When a primary alcohol is converted to a carboxylic acid, the terminal carbon atom increases its oxidation state by four. Oxidants able to perform this operation in complex organic molecules, featuring other oxidation-sensitive functional groups, must possess substantial selectivity. The most common oxidants are potassium permanganate (KMnO4), Jones reagent, PCC in DMF, Heyns oxidation, ruthenium tetroxide (RuO4) and TEMPO.