Dimethylmercury: Difference between revisions

{{Short description|Organomercury chemical compound}}

|Verifiedfields = changed

|Watchedfields = changed

|verifiedrevid = 460790372

|ImageFile = Dimethylmercury Structural Formulae V2.svg

|ImageFile_Ref = {{Chemboximage|correct|??}}

|ImageSize = 150

|ImageName = Skeletal formula of dimethylmercury with all hydrogens added

|ImageFile1 = Dimethyl-mercury-3D-vdW.png

|ImageFile1_Ref = {{Chemboximage|correct|??}}

|ImageSize1 = 150

|ImageName1 = Space-filling model of dimethylmercury

|IUPACName = Dimethylmercury<ref>{{cite web |title=dimethylmercury – Compound Summary |url=https://pubchem.ncbi.nlm.nih.gov/compound/11645#x291 |work=PubChem Compound |publisher=National Center for Biotechnology Information |access-date=2021-01-29 |location=US |date=16 September 2004 |at=Identification and Related Records}}</ref>

|OtherNames = Mercury dimethanide

|Section1={{Chembox Identifiers

|CASNo = 593-74-8

|CASNo_Ref = {{cascite|changed|??}}

|PubChem = 11645

|ChemSpiderID = 11155

|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

|UNII = C60TQU15XY

|UNII_Ref = {{fdacite|correct|FDA}}

|EINECS = 209-805-3

|UNNumber = 2929

|MeSHName = dimethyl+mercury

|ChEBI = 30786

|ChEBI_Ref = {{ebicite|correct|EBI}}

|RTECS = OW3010000

|Beilstein = 3600205

|Gmelin = 25889

|SMILES = C[Hg]C

|StdInChI = 1S/2CH3.Hg/h2*1H3;

|StdInChI_Ref = {{stdinchicite|correct|chemspider}}

|StdInChIKey = ATZBPOVXVPIOMR-UHFFFAOYSA-N

|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

|Section2={{Chembox Properties

|Formula = {{Chem|C|2|H|6|Hg}}<br>{{Chem|({{Chem|C|H|3}})|2|Hg}}

|MolarMass = 230.66 g mol⁻¹

|Appearance = Colorless liquid

|Density = 2.961 g mL⁻¹

|MeltingPtC = -43

|BoilingPtC = 93 to 94

|RefractIndex = 1.543

|Odor = Sweet

}}

|Section3={{Chembox Thermochemistry

|DeltaHf = 57.9–65.7 kJ mol⁻¹

}}

|Section4={{Chembox Hazards

|MainHazards = Extremely flammable, extremely poisonous, persistent environmental pollutant

|GHSPictograms = {{GHS skull and crossbones}}{{GHS health hazard}}{{GHS flame}}{{GHS environment}}

|GHSSignalWord = '''DANGER'''

|HPhrases = {{H-phrases|224|300+310+330|372|410}}

|PPhrases = {{P-phrases|260|264|273|280|284|301+310}}

|NFPA-H = 4

|NFPA-F = 4

|NFPA-R = 3

|FlashPtC = 5

}}

|Section8={{Chembox Related

|OtherAnions= {{ubl

|[[Diethylmercury]]

|[[Diphenylmercury]]

}}

|OtherCations = {{ubl

|[[Dimethylzinc]]

|[[Dimethylcadmium]]

|[[Dimethylmagnesium]]

}}

}}

}}

'''Dimethylmercury''' is an extremely toxic [[organomercury compound]] with the formula ([[methyl|CH₃]])₂[[Mercury (element)|Hg]]. A volatile, flammable, dense and colorless liquid, dimethylmercury is one of the strongest known [[neurotoxin]]s. Less than 0.1&nbsp;mL is capable of inducing severe [[mercury poisoning]] resulting in death.<ref name="OSHA">{{cite web |url=https://www.osha.gov/publications/hib19980309 |title=OSHA Hazard Information Bulletins – Dimethylmercury |website=OSHA.gov |access-date=2021-01-29}}</ref>

