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Diiodomethane - Wikipedia

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(Redirected from Methylene iodide)

Diiodomethane

Names

Preferred IUPAC name

Diiodomethane^[1]

Identifiers

CAS Number

75-11-6^Y

3D model (JSmol)

Interactive image

Beilstein Reference

1696892

ChemSpider

6106^Y

ECHA InfoCard

100.000.765

EC Number

200-841-5

MeSH

methylene+iodide

PubChem CID

6346

RTECS number

PA8575000

UNII

3J731705OX^Y

CompTox Dashboard (EPA)

DTXSID4058784

InChI

InChI=1S/CH2I2/c2-1-3/h1H2^Y
Key: NZZFYRREKKOMAT-UHFFFAOYSA-N^Y

SMILES

Properties

Chemical formula

CH₂I₂

Molar mass

267.836 g·mol⁻¹

Appearance

Colorless liquid

Density

3.325 g mL⁻¹ (3325 kg/m³)

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

Solubility in water

1.24 g L⁻¹ (at 20 °C)^[2]

Henry's law
constant (k_H)

23 μmol Pa⁻¹ kg⁻¹

Magnetic susceptibility (χ)

-93.10·10⁻⁶ cm³/mol

Structure

Coordination geometry

Tetragonal

Molecular shape

Tetrahedron

Thermochemistry

Heat capacity (C)

133.81 J K⁻¹ mol⁻¹

Std enthalpy of
formation (Δ_fH^⦵₂₉₈)

67.7–69.3 kJ mol⁻¹

Std enthalpy of
combustion (Δ_cH^⦵₂₉₈)

−748.4–−747.2 kJ mol⁻¹

Hazards

GHS labelling:

Pictograms

Signal word

Danger

Hazard statements

H302, H315, H318, H335

Precautionary statements

P261, P280, P305+P351+P338

NFPA 704 (fire diamond)

Flash point

110 °C (230 °F; 383 K)

Safety data sheet (SDS)

hazard.com

Related compounds

Related alkanes/haloalkanes

Except where otherwise noted, 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 very dense 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 very 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 CH2+2. 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

^ "methylene iodide - Compound Summary". PubChem Compound. USA: National Center for Biotechnology Information. 26 March 2005. Identification ad Related Records. Retrieved 27 February 2012.
^ "Diiodomethane".
^ Website of Krüss Archived 2013-12-01 at the Wayback Machine (8.10.2009)
^ Two cyclopropanation reactions: Smith, R. D.; Simmons, H. E. "Norcarane". Organic Syntheses; 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; Collected Volumes, vol. 6, p. 327.
^ 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.
^ ^a ^b Roger Adams; C. S. Marvel (1921). "Methylene Iodide". Organic Syntheses. 1: 57. doi:10.15227/orgsyn.001.0057.
^ Miller, William Allen (1880). Elements of Chemistry: Chemistry of carbon compounds (5th ed.). London: Longmans Green and Co. p. 154.

External links

Diiodomethane data sheet
New particle formation from photooxidation of diiodomethane Archived 2012-02-11 at the Wayback Machine

v t e Halomethanes
Unsubstituted	CH₄
Monosubstituted	CH₃F CH₃Cl CH₃Br CH₃I CH₃At
Disubstituted	CH₂F₂ CH₂ClF CH₂BrF CH₂FI CH₂Cl₂ CH₂BrCl CH₂ClI CH₂Br₂ CH₂BrI CH₂I₂
Trisubstituted	CHF₃ CHClF₂ CHBrF₂ CHF₂I CHCl₂F CHBrClF CHClFI CHBr₂F CHBrFI CHFI₂ CHCl₃ CHBrCl₂ CHCl₂I CHBr₂Cl CHBrClI CHClI₂ CHBr₃ CHBr₂I CHBrI₂ CHI₃
Tetrasubstituted	CF₄ CClF₃ CBrF₃ CF₃I CCl₂F₂ CBrClF₂ CClF₂I CBr₂F₂ CBrF₂I CF₂I₂ CCl₃F CBrCl₂F CCl₂FI CBr₂ClF C*BrClFI CClFI₂ CBr₃F CBr₂FI CBrFI₂ CFI₃ CCl₄ CBrCl₃ CCl₃I CBr₂Cl₂ CBrCl₂I CCl₂I₂ CBr₃Cl CBr₂ClI CBrClI₂ CClI₃ CBr₄ CBr₃I CBr₂I₂ CBrI₃ CI₄
* Chiral compound.

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