Preparation The Heterogeneous Catalyst Microspheres CPS-NHPI And Investigating Its Catalytic Property In Oxidation Reaction Of Alcohols To Ketones

The oxidation of alcohols into the corresponding aldehydes or ketones, which plays an important role in and production of fine chemical and fundamental research. The concept of green chemistry and atom economy was put forward, the most traditional oxidants has been phased out, so The green oxidation technology using molecular oxygen as an oxidant has obtained great development. In order to development of both economy and green way, researchers developed a series of catalyst to increase the reaction efficiency of substrate with molecular oxygen. Become homogeneous catalysis for heterogeneous catalysis, this is one of the important development direction of green chemistry. The immobilization of NHPI is one of the most important subjects in the study of catalytic oxidation. In our present investigation, a simple preparation method of crosslinked polystyrene(CPS) microspheres as the carrier to manufacturer immobilized NHPI catalyst has been designed. Subsequently, the catalyst microspheres CPS-NHPI in combination with transition metal salt can effectively catalyze the oxidation transformation of benzhydrol and 1-phenyl ethanol to ketones by molecular oxygen, and their catalytic activity and the mechanism of the catalytic oxidation were investigated. This research has important scientific significance and reference value in the field of green catalytic oxidation technology.In this paper, firstly, using crosslinked polystyrene(CPS) microspheres as the carrier. secondly, via Friedel-Crafts acylation reaction, phthalic anhydride(PA) was bonded on the surfaces of CPS microspheres using trimellitic anhydride chloride(TMAC) as reagent and Lewis acid as catalysts, resulting in the modified microspheres CPS-PA. Subsequently, the microspheres CPS-PA were allowed to be reacted with hydroxylamine hydrochloride, namely imidation reaction was carried out, preparing the microspheres CPS-NHPI, on which the catalyst group NHPI was immobilized. The effects of the main factors on the acylation reaction were examined. On the basis of characterizing microspheres CPS-NHPI by fourier transform infrared spectroscopy(FT-IR), scanning electron microscope(SEM) and chemical analytical method. Results show that the solvent property and the kind of Lewis acid catalysts effect the acylation reaction greatly. The suitable solvent is the mixed solvent of CHCl3 and dimethylacetamide(DMAC) with a volume ratio of 7:3, and the appropriate Lewis acid catalyst is SnCl4,dosage of 0.9 m L.The heterogeneous catalyst microspheres CPS-NHPI in combination with transition metal salt can effectively catalyze the oxidation transformation of benzhydrol to diphenyl ketone by molecular oxygen. and research their catalytic activity and the mechanism of the catalytic oxidation were investigated. The experimental results show that the compositional catalyst CPS-NHPI+VO(acac)2 can highly effectively catalyzed the oxidation transforming of benzhydrol to diphenyl ketone under the mild conditions such as at 75 ℃ and with oxygen at ordinary pressure. The catalytic oxidation follows a mechanism of free radical chain reaction. The mixture of acetonitrile and ethyl acetate with a volume ratio of 7:3 is the appropriate solvent. Among several transition metal salts, the order of co-catalytic effect is VO(acac)2>Co(OAc)2 > CoCl2>Mn(OAc)2. It is obvious that vanadyl acetylacetonate is the best co-catalyst. and 1:15 as the molar ratio of VO(acac)2 to the immobilized NHPI, the added amount of the co-catalyst is the suitable. The compositional catalyst displaying fine catalytic activity and excellent catalysis selectivity(35.8 % conversion of benzhydrol conversion and diphenyl ketone as only one product)when the amount of the CPS-NHPI is 11mol% of the substrate. The heterogeneous catalyst microspheres CPS-NHPI has good cycling and reuse performance.The heterogeneous catalyst microspheres CPS-NHPI in combination with transition metal salt can effectively catalyze the oxidation transformation of 1-phenyl ethanol to acetophenone by molecular oxygen. and research their catalytic activity and the mechanism of the catalytic oxidation and reuse performance were investigated. The experimental results show that, the conversion rate of 1-phenyl ethanol remained at 34.7%, recycled after seven times. The heterogeneous catalyst microspheres CPS-NHPI has good cycling and reuse performance. The catalytic oxidation follows a mechanism of free radical chain reaction. The compositional catalyst CPS-NHPI+VO(acac)2 can highly effectively catalyzed the oxidation transforming of 1-phenyl ethanol to acetophenone under the mild conditions such as at 75 ℃ and with oxygen at ordinary pressure. The best condition of the reaction is: The mixture of acetonitrile and ethyl acetate with a volume ratio of 7:3 is the appropriate solvent. And 1:20 as the molar ratio of VO(acac)2 to the immobilized NHPI, the added amount of the co-catalyst is the suitable. The compositional catalyst displaying fine catalytic activity and excellent catalysis selectivity when the amount of the CPS-NHPI is 11mol% of the substrate.