==Synthesis, structure, and reactions==

The compound was one of the earliest [[organometallic]]s reported, reflecting its considerable stability. The compound was first prepared by [[George Bowdler Buckton|George Buckton]] in 1857 by a reaction of [[methylmercury]] [[iodide]] with [[potassium cyanide]]:<ref name=":0">{{Cite book|url=https://www.worldcat.org/oclc/1057702183|title=The Chemistry of mercury|date=1977|publisher=Macmillan|others=C. A. McAuliffe|isbn=978-1-349-02489-6|location=London|oclc=1057702183}}</ref>

: 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]] [[halide]]s:

: Hg + 2 Na + 2 [[Methyl iodide|CH₃I]] → Hg(CH₃)₂ + 2 [[Sodium iodide|NaI]]

It can also be obtained by [[alkylation]] of [[Mercury(II) chloride|mercuric chloride]] with [[methyllithium]]:

: HgCl₂ + 2 LiCH₃ → Hg(CH₃)₂ + 2 [[Lithium chloride|LiCl]]

The molecule adopts a linear structure with Hg–C bond lengths of 2.083&nbsp;Å.<ref>{{cite book |last1=Holleman |first1=A. F. |last2=Wiberg |first2=Egon |last3=Wiberg |first3=Nils |title=Inorganic Chemistry |publisher=Academic Press |location=San Diego |year=2001 |isbn=0-12-352651-5}}</ref>

===Reactivity and physical properties===

Dimethylmercury is stable in water and reacts with mineral acids at a significant rate only at elevated temperatures,<ref>{{cite book |title=The Organometallic Chemistry of the Transition Metals |last=Crabtree |first=Robert H. |author-link=Robert H. Crabtree |year=2005 |publisher=John Wiley |isbn=0471662569 |edition= 4th |location=Hoboken, N.J. |pages=424 |oclc=61520528}}</ref><ref>{{cite book |url=https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=9100TLU0.TXT |title=Chemistry of Organomercurials in Aquatic Systems |last1=Baughman |first1=George L. |first2=John A. |last2=Gordon |first3=N. Lee |last3=Wolfe |first4=Richard G. |last4=Zepp |publisher=[[U.S. Govt. Print. Off.]] |date=September 1973 |pages=34–40 |series=[[United States Environmental Protection Agency]] Ecological Research Series |access-date=2021-01-29}}</ref> 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 (chemistry)|redistribution reaction]] with mercuric chloride to give methylmercury chloride:

Whereas dimethylmercury is a [[volatile liquids|volatile liquid]], [[methylmercury|methylmercury chloride]] is a [[crystalline solid]].<ref>{{cite web |url=https://pubchem.ncbi.nlm.nih.gov/compound/Methylmercuric_chloride#section=Top |title=Methylmercury chloride |website=[[PubChem]] |publisher=[[National Center for Biotechnology Information]], United States [[National Institutes of Health]] |access-date=2021-01-29}}</ref>

Dimethylmercury has few applications because of the risks involved. 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 spectroscopy|NMR]] instruments for detection of mercury (δ 0&nbsp;ppm for ¹⁹⁹Hg NMR), although diethylmercury and less toxic mercury salts are now preferred.<ref>{{cite web |url=http://www.chem.northwestern.edu/~ohallo/HgNMRStandards/ |title=¹⁹⁹Hg Standards |date=1998-03-10 |last1=O'Halloran |first1=T. V. |last2=Singer |first2=C. P. |publisher=Northwestern University |access-date=2021-01-20 |url-status=dead |archive-url=https://web.archive.org/web/20050514072706/http://www.chem.northwestern.edu/~ohallo/HgNMRStandards/ |archive-date=2005-05-14}}</ref><ref>{{cite web |title=(Hg) Mercury NMR |last=Hoffman |first=R. |date=2011-08-01 |url=http://chem.ch.huji.ac.il/nmr/techniques/1d/row6/hg.html |publisher=The Hebrew University |location=Jerusalem |access-date=2021-01-29}}</ref><ref>{{cite web |url=http://orise.orau.gov/files/reacts/aoo-course-handouts/Module-6-Terrorism-by-Fear-and-Uncertainty-Delayed-Toxic-Syndromes.pdf |title=Delayed Toxic Syndromes |work=Terrorism by Fear and Uncertainty |publisher=[[Oak_Ridge_Associated_Universities|ORAU]] |access-date=2021-01-29 |archive-url=https://web.archive.org/web/20120423091321/http://orise.orau.gov/files/reacts/aoo-course-handouts/Module-6-Terrorism-by-Fear-and-Uncertainty-Delayed-Toxic-Syndromes.pdf |archive-date=2012-04-23 |url-status=dead }}</ref>

