Ethylmercury

Ethylmercury
Identifiers
CAS Number
3D model (JSmol)
Beilstein Reference
 3903035
ChEBI
ChemSpider
Gmelin Reference
 323460
PubChem CID
InChI
  • InChI=1S/C2H5.Hg/c1-2;/h1H2,2H3;/q;+1 checkY
    Key: MJOUBOKSWBMNGQ-UHFFFAOYSA-N checkY
SMILES
  • CC[Hg+]
Properties
Chemical formula
 C2H5Hg+
Molar mass 229.65 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Ethylmercury (sometimes ethyl mercury) is a cation composed of an organic CH3CH2- species (an ethyl group) 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.[1]

Synthesis and structure

Structures of two main types of complexes derived from "ethylmercury". X− = anion, L = neutral Lewis base.

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 as in thiomersal. In the body, ethylmercury is most commonly encountered as derivatives with a thiolate attached to the mercury.[2] 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.[3]: p. 79 

Toxicity

The toxicity of ethylmercury is well studied.[4][1] Like methylmercury, ethylmercury distributes to all body tissues, crossing the blood–brain barrier and the placental barrier, and ethylmercury also moves freely throughout the body.[5] Risk assessment for effects on the human nervous system have been made by extrapolating from dose-response relationships for methylmercury.[1] Estimates have suggested that ethylmercury clears from blood with a half-life of 3–7 days in adult humans; however, this area has not been well studied.[6][7]

Public health concerns

Concerns based on extrapolations from methylmercury caused thiomersal 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 with no thimerosal are available[8]). 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.[1] 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.[1]

See also

References and notes

  1. 1 2 3 4 5 Clarkson, Thomas W.; Magos, Laszlo (September 2006). "The toxicology of mercury and its chemical compounds". Critical Reviews in Toxicology. 36 (8): 609–62. doi:10.1080/10408440600845619. PMID 16973445. S2CID 37652857.
  2. ↑ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  3. ↑ Elschenbroich C (2016). "Main-Group Organometallics [§6.2.3 Organomercury Compounds]". Organometallics (3rd ed.). New York, NY: John Wiley & Sons. pp. 78–86. ISBN 978-3-527-80514-3. Retrieved 13 February 2017.
  4. ↑ Counter, S.Allen; Buchanan, Leo H. (2004). "Mercury exposure in children: A review". Toxicology and Applied Pharmacology. 198 (2): 209–230. doi:10.1016/j.taap.2003.11.032. PMID 15236954.
  5. ↑ Clarkson TW, Vyas JB, Ballatori N (October 2007). "Mechanisms of mercury disposition in the body". American Journal of Industrial Medicine. 50 (10): 757–64. doi:10.1002/ajim.20476. PMID 17477364.
  6. ↑ Clifton JC (April 2007). "Mercury exposure and public health". Pediatric Clinics of North America. 54 (2): 237–69, viii. doi:10.1016/j.pcl.2007.02.005. PMID 17448359.
  7. ↑ "Weekly Epidemiological Record, vol. 87, 30 (pp 277–288)". WHO. 2012-07-27. Archived from the original on October 19, 2014. Retrieved 2020-05-10.
  8. ↑ Research, Center for Biologics Evaluation and (2019-04-05). "Thimerosal and Vaccines". FDA.

Further reading

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