Abstract
A series of N-(2,2-dimethyl-1-(quinolin-2-yl)propylidene) arylamines was sophisticatedly synthesized and reacted with nickel(II) bromine for the formation of the corresponding nickel complexes. All the organic compounds were characterized by IR, NMR spectra and elemental analysis, while all the nickel complexes were characterized by IR spectra and elemental analysis. On activation with ethylaluminium sesquichloride (EASC) and modified methylaluminoxane (MMAO), all nickel precatalysts exhibited good activities toward ethylene oligomerization, indicating the positive efficiency of gem-dimethyl substitutents; in which major hexenes were obtained with MMAO. The catalytic parameters were verified, and the steric and electronic influences of substituents with ligands were observed, with a slight change of activities under different ethylene pressures.
Highlights
The discovery of diiminonickel halides (A, Figure 1) as high active precatalysts in ethylene reactivity symbolized a milestone of late-transition metal catalytic systems [1], and resurrected nickel chemistry in the petrochemical industry with regard to the Shell Higher Olefin Process (SHOP) using a nickel catalyst [2]
In complex orderOligomerization toNi1 determine the in most efficient co-catalyst use in ethylene polymerization studies, (MAO), modified methylaluminoxane (MMAO), ethylaluminium sesquichloride (EASC, Et3Al2Cl2), as inspired by previous experiences of the molar ratios and reaction temperature [16,17,18,19,20], In order to determine the most efficient co-catalyst for use ethylene polymerization as diethylaluminium chloride (Et2AlCl) and ◦triethylaluminium
Iron and cobalt analogs bearing 2-(1-aryliminoethylidene) quinoline [21], which have structures similar to the pre-catalysts examined here, the current series of nickel pre-catalysts showed nearly ten times higher activity for ethylene oligomerization due to the bulkier propyl group attached to the imide carbon, which might stabilize the catalytic center
Summary
The discovery of diiminonickel halides (A, Figure 1) as high active precatalysts in ethylene reactivity symbolized a milestone of late-transition metal catalytic systems [1], and resurrected nickel chemistry in the petrochemical industry with regard to the Shell Higher Olefin Process (SHOP) using a nickel catalyst [2]. B [11,12,13,14,15] and C [16,17,18,19,20] are potential precatalysts toward ethylene polymerization; we extensively investigated and modified C through controlling the fused-ring numbers in five [24] and seven [25,26]. N-(2,2-dimethyl-1-(quinolin-2-yl)propylidene) arylamines and their nickel complexes (F, Figure 1). The title complexes exhibited high activities toward ethylene oligomerization, producing hexenes as the major oligomerization, product. The synthesishexenes and characterization of the title complexes are synthesis reported along ethylene producing as the major product. Characterization of the title complexes are reported along with their ethylene oligomerization. O ethylene oligomerization, producing hexenes as the major product.
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