【作者】 赵婧；

【导师】 高保娇；

【作者基本信息】 中北大学 ， 高分子化学与物理， 2010， 硕士

【摘要】 金属卟啉化合物能模拟细胞色素P-450,温和条件下活化分子氧,高效、高选择性地实现烃类物质的催化氧化,尤其是聚合物固载金属卟啉的催化氧化作用备受关注。本研究构思了一条制备聚合物固载金属卟啉催化剂的新途径:通过固-液间的Adler反应,实现卟啉在甲基丙烯酸缩水甘油酯(GMA)与甲基丙烯酸甲酯(MMA)的交联聚合物微球GMA/MMA表面的同步合成与固载,进而与金属钴配位,制得了固载化钴卟啉催化剂,深入地考察其对分子氧氧化乙苯以及β-萘酚的催化活性,本文的研究结果在非均相金属卟啉仿生催化剂领域具有明显的科学价值。本文首先采用悬浮聚合法制备了交联共聚微球GMA/MMA,由于微球表面含有大量的环氧基团,通过开环成醚反应,可将对羟基苯甲醛(HBA)顺利地键合在微球表面,制得改性微球HBA-GMA/MMA。考察了各种因素(温度、溶剂、投料比等)对化学改性过程的影响。研究结果表明,对羟基苯甲醛本身是一种Br?nsted酸,无需加入催化剂即可顺利地进行环氧键的SN2亲核取代反应;采用极性较强的溶剂并升高温度有利于改性反应的进行。在改性反应中,以DMF为溶剂,当微球表面环氧基团与HBA的摩尔投料比为1:1.8,在110℃下反应12小时可得到键合量为0.21g/g的改性微球。以改性微球HBA-GMA/MMA、吡咯、苯甲醛(或取代苯甲醛)为共反应物,采用固-液之间的Adler反应,使卟啉的合成与固载同步进行,成功制得了固载有苯基卟啉、对氯苯基卟啉与对硝基苯基卟啉的三种功能微球PP-GMA/MMA、CPP-GMA/MMA、NPP-GMA/MMA。重点研究了各种因素对同步合成与固载过程的影响规律。实验结果表明,溶剂的极性、催化剂的酸性以及苯甲醛衍生物的结构是主要的影响因素,选择较高的温度(130℃)、使用极性强的溶剂(二甲亚砜)与pKa在3.0-3.9范围的酸(乳酸),反应7h可制得卟啉固载量为7.86g/100g的功能微球。并且,在三种卟啉功能化共聚物中,采用对氯苯甲醛合成CPP-GMA/MMA是最易进行的,而采用对硝基苯甲醛合成NPP-GMA/MMA则最为困难。在实现卟啉的同步合成与固载后,实施了固载卟啉的微球与钴盐的配合反应,制备了固载有钴卟啉的三种固体催化剂CoPP-GMA/MMA、CoCPP-GMA/MMA、CoNPP-GMA/MMA,采用原子吸收光谱法测定了固体催化剂表面的钴含量。将其用于分子氧对乙苯的催化氧化,并考察了主要因素对催化活性的影响。实验结果表明,钴卟啉固体催化剂能有效地活化分子氧,具有优良的催化活性与选择性,120℃常压下通氧气反应12h,苯乙酮的得率可达21.5%。作为仿生催化剂的钴卟啉,过量的加入反而会抑制催化活性,且固载密度越小,催化活性越高;具有良好的重复使用性能。三种固体催化剂相比较,在芳环上具有强吸电子取代基硝基的CoNPP-GMA/MMA催化活性最高。采用三种固载钴卟啉为催化剂,在碱性甲醇溶液中以分子氧为氧化剂,实施了将β-萘酚氧化为2-羟基-1,4-萘醌(HNQ)的反应过程。实验结果表明,常压下于0℃通氧气反应2.5h,当氢氧化钠用量为5.0g且催化剂用量为0.231g时,可高选择性地合成HNQ,最高产率达30%。研究中发现,氢氧化钠对β-萘酚催化氧化反应起着重要作用,本身虽不起催化作用,但可以加快反应速率;在催化氧化体系中,苯基卟啉催化剂的苯环上取代基种类对其催化活性有很大的影响,具有斥电子的取代基反而能显著提高金属卟啉的催化氧化性能,有利于催化活性。更多还原

