【作者】 柏东升；

【导师】 景欢旺；

【作者基本信息】 兰州大学 ， 物理化学， 2011， 博士

【摘要】 近年来,随着对碳污染的重视和碳化学的发展,二氧化碳作为碳资源的终态,由于储量丰富、无毒和惰性等特点受到越来越多化学工作者的重视。碳酸酯(包括环碳酸酯和聚碳酸酯)是化学固定二氧化碳成功的例子之一。环碳酸酯被广泛用作精细化工中间体、惰性非质子性极性溶剂、生物医药前体以及聚碳酸酯的原料；聚碳酸酯则广泛应用于工程塑料等领域。绿色化学是当今国际化学科学研究的前沿和热门领域,而仿生催化是绿色化学技术和方法学研究的最重要分支之一。主要生物质和酶分子在酶催化作用下的“构-效关系”也可以通过绿色仿生催化进行模拟。利用二氧化碳和环氧化合物通过偶联反应制备环碳酸酯或聚碳酸酯是二氧化碳研究的热点之一,已得到长足的发展；但是利用烯烃、氧气和二氧化碳的串联反应制备环碳酸酯则比较困难。而植物将二氧化碳和水转化成多糖或纤维素所用的催化剂-叶绿素恰恰是卟啉结构。本论文从研究二氧化碳的活化以及二氧化碳和环氧化合物为底物合成环碳酸酯的反应过程和机理为基础,进一步研究在仿生卟啉为催化剂条件下,二氧化碳、氧气和烯烃通过氧化羧化合成环碳酸酯。(1)设计合成新型的磁性四氧化三铁负载钻卟啉催化的二氧化碳与环氧化合物环加成合成环碳酸酯的反应,分别探讨了不同的助催化剂、助催化剂用量以及循环次数对反应的影响。研究表明当使用MNP-P/PTAT催化体系,在室温下,各种环氧化合物都可以生成较高收率的环碳酸酯；并且新型的磁性四氧化三铁负载钴卟啉催化剂使用磁铁吸引分离后循环16次而没有活性的降低和质量的减少。(2)研究了以双功能金属卟啉作为催化剂催化二氧化碳与环氧化合物环加成合成环碳酸酯的反应,分别探讨了不同的中心金属、抗衡离子、反应温度以及循环次数对反应的影响。研究表明当使用Co(TTMAPP)(OAc)I4催化剂,85℃,667 KPa条件下,环丙烯碳酸酯在5小时内产率可达95.4%,其他各种环氧化合物也可以生成较高收率相应的环碳酸酯。(3)合成一系列主族金属卟啉催化剂催化二氧化碳与环氧化合物环加成合成环碳酸酯的反应,分别探讨了不同的主族金属、助催化剂、反应温度、二氧化碳压力等对反应的影响。当使用Al(TPP)Cl/2PTAT为催化体系时,25℃,1 atm温和条件下,二氧化碳和环氧氯丙烷可以偶联得到相应较高产率的环碳酸酯；当使用天然产物叶绿素A作为催化剂时,可以得到具有光学活性的手性环碳酸酯。研究表明：主族金属卟啉催化剂的催化活性与主族金属的路易斯酸性有极大关系,即主族金属离子的路易斯酸性越强,则催化剂的催化活性越高；并且主族金属卟啉催化剂催化二氧化碳与环氧化合物环加成合成环碳酸酯的反应机理进行了详细讨论。(4)开发了以二氯二茂钛(Cp2TiCl2)为催化剂催化二氧化碳与环氧化合物环加成合成环碳酸酯的反应,分别探讨了不同的反应温度、溶剂以及助催化剂对环加成反应的影响。研究表明当使用Cp2TiCl2/2TBAB催化体系,在150℃,1.2MPa, THF为溶剂条件下,反应15分钟,环丙烯碳酸酯产率高达98.1%,TOF值392.4 h-1。截止目前为止,这是首篇以茂金属为催化剂催化二氧化碳与环氧化合物环加成合成环碳酸酯反应。(5)以钌金属卟啉为催化剂催化二氧化碳、氧气与烯烃串联合成环碳酸酯的反应,分别探讨了不同的助催化剂和底物与催化剂比率对三组分串联反应的影响。研究表明当使用Ru(TPP)O2/2TBAB催化体系,在30℃,1.1MPa二氧化碳压力,0.5 MPa氧气压力条件下,反应48小时,苯乙烯环碳酸酯产率可达76%;同时对不同底物的最佳催化条件进行了探讨,并且对反应机理进行了详细讨论。更多还原

