Systematic study was performed on the oxidation of alcs. by twelve 2,2,6,6-tetramethylpiperidine oxoammonium salts I (R = H, MeO, Cl; X = Cl, BF4, ClO4, Br or Br3). All of these oxoammonium salts can oxidize primary alcs. to aldehydes and secondary alcs. to ketones with very high yield. The reactivity of the oxidants is related with both the 4-substituent and the counter-ion with the sequence of Cl > MeO > H for the salts with the same counter-ion and Cl- ?BF4- > ClO4- > Br- for the salts with the same 4-substituent. The selectivity of the oxidants is mainly determine by the counter-ions. The oxidant oxidizes preferably primary alcs. when the counter-ion is Cl-, but oxidizes secondary alcs. selectively when the counter-ions are BF4-, ClO4-, Br- or Br3-.

Key words: PIPERIDINE P, OXIDATION, SELECTIVITY, ACTIVITY, ALCOHOL