共查询到20条相似文献,搜索用时 140 毫秒
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烯烃聚合催化剂的设计是烯烃配位聚合领域的一个核心科学问题,通过设计合成精确结构的催化剂可以有效地调控催化聚合性能以及聚合产物的结构.后过渡金属催化剂由于其易调变性、对聚合产物支化结构的可控性及对极性单体的容忍性,在烯烃聚合领域引起了广泛的关注.本文介绍了近年来本课题组在[N,N]-二齿镍烯烃聚合催化剂设计方面的研究进展,包括四元环的中性脒基镍催化剂、五元环的-二亚胺镍催化剂、2-胺基吡啶和-胺基亚胺系列镍催化剂,以及六元环的-二亚胺和苯胺基亚胺镍催化剂在烯烃聚合的应用.通过优化后过渡金属镍催化剂结构,可成功实施烯烃活性聚合. 相似文献
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仿生催化剂——Salen金属络合物催化不对称环氧化烯烃的基础 总被引:14,自引:0,他引:14
Salen与卟啉、Salen金属络合物与卟啉铁的结构和性质相似, 因此可将Salen金属(Salen-M)络合物认为是仿生催化剂, 它们的仿生性突出表现在不对称催化反应中的高对映异构选择性. 重点介绍了Salen-M络合物催化环氧化烯烃的反应机理, 环氧化合物的对映选择性与Salen配位体中的取代基效应(以取代常数σp表示)之间呈线性关系. 另外, 对映异构选择性的高低还与催化剂配体和底物的结构以及反应条件有关. 相似文献
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过渡金属助剂对催化甲醇羰基化反应的影响 总被引:3,自引:0,他引:3
过渡金属助剂对催化甲醇羰基化反应的影响①彭文庆袁国卿②(中国科学院化学研究所,北京100080)关键词过渡金属助剂铑络合物催化剂羰基化甲醇过渡金属催化剂已广泛地应用于加氢、脱氢、羰基化等反应,并显示了优良的催化活性与选择性,而且过渡金属作为助催化剂在... 相似文献
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Jun Wang Jinyi Liu Tianyu Lan Liduo Chen Libo Wang 《Journal of Coordination Chemistry》2019,72(5-7):814-825
Two new hyperbranched bispyridylamine ligands and multinuclear chromium complexes were synthesized with 1.0?G hyperbranched macromolecules, 2-chloropyridine, 2-chloro-4-methylpyridine and CrCl3(THF)3 as raw materials. The structures of hyperbranched ligands and chromium complexes were characterized by UV, FT-IR, 1H NMR, ESI-MS, and elemental analysis. These hyperbranched chromium complexes were evaluated as catalyst precursors by using MAO as activator in the oligomerization of ethylene. Effects of reaction temperature, reaction pressure, Al/Cr molar ratio, concentration of catalyst, solvent, and the structure of catalysts on the catalytic activity and product selectivity were investigated. The oligomerization results showed that with increase of reaction temperature, reaction pressure, and Al/Cr molar ratio, the catalytic activity increased and then decreased; the catalytic activity continuously decreased as the amount of catalyst increased. The products were mainly based on C6 and C8. Under optimized conditions, the catalytic system of hyperbranched NNN/Cr(III)/MAO led to activity of 1.26?×?105 g/(mol·Cr·h) and 63.34% selectivity for C6 and C8. 相似文献
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Victoria Volkis 《Journal of organometallic chemistry》2007,692(10):1940-1950
Zirconium and titanium bis(benzamidinate) dimethyl complexes were found to be active catalytic precursors for the oligomerization of mono- and bis-substituted silanes. The activation of such complexes, by an excess of MAO or by an equimolar amount of B(C6F5)3, increases the catalytic activity of the complexes and the molecular weight of the obtained oligosilanes. The maximum polymerization index that was accomplished (n = 90) is by far the largest obtained with other organometallic complexes. In addition, the activated benzamidinate catalysts were also found to be active for the polymerization of 1,5-hexadiene producing poly(methyl-1,3-cyclopentane). For the latter, the results obtained with C2-symmetry bis(benzamidinate) dimethyl complexes were compared with a chiral complex bearing a myrtanyl group at the benzamidinate ligand. 相似文献
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Tianzhu Zhang Dawei Guo Suyun Jie Wen‐Hua Sun Ting Li Xiaozhen Yang 《Journal of polymer science. Part A, Polymer chemistry》2004,42(19):4765-4774
A means of correlation between the activity and the net charge, the metal atom net charge correlation (MANCC), which was successful in the activity prediction of the early‐transition metal catalysts, has been used to study the catalytic activities of salicylaldiminato Ni(II) complexes, the late‐transition metal catalysts, in olefin polymerization or oligomerization. A comparison with the available quantum mechanics/molecular mechanics (QM/MM) calculation data suggests that even without a detailed mechanism, MANCC results mostly agree with QM/MM calculation data regarding insertion barrier data and enthalpy change. Eight experimental complexes were further built up by modeling; their catalytic activities predominantly increased in line with the net charges on the metal atoms. The same results were obtained for the other four complexes synthesized in the present work. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4765–4774, 2004 相似文献
