Diiodomethane

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Diiodomethane
Stereo, skeletal formula of diiodomethane with all explicit hydrogens added
Ball and stick model of diiodomethane Spacefill model of diiodomethane
Identifiers
CAS number 75-11-6 YesY
PubChem 6346
ChemSpider 6106 YesY
EC number 200-841-5
MeSH methylene+iodide
RTECS number PA8575000
Beilstein Reference 1696892
Jmol-3D images Image 1
Properties
Molecular formula CH2I2
Molar mass 267.84 g mol−1
Appearance Colorless liquid
Density 3.325 g mL−1
Melting point 5.4 to 6.2 °C; 41.6 to 43.1 °F; 278.5 to 279.3 K
Solubility in water 1.24 g L−1 (at 20 °C)[2]
kH 23 μmol Pa−1 kg−1
Structure
Coordination
geometry
Tetragonal
Molecular shape Tetrahedron
Thermochemistry
Specific
heat capacity
C
133.81 J K−1 mol−1
Std enthalpy of
formation
ΔfHo298
67.7–69.3 kJ mol−1
Std enthalpy of
combustion
ΔcHo298
−748.4–−747.2 kJ mol−1
Hazards
MSDS hazard.com
GHS pictograms The corrosion pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
GHS hazard statements H302, H315, H318, H335
GHS precautionary statements P261, P280, P305+351+338
EU classification Harmful Xn
R-phrases R22, R36/37/38
S-phrases S26
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 110 °C (230 °F; 383 K)
Related compounds
Related alkanes
Related compounds
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Diiodomethane or methylene iodide, commonly abbreviated "MI", is an organoiodine compound. Diiodomethane is a colorless liquid; however, it decomposes upon exposure to light liberating iodine, which colours samples brownish. It is slightly soluble in water, but soluble in organic solvents. It has a relatively high refractive index of 1.741, and a surface tension of 0.0508 N·m−1.[3]

Because of its high density, diiodomethane is used in the determination of the density of mineral and other solid samples. It can also be used as an optical contact liquid, in conjunction with the gemmological refractometer, for determining the refractive index of certain gemstones. Diiodomethane is a reagent in the Simmons–Smith reaction, serving as a source of the free radical methylene (carbene), :CH
2
.[4]

Preparation[edit]

Although commercially available, it can be prepared by reducing iodoform with elemental phosphorus[5] or sodium arsenite:[6]

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:[6]

CH2Cl2 + 2 NaI → CH2I2 + 2 NaCl

Safety[edit]

Alkyl iodides are alkylating agents and contact should be avoided.

References[edit]

  1. ^ "methylene iodide - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification ad Related Records. Retrieved 27 February 2012. 
  2. ^ http://www.surface-tension.de/LIQUIDS/Diiodomethane3.htm
  3. ^ Website of Krüss (8.10.2009)
  4. ^ Two cyclopropanation reactions: Smith, R. D.; Simmons, H. E., "Norcarane", Org. Synth. ; 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. ; Coll. Vol. 6: 327 
  5. ^ Miller, William Allen (1880). Elements of Chemistry: Chemistry of carbon compounds 5th ed.. London: Longmans Green and Co. p. 154. 
  6. ^ a b Roger Adams, C. S. Marvel (1941), "Methylene Iodide", Org. Synth. ; Coll. Vol. 1: 358 

External links[edit]