【作者】 刘文明；

【导师】 聂进；

【作者基本信息】 华中科技大学 ， 有机化学， 2004， 硕士

【摘要】 全氟磺酰亚胺阴离子作为一类重要的弱配位阴离子一直为人们所广泛关注,并开展了深入的研究,它们与过渡金属离子形成的络合物在高效金属Lewis酸催化剂的开发中扮演了越来越重要的角色。研究发现,在同类催化剂La(NTf2)3、Sm(NTf2)3和Yb(NTf2)3中,Yb(NTf2)3的催化活性最好,并且催化性能稳定,但反应后为了回收催化剂需要烦琐的后处理过程。本论文以聚苯乙烯为高分子载体,通过一系列有机反应将Yb(NTf2)3负载在高分子上,结合胶束催化原理合成了一种新型的高分子负载催化剂,开展了将Yb(NTf2)3固载到高分子上的研究与探索。为了评价合成的催化剂的催化性能,以酯化、酰化以及硝化反应为模型反应进行研究。实验表明高分子负载Yb(NTf2)3的催化性能较高,与Yb(NTf2)3均相催化并无明显的差别。但在重复使用的过程中,该高分子催化剂的催化效率呈下降趋势,一般地,重复使用4次,催化产率都会有20%左右的降低,这说明在使用过程中Yb(NTf2)3可能由于溶解等原因出现了“漏损”这一目前高分子负载催化剂普遍存在的问题。本工作对Yb(NTf2)3的高分子负载作出了积极的探索,为提高这类催化剂稳定性的后续研究提供了有益的前期支持。另外,对于傅克酰化反应而言,传统的Lewis酸催化剂如AlCl3存在着用量大,环境污染严重,产物选择性差等一系列问题。而目前广泛研究的Lewis酸催化剂如含氟氧(氮)超酸镧系金属盐在催化活泼芳环的酰化反应时效果显著,对于不活泼的芳环的酰化反应则不太理想。本论文将Bi(OTf)3应用于异丁基苯的乙酰化反应,合成镇痛药Ibuprofen的重要中间体对乙酰基异丁基苯。研究中发现LiClO4对Bi(OTf)3催化异丁基苯乙酰化有明显的助催化作用,在4M LiClO4-CH3NO2体系中Bi(OTf)3催化异丁基苯的乙酰化反应取得了良好的催化效果。通过对催化剂用量,温度,反应时间,酰化试剂,反应溶剂的系统研究探索出Bi(OTf)3催化异丁基苯的乙酰化反应的最佳条件。总之,含氟氮超酸、氧超酸的金属盐作为Lewis酸催化剂催化活性较高,性能稳定,对其进行均相和非均相的催化研究具有一定的理论和应用价值。更多还原

【Abstract】 As a kind of outstanding weakly coordinating anions, bis[(perfluoroalkyl)sulfonyl]imide anions have been receiving continuous interests and have been extensively studied in recent years. Metal bis[(perfluoroalkyl)sulfonyl]imides complexes were found to play an active role in the development of highly efficient Lewis acid catalyst. Yb(NTf2)3 was thought to be the best catalyst in the system of catalysts as La(NTf2)3、Sm(NTf2)3 and Yb(NTf2)3. Nevertheless, the tedious workup to recover the catalyst after reactions make it economically unusable and retrain it for laboratory use only.In this paper, we used polystyrene as the supported polymer, on which Yb(NTf2)3 was immobilized through a series of organic reaction. According to the theory of micellar catalysis, a new kind of polymer-supported catalyst was prepared and related research was reported.In order to evaluate the catalytic properties of this supported catalyst, we then used it in several fundamental and important Lewis acid-catalyzed reactions such as acylation、 esterification and nitration. It is found that its reactivity was very satisfying, almost the same as the monomeric Lewis acid. The catalyst can be recovered by simple filtration and could be reused. But the activity of the recovered catalyst decreased gradually after each recycle. In general, there was nearly a twenty percent declination after four times of uses, which indicated that Yb(NTf2)3 lost partly in the process of reaction due to dissolvent and other reasons. This disadvantage is indeed the ubiquitous problem challenging the research of polymer-supported catalyst. Out work had a positive exploration on the polymer supported Lewis acid catalyst and paved a way to the continuous research aiming to improve its stability. In addition, as Friedel-Crafts acylation is concerned, the reaction is generally performed using stoichiometric aluminium trichloride as a Lewis acid catalyst, which brought out serious effluent problems. The present widely studied transition metal perfluorosulfonate only work with highly electron-donative aromatics because of its low Lewis acidity. For example, while the acylation proceeded with anisole, acylation of benzene and toluene did not occur. We now applied catalytic Bi(OTf)3 to the acylation of isobutylbenzene, synthesized an importand mediate of Ibuprofen 4-isobutylacetophenone. LiClO4 was found to have a remarkable acceleration to the acylation. By using 4 M LiClO4-CH3NO2 as the <WP=5>medium, Bi(OTf)3 demonstrated much higher catalytic activity and yielded better results. Furthermore, the effect of reaction time, reaction temperature, catalyst dosage, acylation reagent and solvent were systematically studied, based on which the optimum condition was set up.更多还原