陽離子型稀土金屬配合物催化烯烴聚合的理論研究
發(fā)布時(shí)間：2018-11-27 12:11
【摘要】：高性能烯烴聚合催化劑的發(fā)展已成為新型聚烯烴材料發(fā)展的主要推動(dòng)力。近年來,陽離子型稀土金屬配合物在烯烴聚合中表現(xiàn)出了獨(dú)特的催化性能,從而受到國內(nèi)外研究者的廣泛關(guān)注。然而現(xiàn)有實(shí)驗(yàn)手段難以檢測和分離相關(guān)催化過程的活性物種,妨礙了有關(guān)聚合機(jī)理等基本化學(xué)問題的探討。運(yùn)用理論計(jì)算化學(xué)方法可以從分子水平上研究反應(yīng)機(jī)理,在很大程度上推動(dòng)了新型聚烯烴催化劑及新型聚合材料的發(fā)展。本論文采用QM(Quantum Mechanics)和ONIOM計(jì)算方法從分子水平上探討了一系列稀土金屬配合物催化烯烴聚合的反應(yīng)機(jī)理,包括金屬和輔助配體影響聚合活性與選擇性的分子機(jī)制等基本化學(xué)問題。主要研究結(jié)果如下：1.對含C3對稱性iPr-triSOX配體的陽離子型稀土金屬烷基配合物催化1-己烯全同聚合過程進(jìn)行了計(jì)算研究。結(jié)果表明,在鏈引發(fā)和鏈增長階段,2,1-插入的過渡態(tài)中輔助配體和1-己烯的(CH2)3CH3鏈之間存在較大的相互排斥作用,而1,2-插入不存在此作用,因此,1,2-插入成為動(dòng)力學(xué)上更有利的插入方式；1-己烯的全同聚合主要為動(dòng)力學(xué)控制過程,遵循鏈端控制機(jī)理；二價(jià)陽離子活性物種催化的聚合過程在動(dòng)力學(xué)和熱力學(xué)上均優(yōu)于一價(jià)物種,計(jì)算結(jié)果與實(shí)驗(yàn)結(jié)果一致。金屬鈧物種催化的1-己烯插入過程在動(dòng)力學(xué)上比釔物種更有利,且陽離子鈧物種比對應(yīng)的釔物種更容易生成,從而解釋了陽離子鈧配合物具有高活性的原因。2.對陽離子型稀土金屬配合物[(η5-C5Me5)Ln(CH2SiMe3)(THF)n]+(A,Ln=Sc,Y,Lu, Gd, Sm； n = 0 (AL.),1 (thfALn))、[(η5-C5Me5)Sc(CH2C6H4NMe2-0)]+ (B)和[(η5-C5Me5)Sc(C6H4OMe-0)]+(C)催化苯乙烯聚合過程中的區(qū)域選擇性、立體選擇性、內(nèi)外源Lewis堿對鏈端微結(jié)構(gòu)的影響以及不同金屬的催化活性進(jìn)行了計(jì)算研究。結(jié)果表明,外源Lewis堿THF不影響聚苯乙烯的選擇性,但能夠降低聚合活性；氨基芐基內(nèi)源Lewis堿,能夠降低鏈引發(fā)過程的區(qū)域選擇性,對鏈增長的立體選擇性無明顯影響；甲氧苯基作為內(nèi)源Lewis堿時(shí),金屬鈧原子與氧原子之間的強(qiáng)相互作用傾向于得到全同的鏈端微結(jié)構(gòu)。首次闡明鈧金屬配合物具有較高活性的原因在于鈧具有較強(qiáng)Lewis酸性、較小的離子半徑以及聚合過程不容易進(jìn)入休眠態(tài)等。3.對含有不同配體的金屬鈧配合物催化戊二烯、丁二烯和異戊二烯立體選擇性聚合過程進(jìn)行了計(jì)算研究。結(jié)果表明,在戊二烯聚合過程中,順式-1,4單體插入過程在動(dòng)力學(xué)上明顯優(yōu)于反式-1,4單體的插入過程；全同立構(gòu)聚合在動(dòng)力學(xué)和熱力學(xué)上均比間同立構(gòu)聚合容易發(fā)生；全同立構(gòu)聚合過程中配體和單體之間存在較大的排斥作用,是導(dǎo)致間同選擇性聚合較難發(fā)生的主要原因。在丁二烯聚合過程中,順式-1,4選擇性主要?dú)w因于對應(yīng)過渡態(tài)中單體與金屬中心間的較強(qiáng)相互作用；相比之下,異戊二烯1,4插入過渡態(tài)中單體與輔助配體之間存在較明顯的相互排斥作用,從而有利于異戊二烯的3,4-選擇性聚合。4.對陽離子型鑭-鋁雙金屬配合物催化的異戊二烯反式-1,4-聚合機(jī)理進(jìn)行了計(jì)算研究。結(jié)果表明,在三種’可能存在的活性物種[(C5Me5)La(μ2-Me)3AlMe]+(A). [(C5Me5)La(μ2-Me)2AlMe2]+(B)和[(C5Me5)La(Me)(μ2-Me)AlMe2]+(C)中,通過探討鏈引發(fā)、三種物種的相互轉(zhuǎn)化以及烯烴配位分離抗衡陰離子的過程,發(fā)現(xiàn)物種C可能是催化合成反式-1,4聚異戊二烯的真實(shí)活性物種；通過對鑭-鋁雙金屬中心協(xié)同催化以及金屬鑭單中心催化聚合路徑進(jìn)行對比,發(fā)現(xiàn)后一種路徑是更加有利的聚合過程。在單金屬中心催化聚合過程中,AlMe3作為配體通過一個(gè)甲基與金屬鑭中心配位；與鑭不同,以金屬釔為中心的聚合體系中,AlMe配體在聚合過程中趨于遠(yuǎn)離金屬釔中心,從而得到順式-1,4聚異戊二烯,與實(shí)驗(yàn)結(jié)果一致,金屬鑭與釔催化體系在聚合選擇性上的差異主要源于金屬釔比金屬鑭離子半徑小以及AlMe在熱力學(xué)上易于從釔金屬中心解離。上述結(jié)果表明,烷基鋁對此聚合體系的選擇性起到了至關(guān)重要的作用。
[Abstract]:The development of high-performance olefin polymerization catalyst has become the main driving force for the development of a new type of polyolefin material. In recent years, cationic rare-earth metal complexes show a unique catalytic performance in the polymerization of olefins, which are of great concern to the researchers at home and abroad. However, the existing experimental means is difficult to detect and separate the active species of the relevant catalytic process, which is an obstacle to the discussion of the basic chemical problems such as the polymerization mechanism. By using the theory, the reaction mechanism can be studied from the molecular level, and the development of the new type of polyolefin catalyst and the new type of polymeric material is promoted to a great extent. In this paper, the reaction mechanism of a series of rare-earth metal complexes to catalyze the polymerization of olefins, including the effects of metals and auxiliary ligands, on the polymerization activity and the molecular mechanism of selective molecular mechanism, is discussed from the molecular level by using the QM (Quantum Mechanics) and the ONIOM calculation