Recent progresses of late-transition metal complexes with nonsymmetric diimine ligands in ethylene polymerization and oligomerization

Researches of late-transition metal complexes for ethylene polymerization and oligomerization have attracted a lot of attention in the last two decades. A large number of late-transition metal complexes with symmetric diimine ligands have been extensively studied. Although the research of unsymmetric diimine late-transition metal complexes was still in the initial stage, some superior performances were observed in olefin polymerization. Recent developments in the research of ethylene poly- merization and oligomerization catalyzed by late-transition metal complexes with unsymmetric diimine ligands were summarized in this review, with the influence of complex structure on the catalytic performance of the catalyst analyzed.     

CuCl/bpy催化的苯乙烯原子转移自由基悬浮聚合

以1-苯基氯乙烷(1-PEC l)为引发剂、氯化亚铜(CuC l)为催化剂、2,2′-联吡啶(bpy)为配体,采用开放体系,在外加搅拌和氮气保护下,研究了苯乙烯的悬浮法原子转移自由基聚合(ATRP),采用分散相水中加入电解质N aC l的方法抑制催化剂配合物向水相的扩散.结果表明,所得聚合物的分子量随转化率呈线性增加,分子量分布较窄(分布指数可达1.40),聚合反应对单体浓度为一级动力学关系,经计算聚合体系的活性自由基浓度为6.89×1-0 8m o l/L;而对A IBN为引发剂时该催化体系的反相ATRP悬浮聚合研究显示,聚合反应可控性很差,原因在于CuC l2的水溶性太强.     

无乳化剂条件下超声波引发苯乙烯乳液聚合

利用超声波二级乳化效应，实现了苯乙烯在水相中无乳化剂条件下的乳液聚合，并且初步探讨了超声时间对粘均分子量、聚合转化率的影响、反应体系的配比与聚合产物产率的关系、以及超声功率的变化对粘均分子量的影响。     

Efficient polymerization of acrylonitrile catalyzed by divalent lanthanide complex/ sodium phenolate systems

Four divalent lanthanide complexes Sm(ArO)₂ - (THF)₄, Yb(ArO)₂(THF)₃, Eu(ArO)₂(THF)₃ (ArO = 2,6-di- tert-butyl-4-methylphenolate) and (Bu^tCp)₂Sm(THF)₂ were synthesized. Their catalytic activities on the polymerization of acrylonitrile were studied. The catalytic activities were influenced by the central metal ions involved. The catalytic activities of these divalent lanthanide complexes can be greatly increased by adding NaOC₆H₂-2,6-Bu^t₂-4-Me, NaOC₆H₄-4-Bu^t, or NaOC₁₀H₆-2-Me. The amount of additive has apparent effect on the catalytic activity, but the additive has no effect on the tacticity of the resulting polyacrylonitrile.     

卤化亚铜催化卤代丁烷引发苯乙烯自由基聚合

研究过渡金属催化条件下,卤代丁烷结构等对苯乙烯自由基聚合反应的影响规律。方法,以卤代丁烷Ｃ４Ｈ９Ｘ（Ｘ＝Ｂｒ,Ｉ）／卤代亚铜ＣｕＸ（Ｘ＝Ｃｌ,Ｂｒ,Ｉ）／配位体（２,２″－联吡啶（ｂｐｙ,三苯基膦（ＰＰｈ３）体系为引发体系,研究苯乙烯本体自由基聚合动力学。     

Half-sandwich β-diketonato complexes of zirconium and their application as catalysts to ethylene polymerization

The bis(β-diketonato) Zr complexes CpZr(acac)2Cl (acac = acetylacetonato) (1) and Cp*Zr(acac)2Cl (2) can be synthesized by the reac-tion of Cp′ZrCl3(Cp′ = Cp or Cp*) with 2 equiv of lith-ium acetylacetonate. CpZr(acac)2Cl (1) can be quan-titatively prepared by treatment of Cp2ZrCl2 with ex-cess acetylacetone. The tris(β-diketonato) Zr com-plex CpZr(tfac)3 (tfac = trisfluoroacetylacetonato) (3) has been prepared by treatment of CpZrCl3 with so-dium trisfluoroacetylacetonate. The replacement of both chlorine atoms and one Cp group from zir-conocene dichloride by nonfluorinated diketone,acetylacetone,readily occurs at room temperature in triethylamine medium,offering the tris(β-diketonato) Zr complex CpZr(acac)3 (4). The complexes were characterized by 1H NMR spectroscopic methods. In addition,the molecular structures of complexes 3 and 4 have been determined by X-ray diffraction methods. When activated by excess methylaluminoxane (MAO),these complexes were active for ethylene polymerization,offering polyethylenes with high mo-lecular weights and narrow molecular weight distribu-tions. Complex 4 showed a very high ethylene po-lymerization activity of up to 7100 kg PE/mol Zr·h at 5 atm. Complexes 1 and 2 were also active for ethyl-ene/1-hexene copolymerization.     