Around 1960 Phil Pomerantz working at the [[Bureau of Naval Weapons]] suggested a that Dimethylmercury be used as a fuel mix with Red fuming nitric acid.<ref name=Ignition162 /> 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]]<ref name=Ignition162>{{cite book | last=Clark | first=John Drury | title=Ignition! | publisher=Rutgers University Press Classics | publication-place=New Brunswick | date=2018-05-23 | isbn=978-0-8135-9583-2 | pages=162-164}}</ref>

Dimethylmercury is extremely toxic and dangerous to handle. Absorption of doses as low as 0.1&nbsp;[[millilitre|mL]] can result in severe mercury poisoning.<ref name="OSHA" /> The risks are enhanced because of the compound's high [[vapor pressure]].<ref name="OSHA" /> 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&nbsp;mm thick), commonly used in most [[Laboratory|laboratories]] and clinical settings, had high and maximal rates of permeation by dimethylmercury within 15 seconds.<ref name="nejm">{{cite journal |last1=Nierenberg |first1=David W. |last2=Nordgren |first2=Richard E. |last3=Chang |first3=Morris B. |last4=Siegler |first4=Richard W. |last5=Blayney |first5=Michael B. |last6=Hochberg |first6=Fred |last7=Toribara |first7=Taft Y. |last8=Cernichiari |first8=Elsa |last9=Clarkson |first9=Thomas |title=Delayed Cerebellar Disease and Death after Accidental Exposure to Dimethylmercury |journal=[[New England Journal of Medicine]] |volume=338 |issue=23 |year=1998 |pages=1672–1676 |doi=10.1056/NEJM199806043382305 |pmid=9614258|doi-access=free }}</ref> The American [[Occupational Safety and Health Administration]] 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]].<ref name="OSHA" /><ref name="story">{{cite journal |url=http://www.chm.bris.ac.uk/motm/dimethylmercury/dmmh.htm |first=Simon |last=Cotton| title=Dimethylmercury and Mercury Poisoning: The Karen Wetterhahn story |doi=10.6084/m9.figshare.5245807 |website=Molecule of the Month |publisher=[[Bristol University]] School of Chemistry |date=October 2003 |access-date=29 January 2021}}</ref>

Dimethylmercury is metabolized after several days to [[methylmercury]].<ref name="nejm" /> Methylmercury crosses the [[blood–brain barrier]] easily, probably owing to formation of a [[Coordination complex|complex]] with [[cysteine]].<ref name="story" /> It easily absorbs into the body, and has a tendency to [[bioaccumulation|bioaccumulate]]. The symptoms of [[Mercury poisoning|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.<ref name="story" /> Methylmercury 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.<ref name=":0" />

[[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.<ref name="OSHA" /><ref>{{Cite web |date=October 2003 |title=DimethylMercury and Mercury poisoning |url=http://www.chm.bris.ac.uk/motm/dimethylmercury/dmmh.htm |access-date=2022-08-25 |website=Molecule of the Month www.chm.bris.ac.uk}}</ref> This incident resulted in improved awareness of the substance's extreme toxicity, and its ability to easily penetrate latex, compared to less porous materials such as [[Nitrile rubber |nitrile]]. New [[OSHA]] material-handling guidelines were published, many institutions purged their supplies of the compound, and it became almost impossible to buy.<ref>{{cite magazine |last=Cavanaugh |first=Ray |date=2019-02-19 |title=The dangers of dimethylmercury |url=https://www.chemistryworld.com/opinion/the-dangers-of-dimethylmercury-/3010064.article |magazine=[[Chemistry World]] |publisher=[[Royal Society of Chemistry]] |access-date=29 January 2021}}</ref>