method. The main results are as follows: 1. The polymerization of 1-hexene with the cation-type rare-earth metal alkyl complex containing the C3-symmetric iPr-trisox ligand was studied. The results show that there is a large mutual exclusion between the auxiliary ligand and the (CH2) 3CH3 chain of 1-hexene in the transition state of the chain initiation and the chain growth. The whole-homopolymerization of 1-hexene is mainly the kinetic control process, followed by the chain end control mechanism, and the polymerization process catalyzed by the divalent cation active species is better than the one-valent species in the dynamics and thermodynamics, and the calculation results are consistent with the experimental results. the 1-hexene insertion process catalyzed by a metal-based species is more advantageous in kinetics than in the native species, and the cationic species is more easily generated than the corresponding species of the species, thus explaining the reason for the high activity of the cationic polymer complex. The regioselectivity and stereoselectivity of the cationic rare-earth metal complex[(H5-C5Me5) Ln (CH2SiMe3) (THF) n] + (A, Ln = Sc, Y, Lu, Gd, Sm; n = 0 (AL.), 1 (thfALn)),[(H5-C5Me5) Sc (CH2C6H4NMe2-0)] + (B) and[(-5-C5Me5) Sc (C6H4OMe-0)] + (C) in the catalytic styrene polymerization process, The effect of the internal and external sources of Lewis base on the microstructure of the chain end and the catalytic activity of different metals were studied. The results show that the exogenous Lewis base THF does not affect the selectivity of the polystyrene, but can reduce the polymerization activity; the amino-base endogenous Lewis base can reduce the regioselectivity of the chain initiation process, has no obvious effect on the stereoselectivity of the chain growth, The strong interaction between the metal atom and the oxygen atom tends to result in a fully-identical chain-end microstructure. The reason for the first time that the metal complex has higher activity is that it has a strong Lewis acidity, a smaller ionic radius, and the polymerization process is not easy to enter the dormant state. The process of stereoselective polymerization of butadiene and isoprene was carried out on the catalytic oxidation, butadiene and isoprene stereoselective polymerization of the metal complex containing different ligands. The results show that the insertion process of cis-1,4-monomer is better than that of trans-1,4-monomer in the process of polymerization. There is a large repulsive interaction between the ligand and the monomer in the whole-homopolymerization process, which is the main reason which leads to the more difficult to occur between the ligand and the monomer. in that proces of butadiene polymerization, the selectivity of cis-1,4 is mainly due to the strong interaction between the monomer in the corresponding transition state and the metal center; in contrast, the isoprene 1, 4 is inserted into the transition state, so as to facilitate the 3,4-selective polymerization of the isoprene. The mechanism of trans-1,4-polymerization of isoprene catalyzed by cationic Al-Al bimetallic complexes was studied. The results show that in three 'Possible active species[(C5Me5) La (. mu. 2-Me) 3AlMe] + (A).[(C5Me5) La (... 2-Me) 2AlMe2] + (B) and[(C5Me5) La (Me) (... 