Polymerization of alkenes with a post‐metallocene catalyst containing a titanium complex with an oxyquinolinyl ligand

Polymerization reactions of ethylene, propylene, higher 1‐alkenes (1‐hexene, 1‐octene, 1‐decene, vinyl cyclohexane, 3‐methyl‐1‐butene), and copolymerization reactions of ethylene with 1‐octene with a post‐metallocene catalyst containing an oxyquinolinyl complex of Ti and a combination of Al(C₂H₅)₂Cl and Mg(C₄H₉)₂ as a cocatalyst were studied. The catalyst is highly active and, judging by the broad molecular weight distribution of the polymers, contains several active center populations. The active centers differ not only in their kinetic parameters but also in stereospecificity. Most of the active centers produce essentially atactic polypropylene but a small fraction of the centers produces polypropylene of moderate isotacticity degree. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1844–1854     

Ethylene–propylene copolymerization with bis(β‐enaminoketonato) titanium complexes activated with modified methylaluminoxane

Ethylene–propylene copolymerization, using [(Ph)NC(R₂)CHC(R₁)O]₂TiCl₂ (R₁ = CF₃, Ph, or t‐Bu; R₂ = CH₃ or CF₃) titanium complexes activated with modified methylaluminoxane as a cocatalyst, was investigated. High‐molecular‐weight ethylene–propylene copolymers with relatively narrow molecular weight distributions and a broad range of chemical compositions were obtained. Substituents R₁ and R₂ influenced the copolymerization behavior, including the copolymerization activity, methylene sequence distribution, molecular weight, and polydispersity. With small steric hindrance at R₁ and R₂, one complex (R₁ = CF₃; R₂ = CH₃) displayed high catalytic activity and produced copolymers with high propylene incorporation but low molecular weight. The microstructures of the copolymers were analyzed with ¹³C NMR to determine the methylene sequence distribution and number‐average sequence lengths of uninterrupted methylene carbons. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5846–5854, 2006     

A Bis(phenoxy‐imine)Zr Complex for Ultrahigh‐Molecular‐Weight Amorphous Ethylene/Propylene Copolymer

A new bis(phenoxy‐imine)Zr complex has been developed. This complex in conjunction with ⁱBu₃Al/Ph₃CB(C₆F₅)₄ at 70°C produces ultrahigh‐molecular‐weight amorphous ethylene/propylene copolymer with a weight‐average molecular weight of 10 200 000 g/mol versus polystyrene standards, which represents the highest molecular weight known for linear, synthetic copolymers to date.     

Monomer-isomerization polymerization. XXVI. Formation of polyallylcyclohexane from propenylcyclohexane through monomer-isomerization polymerization with Ziegler–Natta catalysts

Monomer-isomerization polymerization of propenycyclohexane (PCH) with TiCl₃ and R_3-xAICI_x (R = C₂H₅ or i-C₄H₉, x = 1–3) catalysts was studied. It was found that PCH underwent monomer-isomerization polymerization to give a high molecular weight polymer consisting of an allylcyclohexane (ACH) repeat unit. Among the alkyaluminum cocatalysts examined, (C₂H₅)₃Al was the most effective cocatalyst for the monomer-isomerization polymerization of PCH, and a maximum for the polymerization was observed at a molar ratio of Al/Ti of about 2.0. The addition of isomerization catalysts such as nickel acetylacetonate [Ni(acac)₂] to the TiCl₃–(C₂H₅)₃Al catalyst accelerated the monomer-isomerization polymerization of PCH and gave a maximum for the polymerization at a Ni/Ti molar ratio of 0.5. PCH also undergoes monomer-isomerization copolymerization with 2-butene (2B).     

Polymerization with heterogeneous metalorganic catalysts. VI. Differences in polymerization activity of α-olefins and some kinetic results on butene-1 polymerization

Relative changes in polymerization activity of ethylene, propylene, and butene-1 in Ziegler-Natta polymerization were compared by use of TiCl₃ samples contaminated with O₂ and H₂O to various extents. Catalyst depletion varied for the three monomers which supported the existence of different active centers. In butene-1 polymerizations with the system Al(C₂H₅)₂Cl–TiCl₃, the formation of active centers involves an irreversible and a reversible (adsorption) reaction, the former pertaining to the formation of Al(C₂H₅)Cl₂ and dependent upon the purity of the TiCl₃. The kinetic treatment of the rate curves suggests a mixed order of catalyst deactivation and again points to the importance of Al(C₂H₅)Cl₂.     

