Oxovanadium(IV) complexes with [ONNO]-chelating ligands as catalysts for ethylene homo- and copolymerization

Abstract

Oxovanadium(IV) complexes with [ONNO]-type tetradentate Schiff base ligands: salen, acacen, aceten, acetph (H 2 salen = N,N′-ethylenebis(salicylideneimine), H 2 aceten = N,N′-ethylenebis(2-hydroxyacetophenoneimine), H 2 acacen = N,N′-ethylenebis(acetylacetonimine), H 2 a c e t p h = N , N ′ -p h e n y l e n e -1 , 2 -b i s (2-hydroxyacetophenoneimine)), were the first time investigated in ethylene polymerization and ethylene/1-octene copolymerization processes. In general, all these complexes are moderately active precatalyst for ethylene polymerization upon activation with EtAlCl 2 and they give high molecular weight linear polyethylenes. Their activity in copolymerization was found relatively low. However, they yielded copolymers with high 1-octene incorporation even at low comonomer concentrations in the feed. The catalytic performance in homo-and copolymerization was influenced by both the ligand structure and polymerization parameters (Al/ V molar ratio, polymerization temperature, comonomer feed concentration). In addition, the [VO(acacen)] was supported onto magnesium supports, and in the presence of various cocatalyst and at different reaction conditions it was screened as the catalyst of choice for ethylene homo-and copolymerization.

Overview of Schiff Bases

“…An example of this group is the oxovanadium(IV) complex synthesized with the N,N 0 -bis(salicylidine)ethylenediamine ligand [65]. N,N 0 -bis(salicylidine) ethylenediamine Schiff base, which is obtained with the condensation reaction of salicylaldehyde and ethylenediamine, is commonly known as salen and is an ONNO type tetradentate ligand (Figure 18) [66].…”

Copolymerization of Ethylene with Selected Vinyl Monomers Catalyzed by Group 4 Metal and Vanadium Complexes with Multidentate Ligands: A Short Review

“…Those complexes, when activated with EtAlCl 2 , make it possible to produce poly(ethyleneco-1-octene) with the comonomer content from 5.26 to 6.25 mol% and melting points ~112 • C, at the comonomer concentration of 0.40 mol/L. The copolymer with the highest 1-octene content was obtained with the use of V-29 and it was found to contain isolated comonomer units only [61]. The discussed complexes offered low catalytic activities in copolymerization, from 2.6 kg/(mol V •h) to 18.1 kg/(mol V •h), and it grew up in the following line: V-29 < V-30 < V-31.…”

Progress in vanadium complex catalysts and their catalytic behavior toward copolymerization of ethylene with &alpha;-olefins

“…, 得到的 共聚物中1-辛烯结构单元含量分别为5.4%(mol)和5.3% (mol) [51] . 含O^S^S^O四齿配体的钒(IV)配合物40催化 乙烯与1-辛烯共聚催化活性高于含O^N^N^O四齿配体 的钒(IV)配合物38和39 [52] .…”