Vladislav A. Tuskaev

Titanium(4+) and zirconium(4+) dichloride complexes with pyridinedicarboxylic acid derivatives as ethylene polymerization catalysts

Titanium(4+) and zirconium(4+) complexes with pyridinedicarboxylic acid derivatives have been synthesized. The composition and structure of the synthesized 2,6-bis(diphenylhydroxymethyl)pyridine complexes have been corroborated by NMR and IR spectroscopy, and elemental analysis. The complexes activated with methylaluminoxane (MAO) are catalytically active in ethylene polymerization, Depending on the Ti/AlMAO ratio, the catalytic activity of the complexes varies between 90 and 420 kg PE/mol Ti h atm.

Transformations of 4-oxo-4H-chromene-3-carbaldehyde under the action of Fe(CO)5

Transformations of 4-oxo-4H-chromene-3-carbaldehyde in the presence of pentacarbonyliron and HMPA in benzene and toluene were studied, and their probable mechanism was proposed. The structure of 3-(4-oxochroman-3-ylmethyl)-4H-chromen-4-one was determined by spectral methods and X-ray analysis.

Polymerization of olefins catalyzed by a dichloride complex of titanium with a dioxolane dicarbonate ligand: The promoting effect of LiCl and MgCl2

The polymerizations of propylene and ethylene with two postmetallocene catalysts [(4R,5R)-2,2-dimethyl-α,α,α′,α′-tetra(perfluorophenyl)-1,3-dioxolane-4,5-dimethanol]TiCl2 · MgCl2 and [(4R,5R)-2,2-dimethyl-α,α,α′,α′-tetra-(perfluorophenyl-1,3-dioxolane-4,5-dimethanol]TiCl2· (LiCl)2 are studied. The first catalyst shows higher activity in both reactions and forms a lower molecular mass PP. This PP is characterized by a wide molecular-mass distribution that can be described by a set of five or six Flory components with different average molecular masses. Along with heterogeneity with respect to kinetic parameters, there is heterogeneity with respect to stereospecificity. Some of the sites form a high-molecular-mass highly isotactic polymer whose melting point is ≥150°C, whereas other sites produce syndiotactic and atactic PPs. For the most isospecific sites, a stereocontrol mechanism similar to the mechanism typical for metallocene catalysts with C1-symmetry is advanced. The catalysts under study are composed of the [(4R,5R)-2,2-dimethyl-α,α,α′,α′-tetra(perfluorophenyl)-1,3-dioxolane-4,5-dimethanol]TiCl2 complex supported on LiCl and MgCl2, respectively.

Influence of polymerization conditions on catalytic properties of the TiCl2{η2-1-[C(H)=N(2,3,5,6-tetrafluorophenyl)]-2-O-3,5-di-But-C6H2}2/MAO system in ethylene homopolymerization and copolymerization with α-olefins

Experimental data on ethylene homo- and copolymerization with higher a-olefins (hex-1-ene, oct-1-ene, and dec-1-ene) by the catalytic system TiCl2{η2-1-[C(H)=N(2,3,5,6-tetrafluorophenyl)]-2-O-3,5-di-But-C6H2}2/MAO in a Nefras medium and in toluene are presented. The catalytic system provides ultrahigh-molecular-weight polyethylene and incorporation of comonomer units at a level of 2–3 mol.% in both solvents. Nascent copolymers formed in Nefras (petroleum solvent), unlike those obtained in toluene, are characterized by two melting peaks in the DSC thermograms and only one when obtained in toluene. The molecular weight of polyolefins is efficiently controlled by the introduction of hydrogen into the system.

Effect of trimethylaluminum on the polymerization of ethylene with the catalytic system Bis[N-(3,5-di-tert-butylsalicylidene)-2,3,5,6-tetrafluoroanilinato]titanium(IV) dichloride-methylaluminoxane

The effect of trimethylaluminum in commercial methylaluminoxane on the molecular-mass characteristics of polyethylene formed with the phenoxyimine titanium catalyst bis[N-(3,5-di-tert-butylsalicylidene)-2,3,5,6-tetrafluoroanilinato]titanium(IV) dichloride activated by methylaluminoxane of varying purity is studied. It is shown that, all other conditions being equal, an increase in the content of trimethylaluminum in the reaction solution leads to an appreciable decrease in the molecular mass of the polymer. With an increase in the time of polymerization, the molecular mass tends to increase, while overall polydispersity indexes Mw/Mn remain substantially less than 2. The causes of the above effects are discussed.

