Chemistry:Dimethylmercury

From HandWiki

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.[1]

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[2][3] by a reaction of methylmercury iodide with potassium cyanide:[4]: 32 

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.[5]

Reactivity and physical properties

Dimethylmercury in a bottle

Dimethylmercury is stable in water and reacts with mineral acids at a significant rate only at elevated temperatures,[6][7] 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:

(CH3)2Hg + HgCl2 ⇌ 2 CH3HgCl

Whereas dimethylmercury is a volatile liquid, methylmercury chloride is a crystalline solid.[8]

Use

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.[9][10][11]

Around 1960, Phil Pomerantz, a worker at the Bureau of Naval Weapons, suggested that dimethylmercury be used as a fuel mix with red fuming nitric acid.[12] 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.[12]

Safety

Dimethylmercury is extremely toxic and dangerous to handle. Absorption of doses as low as 0.1 mL can result in severe mercury poisoning.[1] The risks are enhanced because of the compound's high vapor pressure.[1] Since it is highly lipophilic, it is very easily absorbed through the skin and into body fat.[13]

Dimethylmercury can rapidly permeate many materials, including latex, PVC and neoprene.[1] 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.[14] 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.[1][15]

Dimethylmercury is metabolized after several days to methylmercury.[14] Methylmercury crosses the blood–brain barrier easily, probably owing to formation of a complex with cysteine.[15] It easily absorbs into the body and has a tendency to bioaccumulate in adipose tissue, plasma proteins and the brain.[13] 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.[15] Symptoms include tingling, nausea and deterioration of balance, speech, hearing and vision.[13] Organomercury poisoning is also known as Minamata disease.