【Abstract】 As models of cytochrome P-450, metalloporphyrins have been used to oxidate hydrocarbons with molecular oxygen under mild conditions. Especially, the catalytic oxidation of polymer immobilized metalloporphyrins has been paid more attention to. A new preparation method of metalloporphyrins catalyst has been designed in this paper, succeeding in realizing synchronistic synthesis and immobilization of porphyrins on crosslinked microspheres GMA/MMA via the Adler reaction. Then reacted with cobalt, producing cobalt porphyrins. The polymer-supported catalyst was used in the catalytic oxidation of ethyl benzene andβ-Naphthol with molecular oxygen as oxidant, and some valuable research results for the field of heterogeneous biomimetic catalyst were found.Firstly, the crosslinked copolymer microspheres GMA/MMA were prepared in a suspension polymerization system. The microspheres were chemically modified using p-hydroxyl benzaldehyde (HBA) as reagent via the ring-opening reaction of the epoxy groups on the surface of microspheres, resulting in the modified microspheres HBA-GMA/MMA on which HBA was chemically bound. The effects of main factors such as reaction temperature, solvent variety and the feed ratio on the modification reaction were investigated emphatically. The experimental results show that p-hydroxyl benzaldehyde is a Br?nsted acid itself, and it can effectively be bound onto the surface of microspheres without the addition of catalyst via SN2 nucleophilic substitution reaction. It is advantageous to the modification reaction to use the solvent with stronger polarity and enhance temperature. In the modification reaction, a maximum bonding capacity of 0.21g/g of the modified microspheres can be achieved with DMF as the solvent, the feed ratio of epoxy group to HBA as 1:1.8 at 110℃under 12 hours.Subsequently, Adler reaction was performed at the interface of solid/solution by using microspheres HBA-GMA/MMA, derivant of benzaldehade and pyrrole in solution as co-reactants, so that the synchronistic synthesis and immobilization of porphyrins on the microspheres GMA/MMA were realized successfully, resulting in porphyrin- supported microspheres PP-GMA/MMA, CPP-GMA/MMA and NPP-GMA/MMA. In this investigation, the effects of the main factors on the process of synchronistic synthesis and immobilization of porphyrins were studied. The experimental results show that the acidity of the catalysts, the polarity of the solvents and substituent on phenyl porphyrins affect the reaction greatly. As the temperature is 130℃, the stronger polarity solvent DMSO and catalyst with a pKa value in the region of 3.0-3.9 is used, the porphyrin microspheres with a higher immobilization amount of 7.86g/100g will be obtained. In comparison, the synthesis of CPP-GMA/MMA using chlorobenzaldehyde is carried out most easily, while the synthetic NPP-GMA/MMA using nitrobenzaldehyde most difficult.Via the coordination reaction between the functional microspheres and cobalt salt, polymer-supported cobaltporphyrins CoPP-GMA/MMA、CoCPP-GMA/MMA and CoNPP-GMA/MMA were prepared. The cobalt content of solid catalyst was determined by the atomic absorption spectrometry. The catalytic activities of the solid catalysts were tested in the catalytic oxidation reaction of ethyl benzene by dioxygen, and the main factors on the catalytic activity were studied. The experimental results show that the cobaltporphyrin catalyst can effectively activate dioxygen, has excellent catalytic activity and fine selectivity. The yield of acetophenone at ordinary pressure of oxygen and 120℃in 12h can get up to 21.5%. As the biomimetic catalyst, excess addition will inhibit the catalyst activity; the smaller the immobilization density on the surface of microspheres, the higher the catalyst activity is; and the catalyst has a good reuse performance. In comparison, the catalytic activity of CoNPP-GMA/MMA is the highest. Using the solid catalysts on which cobaltporphyrins (CoP) were loaded as catalyst, the catalytic oxidation ofβ-Naphthol to 2-hydroxy-1,4-naphthoquinone was performed in methanol solution of NaOH, and with molecular oxygen as oxidant. The experimental results show that as the amount of NaOH is 5.0g and the used amount of cobaltporphyrin is 0.231g, the product nearly is 2-hydroxy-1,4-naphthoquinone, and the yield can get up to 30%. It is found that sodium hydroxide plays an important role, though not as a catalyst itself, but it can accelerate the reaction rate; In the catalytic oxidation system, the substituent types on phenyl porphyrin affect the reaction greatly, the catalytic activity of metalloporphyrin can be significantly improved with the exclusion of the electron substituents and thus a higher yield.更多还原