Polymers
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2016
·Vol. 8
·期 11
·389
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IF 2.944
Lihua Guo,Xinyu Jing,Shuoyan Xiong,Wenjing Liu,Yanlan Liu,Zhe Liu,Changle Chen
A series of alkyl- and aryl-substituted iminopyridine Fe(II) complexes1a–7aand Co(II) complexes2b,3b,5b, and6bwere synthesized. The activator effect, influence of temperature, and, particularly, the alkyl and aryl substituents’ effect on catalytic activity, polymer molecular weight, and regio-/stereoselectivity were investigated when these complexes were applied in isoprene polymerization. All of the Fe(II) complexes afforded polyisoprene with high molecular weight and moderatecis-1,4 selectivity. In contrast, the Co(II) complexes produced polymers with low molecular weight and relatively highcis-1,4 selectivity. In the iminopyridine Fe(II) system, the alkyl and aryl substituents’ effect exhibits significant variation on the isoprene polymerization. In the iminopyridine Co(II) system, there is little influence observed on isoprene polymerization by alkyl and aryl substituents.Keywords:iminopyridine;Iron(II);Cobalt(II);isoprene polymerization;selectivity
研究领域:
化学
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高分子科学
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PubMed
高影响因子
JOURNAL OF COORDINATION CHEMISTRY
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2021
·
IF 1.751
Na Zhang,Yuying Li,Liduo Chen,Cuiqin Li,Guoliang Mao,Jun Wang
A series of star iminopyridine ligands, containing different groups (H, CH3, Br) in the pyridine ring, have been synthesized and characterized by FT-IR, 1H NMR, and UV-vis. The corresponding nickel(II) complexes have been prepared in good yields. The nature of the Ni complexes has been established by FT-IR, UV-vis, ESI-MS, and ICP. Upon activation with methylaluminoxane (MAO), the nickel complexes were able to oligomerize ethylene to produce C4–C18 fractions at activity of up to 105 g (mol Ni h)−1. The influence of substituent, catalyst structure, solvent, co-catalyst, and reaction conditions on the catalytic activity and product selectivity was investigated. The results showed that substitution on the pyridine ring had large influence on the catalytic activity and product selectivity. The catalytic activity increased at first and then decreased with the increase of reaction temperature and Al/Ni molar ratio. However, the catalytic activity continuously increased with increasing reaction pressure. When toluene was used as solvent and MAO was used as co-catalyst, catalytic activity of 4.39 × 105 g (mol Ni h)−1 and 31.93% selectivity of higher carbon olefins (C8–C18) were obtained at 10 °C, Al/Ni molar ratio 500, and the reaction pressure 1.0 MPa.
研究领域:
有机化学
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催化化学
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高影响因子
POLYMER BULLETIN
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2021
·Vol. 79
·期 6
·4219-4231
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IF 2.87
Zhang Na,Wu Yansong,Li Yuying,Chen Liduo,Zhang Mingshui,Wang Jun
A novel star iminopyridyl ligand was synthesized in modest yield with 1.0 G star macromolecule and pyridine-2-carboxaldehyde as the raw materials. Reactions of the star iminopyridyl ligand with Fe(II), Co(II) and Ni(II) salts afforded metal complexes (Cat-Fe, Cat-Co and Cat-Ni) in good yields. The compounds were characterized by FT-IR, 1 H NMR, 13 C NMR, UV–Vis, ESI–MS and ICP-MS. In the presence of methylalumoxane (MAO), the iron, cobalt and nickel complexes have demonstrated higher ethylene oligomerization activity (up to 4.28 × 10 5 g/(mol Co h)), affording C 4 as the major product as well as C 6 , C 8 and C 10-18 oligomers. The catalytic activity was quite sensitive to the kind of species. The nature of solvent and co-catalyst significantly affected both the catalytic activity and product distribution. Moreover, the effect of oligomerization parameters (reaction temperature, [Al]/[Co] molar ratio, ethylene pressure) on the catalytic activity and the product distribution was investigated.
研究领域:
化学
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材料科学
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催化反应
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高影响因子
INORGANICA CHIMICA ACTA
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2017
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IF 2.002
Na Zhang,Jiaming Wang,Hongliang Huo,Liduo Chen,Weiguang Shi,Cuiqin Li,Jun Wang
A series of hyperbranched iminopyridyl ligands [ethylenediamine as terminal groups (L1), 1,4-butanediamine as terminal groups (L2), 1,6-hexamethylenediamine as terminal groups (L3)] were prepared. Ligands L1-L3 were reacted with MCl 2 ·nH 2 O (M = Fe, Co, Ni) to form three types of complexes (C1-C5). Both L1-L3 and C1-C5 were fully characterized by FT-IR, 1 H NMR, UV and ESI-MS. The nickel complexes exhibited better catalytic properties than iron and cobalt complexes for ethylene oligomerization. On activation with methylaluminoxane (MAO), the nickel complex C1 exhibited moderate catalytic activities up to 1.56 × 10 6 g mol −1 h −1 for ethylene oligomerization and the oligomers showed Schulz-Flory distribution. However, on activation with EtAlCl 2 , the nickel complex C1 exhibited higher catalytic activity up to 8.94 × 10 6 g mol −1 h −1 for ethylene oligomerization, but the products were mainly alkylated-toluenes. The influence of the solvent and reaction parameters such as reaction temperature, ethylene pressure and Al/Ni molar ratio on the catalytic behavior of the nickel complex C1 was also investigated. Moreover, in comparison with the catalytic activity and the distribution of oligomers obtained with related hyperbranched salicylaldimine nickel complex and other non-hyperbranched iminopyridyl nickel complexes, the catalytic activity and the content of low carbon number olefins (C 4 and C 6 ) obtained in this work possessed relatively higher.
