TEMPO is a stable nitroxide (aminoxyl) radical catalyst. Its common name reflects its structure: 2,2,6,6-tetramethylpiperidin-1-oxyl (often written in English as (2,2,6,6-tetramethylpiperidin-1-yl)oxyl), CAS 2564-83-2.
Recently, environmentally friendly oxidation reactions catalyzed by a nitrogen-oxygen radical, TEMPO, have attracted attention. Iwabuchi et al. reported that a nitrogen-oxygen radical, 2-azadamantane-N-oxygen (AZADO), efficiently catalyzed oxidation reaction of alcohols.