| Dimethylmercury | |
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Dimethylmercury |
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Dimethylmercury |
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Other names
Dimethyl mercury |
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| Identifiers | |
| CAS number | 593-74-8 |
| PubChem | 11645 |
| ChemSpider | 11155 |
| UNII | C60TQU15XY |
| EC number | 209-805-3 |
| UN number | 3383 |
| MeSH | Dimethyl+mercury |
| ChEBI | CHEBI:30786 |
| RTECS number | OW3010000 |
| Beilstein Reference | 3600205 |
| Gmelin Reference | 25889 |
| Jmol-3D images | Image 1 Image 2 |
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| Properties | |
| Molecular formula | C2H6Hg |
| Molar mass | 230.66 g mol−1 |
| Exact mass | 232.017575796 g mol-1 |
| Appearance | Colorless liquid |
| Density | 2.961 g cm-3 |
| Melting point |
-43 °C, 230 K, -45 °F |
| Boiling point |
93-94 °C, 366-367 K, 199-201 °F |
| Hazards | |
| EU Index | 080-007-00-3 |
| EU classification | T+ N |
| R-phrases | R26/27/28, R33, R50/53 |
| S-phrases | (S1/2), S13, S28, S36, S45, S60, S61 |
| NFPA 704 |
4
4
1
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| Flash point | 5 °C |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Dimethylmercury ((CH3)2Hg) is an organomercury compound. This colorless liquid is one of the strongest known neurotoxins. It is described as having a slightly sweet smell, although inhaling enough vapor to detect its odor would be hazardous.
Contents |
The compound was one of the earliest organometallic complexes reported, reflecting its considerable stability. It is formed by treating sodium amalgam with methyl halides:
It can also be obtained by alkylation of mercuric chloride with methyllithium. The molecule adopts a linear structure with Hg-C bond lengths of 2.083 Å.[1]
The most striking feature of the compound is its nonreactivity toward water. The corresponding organocadmium and organozinc compounds hydrolyze rapidly. The difference reflects the low affinity of Hg(II) for oxygen ligands. The compound reacts with mercuric chloride to give the mixed chloro-methyl compound:
Whereas dimethylmercury is a volatile liquid, CH3HgCl is a crystalline solid.
Dimethylmercury has almost no applications because of the risks involved. In toxicology, it is used as a reference toxin. It has also been used to calibrate NMR instruments for detection of mercury, although less toxic mercury salts are preferred. U.S. Department of Energy institute ORISE reported the price of dimethylmercury as being $18.38 per gram.[2][3][4]
Dimethylmercury is extremely dangerous. Absorption of doses as low as 0.1 mL has proven fatal.[5] The risks are enhanced because of the high vapor pressure of the liquid.
Dimethylmercury passes through latex, PVC, butyl, and neoprene rapidly (within seconds) and is absorbed through the skin. Therefore, most laboratory gloves do not provide adequate protection from it, and the only safe precaution is to handle dimethylmercury while wearing highly resistant laminated gloves underneath long-cuffed neoprene or other heavy-duty gloves. A long face shield and work under a fume hood are also indicated.[5][6]
Dimethylmercury crosses the blood–brain barrier easily, probably owing to formation of a complex with cysteine. It is eliminated from the organism slowly, and therefore has a tendency to bioaccumulate. The symptoms of poisoning may be delayed by months, possibly too late for effective treatment.
The toxicity of dimethylmercury was highlighted with the death of the inorganic chemist Karen Wetterhahn of Dartmouth College in 1997, months after spilling no more than a few drops of this compound on her latex-gloved hand.[5]