Preparation Of Magnetic Polystyrene Nanospheres Immobilized TEMPO As Catalyst In The Oxidation Of Alcohols

2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) can quantitatively catalyze oxidize primary alcohol and secondary alcohol to their corresponding aldehydes and ketones using green oxidant, such as H2O2, O2, NaCIO under mild conditions. However, TEMPO, a small-molecule organic heterocyclic compound and expensive, can hardly be separated from reaction system or products by conventional process, which limited the large-scale application of TEMPO. In this paper, magnetic polystyrene nanospheres (MPNs) supported TEMPO catalyst was preparated and estimated as catalyst in Anelli system.Firstly, TEMPO was immobilized on chloromethylated magnetic polystyrene nanospheres (CMPNs) with ether linkage, and applied in the Anelli oxidation of various alcohols. The MPNs/TEMPO has close catalytic activity with homogeneous TEMPO in a wide range of oxidation of alcohols, and exhibits a good stability in the case of oxidation of benzyl alcohol. The catalyst was recovered and reused for 20 times with no significant loss of catalytic activity. Lastly, the MPNs/TEMPO was applied in the indirect oxidation of glycerol to dihydroxyacetone. The oxidation intermediate product HPD (5-hydroxyl-2-phenyl-1,3-dioxane) to PDO (2-phenyl-1.3-dioxan-5-one) was investigated with single-factor method. The optimized conditions were 0.03eq MPNs/TEMPO,1.5eq NaCIO,0.1 eq NaBr, pH≈9.1,10 ℃. However, the catalytic activity of catalyst decreased significantly after using 3 times under the optimized conditions. The stability of the MPNs/TEMPO catalyst in reaction system for long time remains to be improved.