Trifluoroacetic acid

Trifluoroacetic acid is a strong carboxylic acid, CF₃COOH, in which three fluorine atoms replace the methyl hydrogens of acetic acid. Its acidity and volatility make it useful in synthesis and peptide analysis.

Trifluoromethyl group: A functional group consisting of a carbon atom bonded to three fluorine atoms, written –CF₃. The –CF₃ group withdraws electron density and makes the acid unusually strong.
Peptide synthesis: The chemical construction of peptides by joining amino acids through peptide bonds. Trifluoroacetic acid removes acid-labile protecting groups during many synthesis workflows.
Acetic acid: A two-carbon carboxylic acid with formula CH₃COOH, found in vinegar. Replacing its methyl hydrogens with fluorine greatly increases acidity.
Trifluoroacetate: The anion CF₃COO⁻ formed when trifluoroacetic acid loses a proton. This stable form can remain after the acid is neutralized or discharged.
Carboxylic acid: An organic compound containing a carboxyl group, –COOH, which can donate a proton. Trifluoroacetic acid belongs to this family of proton-donating compounds.
Solid-phase peptide synthesis: A method for building peptides stepwise while the growing chain remains attached to an insoluble support. It commonly removes the temporary Fmoc protecting group between coupling steps.
Trichloroacetic acid: A strong carboxylic acid, CCl₃COOH, with three chlorine atoms on its methyl carbon. It has a similar electron-withdrawing group but different solubility and reagent behavior.
Environmental persistence: The tendency of a substance to resist breakdown and remain in the environment. Trifluoroacetate is resistant to many degradation processes and can accumulate in water.
Acid dissociation constant: A measure of how readily an acid donates a proton in solution. Its low pKa quantifies trifluoroacetic acid’s high strength in water.
Fmoc protecting group: A base-labile protecting group used to temporarily block amino groups in peptide synthesis. Its removal is a key contrast: Fmoc is generally cleaved with base, not this acid.

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