Incidents

  • As early as 1865, two workers in the laboratory of Edward Frankland died after exhibiting progressive neurological symptoms following accidental exposure to the compound.[4]: 32–33 
  • In 1971, a chemist died in Czechoslovakia after preparing 6000g of dimethylmercury over a three month period.[16][17]
  • Karen Wetterhahn, a professor of chemistry at Dartmouth College, died in 1997, ten months after spilling only a few drops of dimethylmercury onto her latex gloves.[1][18] This incident resulted in improved awareness of the substance's extreme toxicity and its ability to easily penetrate latex. New material-handling guidelines were published, many institutions purged their supplies of the compound, and it became almost impossible to buy.[19]
  • The 2012 death of Christoph Bulwin, a 40-year-old database administrator for IG Bergbau, Chemie, Energie, may have been caused by an attack involving dimethylmercury.[20]
  • On August 26, 2026, a graduate student at the Massachusetts Institute of Technology visited a local emergency room after self-reporting an exposure to synthesized dimethylmercury.[21][22][23] The student showed “no sign of exposure to mercury" in initial blood tests, per a statement from MIT officials. The incident prompted a several day closure of the Camille Edouard Dreyfus Chemistry Building, more commonly known as Building 18, amid "specialized decontamination efforts."[24] Subsequent investigation questioned whether the student had synthesized the compound.[25]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 "OSHA Hazard Information Bulletins – Dimethylmercury". https://www.osha.gov/publications/hib19980309. 
  2. ↑ Seyferth, Dietmar (1 June 2003). "The Rise and Fall of Tetraethyllead. 1. Discovery and Slow Development in European Universities, 1853−1920". Organometallics 22 (12): 2346–2357. doi:10.1021/om030245v. 
  3. ↑ Buckton, George Bowdler (1858). "On the Isolation of the Radical, Mercuric Methyl". Philosophical Transactions of the Royal Society of London (The Royal Society) 148: 163–168. ISSN 02610523.  Received December 4, 1857.
  4. ↑ 4.0 4.1 McAuliffe, C. A., ed (1977). "Part 1. A History of Mercury". The Chemistry of Mercury. London: Macmillan. pp. 1–45. doi:10.1007/978-1-349-02489-6_1. ISBN 978-1-349-02489-6. OCLC 1057702183. 
  5. ↑ Holleman, A. F.; Wiberg, Egon; Wiberg, Nils (2001). Inorganic Chemistry. San Diego: Academic Press. ISBN 0-12-352651-5. 
  6. ↑ Crabtree, Robert H. (2005). The Organometallic Chemistry of the Transition Metals (4th ed.). Hoboken, N.J.: John Wiley. pp. 424. ISBN 0471662569. OCLC 61520528. 
  7. ↑ 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. https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=9100TLU0.TXT. Retrieved 2021-01-29. 
  8. ↑ "Methylmercury chloride". National Center for Biotechnology Information, United States National Institutes of Health. https://pubchem.ncbi.nlm.nih.gov/compound/Methylmercuric_chloride#section=Top. 
  9. ↑ O'Halloran, T. V.; Singer, C. P. (1998-03-10). "199Hg Standards". Northwestern University. http://www.chem.northwestern.edu/~ohallo/HgNMRStandards/. 
  10. ↑ Hoffman, R. (2011-08-01). "(Hg) Mercury NMR". Jerusalem: The Hebrew University. http://chem.ch.huji.ac.il/nmr/techniques/1d/row6/hg.html. 
  11. ↑ "Delayed Toxic Syndromes". Terrorism by Fear and Uncertainty. ORAU. http://orise.orau.gov/files/reacts/aoo-course-handouts/Module-6-Terrorism-by-Fear-and-Uncertainty-Delayed-Toxic-Syndromes.pdf. 
  12. ↑ 12.0 12.1 Clark, John Drury (2018-05-23). Ignition!. New Brunswick: Rutgers University Press Classics. pp. 177–179. ISBN 978-0-8135-9583-2. 
  13. ↑ 13.0 13.1 13.2 Gilbert, Steven G. (2023). "Dimethylmercury". in Wexler, Philip. Encyclopedia of Toxicology (4th ed.). Academic Press. pp. 785-792. doi:10.1016/B978-0-12-824315-2.01143-X. ISBN 978-0-323-85434-4. https://www.sciencedirect.com/science/chapter/referencework/abs/pii/B978012824315201143X. 
  14. ↑ 14.0 14.1 Nierenberg, David W.; Nordgren, Richard E.; Chang, Morris B.; Siegler, Richard W.; Blayney, Michael B.; Hochberg, Fred; Toribara, Taft Y.; Cernichiari, Elsa et al. (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. 
  15. ↑ 15.0 15.1 15.2 Cotton, Simon (October 2003). Dimethylmercury and Mercury Poisoning: The Karen Wetterhahn story. Bristol University School of Chemistry. doi:10.6084/m9.figshare.5245807. http://www.chm.bris.ac.uk/motm/dimethylmercury/dmmh.htm. Retrieved 29 January 2021. 
  16. ↑ Siegler, Richard W; Nierenberg, David W; Hickey, William F (June 1999). "Fatal poisoning from liquid dimethylmercury: A neuropathologic study" (in en). Human Pathology 30 (6): 720–723. doi:10.1016/S0046-8177(99)90101-6. https://linkinghub.elsevier.com/retrieve/pii/S0046817799901016. 
  17. ↑ Pazderová, Jana; Jirásek, A.; Mráz, M.; Pechan, J. (1974-12-01). "Post-mortem findings and clinical signs of dimethyl mercury poisoning in man". Internationales Archiv für Arbeitsmedizin 33 (4): 323–328. doi:10.1007/BF00538936. ISSN 1432-1246. https://doi.org/10.1007/BF00538936. 
  18. ↑ "DimethylMercury and Mercury poisoning". October 2003. http://www.chm.bris.ac.uk/motm/dimethylmercury/dmmh.htm. 
  19. ↑ Cavanaugh, Ray (2019-02-19). "The dangers of dimethylmercury". Chemistry World (Royal Society of Chemistry). https://www.chemistryworld.com/opinion/the-dangers-of-dimethylmercury-/3010064.article. Retrieved 29 January 2021. 
  20. ↑ Albers, Anne; Gies, Ursula; Raatschen, Hans-Jurgen; Klintschar, Michael (2020-09-01). "Another umbrella murder? – A rare case of Minamata disease" (in en). Forensic Science, Medicine and Pathology 16 (3): 504–509. doi:10.1007/s12024-020-00247-y. ISSN 1556-2891. PMID 32323188. PMC 7449996. https://doi.org/10.1007/s12024-020-00247-y. 
  21. ↑ DiGiammerino, Thea (2026-08-29). "MIT student claims to synthesize dangerous chemical, prompting hazmat response" (in en-US). https://www.nbcboston.com/news/local/mit-chemical-hazmat-building-18/4006077/. 
  22. ↑ Crimaldi, Laura (2026-08-29). "MIT student hospitalized, chemistry building closed, after potential exposure to highly toxic mercury compound" (in en-US). The Boston Globe. ISSN 0743-1791. https://www.bostonglobe.com/2026/08/29/metro/mit-student-mercury-exposure/. 
  23. ↑ Frank, BrieAnna J.. "MIT building to reopen after student reports creating dimethyl mercury" (in en-US). https://www.usatoday.com/story/news/nation/2026/08/30/dimethyl-mercury-mit-student/91536561007/. 
  24. ↑ Fitzgerald, Michael F. (2026-08-31). "MIT will reopen Building 18" (in en-US). https://www.cambridgeday.com/2026/08/31/mit-reopen-building-18/. 
  25. ↑ "MIT emergency alerts". https://emergency.mit.edu/emergency/. 



Retrieved from "https://handwiki.org/wiki/index.php?title=Chemistry:Dimethylmercury&oldid=4645873"