Mesoporous zeolite SBA-15 supported nickel diimine catalysts for ethylene polymerization

The novel mesoporous zeolite SBA-15 is successfully used as the support to immobilize late-transition metal nickel diimine catalyst, both in physical and chemical methods, EA, ICP, FT-IR and XRD are applied to characterizing these supported catalysts. The results of ethylene polymerization reveal that these supported catalysts have high catalytic activity as their homogenous counterpart does,moreover, polyethylene with a fibrous morphology is produced due to the channel effect of support, and both the molecular weight and molecular weight distributions of polymers are increased greatly.     

豆油-苯乙烯共聚物的悬浮制备

采用悬浮聚合法将豆油与苯乙烯进行自由基共聚,制备支化和部分交联的聚合材料。结果表明,豆油与苯乙烯发生了共聚,聚合物中甘油酯基最高摩尔分数达到0.81%,豆油单元的质量分数达到6.50%。聚合温度85.0℃,反应时间4.0h,反应物中悬浮剂（聚乙烯醇）的质量分数0.15%,反应物中豆油的质量分数在10%时,共聚物的分子量达到最大值。共聚物中甘油酯基的含量随着反应物豆油含量的增加而增加。当反应物豆油的质量分数为10%时,凝胶的质量分数达到最大值3.70%。     

2-巯基苯并噻唑为引发剂的氮氧稳定自由基聚合

采用2-巯基苯并噻唑(2-Mercaptobenzothiazole)(MBT)为引发剂，在2，2，6，6-四甲基哌啶氮氧自由基(TEMPO)存在下，研究了苯乙烯的氮氧稳定自由基聚合．考察了TEMPO与MBT的浓度比值对聚合反应的影响，发现随着比值的增大，聚合速率明显下降，分子量也有所降低，当比值大于1时，分子量分布可以保持在1．30以下．另外，成功的扩链实验和对聚合物的^1H NMR分析也证实了聚合是按照稳定自由基聚合机理进行的．     

锆配合物催化1-丁烯二聚反应研究

用 Zr Cl4、Zr( CCl3CO2 ) 4、Zr( OEt) 2 Cl2 分别与 Et2 Al Cl组成 Ziegler-Natta型催化剂催化1 -丁烯二聚 .考察了不同反应条件对 1 -丁烯二聚的影响 .在相同的反应条件下 ,这三种催化剂对 1 -丁烯二聚的转化率顺序为 Zr( CCl3CO2 ) 4>Zr Cl4>Zr( OEt) 2 Cl2 .在最佳条件下 ,Zr( CCl3CO2 ) 4-Et2 Al Cl-Ph3P催化 1 -丁烯二聚的转化率为 95.1 % ,二聚物的选择性为 85.4 % .产物中有 C6 烯烃生成 ,证明锆配合物催化 1 -丁烯齐聚的金属锆碳键机理     

α-氯代甲苯/四水合氯化亚铁/三苯基膦引发苯乙烯“活性”/可控自由基聚合

以α-氯代甲苯(C6H5CH2Cl)/四水合氯化亚铁(FeCl2*4H2O)/三苯基膦(PPh3)为引发体系,在120 ℃下引发苯乙烯进行原子转移自由基"活性"/可控聚合反应(ATRP).结果表明:只有当n(Fe)/n(P)=1∶3时,聚合产物数均分子质量(n)与转化率才呈现一定的线性关系,聚合反应机理表现为ATRP.对于其它n(Fe)/n(P)(如1∶2和1∶4),产物的n与转化率不呈线性关系,表明在聚合反应过程中存在多种活性中心.     

双分子Salen金属催化剂的研究进展

双分子Salen金属配合物通过双金属活性中心的协同作用能够有效地催化多种化学反应.双金属催化剂拥有2个金属催化中心,可以同时对底物进行活化,从而加快反应速度和提高反应选择性.某些情况下,有些不能发生的新反应通过这种策略也能很好地反应.对双分子Salen金属催化剂的设计原理、最有效的合成方法作了归纳总结,并讨论了其在催化方面的应用.     

Reverse atom transfer radical polymerization of styrene in emulsion initiated by AIBN or V50

Reverse atom transfer radical polymerization of styrene was conducted in emulsion by using Cu（Ⅱ）/2,2＇bipydine or Cu（Ⅱ）/phen complexes, AIBN or V50 as the initiator, Brij-98 or OP-10 as the surfactant. The results of GPC showed that both polymerization processes exhibit living characters when using AIBN as the initiator. However, when V50 was used, the monomer conversion was fairly low and the whole polymerization was not controlled well. The measurement of particle size and its distribution told us that the latex particles were mean and stable when using Brij-98 as the surfactant.     

