Hyperbranched bisphosphinoamine ligands: synthesis,characterization and application in ethylene oligomerization

Two hyperbranched bisphosphinoamine (PNP) ligands and chromium complexes were synthesized in good yield with 1.0 generation (1.0 G) hyperbranched macromolecules, chlorodiphenylphosphine (Ph₂PCl) and CrCl₃(THF)₃ as raw materials. The hyperbranched PNP ligands and chromium complexes were characterized by FT-IR, ¹H NMR, ³¹P NMR, UV and ESI-MS. Comparing with the chromium complexes, the hyperbranched PNP ligands, in combination with Cr(III), and activation by methylaluminoxane (MAO) in situ generated species with better catalytic performance for ethylene oligomerization. The effect of solvent, chromium source, ligand/Cr molar ratio, reaction temperature, Al/Cr molar ratio and reaction pressure on the catalytic activity and product selectivity were studied. The results showed that with increase of ligand/Cr molar ratio, reaction temperature and Al/Cr molar ratio, the catalytic activity increased at first and then decreased. However, the catalytic activity continuously increased with increase of reaction pressure. Under the optimized conditions, the catalytic system of hyperbranched PNP/Cr(III)/MAO led to catalytic activity of 2.68 × 10⁵ g/(mol Cr·h) and 37.71% selectivity for C₆ and C₈.     

Cobalt complexes based on hyperbranched salicylaldimine ligands as catalyst precursors for ethylene oligomerization

Three hyperbranched salicylaldimine ligands with tetradecyl as core, with hexadecyl as core and with octadecyl as core were synthesized in good yields. These ligands were reacted with cobalt chloride hexahydrate to form three complexes ( C1 – C3 ). The compounds were characterized using Fourier transform infrared, ¹H NMR, mass and UV spectroscopies and thermogravimetric and differential thermal analyses. The catalytic properties of the hyperbranched cobalt complexes were evaluated for ethylene oligomerization. The effects of solvent and reaction parameters (Al/Co molar ratio, temperature and reaction pressure) on ethylene oligomerization were studied using the cobalt complex C3 as pre‐catalyst and methylaluminoxane (MAO) as co‐catalyst. Under these conditions ([Co] = 5 μmol, Al/Co = 500, 25 °C, 0.5 MPa ethylene, 30 min), the catalytic activity of complex C3 in toluene was 1.85 × 10⁵ g (mol Co)⁻¹ h⁻¹ and the selectivity for C₈₊ oligomers was 55.72%. The complex structure also had a significant influence on both the catalytic activity and selectivity. All three cobalt complexes, activated with MAO, showed moderate activities towards ethylene oligomerization and the activity of cobalt complex C1 was up to 1.99 × 10⁵ g (mol Co)⁻¹ h⁻¹. The kinds of metal center of complexes (cobalt complex C1 and nickel complex with tetradecyl as core) and their catalytic properties were investigated in detail under the same conditions.     

超支化双吡啶亚胺铬催化剂的合成及催化乙烯齐聚性能

以1.0代(G)超支化大分子(C₃₈H₅₁N₉O₂)为配体骨架,2-氯-4-甲基吡啶和CrCl₃(THF)₃为原料,依次经过取代和配合反应合成了一种超支化双吡啶亚胺配体及其铬催化剂。 利用紫外-可见光谱(UV-Vis)、傅里叶变换红外光谱(FT-IR)、电喷雾电离质谱(ESI-MS)、核磁共振氢谱(¹H NMR)和元素分析等方法对其进行表征。 结果与理论设计预期一致。 考察了反应温度、乙烯压力、Al与Cr摩尔比(n(Al)/n(Cr))、溶剂及助催化剂种类等因素对催化剂催化乙烯齐聚性能的影响。 结果表明,以甲苯为溶剂,甲基铝氧烷(MAO)为助催化剂,当反应温度为45 ℃,乙烯压力为4 MPa,n(Al)/n(Cr)=300,催化剂用量为7 μmol时,活性可达1.32×10⁵ g/(mol(Cr)·h),C₆和C₈的选择性为59.30%。     

Novel Dendritic PNP Chromium Complexes: Synthesis,Characterization, and Performance on Ethylene Oligomerization

