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Trifluoroacetic acid

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For the abbreviation TFA, or another perfluoro compound, seeTFA (disambiguation)andTrifluoroacetone.
On Wikipedia, TFA refers toToday's featured article.

Trifluoroacetic acid
Names
Preferred IUPAC name
Trifluoroacetic acid
Other names
2,2,2-Trifluoroacetic acid
2,2,2-Trifluoroethanoic acid
Perfluoroacetic acid
Trifluoroethanoic acid
TFA
Identifiers
3D model (JSmol)
742035
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.000.846Edit this at Wikidata
2729
RTECS number
  • AJ9625000
UNII
  • InChI=1S/C2HF3O2/c3-2(4,5)1(6)7/h(H,6,7)checkY
    Key: DTQVDTLACAAQTR-UHFFFAOYSA-NcheckY
  • InChI=1/C2HF3O2/c3-2(4,5)1(6)7/h(H,6,7)
    Key: DTQVDTLACAAQTR-UHFFFAOYAP
  • FC(F)(F)C(=O)O
Properties
C2HF3O2
Molar mass 114.023g·mol−1
Appearance colorless liquid
Odor Pungent/Vinegar
Density 1.489 g/cm3,20 °C
Melting point −15.4 °C (4.3 °F; 257.8 K)
Boiling point 72.4 °C (162.3 °F; 345.5 K)
miscible
Vapor pressure 0.0117 bar (1.17 kPa) at 20 °C[1]
Acidity(pKa) 0.52[2]
Conjugate base trifluoroacetate
-43.3·10−6cm3/mol
Hazards
Occupational safety and health(OHS/OSH):
Main hazards
 Highly corrosive
GHSlabelling:
GHS05: CorrosiveGHS07: Exclamation mark
Danger
H314,H332,H412
P260,P261,P264,P271,P273,P280,P301+P330+P331,P303+P361+P353,P304+P312,P304+P340,P305+P351+P338,P310,P312,P321,P363,P405,P501
NFPA 704(fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
3
1
1
Safety data sheet(SDS) External MSDS
Related compounds
Related perfluorinated acids
 Heptafluorobutyric acid
Perfluorooctanoic acid
Perfluorononanoic acid
Related compounds
 Acetic acid
Trichloroacetic acid
Except where otherwise noted, data are given for materials in theirstandard state(at 25 °C [77 °F], 100 kPa).

Trifluoroacetic acid(TFA) is a syntheticorganofluorinecompound with thechemical formulaCF3CO2H. It is ahaloacetic acid,with all three of the acetyl group's hydrogen atoms replaced by fluorine atoms. It is a colorless liquid with avinegar-like odor. TFA is a stronger acid than acetic acid, having anacid ionisation constant,Ka,that is approximately 34,000 times higher,[3]as the highlyelectronegativefluorine atoms and consequentelectron-withdrawing natureof thetrifluoromethylgroup weakens the oxygen-hydrogen bond (allowing for greater acidity) and stabilises theanionicconjugate base.TFA is commonly used inorganic chemistryfor various purposes.

Synthesis

[edit]

TFA is prepared industrially by theelectrofluorinationofacetyl chlorideoracetic anhydride,followed by hydrolysis of the resulting trifluoroacetyl fluoride:[4]

CH
3COCl+ 4HF→CF
3COF+ 3H
2+HCl
CF
3COF+H
2O→CF
3COOH+HF

Where desired, this compound may be dried by addition oftrifluoroacetic anhydride.[5]

An older route to TFA proceeds via theoxidationof 1,1,1-trifluoro-2,3,3-trichloropropene withpotassium permanganate.The trifluorotrichloropropene can be prepared bySwarts fluorinationofhexachloropropene.[6]

Uses

[edit]
Trifluoroacetic acid in a beaker

TFA is the precursor to many other fluorinated compounds such astrifluoroacetic anhydride,trifluoroperacetic acid,and2,2,2-trifluoroethanol.[4]It is areagentused inorganic synthesisbecause of a combination of convenient properties: volatility,solubilityinorganic solvents,and its strength as an acid.[7]TFA is also lessoxidizingthansulfuric acidbut more readily available in anhydrous form than many other acids. One complication to its use is that TFA forms anazeotropewith water (b. p. 105 °C).

