One-pot synthesis of symmetrical and unsymmetrical α-diimine Nickel complexes in comparison with two-pot synthesis method for ethylene polymerization

Several symmetrical and unsymmetrical oc-diimine Nickel complexes synthesized with a novel method. Complexes symmetrical and unsymmetrical [Ar1N=C(Nap)-C(Nap)=NAr2] NiBr2(Nap = Acenaphthenequinone) (1, Ar-1, Ar-2 =2,6-ipr; 2Ar(1), Ar-2 =2,4,6-trimethylphenyl; 3Ar(1)=2,6-ipr, Ar-2 =2,4,6-trimethylphenyl) were synthesized and used as catalyst precursors for ethylene polymerization. These complexes were prepared by the reaction of one-pot in which the ligand is catalyzed by an acid catalyzed condensation followed by direct addition of Nickel dibromide. The complexes were also provided by a two-step processes in which the ligands were first formed by concentration between the suitable anilines and quinones, and the out coming ligand were then allowed to react with 1,2-Dimethoxyethane-dibromonickel. Ethylene polymerizations catalyzed by these nickel oc-diimine complexes activated by modified methylaluminumoxide (MMAO) were systematically investigated. The activity of C1 and C2 complexes were prepared by single pot method (1166.8 and 3870.03 g PE/ (mol Ni.hr), respectively. In C1 catalyst, the activity is more than two times that of the complex prepared by the two-step method (485 (g PE / (mol Ni.hr)), and in C2 catalyst there is an increase in activity, but this amount is lower (3066.6 (gr PE / (mol Ni.hr)). The polymer produced from the asymmetrical C3 complex with one pot (2631.6 g polymer/ (mol Ni.hr) is approximately 4 times more than that of two pot (666.8 g polymer/ (mol Ni.hr)). Polymer molecular weight and resulting polymer microstructure were changed according to the catalyst structure modification and polymerization parameters and produced high molecular weight polyethylene.

Automated summary

Several symmetrical and unsymmetrical oc-diimine Nickel complexes were synthesized with a novel method and used as catalyst precursors for ethylene polymerization. The molecular weight and microstructure of the resulting polymer were altered by modifying the catalyst structure and polymerization parameters.