Three dendritic PNP ligands with ethylenediamine, 1,4‐butanediamine, 1,6‐diaminohexane as bridged groups are synthesized in good yields, respectively. Three dendritic PNP chromium complexes ( C1  –  C3 ) are prepared with the ligands and chromium(III ) chloride tetrahydrofuran complex (CrCl₃(THF )₃) as materials. The dendritic PNP ligands and the synthetic chromium complexes are fully characterized by spectroscopic and analytical methods. All chromium complexes activated with methylaluminoxane (MAO ) exhibited moderate activities on ethylene oligomerization (7.90 × 10⁴ – 2.15 × 10⁵ g (mol Cr h)⁻¹] and had better selectivity for C₆ and C₈ oligomer, reaching up to 81%. The chromium complex ( C1 ) activated with diethylaluminium chloride (Et₂AlCl) has higher catalytic activity than the chromium complex C1 activated with MAO , although the chromium complex ( C1 ) activated with Et₂AlCl had lower selectivity for C₆ and C₈ oligomer. The effects of solvent and reaction parameters on ethylene oligomerization are also studied using the chromium complex C1 as pre ‐ catalyst and MAO as co ‐ catalyst. Under optimized conditions ([complex] = 2 μmol, Al/Cr = 500, 25 °C, 0.9 MP a ethylene, 30 min), the catalytic activity of complex C1 in toluene is 2.15 × 10⁵ g (mol Cr h)⁻¹ and the selectivity for C₆ and C₈ oligomer is 36.76%. In addition, the structure of complexes significantly affects both the catalytic activity and the selectivity on ethylene oligomerization.     

树枝状吡啶亚胺铬催化剂的合成及其催化性能研究

以1. 0代聚酰胺-胺树枝状大分子为配体骨架、吡啶二甲醛为原料,合成了一种新型树枝状吡啶亚胺(DPI)配体,再以CrCl_3·6H_2O为络合试剂,制备DPI-Cr催化剂。采用IR、UV-Vis、MS、元素分析等确证了产物结构。考察溶剂种类、助催化剂种类、反应温度、乙烯压力以及Al/Cr摩尔比对DPI-Cr催化乙烯齐聚性能的影响。结果表明,DPI-Cr催化剂表现出良好的催化活性和烯烃选择性,优化反应条件下,催化效率可达4. 91×10~4g/mol Cr·h,C_6和C_8选择性为73. 90%。     

超支化铬系催化剂的合成及乙烯齐聚性能研究

以不同端基烷基链长度的1.0G超支化大分子为桥联基,通过对其端基氨基进行催化功能改性,合成了系列具有不同桥联基长度的超支化PNP铬系催化剂。采用红外光谱(IR)、核磁共振氢谱(1H-NMR)、核磁共振磷谱(31P-NMR)、紫外光谱(UV)和质谱(MS)等表征方法证明合成催化剂的结构与理论结构相符。详细考察了溶剂种类、反应温度、Al/Cr摩尔比、反应压力、催化剂用量和催化剂结构对催化剂乙烯齐聚性能的影响。实验结果表明,当以甲苯为溶剂,甲基铝氧烷(MAO)为助催化剂时,超支化PNP铬系催化剂表现出良好的催化乙烯齐聚性能,产物以低碳烯烃为主。最佳条件下,催化活性最高可达到1.69×105g/mol Cr·h,己烯和辛烯的选择性为43.3%以上。相同聚合条件下,其催化活性随着端基烷基链长度的增加而下降。     

Synthesis and application of chromium complexes bearing hyperbranched PNP ligands in the ethylene oligomerization

