Transition-Metal-Free TEMPO Catalyzed Aerobic Oxidation of Alcohols to Carbonyls Using an Efficient Br2 Equivalent under Mild Conditions

An effective transition-metal-free catalytic system is developed for aerobic oxidations of alcohols. Using catalytic amount of bromide-bromate coupling, H2SO4, and NaNO2, together with 2,2,6,6-tetramethylpiperidine N-oxyl radical （TEMPO） in the presence of air, various alcohols could be converted into the corresponding aldehydes or ketones in good to excellent isolated yields under mild conditions.