"Many oxidants transform acyloins (α-hydroxy ketones) into α-diketones. Copper and bismuth oxidants are commonly selected for this transformation. … Cu(II) salts (e.g., Cu(OAc), or CuSO4) in stoichiometric amounts convert acyloins into diketones. Catalytic amounts of cupric acetate can be used in conjunction with ammonium nitrate. … Commercially available Bi2O3, in the presence of acetic acid, oxidizes acyloins to α-diketones in good yields."