Highly active supported catalysts for olefin polymerization. Supports from a grignard reagent for preparation of highly active catalysts

Supports were obtained by the interaction of C₄H₉MgCl with the reaction mixture of AlCl₃ and CH₃Si(OC₂H₅)₃ or Si(OC₂H₅)₄ (Mg/Al/Si = 2/1/1). With the combination of Al(C₂H₅)₃ and methyl-p-toluate, immobilized titanium catalysts prepared by the treatment of the supports with TiCl₄ and ethylbenzoate showed extraordinary high activity and stereoregularity in the polymerization of propylene.¹ By the study of the reaction of AlCl₃ with CH₃Si(OC₂H₅)₃, the elemental analysis and powder x-ray diffractometric measurements of the supports, it was found that the supports comprised of Cl, Mg, Al, and Si atoms, OC₂H₅ groups, C₄H₉ groups, and ethers, and that they were amorphous solids to the extent that the x-ray diffraction peak assigned to the 003 plane in MgCl₂ crystals completely disappeared.     

Propylene polymerization with nickel–diimine complexes containing pseudohalides

DADNiX₂ nickel–diimine complexes [DAD = 2,6‐iPr₂? C₆H₃? N?C(Me)? C(Me)?N? 2,6‐iPr₂? C₆H₃] containing nonchelating pseudohalide ligands [X = isothiocyanate (NCS) for complex 1 and isoselenocyanate (NCSe) for complex 2 ] were synthesized, and the propylene polymerization with these complexes and also with the Br ligand (X = Br for complex 3 ) activated by methylaluminoxane (MAO) were investigated (systems 1 , 2 , and 3 /MAO). The polypropylenes obtained with systems 1 , 2 , and 3 were amorphous polymers and had high molecular weights and narrow molecular weight distributions. Catalyst system 1 showed a relatively high activity even at a low Al/Ni ratio and reached the maximum activity at the molar ratio of Al/Ni = 500, unlike system 3 . Increases in the reaction temperature and propylene pressure favored an increase in the catalytic activity. The spectra of polypropylenes looked like those of propylene–ethylene copolymers containing syndiotactic propylene and ethylene sequences. At the same temperature and pressure, system 2 presented the highest number of propylene sequences, and system 3 presented the lowest. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 458–466, 2006     

Preparation of hindered piperidine and its copolymerization with propylene over a supported high activity ziegler–natta catalyst

A new polymerizable stabilizer 4-(hex-5-enyl)-2,2,6,6-tetramethylpiperidine is prepared. This sterically hindered piperidine was copolymerized with propylene over a fourth generation TiCl₄/MgCl₂ Ziegler–Natta catalyst, using Al(C₂H₅)₃ as cocatalyst and diphenyldimethoxysilane, DMS, as external electron donor. The copolymer exhibited high thermo-oxidative stability even after exhaustive extraction with n-heptane.     

NMR Analysis and Regiochemical Structure of Some Selectively 13C‐Enriched Poly(propylene)s

Summary: The regiochemical structures of poly(propylene)s obtained in the presence of three single‐site catalysts, Cp*Ti(CH₃)₃ + B(C₆F₅)₃ (I + III), CpTi(CH₃)₃ + B(C₆F₅)₃ (II + III), and VCl₄ + anisole + Al(C₂H₅)₂Cl (V + A), are investigated by ¹³C NMR analysis. Polymer 1 , obtained in the presence of I + III is, seemingly, fully regioregular, while, surprisingly, polymer 2 , obtained in the presence of II + III, appears to be alternating sequence of primary and secondary regioblocks, very much like polymer 3 , obtained in the presence of V + A. The stereochemical structure of the polymer obtained in the presence of I + III is in excellent agreement with a Bernoullian statistical model of the stereoselective propagation, while those of the other two polymers possibly require a Coleman‐Fox model.

¹³C NMR spectra of 10%‐enriched poly[(2‐¹³C)propylene], 1′ and 2′ , prepared under the conditions reported in Table 1 for the corresponding poly(propylene)s, 1 and 2 . The resonances of the tertiary carbons are diagnostic of the regioblock structure of sample 2′ .     

