Chemistry:2-Fluoroethanol

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2-Fluoroethanol[1]
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Names
Preferred IUPAC name
2-Fluoroethan-1-ol
Other names
Ethylene fluorohydrine
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
UNII
Properties
C2H5FO
Molar mass 64.059 g·mol−1
Density 1.1040 g cm−3[1]
Melting point −26.3 °C (−15.3 °F; 246.8 K)[1]
Boiling point 103.5 °C (218.3 °F; 376.6 K)[1]
miscible[1]
Solubility Soluble in ethanol, ethyl ether, acetone
Vapor pressure 19 mbar (15 °C)[1]
Acidity (pKa) 14.74 (predicted)[2]
Hazards
GHS pictograms GHS06: Toxic GHS02: Flammable
H226, H300+310+330Script error: No such module "Preview warning".Category:GHS errors
P210, P233, P240, P241, P242, P243, P260, P262, P264, P270, P271, P280, P284, P301+310+330Script error: No such module "Preview warning".Category:GHS errors, P303+361+353, P304+340+310, P363, P370+378, P403+233, P403+235, P405, P501
NFPA 704 (fire diamond)
Flammability code 2: Must be moderately heated or exposed to relatively high ambient temperature before ignition can occur. Flash point between 38 and 93 °C (100 and 200 °F). E.g. diesel fuelHealth code 4: Very short exposure could cause death or major residual injury. E.g. VX gasReactivity (yellow): no hazard codeSpecial hazards (white): no codeNFPA 704 four-colored diamond
2
4
Flash point 34 °C (93.2 °F; 307.15 K)
Related compounds
Other anions
 2-Chloroethanol
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
Tracking categories (test):

2-Fluoroethanol is the organic compound with the formula CH2FCH2OH. This colorless liquid is one of the simplest stable fluorinated alcohols. It was once used as a pesticide. The related difluoro- and trifluoroethanols are far less dangerous.[3]

Synthesis

2-Fluoroethanol was originally synthesized by treating 2-chloroethanol with potassium fluoride, in a simple Finkelstein reaction.[4] The product has a lower boiling point that the starting material and may be conveniently isolated by distillation.

ClCH2CH2OH + KF → FCH2CH2OH + KCl

Similar procedures start from (1,3)-dioxolan-2-one[5] and from 2-bromoethanol.[6]

Structure and reactivity

Hydrogen bonding stabilizes the gauche conformer.[7][8]

In a basic solution, 2-fluoroethanol undergoes dehydrofluorination, giving acetaldehyde.[9]

Reaction of 2-fluoroethanol with trifluoromethanesulfonic anhydride in the presence of base gives the triflate ester.[10]

PET radiotracers

2-[18F]-fluoroethoxy group is a common moiety in the structures of radiotracers used with PET. Such radiotracers include fluoroethyl-l-tyrosine 1-(2-[18F]-fluoroethoxy)-4-nitrobenzene and [18F]-fluoroethyl 4-fluorobenzoate, being a [18F]fluoroalkyl ether and ester respectively.[11][10]

Metabolism

It was patented as a rodenticide in Germany in 1935.[12] In rats, it was found that fluoroethanol induced a similar toxicity as that of fluoroacetate, known to metabolize to fluorocitrate to exert the toxic effect.[12]

2-Fluoroethanol is converted by alcohol dehydrogenase (ADH) using nicotinamide adenine dinucleotide (NAD+) as cofactor,[12] ultimately leading to the formation of fluoroacetaldehyde and then fluoroacetate.[12]

Fluoroacetate is a precursor to fluorocitrate,[13] an inhibitor of aconitase, an enzyme that participates in the TCA cycle.[14]

Toxicity

Reported effects of 2-fluoroethanol are epigastric distress effects, such as vomiting, and central nervous effects, such as auditory hallucinations, numbness feeling of the face or nose. Both these types of effects occur gradually after being exposed to 2-fluoroethanol for several hours. Some more severe reactions of the human body to 2-fluoroethanol can be respiratory failure and epileptiform convulsions or seizures, leading to dysfunctions in the heart mechanism. From the early 20th century, there are multiple reports of deaths caused by 2-fluoroethanol.[15]

2-Fluoroethanol is also toxic to other animals with LD50 ranging from 7 to 1500 mg/kg bodyweight.