Christoph Bulwin, a 40-year-old German database administrator for [[IG Bergbau, Chemie, Energie]], claimed to have been attacked with a [[Bulgarian umbrella|syringe-tipped umbrella]] on 15 July 2011 in [[Hanover]], Germany. Bulwin, who died a year later from [[mercury poisoning]], had said he confiscated the syringe, which was later found to contain dimethylmercury.<ref>{{Cite web |date=2022-08-25 |title=Namen genannt! Wird der Regenschirm-Mord an Familienvater Christoph (†40) endlich gelöst? |url=https://www.tag24.de/unterhaltung/tv/aktenzeichen-xy/namen-genannt-wird-der-regenschirm-mord-an-familienvater-christoph-40-endlich-geloest-2592039 |archive-url=https://web.archive.org/web/20220825122815/https://www.tag24.de/unterhaltung/tv/aktenzeichen-xy/namen-genannt-wird-der-regenschirm-mord-an-familienvater-christoph-40-endlich-geloest-2592039 |archive-date=2022-08-25 |access-date=2022-08-30 |website=TAG24 |language=de}}</ref><ref>{{Cite journal |last=Albers |first=Anne |last2=Gies |first2=Ursula |last3=Raatschen |first3=Hans-Jurgen |last4=Klintschar |first4=Michael |date=2020-09-01 |title=Another umbrella murder? – A rare case of Minamata disease |url=https://doi.org/10.1007/s12024-020-00247-y |journal=Forensic Science, Medicine and Pathology |language=en |volume=16 |issue=3 |pages=504–509 |doi=10.1007/s12024-020-00247-y |issn=1556-2891 |pmc=7449996 |pmid=32323188}}</ref><ref>{{cite news |date=11 May 2012 |title=Umbrella stab victim dies of mercury poisoning |language=en |website=www.thelocal.de |url=https://www.thelocal.de/20120511/42495/ |access-date=13 June 2022}}</ref><ref>{{cite magazine |date=11 May 2012 |title=Quecksilbervergiftung |trans-title=Mercury poisoning |url=https://www.spiegel.de/panorama/justiz/quecksilbervergiftung-mann-stirbt-nach-angrif-mit-spritze-in-hannover-a-832677.html |magazine=[[Der Spiegel]] |language=de |access-date=3 September 2020}}</ref> Police investigations, however, revealed a syringe containing a typical mercury thallium compound in Bulwin's car, and mercury and thallium in thermometers at his workplace. Inconclusive antemortem and postmortem blood, urine, and tissue analysis cast doubts on the assault account. The absence of an identified assailant or motive, as well as the presence of different mercury compounds in Bulwin's car, led police to conclude that the intoxication was likely self-administered, thereby terminating the preliminary investigation.<ref>{{cite journal |last=Albers |first=Anne |last2=Gies |first2=Ursula |last3=Raatschen |first3=Hans-Jurgen |last4=Klintschar |first4=Michael |date=2020-09-01 |title=Another umbrella murder? – A rare case of Minamata disease |url=https://doi.org/10.1007/s12024-020-00247-y |journal=Forensic Science, Medicine and Pathology |language=en |volume=16 |issue=3 |pages=504–509 |doi=10.1007/s12024-020-00247-y |issn=1556-2891 |pmc=7449996 |pmid=32323188}}</ref>

{{Reflist}}

* [https://www.atsdr.cdc.gov/toxfaqs/TF.asp?id=113&tid=24 ATSDR – ToxFAQs: Mercury]

* [https://www.atsdr.cdc.gov/PHS/PHS.asp?id=112&tid=24 ATSDR – Public Health Statement: Mercury]

* [https://www.atsdr.cdc.gov/MMG/MMG.asp?id=106&tid=24 ATSDR – MMG: Mercury]

* [https://www.atsdr.cdc.gov/toxprofiles/TP.asp?id=115&tid=24 ATSDR – Toxicological Profile: Mercury]

* [https://web.archive.org/web/20060425193836/http://www.npi.gov.au/database/substance-info/profiles/53.html National Pollutant Inventory – Mercury and compounds Fact Sheet]

{{Chemical agents}}

{{Mercury compounds}}

{{Neurotoxins}}

{{Use dmy dates|date=January 2021}}

[[Category:Methyl complexes]]