Novel binary chlorides containing TiCl3 as components of coordination catalysts for ethylene polymerization. I. Synthesis and characterization of the solid solutions obtained

New binary chlorides have been obtained by reacting TiCl₄ with V(CO)₆, Cr(CO)₆, Mn₂(CO)₁₀, Mn(CO)₅Cl, Ni(CO)₄, Co₂(CO)₈, Fe(CO)₅, or Mo(CO)₆. The reactions yield quantitatively mixed chlorides having the general formula MCl_n·n TiCl₃, where n = 2 or 3 and M is a divalent or trivalent transition metal cation. MCl_n is generally isomorphous with the α- or γ-modification of TiCl₃. X-Ray and spectroscopic investigations indicate that the mixed chlorides obtained are solid solutions. High surface area values are associated with the adducts displaying lower crystallinity. Catalyst efficiencies two or three times higher than that of AlCl₃·3TiCl₃ were observed in the low-pressure polymerization of ethylene (HDPE) when some binary chloride was associated with Al(i-C₄H₉)₃. These results allow treating the obtained solid solutions as reference systems of high-yield catalysts for HDPE synthesis.     

New crystalline complex chlorides containing transition metal chlorides or oxychlorides as components of coordination catalysts

Novel complex chlorides have been obtained by reacting TiCl₄, VOCl₃, MoOCl₄, WOCl₄, or AlCl₃, with Be, Mg, Ca, or Sr chlorides in the presence of electron donors such as POCl₃ (L) or C₆H₅POCl₂, (L′). The resulting products, obtained with good yield, show defined stoichimetry, ionic character, and crystalline structure, and may be considered reference systems for high-yield catalysts in the low-pressure polymerization of ethylene (HDPE). Complexes (TiCl₆)MgL₆, (TiCl₅L′)₂ MgL′₆, and (Ti₂Cl₁₀)MgL₆ associated with (i-C₄H₉)₃Al were found very active in HDPE synthesis, but completely unable to polymerize propylene. This result and other evidence suggest that part of the catalytic activity of these systems is displayed by soluble species. The role played by the Mg ion in high-yield catalysts is displayed by soluble species. The role played by the Mg ion in high-yield catalysts is discussed in the light of the peculiar behavior shown by the complex chlorides containing this earth-alkali metal.     

Macrokinetics of Polybutadiene Production on a Titanium Ziegler–Natta Catalyst System Prepared in Turbulent Flows

The research was directed at establishing the dependence of the disperse composition of particles of TiCl₄–Al(i-C₄H₉)₃ catalytically active precipitate, and their activity and molecular weight characteristics of polybutadiene formed in their presence on the length of sections and the confuser diameter of the tubular turbulent apparatus of diffuser–confuser design used to prepare a catalytic system in turbulent flows. An approach that combines methods of computational fluid dynamics (ANSYS Workbench 17.1 platform) and formal kinetics, and solves inverse problems of kinetics has been used to solve the stated problem. The following required dependences were established based on numerical experiments on the models developed using this approach: (1) the hydrodynamics of the process of dispersing particles of TiCl₄–Al(i-C₄H₉)₃ catalytically active precipitate in a tubular turbulent apparatus with diffuser–confuser design, and (2) macrokinetics of butadiene polymerization on the particles of TiCl₄–Al(i-C₄H₉)₃ catalytically active precipitate dispersed in turbulent flows (batch reactor, the solvent was toluene, and the temperature of the process was 25°С).     

Syndiospecific styrene polymerization by (tert-BuC5H4)TiCl2(O-2,6-iPr2C6H3) – borate catalyst system

(^tBuC₅H₄)TiCl₂(O-2,6-ⁱPr₂C₆H₃) (2) exhibited relatively high catalytic activity for syndiospecific polymerization of styrene at 25 °C if both [PhMe₂NH]B(C₆F₅)₄ and a mixture of AlⁱBu₃/Al(n-C₈H₁₇)₃ were used as the cocatalyst. Effects of both organoaluminum and organoboron compounds were explored, and the effect of cocatalyst was different from that observed in 1-hexene polymerization catalyzed by Cp*TiCl₂(O-2,6-ⁱPr₂C₆H₃) (1). Resultant syndiotactic polystyrene possessed narrow molecular weight distribution under the optimized conditions, and the M_w values were unchanged during the time course.     

