Dimethylmercury
Names
IUPAC name Dimethylmercury[1]
Other names Mercury dimethanide
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference 3600205
ChEBI
ChemSpider
ECHA InfoCard 100.008.916
EC Number
  • 209-805-3
Gmelin Reference 25889
MeSH dimethyl+mercury
PubChem CID
RTECS number
  • OW3010000
UNII
UN number 2929
CompTox Dashboard (EPA)
InChI
  • InChI=1S/2CH3.Hg/h2*1H3; YKey: ATZBPOVXVPIOMR-UHFFFAOYSA-N Y
SMILES
  • C[Hg]C
Properties
Chemical formula C
2H
6Hg
(CH
3)
2Hg
Molar mass 230.66 g mol−1
Appearance Colorless liquid
Odor Sweet
Density 2.961 g mL−1
Melting point −43 °C (−45 °F; 230 K)
Boiling point 93 to 94 °C (199 to 201 °F; 366 to 367 K)
Refractive index (nD) 1.543
Thermochemistry
Std enthalpy of
formation (ΔfH⦵298) 		57.9–65.7 kJ mol−1
Hazards
Occupational safety and health (OHS/OSH):
Main hazards Extremely flammable, extremely poisonous, persistent environmental pollutant
GHS labelling:
Pictograms
Signal word Danger
Hazard statements H224, H300+H310+H330, H370, H372, H410
Precautionary statements P260, P264, P273, P280, P284, P301+P310
NFPA 704 (fire diamond) 4 4 3
Flash point 5 °C (41 °F; 278 K)
Related compounds
Other anions
  • Diethylmercury
  • Diphenylmercury
Other cations
  • Dimethylzinc
  • Dimethylcadmium
  • Dimethylmagnesium
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Dimethylmercury is an extremely toxic organomercury compound with the formula (CH3)2Hg. A volatile, flammable, dense and colorless liquid, dimethylmercury is one of the strongest known neurotoxins. Less than 0.1 mL is capable of inducing severe mercury poisoning resulting in death.[2]

Synthesis, structure, and reactions

The compound was one of the earliest organometallics reported, reflecting its considerable stability. The compound was first prepared by George Buckton in 1857 by a reaction of methylmercury iodide with potassium cyanide:[3]

2 CH3HgI + 2 KCN → Hg(CH3)2 + 2 KI + (CN)2 + Hg

Later, Edward Frankland discovered that it could be synthesized by treating sodium amalgam with methyl halides:

Hg + 2 Na + 2 CH3I → Hg(CH3)2 + 2 NaI

It can also be obtained by alkylation of mercuric chloride with methyllithium:

HgCl2 + 2 LiCH3 → Hg(CH3)2 + 2 LiCl

The molecule adopts a linear structure with Hg–C bond lengths of 2.083 Å.[4]

Reactivity and physical properties

Dimethylmercury is stable in water and reacts with mineral acids at a significant rate only at elevated temperatures,[5][6] whereas the corresponding organocadmium and organozinc compounds (and most metal alkyls in general) hydrolyze rapidly. The difference reflects the high electronegativity of Hg (Pauling EN = 2.00) and the low affinity of Hg(II) for oxygen ligands. The compound undergoes a redistribution reaction with mercuric chloride to give methylmercury chloride（actually, this is a reversible equilibrium）:

(CH3)2Hg + HgCl2 → 2 CH3HgCl

Whereas dimethylmercury is a volatile liquid, methylmercury chloride is a crystalline solid.[7]

Use

Dimethylmercury has few practical applications because of its danger to human life. It has been studied for reactions involving bonding methylmercury cations to target molecules, forming potent bactericides, but methylmercury's bioaccumulation and ultimate toxicity has led to it being largely abandoned in favor of the less toxic ethylmercury and diethylmercury compounds, which perform a similar function without the bioaccumulation hazard.

In toxicology, it still finds limited use as a reference toxin. It is also used to calibrate NMR instruments for detection of mercury (δ 0 ppm for 199Hg NMR), although diethylmercury and less toxic mercury salts are now preferred.[8][9][10]

Around 1960, Phil Pomerantz, a man working at the Bureau of Naval Weapons, suggested that dimethylmercury be used as a fuel mix with red fuming nitric acid.[11] This was never done, although it did lead to testing a red fuming nitric acid-unsymmetrical dimethylhydrazine rocket with elemental mercury being injected into the combustion chamber at the Naval Ordnance Test Station.[11]

Safety

Dimethylmercury is extremely toxic and dangerous to handle. Absorption of doses as low as 0.1 mL can result in severe mercury poisoning.[2] The risks are enhanced because of the compound's high vapor pressure.[2] Since it is highly lipophilic, it absorbs through the skin and into body fat very easily and can permeate many materials, including many plastics and rubber compounds.