TFA is used as a strong acid to removeprotecting groupssuch asBocused in organic chemistry andpeptide synthesis.[8][9]

At a low concentration, TFA is used as anion pairingagent inliquid chromatography(HPLC) of organic compounds, particularlypeptidesand smallproteins.TFA is a versatile solvent forNMR spectroscopy(for materials stable in acid). It is also used as a calibrant inmass spectrometry.[10]

TFA is used to produce trifluoroacetate salts.[11]

Safety

[edit]

Trifluoroacetic acid is a strong acid.[12]TFA is harmful when inhaled, causes severe skin burns and is toxic foraquatic organismseven at low concentrations.

Environment

[edit]

Although trifluoroacetic acid is not produced biologically or abiotically,[13]it is a metabolic breakdown product of thevolatile anesthetic agenthalothane.It is also thought to be responsible for halothane-inducedhepatitis.[14]It also may be formed byphotooxidationof the commonly usedrefrigerant1,1,1,2-tetrafluoroethane(R-134a).[citation needed]Moreover, it is formed as an atmospheric degradation product of almost all fourth-generation synthetic refrigerants, also calledhydrofluoroolefins(HFO), such as2,3,3,3-tetrafluoropropene.[15][16]

Trifluoroacetic aciddegrades very slowlyin the environment and has been found in increasing amounts as a contaminant in water, soil, food, and the human body.[17]Median concentrations of a few micrograms per liter have been found in beer and tea.[18]Seawatercan contain about 200 ng of TFA per liter.[19][20][21]Biotransformationbydecarboxylationtofluoroformhas been discussed.[22]

Trifluoroacetic acid is mildlyphytotoxic.[23]

See also

[edit]