【Abstract】 The chemistry of carbon dioxide has received much attention in decades from both economical and environmental points of view:utilization of the least-expensive carbon source and reduction of global-warming gas. One of the most successful examples is the synthesis of carbonates from CO2 and epoxides, including cyclic carbonates and polycarbonates. The cyclic carbonates have been widely used as synthetic intermediates, aprotic polar solvents, precursors for biomedical applications and raw materials for engineering plastics.Now, the frontier of chemical science and popular area is green chemistry, and the biomimetic catalysis is the most important branch of green chemistry. Main biomass and enzyme molecule under the action of the enzyme catalysis constitutive structural-activity relationships can also simulated by green biomimetic catalysis. The hot spot of carbon dioxide inserting to epoxides to synthesis of cyclic carbonates or polycarbonates has been considerable development in the past decades, however, the aerobic oxidative carboxylation of olefins to synthesis of cyclic carbonates from carbon dioxide and dioxygen with metalloporphyrin catalysts is difficult. But, carbon dioxide and water can be transformed to polysaccharides or cellulose in plants used catalyst-chlorophyll A that is exactly porphyrin structure.From the study of activation of carbon dioxide and the process and mechanism of the formation of cyclic carbonates via epoxides and carbon dioxide, further research of the synthesis of cyclic carbonate from dioxygen, carbon dioxide and olefins catalyzed by biomimetic porphyrin was detailed documented.(1) A magnetic nanoparticle (MNP)-supported biomimetic cobalt porphyrin (MNP-P) as cytochrome P-450 model was designed, prepared and evaluated as an efficient catalyst for coupling reaction of epoxides and carbon dioxide under 1.0 MPa carbon dioxide pressure at ambient temperature to generate relevant cyclic carbonates. The effects of different co-catalysts, the equivalent of co-catalyst and the recycling of catalyst were studied. The phentrimethyl ammonium tribromide (PTAT) combined with the supported porphyrin MNP-P was the best catalytic system to catalyze the cycloaddition of carbon dioxide to epoxides generating relevant cyclic carbonates at room temperature. The MNP-P catalyst could be simply recycled with the assistance of an external magnet and reused for 16 times without significant loss of activity and mass.(2) The cycloaddition of carbon dioxide to epoxides catalyzed by bifunctional metalloporphyrin (M(TTEMP)I4(X)) was studied. The reaction conditions of different metal center, counterion, reaction temperature and recycling times were optimized. 95.4% yield of propylene carbonate was formed at 85℃under 667 KPa within 5 hours. The moderate yield of submitted cyclic carbonate was obtained.(3) We synthesized a series of main group metalloporphyrins to catalyze the formation of cyclic carbonate from epoxides and carbon dioxide. The effects of different main group metal, co-catalyst, reaction temperature, and carbon dioxide pressure were investigated in detail. The cyclic carbonates was synthesized in high yields catalyzed by Al(TPP)Cl/2 PTAT at 25℃. The chiral cyclic carbonate was formation using chlorophyll A as catalyst. We found that the harder the acid, the stronger the Lewis acidity. The mechanism of this cycloaddition reaction catalyzed by main group metal porphyrin was discussed in detail.(4) We have been developed a new catalyst system of titanocene dichloride/Lewis base to catalyze the synthesis of cyclic carbonate from epoxides and carbon dioxide. The reaction conditions affecting the cycloaddition including reaction temperature, solvent and co-catalyst were optimized. The propylene carbonate was obtained with 98.1% yield and 392.1 h-1 TOF at 150℃under 1.2 MPa carbon dioxide pressure within 15 mins when using THF as solvent. To the best of our knowledge, this is the first report about metallocene catalyzed the coupling of epoxides and carbon dioxide to generate useful cyclic carbonates.(5) The synthesis of cyclic carbonate from carbon dioxide, dioxygen and olefins based on the previous studies on the cycloaddition of carbon dioxide to epoxides were reported. The styrene carbonate with 76% yield were obtained at 30℃under 1.1 MPa carbon dioxide pressure and 0.5 MPa dioxygen pressure within 48 hours using Ru(TPP)O2/2 TBAB as catalytic system from styrene, carbon dioxide and dioxygen. The scope of olefins was investigated. The aerobic oxidative carboxylation of olefins reaction mechanism was researched in detail.更多还原