Methyl iodide
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| Names | |||
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Preferred IUPAC name
Iodomethane
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Other names
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| Identifiers | |||
74-88-4 
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| 3D model (Jmol) | Interactive image | ||
| Abbreviations |
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| 969135 | |||
| ChEBI |
CHEBI:39282
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| ChEMBL |
ChEMBL115849
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| ChemSpider |
6088
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| ECHA InfoCard | 100.000.745 | ||
| EC Number | 200-819-5 | ||
| 1233 | |||
| KEGG |
C18448
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| MeSH | methyl+iodide | ||
| PubChem | 6328 | ||
| RTECS number | PA9450000 | ||
| UN number | 2644 | ||
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| 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)) | ||
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Henry's law
constant (kH) |
1.4 μmol Pa−1 kg−1 | ||
| -57.2·10−6 cm3/mol | |||
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Refractive index (nD)
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1.530–1.531 | ||
| Structure | |||
| Tetrahedron | |||
| Thermochemistry | |||
| 82.75 J K−1 mol−1 | |||
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Std enthalpy of
formation (ΔfH |
−14.1–−13.1 kJ mol−1 | ||
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Std enthalpy of
combustion (ΔcH |
−808.9–−808.3 kJ mol−1 | ||
| Hazards | |||
| GHS pictograms |
 
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| GHS signal word | DANGER | ||
| H301, H312, H315, H331, H335, H351 | |||
| P261, P280, P301+310, P311 | |||
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EU classification (DSD)
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 T |
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| R-phrases | R21, R23/25, R37/38, R40 | ||
| S-phrases | (S1/2), S36/37, S38, S45 | ||
| NFPA 704 | |||
| Lethal dose or concentration (LD, LC): | |||
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LD50 (median dose)
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LC50 (median concentration)
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1550 ppm (rat, 30 min) 860 ppm (mouse, 57 min) 220 ppm (rat, 4 hr) |
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LCLo (lowest published)
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3800 ppm (rat, 15 min) | ||
| US health exposure limits (NIOSH): | |||
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PEL (Permissible)
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TWA 5 ppm (28 mg/m3) [skin] | ||
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REL (Recommended)
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Ca TWA 2 ppm (10 mg/m3) [skin] | ||
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IDLH (Immediate danger)
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Ca [100 ppm] | ||
| Related compounds | |||
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Related iodomethanes
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is  ?) |
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| 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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Wikipedia