Synonyms:Methylaluminoxane;120144-90-3;METHYL(OXO)ALUMANE;mealo
METHYLALUMINOXANE (7% IN TOLUENE) 95.00% *data from reagent suppliers
The research focuses on the synthesis, structural characterization, and catalytic ethylene oligomerization properties of nickel(II) and cobalt(II) complexes with symmetrical and unsymmetrical 2,9-diaryl-1,10-phenanthroline ligands. The study involves the preparation of ligands L1–L3 and subsequent formation of complexes 1–9 through reactions with nickel or cobalt dichloride or dibromide. The synthesized complexes were characterized using elemental analysis, UV–Vis, IR spectroscopy, and X-ray crystal structural studies. The catalytic activities of these complexes were evaluated in ethylene oligomerization reactions, utilizing methylaluminoxane (MAO) as a cocatalyst under varying conditions such as different Al/M molar ratios, temperatures, times, and ethylene pressures. The products were analyzed using gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS) to determine the distribution of oligomers and the yield of linear α-olefins. The experiments aimed to understand the influence of the ligand structure on the catalytic performance and to optimize the conditions for enhanced production of linear α-olefins, which are valuable industrial materials.
The study focuses on the synthesis and characterization of organometallic compounds containing the μ2,η1-N-[(N,N-dimethylamino)dimethylsilyl]-2,6-diisopropylanilido ligand, specifically targeting lithium, zirconium, and hafnium compounds. These compounds were investigated for their catalytic behaviors in ethylene (co)polymerization. The chemicals used in the study include 2,6-diisopropylaniline, nBuLi, (CH3)2N(CH3)2SiCl, and group 4 metal chlorides (ZrCl4 and HfCl4), which serve as precursors for the formation of the organometallic compounds. Methylaluminoxane (MAO) and modified methylaluminoxane (MMAO) were employed as cocatalysts to assess the catalytic activities of the synthesized compounds in polymerization reactions. The purpose of these chemicals is to create novel catalysts that can efficiently polymerize ethylene and copolymerize ethylene with 1-hexene, leading to the production of high-density polyethylene (HDPE) and linear low-density polyethylene (LLDPE), respectively. The study aims to understand the structure-activity relationships of these catalysts and their potential applications in industrial polymer production.
This research investigates the activation and initiation mechanisms of ethylene polymerization by bis(imino)pyridine cobalt catalysts, aiming to elucidate how these catalysts transform from their initial state to an active propagating species. The study synthesized and characterized key intermediates in the activation process, revealing that the initial activation involves reduction of cobalt(II) precatalysts to cobalt(I) species, followed by alkylation and formation of cationic cobalt(I) complexes. Through deuterium labeling studies and NMR spectroscopy, the researchers concluded that the initiation of polymerization likely involves nucleophilic attack by a methide anion on a cobalt-ethylene species, leading to the incorporation of alkyl groups from the cocatalyst. The key chemicals used include bis(imino)pyridine cobalt(II) precursors, MAO (methylaluminoxane) as a cocatalyst, and ethylene as the monomer. The findings provide valuable insights into the mechanistic details of this polymerization process, which could guide the design of more efficient catalysts for olefin polymerization.
The research focuses on the synthesis, coordination chemistry, and catalytic properties of the first 1,2-bis(diphenylphosphino)-1,2-diphenylhydrazine (PNNP) ligand and its complexes with Ni(II), Pd(II), and Pt(II). The ligand was synthesized by reacting chlorodiphenylphosphine with dilithiohydrazobenzene, and its complexes were formed by treating the ligand with NiCl2(DME), PdCl2(PhCN)2, and PtCl2(COD). The molecular structures of the ligand and its complexes were determined using X-ray diffraction. The catalytic activity of the ligand and its Ni(II) complex was evaluated in the oligo- and polymerization of ethylene using methylaluminoxane (MAO) and triethylaluminium (TEA) as cocatalysts. The experiments involved the preparation of the ligand and its complexes, followed by their application in catalytic reactions under controlled conditions. The products were analyzed using techniques such as gas chromatography, NMR spectroscopy, and melting point measurements.
The study focuses on the development and analysis of hafnocene catalysts for the selective oligomerization of propylene to produce 4-methyl-1-pentene, a branched olefin used in the production of polymers with desirable properties. A series of hafnocene complexes with varying substituents were tested as catalyst precursors. Upon activation with methylaluminoxane (MAO) or [Ph3C][B(C6F5)4]/AliBu3, these complexes catalyzed the dimerization of propylene, with selectivities for 4-methyl-1-pentene ranging from 23.9 to 61.6 wt%. The selectivity was found to depend on the nature of the substituents R1 and R2, with the highest selectivity observed for the complex (η5-C5Me4iBu)2HfCl2 (12). The study also investigated the influence of steric effects on the selectivity and the mechanism of propylene oligomerization, including the rate constants for propagation, β-hydride elimination, and β-methyl elimination. The purpose of these chemicals was to evaluate their catalytic performance in producing 4-methyl-1-pentene and to understand the underlying reaction mechanisms that govern the selectivity and activity of the catalysts.
This research study on the synthesis, characterization, and catalytic behavior of β-diketiminate 3d-metal compounds towards ethylene oligomerization and polymerization. The purpose of the study was to explore the physical properties of 1,5-diazapentadienyls (β-diketiminates) and their use as ancillary ligands in transition metal chemistry, with a focus on understanding the formation mechanism of mononuclear, dinuclear, and trinuclear complexes. The researchers synthesized a series of metal compounds (2–7) by reacting a nonsymmetric β-diketiminato lithium complex (1c) with various 3d-metal (II) chlorides. The synthesized compounds were fully characterized using elemental analysis, spectroscopic analyses, and single-crystal X-ray diffraction. The catalytic behavior of these compounds was evaluated using methylaluminoxane (MAO) or diethylaluminum chloride (Et2AlCl) as cocatalysts.
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