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
Names
Preferred IUPAC name
Diiodomethane[1]
Identifiers
3D model (JSmol)
1696892
ChemSpider
ECHA InfoCard 100.000.765 Edit this at Wikidata
EC Number
  • 200-841-5
MeSH methylene+iodide
RTECS number
  • PA8575000
UNII
  • InChI=1S/CH2I2/c2-1-3/h1H2 checkY
    Key: NZZFYRREKKOMAT-UHFFFAOYSA-N checkY
  • ICI
Properties
CH2I2
Molar mass 267.836 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
Boiling point 182.1 °C; 359.7 °F; 455.2 K
1.24 g L−1 (at 20 °C)[2]
23 μmol Pa−1 kg−1
-93.10·10−6 cm3/mol
Structure
Tetragonal
Tetrahedron
Thermochemistry
133.81 J K−1 mol−1
Std enthalpy of
formation (ΔfH⦵298)
 67.7–69.3 kJ mol−1
Std enthalpy of
combustion (ΔcH⦵298)
 −748.4–−747.2 kJ mol−1
Hazards
Safety data sheet hazard.com
GHS labelling:
GHS05: Corrosive GHS07: Exclamation mark
Signal word
 Danger
H302, H315, H318, H335
P261, P280, P305+P351+P338
NFPA 704 (fire diamond)
3
1
0
Flash point 110 °C (230 °F; 383 K)
Related compounds
Related alkanes
Related compounds
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY  (what is checkY☒N ?)
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]

Uses[]

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 for installing the CH2 group. In the Simmons–Smith reaction, it is a source of methylene.[4] In fact the Simmons–Smith reaction does not produce free carbene but proceeds via Zn-CH2I intermediates.

Diiodomethane is also a source of the equivalent of CH22+. The synthesis of Fe2(CH2)(CO)8 illustrates this reactivity:[5]

Na2Fe2(CO)8 + CH2I2 → Fe2(CH2)(CO)8 + 2 NaI

Preparation[]

Diiodomethane can be prepared from the widely available solvent dichloromethane by the action of sodium iodide in acetone in the Finkelstein reaction:[6]

CH2Cl2 + 2 NaI → CH2I2 + 2 NaCl

It can also be prepared by reducing iodoform with elemental phosphorus[7] or sodium arsenite:[6]

CHI3 + Na3AsO3 + NaOH → CH2I2 + NaI + Na3AsO4

Safety[]

Alkyl iodides are alkylating agents, which are potential mutagens.

References[]

  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 Archived 2013-12-01 at the Wayback Machine (8.10.2009)
  4. ^ Two cyclopropanation reactions: Smith, R. D.; Simmons, H. E. "Norcarane". Organic Syntheses.; Collective Volume, 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.; Collective Volume, 6, p. 327
  5. ^ Sumner, Charles E.; Riley, Paul E.; Davis, Raymond E.; Pettit, R. (1980). "Synthesis, Crystal Structure, and Chemical Reactivity of Octacarbonyl-μ-methylene-diiron". Journal of the American Chemical Society. 102 (5): 1752–1754. doi:10.1021/ja00525a062.
  6. ^ a b Roger Adams; C. S. Marvel (1921). "Methylene Iodide". Organic Syntheses. 1: 57. doi:10.15227/orgsyn.001.0057.
  7. ^ Miller, William Allen (1880). Elements of Chemistry: Chemistry of carbon compounds (5th ed.). London: Longmans Green and Co. p. 154.

External links[]

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