Ethylmercury (sometimes ethyl mercury) is a

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

composed of an organic CH₃CH₂— species (an

ethyl group In organic chemistry, an ethyl group (abbr. Et) is an alkyl substituent with the formula , derived from ethane (). ''Ethyl'' is used in the International Union of Pure and Applied Chemistry The International Union of Pure and Applied ...

) bound to a mercury(II) centre, making it a type of

organometallic Organometallic chemistry is the study of organometallic compounds, chemical compounds containing at least one chemical bond between a carbon atom of an organic molecule and a metal, including alkali, alkaline earth, and transition metals, and so ...

cation, and giving it a chemical formula C₂H₅Hg⁺. The main source of ethylmercury is thimerosal.

Synthesis and structure

Ethylmercury (C₂H₅Hg⁺) is a substituent of compounds: it occurs as a component of compounds of the formula C₂H₅HgX where X = chloride,

thiolate In organic chemistry, a thiol (; ), or thiol derivative, is any organosulfur compound of the form , where R represents an alkyl or other organic substituent. The functional group itself is referred to as either a thiol group or a sulfhydryl grou ...

, or another organic group. Most famously X = the mercaptide group of thiosalicylic acid as in

thiomersal Thiomersal (International Nonproprietary Name, INN), or thimerosal (United States Adopted Name, USAN, Japanese Accepted Name, JAN), also sold under the name merthiolate, is an organomercury compound. It is a well-established antiseptic and antif ...

. In the body, ethylmercury is most commonly encountered as derivatives with a thiolate attached to the mercury. In these compounds, Hg(II) has a linear or sometimes trigonal coordination geometry. Given the comparable electronegativities of mercury and carbon, the mercury-carbon bond is described as covalent.

Toxicity

The toxicity of ethylmercury is well studied. Like

methylmercury Methylmercury is an organometallic cation with the formula . It is the simplest organomercury compound. Methylmercury is extremely toxic, and its derivatives are the major source of organic mercury for humans. It is a bioaccumulative environment ...

, ethylmercury distributes to all body tissues, crossing the

blood–brain barrier The blood–brain barrier (BBB) is a highly selective semipermeable membrane, semipermeable border of endothelium, endothelial cells that regulates the transfer of solutes and chemicals between the circulatory system and the central nervous system ...

and the placental barrier, and ethylmercury also moves freely throughout the body. Risk assessment for effects on the human nervous system have been made by extrapolating from dose-response relationships for

. Estimates have suggested that ethylmercury clears from blood with a

half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...

of 3—7 days in adult humans. In monkeys, it clears from brain tissue with a

of 24 days and blood in 7 days. It is a fungicide but has been banned from use in the U.S. on food grain and even on seeds only used to grow crops.

Public health concerns

Concerns based on extrapolations of the effect of methylmercury caused thimerosal to be removed from U.S. childhood vaccines in 1999, but it remains in use in all multi-dose vaccines and flu shots (though many single use vaccines without thimerosal are available). Researchers have argued that risk assessments based on methylmercury were overly conservative in light of observations that ethylmercury is eliminated from the body and the brain significantly faster than methylmercury. Moreover, the same researchers have argued that inorganic mercury metabolized from ethylmercury, despite its much longer half-life in the brain, is much less toxic than the inorganic mercury produced from mercury vapor, for reasons not yet understood.

References and notes

External links

EPA Organic Mercury TEACH Chemical Summary, 2007.

EPA Chemistry Dashboard, Ethyl Mercury Ion, 2017.

ATSDR Toxicological Profile for Mercury, search "Organic Mercury".
{{Mercury compounds Organomercury compounds Cations Mercury(II) compounds

Synthesis and structure

Toxicity

Public health concerns

See also

References and notes

Further reading

External links