Synthesis of pyrrole-bridged constrained geometry complexes and their application for olefin polymerization

In this article, four constrained geometry complexes 4a [(η⁵-C₅H₄)CH₂(α-C₄H₃N)]Ti(NMe₂)₂, 7a [(η⁵-C₉H₆)CH₂(α-C₄H₃N)]Ti(NMe₂)₂, 4b [(η⁵-C₅H₄)CH₂(α-C₄H₃N)]Zr(NEt₂)₂, 7b [(η⁵-C₉H₆)CH₂(α-C₄H₃N)]Zr(NEt₂)₂ with pyrrole-bridged fragment were synthesized and characterized by ¹H NMR, ¹³C NMR, MASS, and EA. When combined with MAO, complex 4b given the highest activity, the activity of copolymerizing ethylene and 1-hexene reached 2.48 × 10⁶ g polymer/mol·M·h. The effects of temperature, pressure, and ratio of Al/Metal on the polymerization reaction and properties of polymers had been investigated. The polymers with these complexes were characterized by ¹³C NMR and DSC, and the results shown that polymer with 4a had the highest α-olefin incorporation, the incorporation of 1-hexene reached up to 9.81 mol%, and the 1-octene was 8.84 mol%. Actually, there was no [HH] or [OO] sequence in the copolymer, according to the formula of reactivity ratio, rE • rH = 0, all these results suggested that the copolymerization mode is alternating copolymerization. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48620.     

Solid-State NMR characterization of a superactive supported ziegler–natta catalyst

The formation of CH-type catalysts has been investigated by high-resolution and solid-state NMR. These catalysts are prepared from a soluble MgCl₂ and 2-ethyl-1-hexanol adduct (MgCl₂·3EH) by reaction with phthalic anhydride (PA) to form dioctylphthalate (DOP) and then with TiCl₄ in the presence of di-i-butylphthalate (BP). In the model systems MgCl₂·3EH/PA, MgCl₂/BP, and MgCl₂/TiCl₄/BP, the ester is complexed with MgCl₂ and /or TiCl₄ in two or more states. Only single-ester C?O and OCH₂ resonances are seen in TiCl₄/BP, probably due to exchange of ester coordinations. CH-catalysts prepared by three different procedures exhibit a single mode of bonding for the ester. The chemical shift values are consistent for ester complexed with MgCl₂. The most active and stereoselective catalyst has the most shielded chemical shift values for the C?O and —OCH₂— carbons, shortest T^H₁ and T^H_1p, and longest T_CH relaxation times. These parameters change monotonically with the decrease of activity and stereoselectivity of the catalyst preparation. © 1993 John Wiley & Sons, Inc.     

A Novel Branched–Hyperbranched Block Polyolefin Produced via Chain Shuttling Polymerization from Ethylene Alone

A novel branched-hyperbranched polyethylene was synthesized via chain walking and chain shuttling polymerization by one step. In polymerization, {2,6- ⁱ Pr₂-C₆H₃N?C(CH₃)-(CH₃)C?N- ⁱ Pr₂-C₆H₂}NiBr₂(CatA) and {2,6-Me₂-C₆H₃N?C(CH₃)-(CH₃)C?N-Me₂-C₆H₂}NiBr₂(CatB) was adopted to yield branched and hyperbranched segments via chain walking polymerization at one ethylene atm and 20°C, respectively. Then the chain transfer agent(ZnEt₂) facilitated chain transfer between two active metal centers to accomplish chain shuttling polymerization of ethylene. This strategy stands out from “living”/controlled polymerization and coupling block polymers techniques for just using ethylene as monomer, carrying out under moderate polymerization and obtaining the resultant polymer with novel microstructure.     

TiO2 thin films synthesized by the spray pyrolysis deposition (SPD) technique

Anatase-type TiO₂ thin films with high transmittance (>70%) in the visible region were successfully synthesized on glass substrates by the spray pyrolysis deposition (SPD) technique. Two kinds of starting solutions; TiCl₄ ethanol solution and Ti(i-OC₃H₇)₄ 2-propanol solution with TiCl₄ as an additive were prepared separately. The TiO₂ thin film obtained from the former solution showed the preferred orientation along the [101] direction. However, a 1·5 μm thick film from the latter solution revealed almost the same transmittance as a 200 nm thick film from the former. The result indicates that the complexes produced by adding TiCl₄ in Ti(i-OC₃H₇)₄ 2-propanol solution plays an important role in the mechanism of the crystallization of TiO₂.     

Studies of a Supported Titanium Catalyst System Using Magnesium Dichloride–Alcohol Adduct

Magnesium dichloride reacts with aliphatic alcohols [ROH; R = n-C₂H₅, n-C₃H₇, i-C₃H₇, n-C₄H₉, i-C₄H₉, t-C₄H₉, n-C₅H₁₁, n-C₆H₁₃, C₆H₁₂(C₂H₅)] to form well-defined solid adducts. Compositional analysis of adducts indicates that the stoichiometric ratio of magnesium dichloride to alcohol depends on length of alkyl group and nature of isomeric alcohol. Magnesium dichloride-2-ethyl-l-hexanol adduct was treated with diphenyldichlorosilane in the presence of dibutylphthalate to obtain active magnesium dichloride support. The titanation process of active magnesium dichloride gives supported magnesium–titanium catalyst (Mg–Ti). The catalyst was characterized by compositional analysis and specific surface area measurements. Performance of the catalyst for polymerization of propene was evaluated with triethylaluminum (TEAL) and phenyltriethoxysilane (PES) as cocatalyst. The yield and isotacticity of the polymer is governed by polymerization parameters such as Si/A1 ratio and polymerization time.     

