新型吡啶双亚胺铁催化乙烯聚合反应

合成与表征了一种新型吡啶双亚胺铁烯烃聚合催化剂2,6-二[1-(4-羟基-2,6-二甲基苯胺)乙基]吡啶氯化铁（1a）。结果表明,在亚胺环的对位引入羟基,可同时提高催化剂的活性和聚合物的分子量。在改性甲基铝氧烷(MMAO)的活化下,该催化剂引发乙烯聚合的活性（以单位时间（h）mol Fe引发乙烯聚合的PE质量（g）来表征）可达到6.78×10⁶ g/（mol•h）,明显高于已知催化剂2,6-二[1-(2,6-二甲基苯胺)乙基]吡啶氯化铁（1b）,且能得到更高分子量的聚乙烯。     

乙烯聚合三齿氮配体金属铁钴催化剂的最新进展

1998年美国Brookhart[1]和英国帝国大学的Gibson[2]各自独立报道了含有吡啶基团的二亚胺型的铁(Ⅱ)和钴(Ⅱ)催化剂,该类催化剂显示了很高的乙烯聚合的活性(高达107g mol-1h-1),而且这种新型催化剂具有制备容易,价格便宜,活性高,耐极性官能团性能较好等优点,使得三齿配体类的后过渡金属烯烃聚合催化剂倍受重视,对其研究也更加深入发展起来.     

2,6-吡啶二亚胺基锰(Ⅲ)配合物的合成、晶体结构及催化性能

由三齿含氮配体2,6-二[1-(2,6-二甲基苯基亚胺)乙基]吡啶(L1)、2,6-二[1-(2,6-二乙基苯基亚胺)乙基]吡啶(L2)和2,6-二[1-(2,4,6-三甲基苯基亚胺)乙基]吡啶(L3)分别与MnCl2·4H2O在乙腈中反应,合成了3个新的具有较大空间位阻的2,6-吡啶二亚胺基氯化锰配合物L1Mn(Ⅱ)...     

无机/有机复合载体负载乙酰丙酮铁/双亚胺基吡啶催化剂及其乙烯聚合

采用溶胶-凝胶法,将苯乙烯-丙烯酸共聚物(PSA)包覆于955 Davison硅胶上得到无机/有机复合微球载体,并在2,6-二[1-(2-异丙基苯基亚胺基)乙基]吡啶/Fe(acac)3均相催化剂中浸渍后得到负载型双亚胺基吡啶铁催化剂.该催化剂在生产高结晶度(72%)聚乙烯的同时,还能生产一定量的α-烯烃.考察了不同膜材料以及聚合条件(不同助催化剂,压力,温度,Al/Fe摩尔比)对聚合活性以及聚合产物性能的影响,发现温度对聚合产物的α-烯烃与聚乙烯的质量比影响最大,助催化剂类型既影响催化剂的活性,也对最终产物的性质有着很大的影响.氯化镁处理的PSA作为膜材料时,负载2,6-二[1-(2-异丙基苯基亚胺基)乙基]吡啶/Fe(acac)3所得到聚乙烯分子量较低(Mw=11.9×104),结晶度较大(72%),熔融指数MI较高(2.35 g/10min),可作为双峰聚乙烯中的低分子量部分加以利用.     

二氯·{2-乙氧甲酰基-6-[1-[(2,6-二乙基苯)亚胺基]乙基]吡啶}合钴(II)的晶体结构极其对乙烯齐聚的催化活性

利用2,6-二甲基吡啶作为起始物合成了不对称前驱体6-乙酰基-2-乙酯基吡啶，在此基础上合成了单亚胺吡啶配体（5）和相应的Co(II)配合物二氯·{2-乙氧甲酰基-6-[1-[(2,6-二乙基苯)亚胺基]乙基]吡啶}合钴(II)（6）。晶体结构分析表明：配体5作为三齿配体以[N, N, O]原子和两个氯离子与中心钴(II)配位，形成畸变的三角双锥配位环境，其中吡啶氮原子和两个氯原子形成赤道平面。将该钴配合物作为催化剂应用于乙烯的聚合过程，以MAO为助催化剂，在15.5ºC下作用1 h，可达到1.820×10⁴ g/mol-Co∙h∙atm的催化活性。     

