Study On Catalytic Oxidation Activity Of NHPI And Triacetate Quaternary Ammonium Salt

The oxidation of aromatic hydrocarbons is a kind of important reaction in the chemical industry, which has played a very important role in the industrial and basic research. It has always been one of the most key challenges to develop high-performance catalysts for aerobic oxidation of carbon-hydrogen bonds using molecular oxygen as oxidant, which has great academic and economic benefits. With oxygen instead of traditional high pollution stoichiometric oxidants, such as potassium permanganate, potassium dichromate, can greatly reduce pollution and cost reduction. In recent years, N-hydroxy phthalimide (NHPI) cause a lot of attention as novel free radical generating agent, which can catalyze a variety of oxidation reactions by transition metals or other small organic compound, but these catalysts suffer from the disadvantages of metallic toxicity and high expense, which are major factors of restricting metal catalysts widely used. The quaternary ammonium salts display well in the catalytic oxidation reaction beaucase of its small molecule weight, simple structure and easy synthesis method, which are considered ideal as co-catalyst synergistic with NHPI. Oxime compounds containing the similar NOH structure of NHPI have a series of advantages, such as its simple and adjustable structure, easy synthesis and low cost, which have a high reactivity. So it is innovative to put quaternary ammonium salts and oximes into one molecule as new compounds of the catalytic oxidation of hydrocarbons.We found brominated copper and NHPI in the reaction of oxidation of ethylbenzene by experiments,has good synergy. Six kinds of NHPI derivatives with the double structure of quaternary ammonium salt and oxime hydroxyl group were designed and synthesized, and they were characterized by elemental analysis, IR and’H-NMR. The new compounds were applied to the catalytic oxidation of ethylbenzene, and satisfactory results were achieved.It can be found that:(1) CuBr2/NHPI can be used in catalytic oxidation reaction of ethylbenzene, and it showing good performance under mild conditions;(2) ethylbenzene can be converted into acetophenone in high conversion (97.8%) and selectivity (94.5%) by the NHPI (10mol%) and CuBr2(0.5mol%) under0.3MPa of dioxygen in10mL acetonitrile at80℃in3h through the study of various impact factors. These new catalyists exhibit catalytic activities and selectivities in the oxygenation of different kinds of hydrocarbons;(3) Several new quaternary ammonium salts containing oxime hydroxyl group are synthesized, and influence factors about the catalytic system of quaternary ammonium salts/NHPI are studied, it is found that85.7%conversion of ethylbenzene with90.2%selectivity for acetophenone can be obtained by the catalyst of NHPI (10mol%) combined with the new quaternary ammonium salts (1mol%) under0.3MPa of dioxygen in acetonitrile at80℃in7h.It is studied that triethyl quaternary ammonium salt containing bromine combined with NHPI as catalyst is better than the triethyl quaternary ammonium salt of chlorine, compared to compounds no oxime hydroxyl group, compounds containing oxime hydroxyl group have good effects. Similarly, the catalytic results are also different with different tertiary amines as raw materials, and the solubility of the catalysts is increased in the derivatives synthetic of didecylmethylamine with longer carbon chain than those of other tertiary amines.