Series of hyperbranched PNP ligands ( L1 – L3 ) were prepared using three low-generation hyperbranched molecules with the same branching chains and functional groups but different alkyl chain length as backbones in a mixed solvent of acetonitrile and dichloromethane. The chromium complexes ( Cr1 – Cr3 ) were obtained by reacting with CrCl₃(THF)₃ and the corresponding ligands ( L1 – L3 ). Both L1 – L3 and Cr1 – Cr3 were characterized by elemental analysis, Fourier transform infrared and electrospray ionization–mass spectrometry as well as ¹H nuclear magnetic resonance (NMR) and ³¹P NMR measurements in the case of the ligands. When activated with different aluminum co-catalysts, all three chromium complexes were able to catalyze the ethylene oligomerization, but the products of the ethylene oligomerization were mainly dependent on ethylene pressure, co-catalyst and ligand backbone. Upon activation with methylaluminoxane, the catalytic activity and the selectivity of C8 olefin increased with increasing of ethylene pressure for Cr1 , the catalytic activity was 13.83 × 10⁵ g·(mol Cr·h)⁻¹ and the main product was C8 olefin (50.68%) at the ethylene pressure of 4.0 MPa. When activated with diethylaluminium chloride, ethylaluminium dichloride and ethylaluminum sesquichloride, Cr1 showed the lower catalytic activity and the higher selectivity of C4 olefin in toluene. An increase in the length of alkyl chain in the hyperbranched PNP ligand backbone caused a decrease in the catalytic activity and an increase in the selectivity of C8 + olefin. The PNP chromium complexes exhibited higher selectivity for higher carbon number olefins compared with the dendritic PNP chromium complex ( Cr5 ).     

Synthesis,Characterization and Ethylene Oligomerization Behavior of Neutral Nickel Complexes Bearing N‐Fluorinated Phenyl Salicylaldiminato Chelate Ligands

A series of neutral nickel complexes featuring N‐fluorinated phenyl salicylaldiminato chelate ligands was synthesized, and the novel molecular structure of complex C14 was further confirmed by X‐ray crystallographic analysis. The neutral nickel complexes showed high activity up to 9.96×10⁵ g oligomers/(mol Ni·h) and high selectivity of C₆ in catalyzing ethylene oligomerization using methylaluminoxane (MAO) as cocatalyst. It was observed that the strong electron‐withdrawing effect of the fluorinated salicylaldiminato ligand was able to significantly increase the catalytic activity for oligomerization of ethylene. In addition, the influence of reaction parameters such as Al/Ni molar ratio, reaction temperature, a variety of cocatalyst and ethylene pressure on catalytic activity was investigated.     

超支化铬系催化剂的合成及乙烯齐聚性能研究

以正辛胺和十二胺为原料,分别制备了两种超支化PNP配体,通过引入金属铬活性位点的方法合成了具有不同烷基链长度的超支化PNP铬系催化剂.采用红外光谱(IR)、核磁共振磷谱(~(31)P-NMR)、核磁共振氢谱(~1H-NMR)、紫外光谱(UV)和质谱(MS)等表征方法证明合成催化剂的结构与理论结构预测相符.详细考察了催化剂用量、溶剂种类、反应条件以及配合物结构对乙烯齐聚性能的影响.实验结果显示,超支化PNP铬系催化剂在甲苯作溶剂,甲基铝氧烷(MAO)做助催化剂时表现出良好的催化乙烯齐聚性能,产物主要为低碳烯烃.在最佳条件下,催化活性最高可达到1.69×10~5 g·(mol Cr·h)~(-1),己烯和辛烯的选择性为43.3%以上.相同聚合条件下,其催化活性随着端基烷基链长度的增加而下降.     

新型树枝状PNP铬催化剂的合成及催化性能

以1.0代聚酰胺-胺(PAMAM)为配体骨架,氯代二苯基膦为原料,通过取代反应合成了1种含有较大空间位阻的新型树枝状PNP配体,再以Cr Cl3(THF)3为络合试剂,通过络合反应合成树枝状PNP铬催化剂.采用傅里叶变换红外光谱(FTIR)、紫外-可见分光光度计(UV-Vis)、核磁共振波谱(NMR)、电喷雾电离质谱(ESI-MS)和元素分析等手段证实合成的新型树枝状PNP配体及其铬催化剂的结构与理论设计的结构一致.以甲基铝氧烷(MAO)为助催化剂,对乙烯齐聚反应进行了研究,考察了溶剂种类、反应温度、反应压力及Al/Cr摩尔比对该催化剂活性和选择性的影响.结果表明,以甲苯为溶剂,MAO为助催化剂,当反应温度为25℃,反应压力为0.9 MPa,Al/Cr摩尔比为500时,该催化剂的活性高达2.15×105g/(mol Cr·h),催化剂对乙烯三聚、四聚反应的选择性共达到36.76%.     