References

[edit]
  1. ^Kreglewski, A. (1962)."Trifluoroacetic acid".Welcome to the NIST WebBook.10(11–12): 629–633.Retrieved1 March2020.
  2. ^W. M. Haynes.; David R. Lide; Thomas J. Bruno, eds. (2016–2017).CRC Handbook of Chemistry and Physics.CRC Press. pp. 954–963.ISBN978-1-4987-5429-3.
  3. ^Note:Calculated from the ratio of theKavalues for TFA (pKa= 0.23) and acetic acid (pKa= 4.76)
  4. ^abG. Siegemund; W. Schwertfeger; A. Feiring; B. Smart; F. Behr; H. Vogel; B. McKusick. "Fluorine Compounds, Organic".Ullmann's Encyclopedia of Industrial Chemistry.Weinheim: Wiley-VCH.doi:10.1002/14356007.a11_349.ISBN978-3527306732.
  5. ^Wilfred L.F. Armarego & Christina Li Lin Chai (2009). "Chapter 4 – Purification of Organic Chemicals".Purification of Laboratory Chemicals(6th ed.). pp. 88–444.doi:10.1016/B978-1-85617-567-8.50012-3.ISBN978-1-85617-567-8.
  6. ^Gergel, Max G.(March 1977).Excuse me sir, would you like to buy a kilo of isopropyl bromide?.Pierce Chemical. pp. 88–90.
  7. ^Eidman, K. F.; Nichols, P. J. (2004). "Trifluoroacetic Acid". In L. Paquette (ed.).Encyclopedia of Reagents for Organic Synthesis.New York: J. Wiley & Sons.doi:10.1002/047084289X.rt236.pub2.hdl:10261/236866.ISBN978-0-471-93623-7.
  8. ^Lundt, Behrend F.; Johansen, Nils L.; Vølund, Aage; Markussen, Jan (1978). "Removal of t-Butyl and t-Butoxycarbonyl Protecting Groups with Trifluoroacetic acid".International Journal of Peptide and Protein Research.12(5): 258–268.doi:10.1111/j.1399-3011.1978.tb02896.x.PMID744685.
  9. ^Andrew B. Hughes (2011). "1. Protection Reactions". In Vommina V. Sureshbabu; Narasimhamurthy Narendra (eds.).Amino Acids, Peptides and Proteins in Organic Chemistry: Protection Reactions, Medicinal Chemistry, Combinatorial Synthesis.Vol. 4. pp. 1–97.doi:10.1002/9783527631827.ch1.ISBN978-3-527-63182-7.
  10. ^Stout, Steven J.; Dacunha, Adrian R. (1989). "Tuning and calibration in thermospray liquid chromatography/mass spectrometry using trifluoroacetic acid cluster ions".Analytical Chemistry.61(18): 2126.doi:10.1021/ac00193a027.
  11. ^O. Castano; A. Cavallaro; A. Palau; J. C. Gonzalez; M. Rossell; T. Puig; F. Sandiumenge; N. Mestres; S. Pinol; A. Pomar & X. Obradors (2003). "High quality YBa2Cu3O7thin films grown by trifluoroacetates metal-organic deposition ".Superconductor Science and Technology.16(1): 45–53.Bibcode:2003SuScT..16...45C.doi:10.1088/0953-2048/16/1/309.S2CID250765145.
  12. ^Henne, Albert L; Fox, Charles J (1951)."Ionization constants of fluorinated acids".Journal of the American Chemical Society.73(5): 2323–2325.doi:10.1021/ja01149a122.
  13. ^Joudan, Shira; De Silva, Amila O.; Young, Cora J. (2021). "Insufficient evidence for the existence of natural trifluoroacetic acid".Environmental Science: Processes & Impacts.23(11): 1641–1649.doi:10.1039/D1EM00306B.hdl:10315/40884.ISSN2050-7887.PMID34693963.S2CID239768006.
  14. ^"Halothane",LiverTox: Clinical and Research Information on Drug-Induced Liver Injury,Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases, 2012,PMID31643481,retrieved15 July2021
  15. ^"Degradation products of fluorinated greenhouse gases".Umweltbundesamt.19 June 2023.Retrieved27 September2024.
  16. ^"TFA as an atmospheric breakdown product".Fluorocarbons.European FluoroCarbons Technical Committee, (Ceficsector group). 6 December 2023.Retrieved27 September2024.
  17. ^Hosea, Leana; Salvidge, Rachel (1 May 2024)."Rapidly rising levels of TFA 'forever chemical' alarm experts".The Guardian.ISSN0261-3077.Retrieved29 May2024.
  18. ^Marco Scheurer, Karsten Nödler (2021). "Ultrashort-chain perfluoroalkyl substance trifluoroacetate (TFA) in beer and tea – An unintended aqueous extraction".Food Chemistry.351:129304.doi:10.1016/j.foodchem.2021.129304.ISSN0308-8146.PMID33657499.S2CID232115008.
  19. ^Frank, H.; Christoph, E. H.; Holm-Hansen, O.; Bullister, J. L. (January 2002). "Trifluoroacetate in ocean waters".Environ. Sci. Technol.36(1): 12–5.Bibcode:2002EnST...36...12P.doi:10.1021/es0221659.PMID11811478.
  20. ^Scott, B. F.; MacDonald, R. W.; Kannan, K.; Fisk, A.; Witter, A.; Yamashita, N.; Durham, L.; Spencer, C.; Muir, D. C. G. (September 2005). "Trifluoroacetate profiles in the Arctic, Atlantic, and Pacific Oceans".Environ. Sci. Technol.39(17): 6555–60.Bibcode:2005EnST...39.6555S.doi:10.1021/es047975u.PMID16190212.
  21. ^Frank, Hartmut; Christoph, Eugen H.; Holm-Hansen, Osmund; Bullister, John L. (2002). "Trifluoroacetate in Ocean Waters".Environmental Science & Technology.36(1): 12–15.Bibcode:2002EnST...36...12F.doi:10.1021/es0101532.ISSN0013-936X.PMID11811478.
  22. ^Visscher, Pieter T.; Culbertson, Charles W.; Oremland, Ronald S. (June 1994). "Degradation of trifluoroacetate in oxic and anoxic sediments".Nature.369(6483): 729–731.Bibcode:1994Natur.369..729V.doi:10.1038/369729a0.
  23. ^Boutonnet, Jean Charles; Bingham, Pauline; Calamari, Davide; Rooij, Christ de; Franklin, James; Kawano, Toshihiko; Libre, Jean-Marie; McCul-Loch, Archie; Malinverno, Giuseppe; Odom, J Martin; Rusch, George M; Smythe, Katie; Sobolev, Igor; Thompson, Roy; Tiedje, James M (1999). "Environmental risk assessment of trifluoroacetic acid".International Journal of Human and Ecological Risk Assessment.5(1): 59–124.Bibcode:1999HERA....5...59B.doi:10.1080/10807039991289644.
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