Ethylmercury (sometimes ethyl mercury) is a cation composed of an

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...

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's nomenclature of organic chemistry for a saturated ...

) bound to a mercury(II) centre, making it a type of organometallic 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, or another organic group. Most famously X = the mercaptide group of

thiosalicylic acid Thiosalicylic acid is an organosulfur compound containing carboxyl and sulfhydryl functional groups. Its molecular formula is C6H4(SH)(CO2H). it is a yellow solid that is slightly soluble in water, ethanol and diethyl ether, and alkanes, but more ...

as in thiomersal. 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 Electronegativity, symbolized as , is the tendency for an atom of a given chemical element to attract shared electrons (or electron density) when forming a chemical bond. An atom's electronegativity is affected by both its atomic number and the d ...

of mercury and carbon, the mercury-carbon bond is described as covalent.

Toxicity

The toxicity of ethylmercury is well studied. Like methylmercury, ethylmercury distributes to all body tissues, crossing the

blood–brain barrier The blood–brain barrier (BBB) is a highly selective semipermeable border of endothelial cells that prevents solutes in the circulating blood from ''non-selectively'' crossing into the extracellular fluid of the central nervous system where ne ...

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

methylmercury Methylmercury (sometimes methyl mercury) 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 i ...

. Estimates have suggested that ethylmercury clears from blood with a

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ...

of 3–7 days in adult humans; however, this area has not been well studied.

Public health concerns

Concerns based on extrapolations from methylmercury caused thimerosal to be removed from U.S. childhood vaccines, starting in 1999, but remains in all multi-dose vaccines and flu shots (though many single use vaccines without thimerosal are available). Clarkson has 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, Clarkson has 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