A comparative study on the polymerization of 1-octene promoted by vanadium and titanium complexes supported by phenoxyimine and salen type ligands

Abstract

Polymerizations of 1-octene were carried out in the presence of vanadium and titanium complexes bearing salentype or phenoxyimine ligands activated with various cocatalysts. Vanadium complexes turned out active only in conjunction with MAO, whereas the titanium ones were active in combination with Al(i-Bu) 3 /Ph 3 CB(C 6 F 5 ) 4 . The activity of all catalysts was moderate or low and it was dependent on the ligand type: bis(phenoxyimine) complexes were more active than the salen ones. Both vanadium and titanium catalytic systems produced poly(1-octene)s possessing atactic structures with [mmmm] sequences in the range from 12 to 56 % at room temperature. A temperature decrease to 0.5°C for the reaction catalyzed by the vanadium catalyst led to poly(1-octene) of [mmmm] = 70 %. The 1 H NMR analysis showed that unsaturated end groups were present in poly(1-octenes) which were introduced to the polymer chains as a results of various chain transfer reactions. In case of vanadium catalysts, vinylidene and vinylene end groups were present in polymer products. For titanium catalyst, vinyl and tri-substituted unsaturated groups were present in poly(1-octenes) in addition to the end groups as mentioned before.

Vanadium(III) complexes containing phenoxy–imine–thiophene ligands: Synthesis, characterization and application to homo‐ and copolymerization of ethylene

“…Particularly, the IR spectra of 2a – 2g show the absence of O─H stretching bands in the range 3332–3453 cm −1 indicating the coordination of the phenoxy group to the vanadium metal center. Furthermore, the IR spectra of the these complexes show absorption bands at 1592–1619 cm −1 corresponding to the coordinated HC═N unit of the ligands ( 1a – 1g ) …”

Preparation of ansa-metallocenes for production of poly(α-olefin) lubricants

“…3(a)). 43,44 The integration ratios of the three signals were 16 : 10 : 1.0, which corresponded to the molar ratios of vinylidene (CvCH 2 ), trisubstituted vinylene (-(C)CvCH-), and disubstituted vinylene (-CHvCH-) being 16 : 20 : 1.0. This assignment agreed with the integration values observed for allylic CvC-CH 2and CvC-CH 3 signals at 2.0-2.2 ppm and 1.6-1.8 ppm, respectively.…”

“…3(b)). 43,44 It has been previously reported that atactic PAO is better for lubricant applications because it exhibits a low pour point relative to the isotactic-or syndiotactic-rich analogs. 31…”

Recent developments in catalyst systems for selective oligomerization and polymerization of higher α-olefins

“…In a report by Białek et al , the well-known salen ligand (salen = N , N ′-bis(salicylidene)ethylenediamine) and its vanadium complex were investigated in 1-octene polymerization. 109 The V-salen catalyst produced poly(1-octene) in the presence of MAO and displayed atactic structures with a [mmmr] sequence (∼35%) at room temperature. Moreover, the activity was very poor (<3.0 kg mol cat −1 ) accompanied by a broad molecular weight distribution ( M w / M n = 5.3), clearly indicating the presence of multiple active sites.…”