Cobalt complexes based on dendritic PAMAM bridged salicylaldimine ligands: Synthesis,characterization and performance in ethylene oligomerization

Two novel dendritic poly(amido-amine) (PAMAM) bridged salicylaldimine ligands were synthesized by Schiff base reaction using 1.0 generation dendritic PAMAM as bridged groups. The cobalt complex with 1,4-butanediamine as core (C1) and the cobalt complex with 1,6-hexanediamine as core (C2) based on dendritic PAMAM bridged salicylaldimine ligands were prepared by metallic coordination reaction, respectively. The structures of the ligands and the dendritic cobalt complexes were characterized by fourier transform infrared (FTIR), ultraviolet spectra (UV), hydrogen nuclear magnetic resonance (¹H NMR) and electrospray ionization mass spectra (ESI-MS). The complexes C1 and C2 were evaluated as catalyst precursors for ethylene oligomerization after being activated with methylaluminoxane (MAO), diethylaluminum chloride (Et₂AlCl), ethylaluminium dichloride (EtAlCl₂) and ethylaluminum sesquichloride (EASC). The dendritic cobalt complexes exhibited the highest activity and selectivity for high carbon oligomers with EASC as activator. Under the conditions of 1.0 MPa, 25°C and Al/Co molar ratio 1500, the catalytic activity and selectivity for C₁₀–C₂₀ using C1 were 3.44×10⁶ g·(mol Co·h)^?1 and 76.53% after activation with EASC, and the catalytic activity and selectivity for C₁₀–C₂₀ using C2 were 3.42×10⁶ g·(mol Co·h)^?1 and 84.50%, respectively.     

Chromium Complexes Supported by Phenyl Ether-Pyrazolyl [N,O] Ligands as Catalysts for the Oligo- and Polymerization of Ethylene

A new series of Cr (III) complexes [Cr{1-(3-phenoxypropyl)-1H-pyrazole}Cl₃]₂ (Cr1), [Cr{1-(3-phenoxypropyl)-3,5-dimethyl-1H-pyrazole}Cl₃]₂ (Cr2 ), and [Cr{1-(3-phenoxypropyl)-3-phenyl-1H-pyrazole}Cl₃]₂ (Cr3) have been synthesized and characterized by elemental analysis, high-resolution mass spectrometry (HRMS) and IR spectroscopy. Upon activation with methylaluminoxane (MAO), chromium precatalysts Cr2 and Cr3 showed moderate activity in ethylene oligomerization [TOF = 17,900–29,200 mol (ethylene)·mol (Cr)⁻¹·h⁻¹ at 80 °C] with Schultz-Flory distribution of oligomers (K = 0.54–0.66) and production of polymer varying from 2.8 to 6.7 wt.%. On the other hand, under identical oligomerization conditions, Cr1 /MAO behaved as a polymerization catalyst generating predominantly polyethylene (63.7 wt%). The amount of 1-butene is the largest component in the liquid fraction suggesting that these precatalysts operate via a Cossee-Arlman mechanism. The catalytic activities, selectivity and product distribution are quite sensitive to the R-group at the 3- and 5-position of the pyrazolyl ring. Based on the electronic and steric effects of R- substituents, it is possible to stablish a trend of activity: Cr2 (Pz^Me2) > Cr3 (Pz^Ph) > Cr1 (Pz). Moreover, the effect of oligomerization parameters (cocatalyst, temperature, [Al]/[Cr] molar ratio, time) on the activity and on the product distribution were examined.     

新型均相铬系催化剂的制备与催化乙烯齐聚

合成了3种新型的N取代基中含有O/N杂原子的1,3,5-三氮杂环己烷[NNN]型配体,利用氢核磁共振谱(1H NMR)、碳核磁共振谱(13C NMR)及电子轰击质谱(EI-MS)等方法对其进行表征.将[NNN]型配体与Cr(Ⅲ)络合制备相应的均相铬催化剂,采用电喷雾质谱(ESI-MS)及元素分析分别对其进行表征.以甲基烷氧铝(MAO)为助催化剂,考察了反应温度、反应压力及铝铬摩尔比等因素对催化乙烯齐聚催化性能的影响.研究结果表明,在以甲苯为溶剂,反应温度50℃,反应压力0.8 MPa,铝铬摩尔比为500∶1,Cr浓度为2.0×10-4mol/L的反应条件下,取代基为3-二甲氨基丙基的均相铬催化剂的催化活性能够达到15.71×105g/(mol Cr·h),对1-己烯和1-辛烯的选择性达到91.02%,而取代基为3-乙氧基丙基的均相铬催化剂的催化活性比较低,为11.54×105g/(mol Cr·h),但对1-己烯和1-辛烯的选择性较高,达到93.05%.     