多氮螯合配位后过渡金属络合物烯烃聚合催化剂

A2二亚胺镍、钯络合物和吡啶二亚胺铁、钴络合物是近几年来发现的新一代烯烃均相聚合后过渡金属催化剂。这类催化剂具有活性高、选择性易调变、聚合物性质可控制的特点, 尤其是对官能团中的杂原子的稳定性方面优于前过渡金属催化剂。本文将近年来的有关报道归纳为4 个方面进行评述: 络合物的合成和结构; 配体结构因素对络合物催化性能的影响; 催化烯烃高聚、齐聚和共聚以及催化反应机理。     

吡啶-2-羧酸钴催化氯苄双羰化合成新型α-酮酸研究

α-酮酸在生物化学、农药、医药、食品生产及精细有机合成中具有潜在的应用价值[1] .从有机卤化物一步双羰化合成α-酮酸或其衍生物是近年来有机过渡金属化学中新发现的反应之一 [2 ,3] .迄今为止 ,双羰化合成α-酮酸的催化剂主要为羰基钴类络合物 [4 ] 或钯络合物 [5] ,合成产物均为苯丙酮酸 .我们在进行吡啶 - 2 -羧酸钴氧化羰化合成碳酸二甲酯研究的基础上 [6 ] ,发现吡啶 - 2 -羧酸钴具有良好的双羰化性能 ,在 333K,3.0 MPa条件下 ,可使氯苄一步双羰化合成一种新的α-酮酸 ( 1 ) :β-苄基 -α-苯丙酮酸( BPPA) .反应式如下 :CH2 Cl+…     

一种新型双亚胺吡啶铁系催化剂的乙烯低聚研究

线性α 烯烃广泛地应用于洗涤剂、增塑剂、润滑油等精细化学品的合成以及作为共单体制备线性低密度聚乙烯 (ＬＬＤＰＥ) .目前工业上主要是应用ＳＨＯＰ法[1] 、Ｃｈｅｖｒｏｎ工艺和Ａｍｏｃｏ工艺[2 ] 通过乙烯低聚制备 .近些年发展起来的新型高活性后过渡金属乙烯低聚催化剂能够高选择性地制备线性α 烯烃[3 ,4] .Ｂｒｏｏｋｈａｒｔ等[4] 的研究表明 ,对于双亚胺吡啶铁系乙烯聚合催化剂而言 ,配体上苯基的邻位取代基位阻减小可以实现乙烯低聚 ,并具有高活性、高选择性以及理想的低聚产物分布 .本文的工作是从配体的空间位阻效应对催化剂…     

α-二亚胺镍复式催化剂/MAO制备高支化的长支链聚乙烯

研究了由两种α-二亚胺镍催化剂[Cat1:α-萘基-丁二亚胺二溴化镍,Cat2:2,6-二异丙基苯基苊二亚胺二溴化镍]组成的复式镍催化剂在MAO活化下催化单一乙烯聚合.可制备得到支化度高达上百个支链(每1000个碳),长支链的比例占到30%左右的聚乙烯.13C-NMR、GPC、DSC、WAXD、DMA结果表明此复式催化剂催化乙烯聚合可得到分子量较高、分子量分布较窄的长支链聚乙烯弹性体.在合适的条件下,此复式催化体系还具有促进提高催化活性的良好协同作用,其聚合活性比两种单一催化剂都高(4·6×105g PE/mol Ni·h).     

