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

ABSTRACT

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.

KEYWORDS:

• Co-catalyst effect
• ethylene oligomerization
• hyperbranched molecule
• salicylaldimine nickel complex

Funding

The authors thank the National Natural Science Foundation of China (21576048), Innovation Foundation of PetroChina (2014D-5006-0503) and Youth Science Foundation of Northeast Petroleum University(2013NQ130) for financial support.