Transition metal promoted alkylations of unsaturated alcohols: the methylation and ethylation of 3-buten-1-ol using titanium tetrachloride-organoaluminum systems

The ethylation and methylation of the olefinic linkage in 3-buten 1-ol by incorporating the alkenol into a titanium-organoaluminum system was studied under a variety of conditions. Systems were derived from titanium tetrachloride and the organoaluminum compounds Al(C₂H₅)₃, Al(C₂H₅)₂Cl, Al(CH₃)₃, and Al(CH₃)₂Cl. With diethylaluminum chloride the major products obtained were 1-hexanol, 3-methyl-1-pentanol, trans-3-hexen-1-ol, and 1-butan I. Triethylaluminum gave no alkylation products. Dimethylaluminum chloride and trimethylaluminum gave product distributions similar to the analogous diethylaluminum chloride system.     

Influence of SeOCl2 on the polymerization of propylene by TiCl3–Al(C2H5)3

The influence of SeOCl₂ on the polymerization of propylene by TiCl₃–Al(C₂H₅)₃, and the temperature dependence of the stereospecificity of the catalyst, TiCl₃–Al(C₂H₅)₃, have been investigated. SeOCl₂ decreases the rate of polymerization and increase the stereospecificity of the catalyst, which could be explained on the basis of a decrease of the concentration of Al(C₂H₅)₃ accompanied by a reaction between Al(C₂H₅)₃ and SeOCl₂. On the other hand, the stereospecificity of the catalyst, TiCl₃–Al(C₂H₅)₃, increases gradually with a decrease in polymerization temperature from 40 to 0°C. From these results, we conclude that SeOCl₂ exerts no essential influence on the polymerization of propylene by TiCl₃–Al(C₂H₅)₃, and that the stereospecificity of the catalyst is attributed mainly to the reducing ability of the organometallic compound.     

Polymerization of propylene with the [ArN(CH2)3NAr]TiCl2 (Ar = 2,6-iPr2C6H3) complex using R3Al/Ph3CB(C6F5)4 (R = Me,Et, iBu) as cocatalyst

Polymerization of propylene was conducted at 0 ∼ 150°C with the [ArN(CH₂)₃NAr]TiCl₂ (Ar = 2,6-ⁱPr₂C₆H₃) complex using a mixture of trialkylaluminium (AIR₃, R = methyl, ethyl and isobutyl) and Ph₃CB(C₆F₅₎₄ as cocatalyst. When AlMe₃ or AlEt₃ was employed, atactic polypropylene (PP) was selectively produced, whereas the use of Al(ⁱBu)₃ gave a mixture of atactic and isotactic PP. The isotactic index (I.I.; weight fraction of isotactic polymer) depended strongly upon the polymerization temperature, and the highest I.I. was obtained at ca. 40°C. The ¹³C NMR analysis of the isotactic polymer suggests that the isotactic polymerization proceeds by an enantiomorphic-site mechanism. It was also demonstrated that the present catalyst shows a very high regiospecificity.     

Silyl‐functionalized polyolefins via co‐polymerization of vinylsilanes with ethylene or propylene catalyzed by group IV metallocene complexes

Vinylsilanes CH₂CHSiR₃ (R = Me, NMe₂, OMe, OTMS) copolymerize with ethylene rapidly in the presence of catalytic amounts of [Cp′₂ZrMe][MeB(C₆F₅)₃] (Cp′ = η⁵‐C₅Me₅) ( I ) to give high molecular weight silyl‐functionalized polyethylene. The molecular weight of the polymer can be controlled by varying the comonomer concentration as well as the reaction temperature. Relatively low molecular weight polymer was produced at a higher silyl monomer concentration and a higher polymerization temperature. The incorporation of silyl monomer in the polymer is in the range of 0.1‐ 6.0%. On the other hands, catalysts [Cp₂ZrMe][MeB(C₆F₅)₃] (Cp′ = η⁵‐C₅H₅) ( II ) and [Cp″₂ZrMe][MeB(C₆F₅)₃] (Cp″ = η⁵‐1,2‐C₅Me₂H₃) ( III ) show much lower activity. With the use of more coordinatively unsaturated constrained geometry catalysts (CGC), Me₂Si(η⁵‐C₅Me₄)(N^tBu)MMe][MeB(C₆F₅)₃] ( IV , M = Zr; V , M = Ti), the silyl monomer incorporation in the polymer was increased to 40%. The Ti catalyst is more active and produces polymer with a higher molecular weight with a higher silyl monomer incorporation at 23 °C. The copolymerization of vinyltrimethylsilane with propylene was also investigated with these catalysts, yielding high silyl‐functionalized propylene copolymer/oligmer. The microstructure of the copolymers/oligomers has been thoroughly investigated by 1D and 2D NMR techniques (¹H, ¹³C, NOE, DEPT, HETCOR, and FLOCK). The results show that the backbone of the copolymers/oligomers is essentially random. Several termination pathways have been identified. In particular, two unsaturated silyl terminations, cis and/or trans‐TMS CHCH , were identified with the constrained geometry catalysts. Their formation was rationalized based on transition state models. It was found that occasional 1,2‐insertion of either propylene or vinyltrimethylsilane into the chain propagation process has a high probability serving as the trigger for polymer chain termination via β‐H elimination. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1308–1321     

