Trifluoroacetic acid

Structural formula
	Wedges to clarify the geometry
General
Surname	Trifluoroacetic acid
other names	Trifluoroethanoic acid; 2,2,2-trifluoroethanoic acid; TFA;
Molecular formula	C 2 HF 3 O 2
Brief description	colorless, pungent smelling liquid
External identifiers / databases
EC number	200-929-3
ECHA InfoCard	100,000,846
PubChem	6422
ChemSpider	10239201
Wikidata	Q412033
properties
Molar mass	114.02 g mol −1
Physical state	liquid
density	1.48 g cm −3 (20 ° C)
Melting point	−15.25 ° C
boiling point	72.5 ° C
Vapor pressure	130 h Pa (20 ° C)
pK s value	0.23
solubility	miscible with water, ethanol , acetone and diethyl ether
Refractive index	1.2855
safety instructions
H and P phrases	H: 290-331-314-412
	EUH: 071
	P: 260-273-280-303 + 361 + 353-305 + 351 + 338-312
Thermodynamic properties
ΔH f 0	−1069.9 kJ / mol
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Trifluoroacetic acid (abbreviation: TFA) is a synthetic chemical compound from the group of carboxylic acids . It is a fluorinated derivative of acetic acid , with all three hydrogen atoms of the methyl group being replaced (" substituted ") by fluorine atoms . Their salts and esters are called trifluoroacetates .

Occurrence

Trifluoroacetic acid is formed in the environment through photo-oxidation of the frequently used refrigerant 1,1,1,2-tetrafluoroethane . Trifluoroacetic acid is also formed as an atmospheric breakdown product in almost all synthetic refrigerants of the fourth generation, which are also called HFO or hydrofluoroolefins , such as 2,3,3,3-tetrafluoropropene . It is practically no longer degradable in the environment ( persistent ).

properties

Trifluoroacetic acid is a colorless liquid with a pungent vinegar odor. It is harmful to health when inhaled, causes severe burns and is harmful to aquatic organisms even when diluted. When exposed to heat or ultrasound, trifluoroacetic acid decomposes with the formation of hydrogen fluoride . Strongly exothermic reactions occur with metals (especially light metals ) and alkalis . The reaction of trifluoroacetic acid with lithium aluminum hydride leads to an explosion.

Trifluoroacetic acid is a strong organic acid. It is miscible with water, chlorofluorocarbons and organic solvents . TFA is stable up to 400 ° C; Trifluoroacetic acid is stable up to approx. 200 ° C under oxygen. Your pK _s value is 0.23. The big difference of the pK _s -value , compared to acetic acid, comes through the electron-withdrawing effect of the fluorine atoms about, is stabilized whereby the acid anion.

use

Trifluoroacetic acid is used in biotechnology as a solvent for proteins . The further treatment of this solution is problematic. On a larger scale, TFA must be recovered in view of environmental regulations (e.g. through distillation).

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on trifluoroacetic acid in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
↑ ^a ^b chem.wisc.edu: pKa Data , Compiled by R. Williams (PDF, 78 kB).
↑ ^a ^b Entry on trifluoroacetic acid. In: Römpp Online . Georg Thieme Verlag, accessed on May 20, 2014.
↑ Entry on trifluoroacetic acid in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-21.
^ EH Christoph: Balancing and biomonitoring of trifluoroacetate and other halogen acetates , dissertation, 2002, University of Bayreuth
↑ Data sheet trifluoroacetic acid (PDF) from Merck , accessed on January 19, 2011.
↑ F. Swarts, Bull. Acad. R. Belg. Classe Sci. 8, 343, 1922
↑ Joseph J. Katz: Anhydrous Trifluoroacetic Acid as a Solvent for Proteins . In: Nature . tape 174 , no. 4428 , September 11, 1954, pp. 509-509 , doi : 10.1038 / 174509a0 .

Web links

Wiktionary: Trifluoroacetic acid - explanations of meanings, word origins, synonyms, translations

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on trifluoroacetic acid in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .

[williams-2] .wisc.edu: pKa Data , Compiled by R. Williams (PDF, 78 kB).

[roempp-3] Entry on trifluoroacetic acid. In: Römpp Online . Georg Thieme Verlag, accessed on May 20, 2014.

[CLP_100.000.846-4] Entry on trifluoroacetic acid in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[CRC90_5_21-5] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-21.

[ehc-6] EH Christoph: Balancing and biomonitoring of trifluoroacetate and other halogen acetates , dissertation, 2002, University of Bayreuth

[Merck-7] Data sheet trifluoroacetic acid (PDF) from Merck , accessed on January 19, 2011.

[8] F. Swarts, Bull. Acad. R. Belg. Classe Sci. 8, 343, 1922

[9] Joseph J. Katz: Anhydrous Trifluoroacetic Acid as a Solvent for Proteins . In: Nature . tape 174 , no. 4428 , September 11, 1954, pp. 509-509 , doi : 10.1038 / 174509a0 .