论文部分内容阅读
离子液体因其所独有的物理化学性质如蒸气压低、热稳定性好以及结构和性能的可调性等优点而备受关注.四羰基钴阴离子是多种重要均相催化反应的催化活性物种,含有四羰基钴阴离子的金属有机离子液体有效结合了羰基金属和离子液体各自的特点和优势,作为一类新颖而且重要的功能化离子液体,受到国内外研究者的青睐.2001年,Dyson等首次报道了一种室温下为液态的羰基钴金属有机离子液体[bmim][Co(CO)_4],为四羰基钴阴离子离子液体的研究开创了先河.此后,有关羰基钴金属有机离子液体的催化应用研究也相继报道.目前[CnPy][Co(CO)_4]以及[bmim][Co(CO)_4]在环氧化合物的羰基化反应中已有报道,但该类催化剂的催化活性特别是循环使用性能有待进一步提高.胍盐具有阳离子电荷分散程度高、热稳定性和化学稳定性高、三个氮原子上的基团可以调节等特点,使得胍盐离子液体的设计、合成和应用研究受到国内外学者关注.由于其自身结构特点,氮原子上有取代氢可以和含F,O,N底物作用形成氢键,并且氮原子上取代烷基之间作用使阳离子的平面结构发生变化,使得与三个氮原子相连的碳原子处于缺电子状态,使阳离子表现出Lewis酸性.所以其在环氧化合物氢酯基化反应中可起到稳定四羰基钴阴离子以及活化环氧化合物的作用.基于此,本文以较高收率合成了四种新型的1,1,3,3-四烷基胍羰基钴金属有机离子液体:1,1-二甲基-3,3-二乙基胍羰基钴(3a),1,1-二甲基-3,3-二正丁基胍羰基钴(3b),1,1-二甲基-3,3-四亚甲基胍羰基钴(3c),1,1-二甲基-3,3-五亚甲基胍羰基钴(3d).通过红外光谱、紫外-可见光谱、1H核磁共振谱、13C核磁共振谱、高分辨质谱、差示量热扫描仪和热重分析对该类化合物进行了结构确认及性质研究.这四种催化剂,特别是3a,在环氧化合物的氢酯基化反应中表现出优异的催化性能,在无需任何助剂的情况下具有较好的催化活性及底物适用性.此外,以不同构型的环氧丙烷为反应底物,氢酯基化反应结果显示:在该催化体系作用下,产物的构型与底物保持一致,没有发生消旋.尤其值得指出的是,催化剂3a在环氧丙烷的氢酯基化反应中表现出了优异的循环稳定性能,在循环使用6次后依然可以获得较好的转化率(91%)和选择性(94%).
Due to its unique physicochemical properties such as low vapor pressure, good thermal stability, and the structure and properties of the adjustable ionic liquid etc. The ionic liquid of cobalt carbonyl is a variety of important homogeneous catalytic reaction catalytically active species , Metal organic ionic liquids containing cobalt carbonyl ions effectively combine the characteristics and advantages of metal carbonyls and ionic liquids and are favored by researchers at home and abroad as a new and important functionalized ionic liquid.In 2001, Dyson et al It is the first time to report that a liquid cobalt carbonyl organometallic ionic liquid [bmim] [Co (CO) 4] at room temperature has opened the door to the research of tetracarboxy cobalt anion ionic liquids. Catalytic applications are also reported in succession.Currently, [CnPy] [Co (CO) _4] and [bmim] [Co (CO) _4] have been reported in the carbonylation of epoxy compounds, Is to be further improved recycling performance.Guanggui salt has a high degree of cationic charge dispersion, thermal stability and chemical stability, the three groups can be adjusted on the nitrogen atoms and other characteristics, making the guanidine from The design, synthesis and application of sub-liquid have drawn much attention from domestic and foreign scholars.Because of its own structural characteristics, substituted hydrogen on the nitrogen atom can form a hydrogen bond with the substrate containing F, O, and N and the alkyl group on the nitrogen atom The interfacial effect changes the planar structure of the cation so that the carbon atoms connected to the three nitrogen atoms are in an electron deficient state and the cation shows Lewis acidity so that it can stabilize the tetracarbonyl group in the epoxidation of epoxy compounds Cobalt anions and activated epoxy compounds.On the basis of this, four novel 1,1,3,3-tetraalkylguanidine carbonyl cobalt metal organic ionic liquids were synthesized in higher yields: 1,1-dimethyl 3,3-diethylguanidine carbonyl cobalt (3a), 1,1-dimethyl-3,3-di-n-butylguanidine carbonyl cobalt (3b), 1,1-dimethyl-3,3 (3c), Cobalt (1,1) -dimethyl-3,3-pentamethyleneguanidine Cobalt Cobalt (3d) Tetramethylguanidinium Carbonyl Cobalt (3c) NMR, high resolution mass spectrometry, differential scanning calorimetry and thermogravimetric analysis were used to characterize the structures of these compounds. The four catalysts, especially 3a, Of the hydrogenation reaction showed excellent catalytic performance without any additives in the case has good catalytic activity and substrate applicability.In addition, different configurations of propylene oxide as the reaction substrate, hydrogen The results of the esterification reaction show that the structure of the product is consistent with that of the substrate without racemization under the action of the catalytic system, and it is worth noting that the catalyst 3a shows in the hydroesterification of propylene oxide Excellent cycling stability was achieved with good conversion (91%) and selectivity (94%) after 6 cycles.