Study On Synthesis And Catalytic Activity Of The NHPI Derivatives With The Structure Of Oximes

The selective catalytic oxidation of hydrocarbons is an important functional groupconversion reaction, which is the core technology to make organic intermediates such asalcohols, aldehydes, ketones and carboxylic acids, and plays an impormant role in thechemical industry and basic research. It has always been one of the most key challenges toimprove the rates of oxidation of organic compounds and product selectivities. Therefore, thedevelopment of catalyst in largely determine to the success of oxidation reaction. In traditionalmethods, high pollution stoichiometric oxidants, such as potassium permanganate, potassiumdichromate were used, which produced large amount of inorganic salts and led to the pollutionof environment. So using molecular oxygen as oxidant has broad application prospects. Inrecent years, N-hydroxy phthalimide (NHPI) has emerged as a powerful and popular catalystfor organic oxidation reactions and caused a lot of attention. But it needs helps of transitionmetals or other small organic compound which suffer from the disadvantages of metallictoxicity and high expense. Oxime compounds have a series of advantages, such as its simpleand adjustable structure, low cost and easy to be synthesized, so they are considered as idealco-catalysts with NHPI. So it is innovative to put oxime compoundsand NHPI into one molecule as new compounds of the catalytic oxidation of hydrocarbons.Three kinds of NHPI derivatives with the double structure of oxime hydroxyl group andNHPI were synthesized with high purity (>96.0%), and they were characterized by elementalanalysis,1H-NMR and IR. Such new compounds were used as catalysts for the catalyticoxidation of ethylbenzene and achieved good results. Otherwise, Several new quaternaryammonium salts containing oxime hydroxyl group were synthesized and used as co-catalystwith NHPI in the catalytic oxidation of ethylbenzene, and also got satisfactory results.It can be found that:(1) the NHPI derivatives with the double structure of oxime hydroxylgroup and NHPI can be used in the catalytic oxidation of ethylbenzene under mild conditionsand have a good activity;(2) ethylbenzene can be sufficiently converted into acetophenone bythe NHPI derivatives (10mol%) with the conversion of80.5%and selectivity of92.3%at80°C in10mL acetonitrile under0.3MPa of dioxygen in10h. Otherwise these new kinds ofcatalysts exhibit good catalytic activities and selectivities for the oxidation of the other hydrocarbons.;(3) Several new quaternary ammonium salts were synthesized, and it was foundthat when it was used as co-catalyst (1mol%) the conversion of ethylbenzene and selectivityof acetophenone can reach86.1%and90.1%respectively by10mol%NHPI in acetonitrileunder0.3MPa of dioxygen at80°C in7h.It is studied that the NHPI derivatives with the structure of oxime hydroxyl group ascatalyst is better than NHPI. Similarly, compared to quaternary ammonium salts, compoundscontaining oxime hydroxyl group have better effects. It maybe because the N-hydroxy group inoxime compounds plays an important role in the activation process of NHPI.