D072酸性树脂催化下乙醛聚合反应的研究

研究了D072型阳离子交换树脂对乙醛聚合反应的催化作用，通过气相色谱分析系统地探讨了各反应因素对乙醛聚合反应的影响．结果表明：D072型阳离子交换树脂具有较高的催化活性，乙醛聚合产物为三聚乙醛；在15℃时，反应达到平衡时乙醛和三聚乙醛的含量分别为10．0％和31．6％，乙醛和三聚乙醛的总量与商标标示的乙醛含量40％相接近；在此基础上测得反应速率，获得乙醛聚合反应的动力学方程为：v=kc=319．2e^4286.3/τc．     

苯乙烯-丁二烯-甲基丙烯酸甲酯三嵌段共聚物的阴离子聚合及其表征

以正丁基锂为引发剂, 1 ,1-二苯基乙烯为戴帽剂, 2-(2-甲氧基乙氧基)乙氧基锂为络合剂, 在环己烷、四氢呋喃混合溶剂中, 采用阴离子聚合法, 于－70℃～－40℃合成了非极性-极性的三嵌段共聚物聚苯乙烯-聚丁二烯-聚甲基丙烯酸甲酯(S-B-MMA) ,并借用GPC、¹H-NMR、DSC、TEM、IR等仪器对共聚物进行了表征。结果表明, 所得产物具备较窄的分子量分布 (Mw/Mn<1.3) 及微观相分离结构。     

肼还原法制备镍纳米粒子及其机理

在乙二醇中用肼作还原剂还原Ni2 制备镍纳米粒子。用X射线衍射仪测定出产物的相结构,用扫描电子显微镜观察产物的微观结构。根据反应现象和产物的相结构,研究温度、pH值调节剂种类和pH值对镍纳米粒子形成的影响,并推断其形成机理。研究结果表明,用肼作还原剂还原Ni2 制备纳米Ni的最佳反应温度为60℃,用NaOH作pH值调节剂调pH值到10～11得到的镍纳米粒子为体心立方结构,平均粒径为25nm。在Ni纳米粒子的形成过程中,NaOH不仅起到调节pH值的作用,还起催化作用。     

四甲氧基苯醌与胺类电荷转移络合物对甲基丙烯酸甲酯阻聚反应

为研究有机分子受体和给体形成电荷转移络合物（CTC）的相互作用,用四甲氧基苯醌(TMOQ)为电子受体,研究了二乙胺（DEA）,三乙胺（TEA）,N,N－二甲基苯胺（DMA）,哌啶（PD）,吗啉（ML）和N－甲基吗啉（MML）与其形成的CTC对偶氮二异丁腈（AIBN）引发的甲基丙烯酸甲酯（MMA）自由基本体聚合的阻聚效应。结果表明,TMOQ与胺所形成的CTC显著地提高了对MMA的阻聚能力,产生的阻聚诱导期取决于所用胺的碱性。另外还观察了温度对CTC形成的影响,讨论了CTC对MMA自由基聚合阻聚反应的机理,证实了反应中存在半醌负离子自由基中间体。     

骨架镍催化糠醇液相加氢制备四氢糠醇

以骨架镍作为加氢催化剂 ,在悬浮床中液相加氢还原糠醇制备四氢糠醇。分析了催化剂制备条件和加氢反应条件对骨架镍催化糠醇液相加氢制备四氢糠醇的影响。实验结果表明 ,在适当的反应条件下 ,糠醇可完全转化 ,四氢糠醇的收率和选择性较高。骨架镍催化剂适宜的制备条件为 5 0℃下镍铝合金在NaOH溶液中溶解 90min。在镍铝合金用量为 2 .0 %～ 6 .0 %、氢压为 5 .0～ 6 .0MPa的反应条件下 ,糠醇转化率可达 99%以上 ,四氢糠醇收率和选择性约为 97%。加入乙醇作为溶剂 ,可以降低杂质 1,2 戊二醇的含量 ,提高四氢糠醇的选择性。     

双苯氧基亚胺钛配合物催化甲基丙烯酸甲酯聚合

以2，4-二叔丁基苯酚为原料，通过甲酰化、希夫碱缩合等反应，制得3，5-二叔丁基水杨醛缩2，6-二异丙基苯胺（配体1a）。在四氢呋喃（THF）溶剂中，配体1a分别与NaH和TiCl4·2THF反应生成相应的水杨醛亚胺钛配合物1。气相色谱-质谱联用（GC／MS）表征了各中间产物，核磁共振氢谱（^1H NMR）、元素分析等手段表征了配合物1。在三异丁基铝助催化剂作用下，所合成的钛配合物高效催化甲基丙烯酸甲酯（MMA）本体聚合。温度为60℃，mMMA：m三异丁基铝：m钛配合物=2000：20：1下反应18h，88．16％MMA转化黏均分子量为34．8万的聚甲基丙烯酸甲酯（PMMA）。