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Record of CAS RN 371-62-0 in the GESTIS Substance Database of the Institute for Occupational Safety and Health, accessed on 18. February 2010.
  2. ↑ "Ethylene fluorohydrin (CHEM004230)". https://contaminantdb.ca/contaminants/CHEM004230. 
  3. ↑ Siegemund, Günter; Schwertfeger, Werner; Feiring, Andrew; Smart, Bruce; Behr, Fred; Vogel, Herward; McKusick, Blaine (2000). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_349. 
  4. ↑ Hoffmann, Friedrich W. (1948). "Preparation of Aliphatic Fluorides". Journal of the American Chemical Society 70 (7): 2596–2597. doi:10.1021/ja01187a505. PMID 18875124. 
  5. ↑ Shahak, Israel; Bergmann, Ernst D. (1965). "A convenient of synthesis β- and γ-fluoro-alcohols". Chem. Commun. (7): 122a. doi:10.1039/c1965000122a. 
  6. ↑ Bhadury, Pinaki S.; Raza, Syed K.; Jaiswal, Devendra K. (1999). "A semi-molten mixture of hexadecyltributylphosphonium bromide and potassium fluoride in the synthesis of organofluorine compounds". Journal of Fluorine Chemistry 99 (2): 115–117. doi:10.1016/s0022-1139(99)00121-9. 
  7. ↑ Huang, Jinfan; Hedberg, Kenneth (1989). "Conformational analysis. 13. 2-Fluoroethanol. An investigation of the molecular structure and conformational composition at 20, 156, and 240.degree.. Estimate of the anti-gauche energy difference". Journal of the American Chemical Society 111 (18): 6909–6913. doi:10.1021/ja00200a003. 
  8. ↑ Dixon, David A.; Smart, Bruce E. (1991). "Conformational energies of 2-fluoroethanol and 2-fluoroacetaldehyde enol: Strength of the internal hydrogen bond". The Journal of Physical Chemistry 95 (4): 1609–1612. doi:10.1021/j100157a020. 
  9. ↑ Bronnert, D.L.E.; Saunders, B.C. (1960). "Toxic fluorine compounds containing the C—F link—XI". Tetrahedron 10 (3–4): 160–163. doi:10.1016/s0040-4020(01)97802-0. 
  10. ↑ 10.0 10.1 Falzon, C. L., Ackermann, U., Spratt, N., Tochon-Danguy, H. J., White, J., Howells, D., & Scott, A. M. (2006).F-18 labelledN,N-bis-haloethylamino-phenylsulfoxides — a new class of compounds for the imaging of hypoxic tissue. Journal of Labelled Compounds and Radiopharmaceuticals, 49(12), 1089–1103. https://doi.org/10.1002/jlcr.1129
  11. ↑ Pan, J., Pourghiasian, M., Hundal, N., Lau, J., Bénard, F., Dedhar, S., & Lin, K.-S. (2013). 2-[18F]-fluoroethanol and 3-[18F]-fluoropropanol: facile preparation, biodistribution in mice, and their application as nucleophiles in the synthesis of [18F]fluoroalkyl aryl ester and ether PET tracers. Nuclear Medicine and Biology, 40(6), 850–857. https://doi.org/10.1016/j.nucmedbio.2013.04.009
  12. ↑ 12.0 12.1 12.2 12.3 Treble D. H. (1962). The metabolism of 2-fluoroethanol. The Biochemical journal, 82(1), 129–134. https://doi.org/10.1042/bj0820129
  13. ↑ Goncharov, N. V., Jenkins, R. O., & Radilov, A. S. (2006). Toxicology of fluoroacetate: a review, with possible directions for therapy research. Journal of applied toxicology : JAT, 26(2), 148–161. https://doi.org/10.1002/jat.1118
  14. ↑ Timbrell, J. A. (2008). Principles of Biochemical Toxicology (Fourth Edition). Taylor & Francis. p. 358-359.
  15. ↑ Saunders, B. C., Stacey, G. J., & Wilding, I. G. E. (1948). Toxic Fluorine Compounds Containing the C-F Link. Part II. 2-Fluoroethanol and its Derivatives. University Chemical Laboratory Cambridge, 1. Retrieved from https://pubs-rsc-org.ru.idm.oclc.org/en/content/articlepdf/1949/jr/jr9490000773.




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