Dimethylmercury is an extremely toxicorganomercury compound with the formula (CH3)2Hg. A volatile, flammable, dense and colorless liquid, dimethylmercury is one of the strongest knownneurotoxins. Less than 0.1 mL is capable of inducing severemercury poisoning resulting in death.[2]
Dimethylmercury is stable in water and reacts with mineral acids at a significant rate only at elevated temperatures,[5][6] whereas the correspondingorganocadmium andorganozinc compounds (and most metal alkyls in general) hydrolyze rapidly. The difference reflects the highelectronegativity of Hg (Pauling EN = 2.00) and the low affinity of Hg(II) for oxygen ligands. The compound undergoes aredistribution reaction with mercuric chloride to give methylmercury chloride（actually, this is a reversible equilibrium）:
Dimethylmercury has few practical applications because of its danger to human life. It has been studied for reactions involving bondingmethylmercury cations to target molecules, forming potentbactericides, but methylmercury'sbioaccumulation and ultimate toxicity has led to it being largely abandoned in favor of the less toxicethylmercury anddiethylmercury compounds, which perform a similar function without the bioaccumulation hazard.[citation needed]
Intoxicology, it still finds limited use as a reference toxin. It is also used to calibrateNMR instruments for detection of mercury (δ 0 ppm for199Hg NMR), although diethylmercury and less toxic mercury salts are now preferred.[8][9][10]
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 highvapor 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.[citation needed]
Permeation tests showed that several types of disposable latex or polyvinyl chloride gloves (typically, about 0.1 mm thick), commonly used in mostlaboratories and clinical settings, had high and maximal rates of permeation by dimethylmercury within 15 seconds.[12] The AmericanOccupational 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 afume hood.[2][13]
Dimethylmercury is metabolized after several days tomethylmercury.[12] Methylmercury crosses theblood–brain barrier easily, probably owing to formation of acomplex withcysteine.[13] It easily absorbs into the body and has a tendency tobioaccumulate. 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] Methylmercury poisoning is also known asMinamata disease.
As early as 1865, two workers in the laboratory ofEdward Frankland died after exhibiting progressive neurological symptoms following accidental exposure to the compound.[3]
Karen Wetterhahn, a professor of chemistry atDartmouth College, died in 1997, ten months after spilling only a few drops of dimethylmercury onto her latex gloves.[2][14] 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 asnitrile. NewOSHA material-handling guidelines were published, many institutions purged their supplies of the compound, and it became almost impossible to buy.[15]
Christoph Bulwin, a 40-year-old database administrator forIG Bergbau, Chemie, Energie, claimed to have been attacked with asyringe-tipped umbrella on 15 July 2011 inHanover. Bulwin, who died a year later from mercury poisoning, had said he confiscated the syringe, which was later found to contain dimethylmercury.[16][17][18] According to a 2020 article inForensic Science, Medicine and Pathology, police investigations 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.[19] TheForensic Science, Medicine and Pathology account is contradicted by other reports, including the August 24, 2022 episode of the German flagship true crime TV programAktenzeichen XY... ungelöst that was co-edited by the Hannover criminal police and in which information was solicited from the public based on Bulwin's own umbrella scenario.[20]
^"dimethylmercury – Compound Summary".PubChem Compound. US: National Center for Biotechnology Information. 16 September 2004. Identification and Related Records. Retrieved29 January 2021.
^O'Halloran, T. V.; Singer, C. P. (10 March 1998)."199Hg Standards". Northwestern University. Archived fromthe original on 14 May 2005. Retrieved20 January 2021.
^Hoffman, R. (1 August 2011)."(Hg) Mercury NMR". Jerusalem: The Hebrew University. Retrieved29 January 2021.