Copolymerization of propylene with 1-octene initiated by highly efficient isospecific metallocene catalytic systems

The copolymerization of propylene with 1-octene in liquid propylene is carried out in the presence of a highly active homogeneous ansa-m etallocene catalyst with the C ₂-symmetry rac-Me₂Si(4-Ph-2- MeInd)₂ZrCl₂ activated by methyl aluminoxane and in the presence of ansa- metallocene C₄H₆Si(2-Et4- PhInd)₂ZrCl₂ (rac: meso = 2:1) supported on silica gel treated with methylaluminoxane. In the case of the heterogenized metallocene, (iso-C ₄ H ₉ )₃Al is used as a cocatalyst. The copolymers of propylene and 1-octene containing up to 24 and 9.3 mol% units of the second comonomer are prepared with the homogeneous and heterogenized systems, respectively. The copolymerization of propylene with 1-octene in liquid propylene shows the azeotropic (ideal) character, and the distribution of comonomer units in the copolymers is close to statistical. The modification of PP with even small amounts of 1-octene affects the regularity of polymer chains, molecular-mass characteristics of the copolymers, their melting temperature, and the degree of crystallinity and makes it possible to vary their rigidity and elasticity in a wide range. The character of changes in thermal and mechanical properties is almost the same for the copolymers synthesized with homogeneous and heterogenized catalysts.     

[(C7H13N2)2Al]BPh4 – ein spirozyklischer Vinamidin‐Komplex des Aluminiums

[(C₇H₁₃N₂)₂Al]BPh₄ – a Spirocyclic Vinamidine Complex of Aluminum (C₇H₁₃N₂)AlH₂ ( 3 ) reacts with the vinamidinium salts C₇H₁₄N₂ · HX [ 4 , X = BPh₄ ( a ), Cl ( b )] to give the spirocyclic vinamidine aluminum complexes [(C₇H₁₃N₂)₂Al]BPh₄ ( 5 a ) and (C₇H₁₃N₂)₂AlCl ( 5 b ); the crystal structure of 5 a is reported.     

Kinetic studies of polymerization of propylene with active TiCl3–Zn(C2H5)2

In order to elucidate the structure of the Ziegler-Natta polymerization center, we have carried out some kinetic studies on the polymerization of propylene with active TiCl₃—Zn(C₂H₅)₂ in the temperature range of 25–56°C. and the Zn(C₂H₅)₂ concentration range of 4 × 10^?3–8 × 10^?2 mole/1., and compared the results with those obtained with active TiCl₃—Al(C₂H₅)₃. The following differences were found: (1) the activation energy of the stationary rate of polymerization is 6.5 kcal/mole with Zn(C₂H₅)₂ and 13.8 kcal./mole with Al(C₂H₅)₃; (2) the growth rate of the polymer chains with Zn(C₂H₅)₂ is about times slower at 43.5°C.; and (3) the polymerization centers formed with Zn(C₂H₅)₂ are more unstable. It can be concluded that the structure of the polymerization center with Zn(C₂H₅)₂ is different from that with Al(C₂H₅)₃.     