Synthesis and application of bidentate nickel complexes bearing hyperbranched salicylaldimine ligands in ethylene oligomerization

Three bidentate salicylaldimine nickel complexes containing different long-chain alkyl groups in their ligand backbone were synthesized in good yield. All the bidentate salicylaldimine ligands and their nickel complexes were fully characterized by FT-IR, ¹H NMR, UV spectroscopies, and mass spectrometry. Three bidentate nickel complexes were evaluated as catalyst precursors in ethylene oligomerization. Upon activation with methylaluminoxane (MAO), the catalytic activity was 5.75 × 10⁵ g/(mol Ni·h) and the oligomers were mainly butenes (52.10%) and octenes (32.63%) for bidentate nickel complex with 1-tetradecyl as core in the ligand backbone (R₁₄-complex) using toluene as solvent. However, bidentate nickel complex with 1-octadecyl as core in the ligand backbone (R₁₈-complex) produced mainly octenes (59.38%) and C10 + olefins (29.01%) and the catalytic activity was 2.23 × 10⁵ g/(mol Ni·h). After activation with ethylaluminum sesquichloride (EASC) in toluene, three nickel complexes yielded mainly C10 + products which contained Friedel-Craft alkylated-toluene, and their catalytic activities were above 1.5 × 10⁶ g/(mol Ni·h). For the bidentate salicylaldimine nickel catalysts with hyperbranched molecules as ligand backbones, the solvent and the reaction conditions had a large effect on catalytic activity as well as oligomerization distribution except the structure of the catalyst and the co-catalyst.     

Bidentate iron complexes based on hyperbranched salicylaldimine ligands and their catalytic behavior toward ethylene oligomerization

A series of bidentate iron complexes based on hyperbranched salicylaldimine ligands were synthesized and characterized by spectroscopic and analytical methods. Upon activation with methylaluminoxane (MAO), the complexes showed good activities [up to 8.17 × 10⁴ g/(mol Fe h)] for ethylene oligomerization. Activation of the bidentate iron complex with a 1-octadecyl moiety in the ligand backbone (complex C3) with Et₂AlCl produced higher catalytic activity than C3 with MAO, although the selectivity for C₈₊ oligomers was lower. The choice of solvent and reaction parameters significantly affected both the activities and selectivities of these complexes. Under the conditions ([Fe] = 5 μmol; temperature = 25 °C; toluene = 50 mL; time = 30 min; ethylene pressure = 0.5 MPa; MAO as cocatalyst), complex C3 gave high activity [7.46 × 10⁴ g/(mol Fe h)] with better selectivity for C₈₊ oligomers (26.58%). The catalytic activities and selectivities were also influenced by the ligand structure and choice of metal. The catalytic activities declined with increasing alkyl chain length of the ligand backbone. Compared to the nickel complex with 1-tetradecyl as core in the ligand backbone (C4), the iron complexes exhibited lower catalytic activities but the better selectivities for C₁₀₊ oligomers.     

用于乙烯齐聚高选择性制 1-辛烯反应的Cr(Ⅲ)基催化剂体系

将四元催化剂体系(乙酰丙酮铬-膦胺型配体-助催化剂甲基铝氧烷-促进剂六氯乙烷)用于乙烯齐聚制1-辛烯反应,考察了促进剂、助催化剂、Al/Cr摩尔比、反应温度和反应压力等对催化剂的活性和1-辛烯的选择性的影响.结果表明,该四元催化剂体系比三元催化剂体系(铬化合物-膦胺型配体-甲基铝氧烷)对乙烯齐聚反应具有更高的1-辛烯选择性.产物除有1-辛烯外,还有较大量的1-己烯、甲基环戊烷和亚甲基环戊烷.甲基铝氧烷是高选择性生成1-辛烯必不可少的助催化剂.作为促进剂的六氯乙烷可以使乙酰丙酮铬更有利于催化乙烯齐聚反应生成1-辛烯.     