Preparation and characterization of cordierite powders

The current paper presents different preparation methods for cordierite ceramic powders: solid state reactions and wet preparation. In the solid state method, γ-Al₂O₃, SiO₂ and Mg(CO₃)₂ were used as raw materials. For wet preparation, the following compounds were used as precursors: silica gel, AlCl₃·6H₂O and Mg(NO₃)₂·6H₂O. The powders obtained by the different methods employed were characterized in what concerns mineralogical composition and granulometric distribution. It was determined that the results are influenced by the nature of raw materials used and the processing conditions.     

A novel route to titanium compounds containing cyclopentadienyl ligands with bromoethyl substituents; molecular structure of [(η5-C5H4CH2CH2Br)TiBr(μ-O)]4

Compounds (η⁵-C₅H₄CH₂CH₂OCH₃)TiCl₃, (η⁵-C₅H₄CH₂CH₂OCH₃)₂TiCl₂ and (η⁵-C₅H₄CH₂CH₂OCH₃)(η⁵-C₅H₅)TiCl₂ react with BBr₃ to give a high yield of titanium compounds containing cyclopentadienyl ligands with bromoethyl substituents, (η⁵-C₅H₄CH₂CH₂Br)TiBr₃ (1), (η⁵-C₅H₄CH₂CH₂Br)₂TiBr₂ (3) and (η⁵-C₅H₄CH₂CH₂Br)(η⁵-C₅H₅)TiBr₂ (4), respectively. Hydrolysis of 1 in the presence of tert-butylamine affords cyclo-[(η⁵-C₅H₄CH₂CH₂Br)TiBr(μ-O)]₄ (2) in quantitative yield. The molecular structure of 2 was determined by X-ray diffraction.     

Metal Chelates with Some Cellulose Derivatives: V. Synthesis and Characterization of Some Iron(III) Complexes with Cellulose Ethers

Two types of monoligand complexes of FeCl₃, Fe(NO₃)₃ and Fe₂(SO₄)₃ with hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC) were prepared and characterized. Elemental analysis, UV and IR spectro-scopies, conductance and magnetic measurements were used to assign the mode of coordination in the isolated species. The investigation revealed that Fe(III ) exhibits tetrahedral coordination with HEC and CMC. These ligands act as a bidentate chelating agent via the two oxygen atoms of the vicinal hydroxyl and ether groups (ethoxyl or carboxymethyl groups). The prepared complexes have the formula [(HEC) FeCl]Cl, [(HEC) FeNO₃]NO₃, [(HEC)FeSO₄·H₂O]H₂O, [(CMC)FeCl·H₂O]Cl·2H₂O, [(CMC)Fe·2NO₃]3H₂O and [(CMC)-FeSO₄·H₂O]H₂O. The results also showed that the type of cellulose ether (functional group) and the anion of the metal salts used have an effect on the conductivity, structure and absorptivity of Fe(III ) complexes. © of SCI.     

Influence of type and positioning of N-aryl substituents on vinyl polymerization of norbornene by Ni(II) α-diimine complexes

Effects of structural variations of the diimine ligand on catalyst activities for vinyl polymerization of norbornene (NB) have been investigated by a series of Ni(II) α-diimine catalysts of the general formula: [{ArN=C(Ac)-C(Ac)=NAr}]NiBr₂ (Ac=acenaphthyl) (Cat(H), Ar=C₆H₅; Cat(2,6-Me), Ar=2,6-C₆H₃Me₂; Cat(2,6-Et), Ar=2,6-C₆H₃Et₂; Cat(2,6- i Pr), Ar=2,6-C₆H₃ i-Pr₂; Cat(2,3-Me), Ar=2,3-C₆H₃Me₂; Cat(2,4-Me), Ar=2,4-C₆H₃Me₂; Cat(2,5-Me), Ar=2,5-C₆H₃Me₂; Cat(3,5-Me), Ar=3,5-C₆H₃Me₂; Cat(2,4,6-Me), Ar=2,4,6-C₆H₂Me₃). In situ reactions with methylaluminoxane generated the active catalysts, and they showed good activity towards NB polymerizations. As indicated by relatively higher activities of Cat(H) and Cat(3,5-Me), it can be generalized that catalysts having 2,6-substituents are less active due to steric interaction between monomer and substituents. In addition, electron donating methyl groups at 2-, 4-or 6-position on the N-aryl have a con effect and that at 3,5-position has a pro effect. This paper was presented at the 11th Korea-Japan Symposium on Catatysis held at Seoul, Korea, May 21–24, 2007.     

