Catalytic Activity and Mechanism of Co‐Catalysts Used in Combinational Catalysts for Aerobic Oxidation

(2,2,6,6‐Tetramethylpiperidin‐1‐yl)oxyl (TEMPO) was immobilized on crosslinked polystyrene (CPS) microspheres by polymer reaction to obtain microspheres of the heterogeneous catalyst TEMPO/CPS. TEMPO/CPS microspheres in combination with different transition metal salts were used in the aerobic oxidation of 1‐phenylethanol. This work focuses on the catalytic activities and mechanisms of various co‐catalysts, and the different behavior of these co‐catalysts is explained for the first time with the theory of redox potentials, so that some important principles for selecting better transition metal salts as co‐catalysts of TEMPO are presented. The experimental results show that 1‐phenylethanol can be oxidized to acetophenone as the sole product with a high conversion of 96 % under mild conditions (at 55 °C and with molecular oxygen at ordinary pressure) by using the combinational catalyst consisting of TEMPO/CPS microspheres and transition metal salts. (2,2,6,6‐Tetramethylpiperidin‐1‐yl)oxyl (TEMPO) immobilized on crosslinked polystyrene (CPS) microspheres in combination with transition metal salts were used in the aerobic oxidation of 1‐phenylethanol. For some nitrates of transition metals, such as Fe(NO3)3 and Cu(NO3)2, the metal ion and NO3– ion work together in the catalytic process, acting together as co‐catalysts.