Synthesis of short straight-chain alkylamine based hyperbranched nickel complexes and their catalytic performance of ethylene oligomerization

Short straight-chain alkylamine based hyperbranched molecules and their corresponding salicylaldimine nickel complexes have been synthesized in high yield and characterized by FTIR, ¹H-NMR and mass spectrometry. The optimal reaction parameters were determined under the catalytic system of methylaluminoxane (MAO) as co-catalyst and toluene as solvent. Under these conditions, the effect of catalyst structure, solvent and co-catalyst were determined. Upon activation of MAO in toluene, ethylene oligomerization products were homogeneous distribution of butene, hexene and octene with trace higher olefin. The same catalytic system under cyclohexane and methyl cyclohexane as solvent, however, produced majority of butene. Under the activation of EtAlCl₂, Et₂AlCl and EASC as co-catalyst in toluene, ethylene oligomerization reaction was tandem with Friedel-Crafts reaction in catalytic system.     

含氟苯基水杨醛亚胺配体的中性镍络合物的合成、表征及对乙烯齐聚的催化活性

合成了一系列含N-氟苯基-水杨醛亚胺配体的中性镍络合物，并对代表性的络合物4进行了X-ray晶体结构分析以进一步确证其结构。这种中性镍络合物在助催化剂烷基铝氧烷(MAO)的作用下，具有较高的催化乙烯齐聚的活性和对C₆烯烃的选择性，催化活性高达4.22×l05 g o1igomers/(mol Ni•h)，对C6烯烃的选择性达到94％。     

Ethylene Oligomerization Catalyzed by Nickel（Ⅱ） Diimine Complexes

Ethylene oligomerization has been investigated by using catalyst systems composed of nickel(II) diimine complexes (diimine = N, N′‐o‐phenylene bis (salicylideneaminato), N, N′‐o‐phenylenebisbenzal, N, N′‐ethylenebisbenzal) and ethylaluminoxane (EAO). The main products in toluene and at 110–200 °C were olefins with low carbon numbers (C₄—C₁₀). Effects of reaction temperature, Al/Ni molar ratio and reaction period on both the catalytic activity and product distribution were explored. The activity of 1.84 × 10⁵ g of oligomer/(mol_NI · h), with 87.4% of selectivity to C₄—C₁₀ olefins, was attained at 200 °C in the reaction when a catalyst composed of NiCl₂ (PhCH = o‐NC₆H₄N = CHPh) and EAO was used.     

Hyperbranched macromolecules bridged salicylaldimine cobalt complexes: synthesis,characterization and ethylene oligomerization studies

A series of novel 1.0 generation (1.0G) hyperbranched macromolecules bridged salicylaldimine cobalt complexes were synthesized in high yields. The compounds were characterized by fourier transform infrared (FT-IR) spectroscopy, ultraviolet (UV) visible spectroscopy, electrospray ionization mass spectrometry (ESI–MS), elemental analysis and thermal gravimetric analysis (TGA), as well as were investigated as precatalysts for the oligomerization of ethylene. Upon activation with methylaluminoxane (MAO) and diethylaluminumchloride (DEAC), the cobalt precatalysts showed moderate catalytic activities in the range of 10⁵ g/(mol Co h) in ethylene reactivity with the high selectivity for the butenes and high carbon number olefins products. The correlation between cobalt complexes and their catalytic activities and product distribution were investigated in detail under various reaction parameters. The research results showed that the catalytic activities of precatalysts increased with the increase of ethylene pressure and Al/Co molar ratio; however, the catalytic activities firstly increased and then decreased with the increase of reaction temperature. The highest activity of 2.54 × 10⁵ g/(mol Co h) and 50.18% selectivity of high number carbon olefins was obtained under the reaction temperature of 25 °C, ethylene pressure of 0.5 MPa, and Al/Co molar ratio of 1500. In addition, the nature of solvent and co-catalyst, as well as the structure of precatalysts, significantly affected both the activity and the product distribution of the resultant catalysts.