Permeation tests showed that several types of disposable latex or polyvinyl chloride gloves (typically, about 0.1 mm thick), commonly used in most laboratories and clinical settings, had high and maximal rates of permeation by dimethylmercury within 15 seconds.[12] The American Occupational Safety and Health Administration (OSHA) advises handling dimethylmercury with highly resistant laminated gloves with an additional pair of abrasion-resistant gloves worn over the laminate pair, and also recommends using a face shield and working in a fume hood.[2][13]

Dimethylmercury is metabolized after several days to methylmercury.[12] Methylmercury crosses the blood–brain barrier easily, probably owing to formation of a complex with cysteine.[13] It easily absorbs into the body and has a tendency to bioaccumulate. The symptoms of mercury poisoning may be delayed by months, resulting in cases in which a diagnosis is ultimately discovered, but only at a point in which it is too late or almost too late for an effective treatment regimen to be successful.[13] Organomercury poisoning is also known as Minamata disease.

Incidents

References

  1. "dimethylmercury – Compound Summary". PubChem Compound. US: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records.
  2. "OSHA Hazard Information Bulletins – Dimethylmercury". OSHA.gov.
  3. McAuliffe, C. A., ed. (1977). The Chemistry of mercury. London: Macmillan. ISBN 978-1-349-02489-6. OCLC 1057702183.
  4. Holleman, A. F.; Wiberg, Egon; Wiberg, Nils (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 0-12-352651-5.
  5. Crabtree, Robert H. (2005). The Organometallic Chemistry of the Transition Metals (4th ed.). Hoboken, N.J.: John Wiley. p. 424. ISBN 0471662569. OCLC 61520528.
  6. Baughman, George L.; Gordon, John A.; Wolfe, N. Lee; Zepp, Richard G. (September 1973). Chemistry of Organomercurials in Aquatic Systems. United States Environmental Protection Agency Ecological Research Series. U.S. Govt. Print. Off. pp. 34–40.
  7. "Methylmercury chloride". PubChem. National Center for Biotechnology Information, United States National Institutes of Health.
  8. O'Halloran, T. V.; Singer, C. P. (10 March 1998). "199Hg Standards". Northwestern University. Archived from the original on 14 May 2005.
  9. Hoffman, R. (1 August 2011). "(Hg) Mercury NMR". Jerusalem: The Hebrew University.
  10. "Delayed Toxic Syndromes" (PDF). Terrorism by Fear and Uncertainty. ORAU. Archived from the original (PDF) on 23 April 2012.
  11. Clark, John Drury (23 May 2018). Ignition!. New Brunswick: Rutgers University Press Classics. pp. 177–179. ISBN 978-0-8135-9583-2.
  12. Nierenberg, David W.; Nordgren, Richard E.; Chang, Morris B.; Siegler, Richard W.; Blayney, Michael B.; Hochberg, Fred; Toribara, Taft Y.; Cernichiari, Elsa; Clarkson, Thomas (1998). "Delayed Cerebellar Disease and Death after Accidental Exposure to Dimethylmercury". New England Journal of Medicine. 338 (23): 1672–1676. doi:10.1056/NEJM199806043382305. PMID 9614258.
  13. Cotton, Simon (October 2003). "Dimethylmercury and Mercury Poisoning: The Karen Wetterhahn story". Molecule of the Month. Bristol University School of Chemistry. doi:10.6084/m9.figshare.5245807.
  14. "DimethylMercury and Mercury poisoning". Molecule of the Month www.chm.bris.ac.uk. October 2003.
  15. Cavanaugh, Ray (19 February 2019). "The dangers of dimethylmercury". Chemistry World. Royal Society of Chemistry.
  16. Albers, Anne; Gies, Ursula; Raatschen, Hans-Jurgen; Klintschar, Michael (1 September 2020). "Another umbrella murder? – A rare case of Minamata disease". Forensic Science, Medicine and Pathology. 16 (3): 504–509. doi:10.1007/s12024-020-00247-y. ISSN 1556-2891. PMC 7449996. PMID 32323188.
  17. "Umbrella stab victim dies of mercury poisoning". www.thelocal.de. 11 May 2012.
  18. "Quecksilbervergiftung" [Mercury poisoning]. Der Spiegel (in German). 11 May 2012.
  19. Albers, Anne; Gies, Ursula; Raatschen, Hans-Jurgen; Klintschar, Michael (1 September 2020). "Another umbrella murder? – A rare case of Minamata disease". Forensic Science, Medicine and Pathology. 16 (3): 504–509. doi:10.1007/s12024-020-00247-y. ISSN 1556-2891. PMC 7449996. PMID 32323188.
  20. "Heimtückischer Mord - Familienvater stirbt nach Spritzenattacke - ZDFmediathek". 30 August 2022. Archived from the original on 30 August 2022.