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Trifluoroacetic acid Formula – Structure, Properties, Uses, Sample Questions

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  • Last Updated : 13 May, 2022

Trifluoroacetic acid consists of elements Carbon, Fluorine, Oxygen, and Hydrogen. Carbon is a nonmetallic element present in group-14 of the periodic table. Its atomic number is six and is represented by the symbol C. Fluorine is a highly toxic diatomic gas that appears in pale yellow color. It is the most electronegative element present in group-17 of the periodic table. Its atomic number is nine and is represented with the symbol F. Oxygen is a highly reactive nonmetal present in the chalcogen group, i.e., group-16. Its atomic number is eight and is represented by the symbol O. Hydrogen is the lightest, colorless, odorless, tasteless, and flammable gas. Its atomic number is one and is represented by the symbol H.

Trifluoroacetic acid Formula

Trifluoroacetic acid is a very strong, colorless fuming liquid with a pungent smell. In short, Trifluoroacetic acid is called TFA. The chemical formula for Trifluoroacetic acid is CF3CO2H. Trifluoroacetic acid (TFA) is synthesized by treating the acetyl chloride (CH3COCl) in electrochemical fluorination. TFA is used is in acid-catalyzed reactions, especially where an ester is cleaved in peptide synthesis. It is also called Trifluoroethanoic acid. TFA is the conjugate acid of a trifluoroacetate. TFA is soluble in water and denser than water. The IUPAC name of Trifluoroacetic acid is 2,2,2-trifluoroacetic acid.

Preparation of Trifluoroacetic acid

There are two ways to prepare Trifluoroacetic acid,

  • Trifluoroacetic acid is prepared by heating hexachloropropene with AgF to obtain trichloro trifluoropropene which on further oxidation with potassium permanganate gives resultant Trifluoroacetic acid. It is a conventional method to prepare TFA.
  • Trifluoroacetic acid is also prepared by the electrochemical fluorination of acetyl chloride or acetic acid using the Simons method and then followed by hydrolysis of the trifluoroacetyl fluoride.

CH3COCl + 4HF → CF3COF + 3H2 + H+ + Cl

Structure of Trifluoroacetic acid

Trifluoroacetic acid structure

Physical Properties of Trifluoroacetic acid

  • The molecular weight of Trifluoroacetic acid is 114.023 g/mol.
  • The density of TFA is 1.489 gmL-1.
  • The melting point of Trifluoroacetic acid is -15.4°C.
  • The boiling point of Trifluoroacetic acid is 72.4°C.
  • Its Enthalpy of vapourization is 33 kJ/mol.
  • The appearance of Trifluoroacetic acid Colorless liquid.
  • The odor of Trifluoroacetic acid is a pungent smell.

Chemical Properties of Trifluoroacetic acid

  • Trifluoroacetic acid is corrosive to the skin and eyes.
  • Because of the presence of three fluorine atoms, the acidity of Trifluoroacetic acid is higher than acetic acid.
  • TFA is soluble in water.
  • Fluorine atoms are highly electron-withdrawing groups and carry high negative inductive effects. Hence carbon is highly electron-deficient and can easily lose the hydrogen atom in the primary functional group. 

Uses of Trifluoroacetic acid

  • Trifluoroacetic acid is used as an adhesive and sealant chemical.
  • It is used as a precursor to producing fluorinate compounds.
  • TFA is used as a solvent for NMR and mass spectroscopy analysis.

Sample Questions

Question 1: Is Trifluoroacetic acid a carboxylic acid?

Answer:

Yes. TFA is a carboxylic acid with chemical formula CF3CO2H. Due to the influence of the electronegative trifluoromethyl group it is a strong carboxylic acid.

Question 2: Find the molar mass of the CF3CO2H compound.

Answer:

  • Atomic weight of each carbon atom = 12.01
  • Atomic weight of each fluorine = 18.998403
  • Atomic weight of each oxygen = 15.999
  • Atomic weight of hydrogen atom = 1.00784 

Molecular weight of CF3CO2H = (2 × 12.01) + (3 × 18.998403) + (2 × 15.999) + 1.00784

= 114.02 g/mol

Question 3: In which compounds Trifluoroacetic acid is soluble?

Answer:

Trifluoroacetic acid is soluble in benzene, ether, dichloromethane, DMF, THF, acetonitrile. TFA is also soluble in water.

Question 4: Is Trifluoroacetic acid heath hazardous?

Answer:

Yes, Trifluoroacetic acid is hazardous to health. It is extremely corrosive to skin and eyes. TFA is harmful on swallowing.

Question 5: What does Trifluoroacetic acid do?

Answer:

TFA is used as reagent of choice for the removal of nitrogen and oxygen protecting groups by solvolysis under aqueous or anhydrous conditions.

Question 6: How to store the Trifluoroacetic acid?

Answer:

Trifluoroacetic acid is a moisture-sensitive liquid. It is stored in a brown bottle or amber ampul at room temperature, in a dry, well ventilated area away from ignition sources. Because it release poisonous gases when ignited.

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