在CPS微球表面实现N-羟基邻苯二甲酰亚胺的同步合成与固载及固体催化剂催化氧化性能初探

通过分子设计的构思,仅通过两步大分子反应,便实现了N-羟基邻苯二甲酰亚胺(NHPI)在交联聚苯乙烯(CPS)微球表面的同步合成与固载,并制得了非均相催化剂微球CPS-NHPI。以氯化偏苯三酸酐(TMAC)为试剂、Lewis酸为催化剂,通过Friedel-Crafts酰基化反应,先将邻苯二甲酸酐(PA)基团键合在CPS微球表面,得到改性微球CPS-PA;再与盐酸羟胺进行酰亚胺反应,制备出固载有NHPI基团的非均相催化剂微球CPS-NHPI。重点研究了CPS微球表面发生Friedel-Crafts酰基化反应的影响因素。采用红外光谱(FT-IR)及扫描电子显微镜(SEM)等对微球CPS-NHPI进行表征,将微球CPS-NHPI分别用于分子氧氧化乙苯及环己烷两种烃类物质的氧化过程,初步考察了该微球的催化活性。研究结果表明,对于微球CPS与TMAC之间的Friedel-Crafts酰基化反应,适宜的溶剂为氯仿与N,N-二甲基乙酰胺(DMAC)混合溶剂(氯仿与DMAC的体积比为7:3),适宜的Lewis酸催化剂为SnCl₄。初步探索实验表明,催化剂微球CPS-NHPI与Co(OAc)₂ 所构成的共催化体系,在分子氧氧化乙苯及环己烷的催化氧化过程中,都表现出了良好的催化活性,温和条件下,反应35 h时乙苯氧化为苯乙酮的转化率可达37%,反应30 h时环己烷氧化为环己酮的转化率可达21%。

Synchronously Synthesizing and Immobilizing NHPI on CPS Microspheres and Primarily Investigating Catalytic Oxidation Activity of Solid Catalyst

Through a conception of molecular design, only via two steps of macromolecule reactions, it was realized to synchronously synthesize and immobilize N-hydroxyphthalimide (NHPI) on crosslinked polystyrene (CPS) microspheres, and the heterogeneous catalyst microspheres CPS-NHPI were obtained. 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, the microspheres CPS-NHPI were used in the oxidations of ethylbenzene and cyclohexane with molecular oxygen, respectively, and the catalytic activity of CPS-NHPI were examined preliminarily. 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. The results of primarily exploring reveal that a compositional catalyst system constituted by microspheres CPS-NHPI and a little of Co(OAc)₂ displays fine catalytic activity in the oxidation reactions of ethylbenzene and cyclohexane with molecular oxygen as oxidant.The conversion rate of ethylbenzene oxidation to acetophenone is 37% for 35 h, and the conversion rate of cyclohexane oxidation to cyclohexanone is 21% for 30 h.