Study On Catalytic Performance For Derivatives Of TEMPO With Amino Structure

The selective oxidation of alcohols into corresponding carbonyl compounds arevery important transformations in organic chemistry, which plays an important role inorganic synthesis and fine chemical industry. Developing high efficent catalysts wasone of the most key challenges for selective oxidation of alcohols by using molecularoxygen as oxidant, which has great academic and economic significance.Various investigations have showed that2,2,6,6-tetramethyl-piperidyl-1-oxyl(TEMPO) was capable for catalyzing the oxidation of alcohols into correspondingaldehydes or ketones with molecular oxygen. Generally, N-donor ligands were appliedto many highly efficient systems consisting of TEMPO for catalytic aerobic alcoholreaction.The currently catalytic systems comprising main catalyst TEMPO and theco-catalyst have some disadvantages for the selective oxidation of alcohols usingmolecular oxygen, for example, complexity of catalytic system, product separationand catalyst re-use difficulty, and so on. In order to overcome the disadvantage, thenew idea was designed to integrating the main catalyst TEMPO and co-catalyst in amolecule. According to previously studied, the novel nitroxides catalysts withbifunctional structure of TEMPO and amino compound have been designed. It couldbe found that the novel one-component nitroxides catalysts could overcome somedisadvantages for multi-component systems, which could provide theoreticalfoundation and technical support to develop one-component catalyst for selectiveoxidation of alcohols by using molecular oxygen as oxidant.1. Four kinds of derivatives of TEMPO with amino structure were designed andsynthesized, and they were characterized by elemental analysis, IR and1H-NMR.2. Four derivatives TEMPO with amino structure were designed and synthesized andexhibited benign catalytic performance for oxidation benzyl alcohol with CuBr2.(1) Thecatalytic performance was discussed by using the catalysis system composing ofderivatives of TEMPO with amino structure and CuBr2for oxidation alcohols, and variousreaction factors and best reaction conditions were studied.(2) The4-benzylamino-TEMPO was used as catalyst for oxidation benzyl alcohol with CuBr2, and best reaction conditionswere studied. The optimal reaction conditions:3.0mmol benzyl alcohol as model substrate,3mol%4-benzylamino-TEMPO,2mol%copper bromide,80oC,6ml H2O,5h,98%conversion was obtained when benzyl alcohol was oxidated, and the selectivity ofbenzaldehyde is above99%, the system has a good applicability for oxidation of substrates.(3) The system is a simple and efficient for oxidation of alcohols without any extra base,N-donor ligand and organic solvent.3. A new catalysis system was designed, which comprising4-benzylamino-TEMPO,CuBr2and Al2O3.(1) In order to exploring best reaction conditions, the benzyl alcohol wasstudied as model substrate. The optimal reaction conditions:3.0mmol benzyl alcohol,3mol%4-benzylamino-TEMPO,2mol%CuBr2,0.8g Al2O3, room temperature, in air,24h,100%benzyl alcohol was converted into corresponding aldehyde, and the selectivity ofbenzaldehyde was above99%and the system has a good applicability for oxidation ofsubstrate.(2) This simple catalytic system showed highly efficiency and selectivity duringthe oxidation of benzyl alcohols. In particular, the catalytic system conducted well withoutany solvent, N-donor ligand or additional base. Moreover, the reaction could be developedunder the room temperature in air and the Al2O3was recycled for three times withoutsignificant loss of activity. The system is a simple, economic and green catalysis system.The the new catalytic system exhibited excellent catalysis performance for oxidationof various alcohols by using new designed catalyst, and the catalyst and correspondingcatalysis system have a good application prospect.