冠醚化双Schiff碱钴(Ⅱ)络合物对异丙苯催化氧化行为研究

在研究异丙苯的均相催化氧化反应中,多以金属-卟啉,金属-酞菁和乙酰丙酮合钴作催化剂。用双Schiff碱的金属络合物,如双(水杨基)乙二亚胺合钴1仅见一例,而以四个配位原子共平面性更佳的双(水杨基)邻苯二亚胺合钴2作催化剂则未见报道。在乙酰丙酮合钴的催化体系中添加少量冠醚,能加速对异丙苯的氧化。我们合成的络合物3a—d则将刚性桥链双Schiff碱和冠醚环结构集为一体.有可能成为具有特殊催化性能的新型络合催化剂,在常压条件下以空气为氧源,用乙酰丙酮钴和1、2作对照物,     

Polymerization of Norbornene via an Iron-Based Complex/MAO Catalytic System

IntroductionOwing to the high thermal stability,low waterabsorption and excellent optical properties as wellas the utility in an elastomeric material forvibration and sound damping or in a soakingmaterial for oil spills[1— 4 ] ,the homopolymers andthe copolymers of norbornene have attracted aconsiderable attention.So far,a large number oftransition- metal compounds have been known tocatalyze the ring- opening olefin metathesispolymerization (ROMP) ,or the vinyl additionpolymerization (VAP) …     

Iron‐based catalysts bearing bis(imido)–pyridine ligands for the polymerization of tert‐butyl acrylate

Iron(II) dichloride complexes bearing a tridentate nitrogen donor ligand were investigated for the homopolymerization of tert‐butyl acrylate after activation with methylaluminoxane. Two new complexes were synthesized, 2,6‐bis[1‐(cyclohexylimido)ethyl]pyridine iron chloride (FeCl₂) and 2,6‐bis[1‐(isopropylimido)ethyl]pyridine FeCl₂, and the single‐crystal X‐ray structure of the latter one was determined. Turnover frequencies of the catalysts during polymerization ranged from 36 to 241 cycles/mol/h. The obtained polymers exhibited weight‐average molecular weights ranging from 24,000 to 438,500 g/mol, and the molar mass distribution varied between 1.8 and 4.3. Activity of the catalytic system and the molar mass of the polymer are influenced by the ligand structure of the complexes as well as other polymerization conditions such as monomer concentration and temperature. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1380–1389, 2003     

In situ polymerization of ethylene with bis(imino)pyridine iron(II) catalysts supported on clay: The synthesis and characterization of polyethylene–clay nanocomposites

Polyethylene–clay nanocomposites were synthesized by in situ polymerization with 2,6‐bis[1‐(2,6‐diisopropylphenylimino)ethyl] pyridine iron(II) dichloride supported on a modified montmorillonite clay pretreated with methylaluminoxane (MAO). The catalysts and the obtained nanocomposites were examined with wide‐angle X‐ray scattering. The exfoliation of the clay was further established by transmission electron microscopy. Upon the treatment of the clay with MAO, there was an increase in the d‐spacing of the clay galleries. No further increase in the d‐spacing of the galleries was observed with the iron catalyst supported on the MAO‐treated clay. The catalyst activity for ethylene polymerization was independent of the Al/Fe ratio. The exfoliation of the clay inside the polymer matrix depended on various parameters, such as the clay content, catalyst content, and Al/Fe ratio. The crystallinity percentage and crystallite size of the nanocomposites were affected by the degree of exfoliation of the clay. Moreover, when ethylene was polymerized with a mixture of the homogeneous iron(II) catalyst and clay, the degree of exfoliation was significantly lower than when the polymerization was performed with a preformed clay‐supported catalyst. This observation suggested that in the supported catalyst, at least some of the active centers resided within the galleries of the clay. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 304–318, 2005     

Carbon–Carbon Bond Formation in a Weak Ligand Field: Leveraging Open‐Shell First‐Row Transition‐Metal Catalysts

Unique features of earth‐abundant transition‐metal catalysts are reviewed in the context of catalytic carbon–carbon bond‐forming reactions. Aryl‐substituted bis(imino)pyridine iron and cobalt dihalide compounds, when activated with alkyl aluminum reagents, form highly active catalysts for the polymerization of ethylene. Open‐shell iron and cobalt alkyl complexes have been synthesized that serve as single‐component olefin polymerization catalysts. Reduced bis(imino)pyridine iron and cobalt dinitrogen compounds have also been discovered that promote the unique [2+2] cycloaddition of unactivated terminal alkenes. Studies of the electronic structure support open‐shell intermediates, a deviation from traditional strong‐field organometallic compounds that promote catalytic C−C bond formation.     