Titanium(III, IV)-Containing Catalytic Systems for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solventless Processing—Impact of Oxidation States of Transition Metal

Catalytic systems containing TiCl4 or TiCl3, THF, organomagnesium (n-Bu2Mg) and organoaluminum compounds capable of producing ultrahigh molecular weight polyethylene (UHMWPE) were developed. The resulting polymers were characterized by a molecular weight in the range of (1.8–7.8) × 106 Da and desirable morphology, suitable for modern methods of polymer processing—the solvent-free solid-state processing of superhigh-strength (tensile strength up to 2.1 GPa) and high-modulus (elastic modulus up to 125 GPa) oriented films and film tapes. The impacts of a THF additive, the oxidation state of the titanium atom, and the composition and nature of the nontransition organometallic compounds on the formation of catalytic systems for UHMWPE production were evaluated. The results indicate the suitability of individual titanium chloride tetrahydrofuran complex application for the formation of THF-containing catalytic systems. This approach also results in a significant increase in the system catalytic activity and mechanical properties of UHMWPE. The catalysts based on Ti(III) were inferior to systems containing Ti(IV) in productivity but were markedly superior in the mechanical properties of UHMWPE.

Mechanochemical synthesis of zirconium and hafnium phenoxyimine complexes L2MCl2 (L = N-(3,5-di-tert-butylsalicylidene)-2,3,5,6-tetrafluoroanilinate anion) and their catalytic properties in ethylene polymerization

A new method for preparation of zirconium and hafnium phenoxyimine complexes L2MCl2 (L is N-(3,5-di-tert-butylsalicylidene)-2,3,5,6-tetrafluoroanilinate anion, M = Zr, Hf) by the solid state interaction of N-(3,5-di-tert-butylsalicylidene)-2,3,5,6-tetrafluoroaniline, the corresponding metal chlorides, and sodium hydride under mechanical activation followed by heating of the activated mixture was developed. The obtained complexes have a high catalytic activity in the reaction of ethylene polymerization.

Polymerization of higher α-olefins with the catalytic system (4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-bis(perfluorophenyldimethanolate) titanium(IV) dichloride-organoaluminum compound

The catalytic activity of the titanium(IV) dichloride complex with the (4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-bis(perfluorophenyldimethanol) ligand in the presence of a cocatalyst (polymethylaluminoxane, triethylaluminum, or triisobutylaluminum) in the polymerization of higher α-olefins (1-hexene, 1-octene, 1-decene) is investigated. It is shown that, depending on the types of cocatalyst and monomer and the molar ratio of components of the catalytic system, high- or ultrahigh-molecular-mass poly(α-olefins) with M w = (4 × 105)−(3 × 106) can be prepared. The chain microstructure of polyhexene is examined.

New titanium(IV) coordination compounds with 2-hydroxybenzyl alcohol derivatives used in the preparation of ultra-high molecular weight polyethylene

A reaction of 2,4-bis(α,α-dimethylbenzyl)phenol with TiCl2(ОPri)2 and Ti(ОPri)4 was used to obtain the coordination compounds (HL)2L2Ti2Cl2•MeC6H5 and L4Ti4(OPri)8, respectively. The compounds were characterized by elemental analysis, NMR spectroscopy, and X-ray diffraction. The titanium(IV) coordination compounds obtained polymerize ethylene in the presence of binary cocatalysts {3Et2AlCl + Bu2Mg} or {3Et3Al2Cl3 + Bu2Mg} at moderate to high rates, giving rise to ultra-high molecular weight polyethylene with a wide range of molecular masses. The highest values of tensile strength (2.4 GPa) and modulus of elasticity (ε = 2.67%) were obtained for the sample with a molecular mass of 3.14•106 Da under comparable conditions of orientation drawing of the film filaments. This sample was obtained when complex (HL)2L2Ti2Cl2 was activated by a 3: 1 mixture of Et2AlCl—Bu2Mg.

Oligomerization of higher olefins and alkylation of toluene catalyzed by 2-[hydroxy(diaryl)methyl]-8-hydroxyquinoline oxovanadium(v) complexes

New oxovanadium(V) complexes with 2-[hydroxy(diaryl)methyl]-8-hydroxyquinoline ligands were synthesized. These compounds were found to be efficient tandem catalysts of oligomerization of hex-1-ene and alkylation of toluene, which leads to the mixture of hexyl-, dihexyl-, and trihexyltoluenes with the conversion of the starting alkene more than 99%.