Jump to content

Ethylmercury

From Wikipedia, the free encyclopedia
(Redirected from Ethyl mercury)
Ethylmercury
Identifiers
3D model (JSmol)
3903035
ChEBI
ChemSpider
EC Number
  • chloride: 203-478-0
  • bromide: 203-477-5
  • iodide: 219-471-0
323460
UNII
  • InChI=1S/C2H5.Hg/c1-2;/h1H2,2H3;/q;+1 checkY
    Key: MJOUBOKSWBMNGQ-UHFFFAOYSA-N checkY
  • chloride: InChI=1S/C2H5.ClH.Hg/c1-2;;/h1H2,2H3;1H;/q;;+1/p-1
    Key: QWUGXIXRFGEYBD-UHFFFAOYSA-M
  • bromide: InChI=1S/C2H5.BrH.Hg/c1-2;;/h1H2,2H3;1H;/q;;+1/p-1
    Key: UREACWLAXSOUKG-UHFFFAOYSA-M
  • iodide: InChI=1S/C2H5.Hg.HI/c1-2;;/h1H2,2H3;;1H/q;+1;/p-1
    Key: BYIGJUQTUPMNMF-UHFFFAOYSA-M
  • CC[Hg+]
  • chloride: CC[Hg]Cl
  • bromide: CC[Hg]Br
  • iodide: CC[Hg]I
Properties
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).
☒N verify (what is checkY☒N ?)

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

[edit]
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

[edit]

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.[6][7] In monkeys, it clears from brain tissue with a half-life of 24 days and blood in 7 days.[8]

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.[9]

Public health concerns

[edit]

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).[10] 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.[1] 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.[1]

See also

[edit]

References and notes

[edit]
  1. ^ a b c d e 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.[verification needed]
  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. ^ Burbacher, Thomas M. (2005). "Comparison of Blood and Brain Mercury Levels in Infant Monkeys Exposed to Methylmercury or Vaccines Containing Thimerosal". Environmental Health Perspectives. 113 (8): 1015–1021. doi:10.1289/ehp.7712. ISSN 0091-6765. PMC 1280342. PMID 16079072. See researchgate.net/figure/A-semilogarithmic-plot-of-washout-of-total-Hg-in-blood-and-the-brain-after-four-weekly-im_fig6_7681091
  9. ^ "Organic Mercury--TEACH Chemical Summary--U.S. EPA, Toxicity and Exposure Assessment for Children's Health" (PDF). Methyl- and ethylmercury have been used previously as fungicides on seeds used for growing crops, but such use is currently cancelled in the U.S.
  10. ^ Research, Center for Biologics Evaluation and (2019-04-05). "Thimerosal and Vaccines". FDA.

Further reading

[edit]
[edit]