |
| Solubility in water | 14 g L−1 (at 20 °C) |
| kH | 23 μmol Pa−1 kg−1 |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
67.7–69.3 kJ mol−1 |
| Std enthalpy of combustion ΔcH |
−748.4–−747.2 kJ mol−1 |
| Specific heat capacity, C | 133.81 J K−1 mol−1 |
| Hazards | |
| MSDS | hazard.com |
| GHS pictograms |   |
| GHS signal word | DANGER |
| GHS hazard statements | H302, H315, H318, H335 |
| GHS precautionary statements | P261, P280, P305+351+338 |
| EU classification |  Xn |
| R-phrases | R22, R36/37/38 |
| S-phrases | S26 |
| NFPA 704 |
 1
3
0
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| Flash point | 110 °C |
| Related compounds | |
| Related alkanes | |
| Related compounds | Guanidine |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
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.[2] Diiodomethane is a colorless liquid, however, it decomposes upon exposure to light liberating iodine, which colours samples brownish.
Because of its high density, 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.[3]
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[edit] Preparation
Although commercially available, it can be prepared by reducing iodoform with sodium arsenite:[4]
- CHI3 + Na3AsO3 + NaOH → CH2I2 + NaI + Na3AsO4
Diiodomethane can also be prepared from dichloromethane by the action of sodium iodide in acetone in the Finkelstein reaction:[4]
- CH2Cl2 + 2 NaI → CH2I2 + 2 NaCl
[edit] Safety
Alkyl iodides are alkylating agents and contact should be avoided.
[edit] References
- ^ "methylene iodide - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification ad Related Records. http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=6346&loc=ec_rcs. Retrieved 27 February 2012.
- ^ Website of Krüss (8.10.2009)
- ^ Two cyclopropanation reactions: Smith, R. D.; Simmons, H. E., "Norcarane", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv5p0855; Coll. Vol. 5: 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", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv6p0327; Coll. Vol. 6: 327
- ^ a b Roger Adams, C. S. Marvel (1941), "Methylene Iodide", Org. Synth., http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv1p0358; Coll. Vol. 1: 358
[edit] External links
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