2-Me) AlMe2] + (C), it was found that species C may be a real active species that catalyzes the synthesis of trans-1,4-polyisoprene by exploring the process of chain initiation, the conversion of three species, and the separation of olefins to counter anions. It is found that the latter path is a more favorable polymerization process by the co-catalysis of the double-metal center of the Al-Al and the catalytic polymerization path of the single-center of the metal. in that proces of the catalytic polymerization of the single-metal center, AlMe3 is coordinated by a methyl group and a metal contact center as the ligand; in the polymerization system with the metal base as the center, the AlMe ligand tends to be far away from the metal contact center in the polymerization process so as to obtain the cis-1,4-polyisoprene, In agreement with the experimental results, the difference in the polymerization selectivity of the metal-and-metal-catalyzed system is mainly due to the fact that the metal-to-metal ratio is smaller than that of the metal, and the AlMe is easily dissociated from the metal center in the thermodynamics. The results show that the selectivity of the alkyl aluminum to the polymerization system plays a very important role.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：O631.5
，
本文編號：2360711
[Abstract]:The development of high-performance olefin polymerization catalyst has become the main driving force for the development of a new type of polyolefin material. In recent years, cationic rare-earth metal complexes show a unique catalytic performance in the polymerization of olefins, which are of great concern to the researchers at home and abroad. However, the existing experimental means is difficult to detect and separate the active species of the relevant catalytic process, which is an obstacle to the discussion of the basic chemical problems such as the polymerization mechanism. By using the theory, the reaction mechanism can be studied from the molecular level, and the development of the new type of polyolefin catalyst and the new type of polymeric material is promoted to a great extent. In this paper, the reaction mechanism of a series of rare-earth metal complexes to catalyze the polymerization of olefins, including the effects of metals and auxiliary ligands, on the polymerization activity and the molecular mechanism of selective molecular mechanism, is discussed from the molecular level by using the QM (Quantum Mechanics) and the ONIOM calculation method. The main results are as follows: 1. The polymerization of 1-hexene with the cation-type rare-earth metal alkyl complex containing the C3-symmetric iPr-trisox ligand was studied. The results show that there is a large mutual exclusion between the auxiliary ligand and the (CH2) 3CH3 chain of 1-hexene in the transition state of the chain initiation and the chain growth. The whole-homopolymerization of 1-hexene is mainly the kinetic control process, followed by the chain end control mechanism, and the polymerization process catalyzed by the divalent cation active species is better than the one-valent species in the dynamics and thermodynamics, and the calculation results are consistent with the experimental results. the 1-hexene insertion process catalyzed by a metal-based species is more advantageous in kinetics than in the native species, and the cationic species is more easily generated than the corresponding species of the species, thus explaining the reason for the high activity of the cationic polymer complex. The regioselectivity and stereoselectivity of the cationic rare-earth metal complex[(H5-C5Me5) Ln (CH2SiMe3) (THF) n] + (A, Ln = Sc, Y, Lu, Gd, Sm; n = 0 (AL.), 1 (thfALn)),[(H5-C5Me5) Sc (CH2C6H4NMe2-0)] + (B) and[(-5-C5Me5) Sc (C6H4OMe-0)] + (C) in the catalytic styrene polymerization process, The effect of the internal and external sources of Lewis base on the microstructure of the chain end and the catalytic activity of different metals were studied. The results show that the exogenous Lewis base THF does not affect the selectivity of the polystyrene, but can reduce the polymerization activity; the amino-base endogenous Lewis base can reduce the regioselectivity of the chain initiation process, has no obvious effect on the stereoselectivity of the chain growth, The strong interaction between the metal atom and the oxygen atom tends to result in a fully-identical chain-end microstructure. The reason for the first time that the metal complex has higher activity is that it has a strong Lewis acidity, a smaller ionic radius, and the polymerization process is not easy to enter the dormant state. The process of stereoselective polymerization of butadiene and isoprene was carried out on the catalytic oxidation, butadiene and isoprene stereoselective polymerization of the metal complex containing different ligands. The results show that the insertion process of cis-1,4-monomer is better than that of trans-1,4-monomer in the process of polymerization. There is a large repulsive interaction between the ligand and the monomer in the whole-homopolymerization process, which is the main reason which leads to the more difficult to occur between the ligand and the monomer. in that proces of butadiene polymerization, the selectivity of cis-1,4 is mainly due to the strong interaction between the monomer in the corresponding transition state and the metal center; in contrast, the isoprene 1, 4 is inserted into the transition state, so as to facilitate the 3,4-selective polymerization of the isoprene. The mechanism of trans-1,4-polymerization of isoprene catalyzed by cationic Al-Al bimetallic complexes was studied. The results show that in three 'Possible active species[(C5Me5) La (. mu. 2-Me) 3AlMe] + (A).[(C5Me5) La (... 2-Me) 2AlMe2] + (B) and[(C5Me5) La (Me) (... 2-Me) AlMe2] + (C), it was found that species C may be a real active species that catalyzes the synthesis of trans-1,4-polyisoprene by exploring the process of chain initiation, the conversion of three species, and the separation of olefins to counter anions. It is found that the latter path is a more favorable polymerization process by the co-catalysis of the double-metal center of the Al-Al and the catalytic polymerization path of the single-center of the metal. in that proces of the catalytic polymerization of the single-metal center, AlMe3 is coordinated by a methyl group and a metal contact center as the ligand; in the polymerization system with the metal base as the center, the AlMe ligand tends to be far away from the metal contact center in the polymerization process so as to obtain the cis-1,4-polyisoprene, In agreement with the experimental results, the difference in the polymerization selectivity of the metal-and-metal-catalyzed system is mainly due to the fact that the metal-to-metal ratio is smaller than that of the metal, and the AlMe is easily dissociated from the metal center in the thermodynamics. The results show that the selectivity of the alkyl aluminum to the polymerization system plays a very important role.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：O631.5
，
本文編號：2360711
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