研究领域:
化学
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材料科学
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高影响因子
Russian Journal of Physical Chemistry A
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2020
·Vol. 94
·期 5
·1024-1033
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IF 0.719
Na Zhang,Chen Liduo,Li Cuiqin,Wang Jun
Abstract Two kinds of soft-bridged iminopyridyl ligands and their metal (iron and cobalt) complexes were synthesized. All soft-bridged iminopyridyl ligands and metal complexes were fully characterized by FT-IR, 1 H NMR, UV–Vis, ESI-MS, and ICP-MS. Upon activation with methylaluminoxane (MAO), these metal complexes exhibited moderate catalytic activity up to the range of 10 5 g/(mol Me h) for ethylene oligomerization, and butene was the major product, while for the cobalt complexes, activation with EtAlCl 2 in toluene produced Friedel–Crafts toluene alkylation products. In the catalytic systems, cobalt complexes exhibited better catalytic activity and selectivity towards higher carbon number olefins (≥C 8 ) than their iron analogues. The correlations between metal complexes and their catalytic activities and product distribution were investigated in detail under various reaction parameters such as reaction temperature, ethylene pressure and amount of co-catalyst. Under optimized conditions ([Co] = 7 μmol, 35°C, 1.0 MPa, MAO-to-Co = 500), soft-bridged iminopyridyl cobalt catalyst Co1 led to catalytic activity of 6.18 × 10 5 g/(mol Co h) and 29.97% selectivity for higher carbon number olefins. However, under optimized conditions ([Fe] = 7 μmol, 25°C, 1.0 MPa, MAO-to-Fe = 500), soft-bridged iminopyridyl iron catalyst Fe1 led to catalytic activity of 4.73 × 10 5 g/(mol Fe h) and 22.60% selectivity for higher carbon number olefins.
研究领域:
化学
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材料科学
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催化反应
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高影响因子
POLYMER ENGINEERING AND SCIENCE
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2019
·Vol. 59
·期 5
·1010-1016
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IF 1.92
Jian Ye,Yu Li,Binbo Jiang,Wei Zhang,Jingdai Wang,Zuwei Liao,Zhengliang Huang,Yongrong Yang,Zhibin Ye
For the purpose of reducing the simultaneous production of insoluble polymers during the bis(imino)pyridyl iron-catalyzed ethylene oligomerization, various modifiers like phenol, anisole, 1-naphthol, 2-naphthol, benzoic acid, cyclohexanol, cyclohexyl carbinol, and benzyl alcohol were employed to modify the co-catalyst methylaluminoxane (MAO) and tune the catalytic behaviors in this work. It was found that phenol could serve as a good polymer-retarding modifier, the phenolic hydroxyl group was responsible for the interactions with MAO. Further increasing the aromatic ring size from phenol to naphthols was beneficial for retarding the polymer formation. Meanwhile, an increase of the acidity of the modifiers would promote the interactions between them and MAO, but also tend to easily deactivate the catalytic system. In addition, the alcohol modifiers with a phenol-like structure were also studied, their deactivation effect was found to be stronger than their polymer-retarding effect, making them difficult to obtain a satisfactory low polymer formation with the catalytic system remaining a high activity. POLYM. ENG. SCI., 59:1010–1016, 2019. © 2019 Society of Plastics Engineers
研究领域:
高分子化学
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催化化学
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高影响因子
Journal of the American Chemical Society
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2013
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IF 10.677
Dongjie Peng,Yanlu Zhang,Xiaoyong Du,Lei Zhang,Xuebing Leng,Marc D. Walter,Zheng Huang
A series of new pincer iron complexes with electron-donating phosphinite-iminopyridine (PNN) ligands has been prepared and characterized. These iron compounds are efficient and selective catalysts for the anti-Markovnikov alkene hydrosilylation of primary, secondary, and tertiary silanes. More importantly, the system exhibits unprecedented functional group tolerance with reactive groups such as ketones, esters, and amides. Furthermore, the iron-catalyzed alkene hydrosilylation was successfully applied to the synthesis of a valuable insecticide, silafluofen. The electronic properties and structures of the iron complexes have been studied by spectroscopies and computational methods. Overall, the iron catalysts may provide a low-cost and environmentally benign alternative to currently employed precious metal systems for alkene hydrosilylation.
研究领域:
有机化学
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催化化学
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环境化学
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PubMed
高影响因子
TRANSITION METAL CHEMISTRY
·
2019
·Vol. 44
·期 7
·595-602
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IF 1.016
Qin Yutian,Wang Bowei,Li Jiayi,Wu Xingchun,Chen Ligong
Aerobic epoxidation of alkene is a green and economical route to produce epoxides. For such reaction, transition metal complexes exhibit favorable catalytic activity. In this work, NH 2 -MIL-101, a stable metal–organic framework (MOF) material with large surface area and high pore volume, was functionalized with pyridine-2,6-dicarbaldehyde and Co(NO 3 ) 2 , to realize the immobilization of Co(II) via imine–pyridine–carbonyl (N,N,O) tridentate ligands bonding to MOF skeleton. The modified materials were applied as heterogeneous catalysts for the aerobic epoxidation of cyclohexene at ambient temperature, and multiple factors were studied to explore their influences on catalytic effects. Under the optimal reaction conditions, satisfactory substrate conversion and epoxide selectivity were reached. In addition, this catalytic system is suitable for a variety of alkene substrates. Furthermore, recycle experiments and infrared spectroscopy characterization illustrated that the coordination surroundings of Co are altering smoothly during the reaction process, thus having an impact on the performance of catalyst.
研究领域:
化学
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材料科学
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催化
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高影响因子
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