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Iodomethane

Methyl iodide
Stereo skeletal formula of methyl iodide with all explicit hydrogens added
Ball and stick model of methyl iodide
Spacefill model of methyl iodide
Names
Preferred IUPAC name
Iodomethane
Other names
  • Methyl iodide
  • Methyl iodine
  • Monoiodomethane
Identifiers
74-88-4 YesY
3D model (Jmol) Interactive image
Abbreviations
  • Halon 10001
  • MeI
969135
ChEBI CHEBI:39282 YesY
ChEMBL ChEMBL115849 YesY
ChemSpider 6088 YesY
ECHA InfoCard 100.000.745
EC Number 200-819-5
1233
KEGG C18448 YesY
MeSH methyl+iodide
PubChem 6328
RTECS number PA9450000
UN number 2644
Properties
CH3I
Molar mass 141.94 g·mol−1
Appearance Colorless liquid
Odor pungent, ether-like
Density 2.28 g mL−1
Melting point −66.5 °C; −87.6 °F; 206.7 K
Boiling point 42.4 to 42.8 °C; 108.2 to 108.9 °F; 315.5 to 315.9 K
14 g L−1 (at 20 °C (68 °F))
log P 1.609
Vapor pressure 54.4 kPa (at 20 °C (68 °F))
1.4 μmol Pa−1 kg−1
-57.2·10−6 cm3/mol
1.530–1.531
Structure
Tetrahedron
Thermochemistry
82.75 J K−1 mol−1
−14.1–−13.1 kJ mol−1
−808.9–−808.3 kJ mol−1
Hazards
GHS pictograms The skull-and-crossbones pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) The health hazard pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word DANGER
H301, H312, H315, H331, H335, H351
P261, P280, P301+310, P311
Toxic T
R-phrases R21, R23/25, R37/38, R40
S-phrases (S1/2), S36/37, S38, S45
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 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazards (white): no codeNFPA 704 four-colored diamond
Lethal dose or concentration (LD, LC):
LD50 (median dose)
  • 76 mg kg−1(oral, rat)
  • 800 mg kg−1(dermal, guinea pig)
1550 ppm (rat, 30 min)
860 ppm (mouse, 57 min)
220 ppm (rat, 4 hr)
3800 ppm (rat, 15 min)
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 5 ppm (28 mg/m3) [skin]
REL (Recommended)
Ca TWA 2 ppm (10 mg/m3) [skin]
IDLH (Immediate danger)
Ca [100 ppm]
Related compounds
Related iodomethanes
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY  (what is YesYN ?)
Infobox references

Methyl iodide, also called iodomethane, and commonly abbreviated "MeI", is the chemical compound with the formula CH3I. It is a dense, colorless, volatile liquid. In terms of chemical structure, it is related to methane by replacement of one hydrogen atom by an atom of iodine. It is naturally emitted by rice plantations in small amounts. It is also produced in vast quantities estimated to be greater than 214,000 tons annually by algae and kelp in the world's temperate oceans, and in lesser amounts on land by terrestrial fungi and bacteria. It is used in organic synthesis as a source of methyl groups.

Methyl iodide had been approved for use as a pesticide by the United States Environmental Protection Agency in 2007 as a pre-plant biocide used to control insects, plant parasitic nematodes, soil borne pathogens, and weed seeds. The compound was registered for use as a preplant soil treatment for field grown strawberries, peppers, tomatoes, grape vines, ornamentals and turf and nursery grown strawberries, stone fruits, tree nuts, and conifer trees. After the discovery phase in a consumer lawsuit, the manufacturer withdrew the fumigant citing its lack of market viability.

Methyl iodide is formed via the exothermic reaction that occurs when iodine is added to a mixture of methanol with red phosphorus. The iodinating reagent is phosphorus triiodide that is formed in situ:

Alternatively, it is prepared from the reaction of dimethyl sulfate with potassium iodide in the presence of calcium carbonate:

Methyl iodide can also be prepared by the reaction of methanol with aqueous hydrogen iodide:


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