Ethylene-hexene-1 copolymers through modified phillips catalysis

Copolymerization of ethylene and hexene has been carried out using Phillips' catalysts (chromium oxide deposited on silica) modified with small amounts of triethylaluminium [Al(C₂H₅)₃], without solvent other than hexene itself and under constant ethylene pressure. The copolymers are highly disperse, not only in molecular weight but also in composition; the amount of hexene incorporated in the solid fraction is always less than 4%. Most of the hexene units are in a waxy fraction, which may account for a very high proportion of the copolymer produced. The behaviour of the catalyst is strongly dependent upon the amount of Al(C₂H₅)₃ used.     

Oligomerization of ethylene with a homogeneous sulfonated nickel ylide–aluminum alkoxide catalyst

Various organoaluminum compounds strongly affect reactivity of a sulfonated nickel ylide complex in its reactions with ethylene. The complex, if used alone, is an active single-component catalyst for ethylene oligomerization to linear 1-alkenes. Al(C₂H₅)₃ and tetraethylaluminoxane completely deactivate the catalyst by reducing it to Ni(O). Alkylaluminum halides, such as Al(C₂H₅)₂Cl and Al(C₂H₅)Cl₂, convert the nickel complex into a very active catalyst for ethylene dimerization to mixtures of butenes. Aluminum alkoxides, e.g., Al(C₂H₅)₂OC₂H₅, AlC₂H₅(OC₂H₅)₂, and Al(OC₂H₅)₃, significantly increase oligomerization activity by a factor of 20–100. The distribution of 1-alkenes (in the C₄? C₄₀ + range) produced with the sulfonated nickel ylide–aluminum alkoxide catalyst follows the Flory molecular weight distribution law. The ratio of the chain termination to chain propagation rate constants is ca. 0.3 and is not temperature-sensitive in the 50–120°C range. Kinetic analysis of the ethylene oligomerization reaction with the binary catalytic system showed that the number of active centers is proportional to the nickel complex concentration. The effective activation energy of ethylene oligomerization with the catalyst is ca. 27 kJ/mol. The oligomerization catalysts loose their activity in time. The activity decay follows the first-order kinetic law. The rate of the decay increases with increasing temperature and is caused mainly by the intrinsic instability of active species.     

Living regioselective copolymerization of ethylene with nonconjugated bicyclic dienes using (salicylaldiminato)(β‐enaminoketonato) titanium catalysts

A series of heteroligated (salicylaldiminato)(β‐enaminoketonato)titanium complexes [3‐^tBu‐2‐OC₆H₃CH?N(C₆F₅)] [PhN?C(CF₃)CHCRO]TiCl₂ [ 3a : R = Ph, 3b : R = C₆H₄Cl(p), 3c : R = C₆H₄OMe(p), 3d : R = C₆H₄Me(p), 3e : R = C₆H₄Me(o)] were synthesized and characterized. Molecular structures of 3b and 3c were further confirmed by X‐ray crystallographic analyses. In the presence of modified methylaluminoxane as a cocatalyst, these unsymmetric catalysts displayed favorable ability to incorporate 5‐vinyl‐2‐norbornene (VNB) and 5‐ethylidene‐2‐norbornene (ENB) into the polymer chains, affording high‐molecular weight copolymers with high‐comonomer incorporations and alternating sequence under the mild conditions. The comonomer concentration in the polymerization medium had a profound influence on the molecular weight distribution of the resultant copolymer. At initial comonomer concentration of higher than 0.4 mol/L, the titanium complexes with electron‐donating groups in the β‐enaminoketonato moiety mediated room‐temperature living ethylene/VNB or ENB copolymerizations. Polymerization results coupled with density functional theory calculations suggested that the highly controlled living copolymerization is probably a consequence of the difficulty in chain transfer of VNB (or ENB)‐last‐inserted species and some characteristics of living ethylene polymerization under limited conditions. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and properties of dicyclopentadienyltantalum hydride olefin compounds

Reactions of Cp₂TaCl₂ with RMgCl (R = n-C₃H₇, i-C₃H₇, n-C₄H₉, s-C₄H₉, n-C₅H₁₁ and C₅H₉) give tantalum hydride π-olefin complexes Cp₂Ta(H)L (L = C₃H₆, C₄H₈, C₅H₁₀ and C₅H₈). Two isomers of Cp₂Ta(H)C₃H₆ were obtained. The complexes are useful starting materials for the synthesis of other tantalum hydride species, e.g. Cp₂Ta(H)PEt₃ and Cp₂TaH₃.