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乙烯齐聚合成线性α-烯烃镍系催化剂 总被引:5,自引:0,他引:5
利用SHOP型工艺由乙烯齐聚制备线性α-烯烃不仅具有工业应用价值,而且具有很高的学术意义。SHOP型工艺的工业化引起了人们对基于P∩O配位型及其他配位型镍催化剂的广泛的研究兴趣。镍系催化剂具有活性高、选择性好、产品分布可调、反应条件温和等优良性能。本文介绍了镍系催化剂的类型和性能等,并对影响催化性能的因素进行了分析。 相似文献
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Matlab Khamiyev Akbar Khanmetov Vakhshouri Amir Reza Reyhan Aliyeva Kamala Hajıyeva-Atayi Zeynab Akhundova Gunay Khamiyeva 《应用有机金属化学》2020,34(3):e5409
A review of the scientific and patent literature on oligomerization of ethylene to linear olefins in the presence of homogenous or heterogeneous zirconium complexes and various aluminum organic compounds has been fulfilled for last twenty-five years. Over these years, a wide range of studies had been conducted for selective oligomerization of ethylene into a narrow fraction of linear α-olefins such as C4-C8 and C6-C10 fractions. During the discussion of these catalytic systems, exceptional attention is also paid to feature works such as the activity of the catalysts and the acquisition of clear liquid product without any trace of polymer, all of which play important roles in the selection of the best technology. 相似文献
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<正>The discovery of highly active 2,6-bis(imino)pyridyl iron and cobalt complexes provided a milestone of latetransition metal catalysts for ethylene oligomerization and polymerization with being currently investigated for the scale-up process.The crucial problems are remaining in the catalytic systems:the catalytic systems targeting ethylene polymerization produce more oligomers at elevated reaction temperatures,however,there is a recognizable amount of high-molecular-weight polyethylene remained in the modified catalytic system for the oligomerization process.Beyond the modification of bis(imino)pyridyl metal complexes,several alternative procatalysts' models have been developed in our group.This review highlighted the achievements in exploring new iron and cobalt complexes with tridentate NNN ligands as procatalysts for ethylene oligomerization and polymerization. 相似文献
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Huijun Fan Guoyong Xu Hui Wang Shengyu Dai 《Journal of polymer science. Part A, Polymer chemistry》2022,60(13):1944-1953
The synthesis of hyper-branched ethene oligomers through catalytic insertion reactions with late transition metal catalysts is unique in its synthetic and practical scope. In this study, a series of iminopyridyl Ni(II) and Pd(II) complexes with electron-rich distal aryl motifs were synthesized and characterized. These complexes were very efficient in ethene oligomerization and co-oligomerization with methyl acrylate (MA). Hyperbranched ethene oligomers with different microstructures were generated using different metal species in ethene oligomerization. More importantly, hyperbranched ethene-MA co-oligomers with varying incorporation ratios were generated via ethene and MA co-oligomerization using the Pd(II) complexes. Most notably, weak neighboring group interactions of distal aryl motifs in the nickel system are more effective in influencing the microstructure of ethene oligomers than the corresponding palladium system. 相似文献
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The nickel complexes are of special relevance to catalysis for ethylene oligomerization and polymerization. Beyond the famous
commercial SHOP process for ethylene oligomerization, among recent progress of nickel catalysts, various nickel complexes
containing different ligands such as the bidentate and tridentate ligands are of interest. In contrast to the importance of
hetereogeneous catalysis, the homogeneous catalyst is a small share for polyolefins, while the well-defined complexes affect
the microstructure of the resultant polyolefin. The nickel catalysts often perform ethylene activations for inner olefins
and the branched polyethylene with broad or bimodal molecular weight distribution. The catalytic behavior will be affected
by adaptation of ligands coordinating around the nickel center. In addition, the auxiliary ligand Ph3P can improve the catalytic activity by one order of magnitude, and its active center can be confirmed through isolating and
characterizing the reliable intermediate.
The text was submitted by the authors in English. 相似文献