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Title: Diiodomethane  
Author: World Heritage Encyclopedia
Language: English
Subject: Iodomethylzinc iodide, Methylene (compound), Ethyl iodide, Methane, Bromochloromethane
Collection: Halogenated Solvents, Halomethanes, Iodoalkanes, Organoiodides
Publisher: World Heritage Encyclopedia


Stereo, skeletal formula of diiodomethane with all explicit hydrogens added
Ball and stick model of diiodomethane Spacefill model of diiodomethane
CAS number  YesY
ChemSpider  YesY
EC number
RTECS number PA8575000
Beilstein Reference 1696892
Jmol-3D images Image 1
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
Molecular shape Tetrahedron
heat capacity
133.81 J K−1 mol−1
Std enthalpy of
67.7–69.3 kJ mol−1
Std enthalpy of
−748.4–−747.2 kJ mol−1
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
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)
 YesY   YesY/N?)

Diiodomethane or methylene iodide, commonly abbreviated "MI", is an 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


  • Preparation 1
  • Safety 2
  • References 3
  • External links 4


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


Alkyl iodides are alkylating agents and contact should be avoided.


  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. ^
  3. ^ Website of Krüss (8.10.2009)
  4. ^ Two cyclopropanation reactions: Smith, R. D.; Simmons, H. E., "Norcarane",  
  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",  

External links

  • Diiodomethane data sheet
  • New particle formation from photooxidation of diiodomethane
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