Chromic acid is an effective oxidant for the conversion of phenols to quinones only when a para-substituent (e.g., halogen, hydroxyl, or amino) is present. Chromic acid may also refer to the molecular species, H2CrO4 of which the trioxide is the anhydride. Chromic acid features chromium in an oxidation state of +6 (or VI). It is a strong and corrosive oxidising agent.
