Trifluoroacetic acid Trifluoroacetic acid Trifluoroacetic acid (TFA) is an organofluorine compound with the chemical formula CFCOH. It is a structural analogue of acetic acid with all three of the acetyl group’s hydrogen atoms replaced by fluorine atoms and is a colorless liquid with a vinegar like odor. TFA is a stronger acid than acetic acid, having an acid ionisation constant that is approximately 34,000 times higher, as the highly electronegative fluorine atoms and consequent electron-withdrawing nature of the trifluoromethyl group weakens the oxygen-hydrogen bond (allowing for greater acidity) and stabilises the anionic conjugate base. TFA is widely used in organic chemistry for
Phenylarsonic acid Phenylarsonic acid Phenylarsonic acid is the chemical compound with the formula CHAsO(OH), commonly abbreviated PhAsOH. This colourless solid is an organic derivative of arsenic acid, AsO(OH), where one OH group has been replaced by a phenyl group. The compound is a buffering agent and a precursor to other organoarsenic compounds, some of which are used in animal nutrition, e.g. 4-hydroxy-3-nitrobenzenearsonic acid. PhAsOH can be prepared in several routes, but a common one entails treatment of phenyl diazonium salts with sodium arsenite (prepared from arsenious acid and base) in the presence of a copper(II) catalyst. Related derivatives are prepared similarly. It