Transition metal complexes bearing 2,6-bis(imino)pyridyl:Synthesis, structure, ethylene polymerization/oligomerization studies

A series of new complexes {2,6-bis[1-((2-methyl-4-methoxyphenyl)imino)ethyl]pyri-dine}MCI2 [M=Fe(Ⅱ) (2), Co(Ⅱ) (3), Ni(Ⅱ) (4), Cu(Ⅱ) (5), Zn(Ⅱ) (6)] have been synthesized. At 25℃, using 500 equiv of methylaluminoxane (MAO), the activities of Fe(Ⅱ), Co(Ⅱ) catalysts can reach 4.02×106 g/mol-Fehatm for ethylene polymerization and 3.98×105 g/mol-Cohatm for ethylene oligomerization. The effects of polymerization conditions such as reaction temperature, Al/M molar ratio and time on the activity of catalyst have been explored.     

一种光响应性热敏聚合物的合成及性能表征

合成了偶氮单体 2 [4 (4′ 乙氧基苯基偶氮 )苯氧基 ]乙基丙烯酸酯 (EAPEA) ,利用核磁共振、傅立叶红外和元素分析法对其分子结构进行了表征 .利用该单体与异丙基丙烯酰胺共聚得到一种对温度和光敏感的共聚物 .共聚物中少量的EAPEA单元能够显著降低聚异丙基丙烯酰胺 (PNIPA)的相转变温度 .当EAPEA的摩尔含量为 2 94%时 ,相转变温度从PNIPA均聚物的 31 8℃下降为 2 2 0℃ .在波长为 36 5nm的紫外光照射下 ,共聚物中的偶氮基团能够从反式构型转变为顺式构型 .在紫外光下照 30s后 ,EAPEA摩尔含量为 0 98%的聚 {异丙基丙烯酰胺 共 2 [4 (4′ 乙氧基苯基偶氮 )苯氧基 ]乙基丙烯酸酯 }的相转变温度从 2 7 2℃上升到2 9 3℃     

Aldimine 2,6-bis(imino)pyridine iron(II) and cobalt(II)/methyl aluminoxane catalyst systems for polymerization of <Emphasis Type="Italic">tert-</Emphasis>butylacrylate

Aldimine 2,6-bis[(imino)methyl]pyridine iron(II) (1, 4, and 6) and cobalt(II) (3 and 5) complexes bearing bulky cycloaliphatic (bornyl and myrtanyl) or aromatic (naphthyl) terminal groups have been applied successfully, after activation with methyl aluminoxane (MAO), as catalysts for the polymerization of tert-butylacrylate. For comparison reasons, complex 2 that contains the ketimine ligand, 2,6-bis[(−)-cis-myrtanylimino)ethyl]pyridine (BMEP), has also been utilized. All studied complexes showed moderate polymerization activities, and they produced high molar mass syndiorich-atactic polymers. Surprisingly, the aldimine-based catalyst systems showed comparable activities compared with the corresponding ketimine complex (2), and they produced high molar mass polymers. In addition, complexes with bulky terminal cycloaliphatic substituents on the tridentate aldimine ligands showed higher polymerization activity compared with the aromatic ones (6). Polymerization activity and polymer molar masses are dependent on the ligand framework.     

A Novel Highly Active Iron/2,6‐Bis(imino)pyridyl Catalyst for Ethylene Polymerization

A novel highly active catalyst 2,6‐bis[1‐(2‐methylnaphthylimino)ethyl]pyridineiron(II) chloride ( 1 ) is reported for ethylene polymerization. Compared with 2,6‐bis[(1‐naphthylimino)ethyl]pyridineiron(II) chloride ( 2 ) reported recently, catalytic activities of this new complex are high with maximum activity 6.51×10⁶ g PE·mol^–1·Fe·h^–1·bar^–1 at 40°C. The activity of the catalyst, and the molecular weight and melting temperature of the polymers depend on the methylaluminoxane/ 1 molar ratio and polymerization temperature.