Fabrication and characterization of the monolithic hydrophobic alumina aerogels

The monolithic hydrophobic mesoporous alumina aerogels were successfully synthesized by acid–base sol–gel polymerization of aluminium chloride hexahydrate (AlCl₃·6H₂O) in deionized water/alcohol solution (v/v = 3:7). To minimize shrinkage during drying, alumina hydrogels were aged in tetraethylorthosilicate (TEOS)/acetonitrile solution, and modified using trimethylchlorosilane (TMCS)/acetonitrile solution. Properties of the final product were examined by contact angle measurement, FTIR, FESEM, TEM and BET analyses. Surface modification was confirmed by FTIR spectroscopy. It was found that hydrophobic property of the alumina aerogels was affected by the contents of TMCS. When the molar ratio of TMCS to AlCl₃·6H₂O is 0.35, hydrophobic alumina aerogels shows lower bulk density (0.453 g/cm³) and higher surface area (495 m²/g) than those of unmodified alumina aerogels (0.933 g/cm³, 413 m²/g).     

Polymerization of 4-n-alkylstyrenes with typical Ziegler-Natta and metallocene catalysts

Polymerization of 4-n-alkylstyrenes (alkyl side group; methyl, ethyl, propyl and buthyl) was carried out with the η-C₅(CH₃)₅TiCl₃-methylaluminoxane (MAO) and TiCl₃-triethylaluminum (TEA) catalyst systems. When the η-C₅(CH₃)₅TiCl₃-MAO catalyst was used, the stereoregularity of resulting polymers markedly depended on the length of substituted alkyl groups, i.e., the catalyst gave highly syndiotactic poly(4-methylstyrene), but produced atactic polymers for the monomers with ethyl, propyl and buthyl substituents. On the other hand, all the poly(4-n-alkylstyrene)s obtained with the TiCl₃-TEA catalyst were highly isotactic. As a result, a large difference was observed in the thermal properties of polymers obtained between the two catalyst systems. Received: 6 September 1996/Accepted: 16 October 1996     

Gas permeation properties of poly(2,5-dialkyl-p-phenyleneethynylene) membranes

Dipropynylbenzenes with alkyl groups (CH₃C ≡ CRC₆H₂RC≡CCH₃, R=n-C₆H₁₃, n-C₈H₁₇, n-C₁₀H₂₁, 1a–c, respectively) were polymerized with Mo(CO)₆ to afford solvent-soluble poly(2,5-dialkyl-p-phenyleneethynylene)s (2a–c). The polymers (2a–c) had high molecular weight over 3×10⁴, and gave free-standing membranes by solution casting method. According to thermogravimetric analysis (TGA), these poly(p-phenyleneethynylene)s showed high thermal stability (T₀ ≥380 °C). The densities of membranes of poly(2,5-dialkyl-p-phenyleneethynylene)s (2a–c) were 0.936–0.965, and their fractional free volume (FFV) were relatively large (ca. 0.14–0.15). The oxygen permeability coefficients (PO₂) of membranes of 2a–c were 4.88, 7.06, and 16.6 barrers, respectively.     

Perfluoroalkylene-linked aromatic polymers

Polymers of the type (m-C₆H₄·(CF₂)_m·m-C₆H₄-X))n have been synthesised and their properties are reported. They include polyesters and polycarbonates, polysiloxanes, polyimides and poly-(1,3-phenylenehexafluoro-trimethylene. Preparation of the precursors was facilitated by the discovery of a direct fluoroalkylation process involving fluoroalkylcopper intermediates. In various instances, the effects of introducing m-phenylene-perfluoroalkylene units on the properties of these polymers, particularly their glass transition temperatures, are compared with the corresponding effects from m-phenylene ether units.     

Coal reduction studies. 4. Hydrogenation in the presence of AlCl3 and AlCl3 + MClx (M = Cu,Zn, Fe,Cr, Mo and Ni)

Coal has been reduced to low-molecular-weight hydrocarbons in the presence of various metal halides by H₂ at pressures up to 19.3 MPa and temperatures to 600 °C, in all quartz reactors. The mixed halides MoCl₃ + AlCl₃ and NiCl₂ + AlCl₃ were found to be superior catalyst combinations. With the former, initial H₂ pressures of 4.1–6.9 MPa and temperatures of 300–400 °C resulted in 75% coal carbon conversion to low-molecular-weight hydrocarbons. It is tentatively suggested that gaseous mixed metal halide complexes of the type Mo(AlCl₄)_x, and Ni(AlCl₄)₂ may be of importance in the catalytic process. It is possible that such complexes may be able to incorporate H₂ in their structure which could account for their catalytic activity.     

Performance of combined use of chlorosilanes and AlCl3 in the carboxylation of toluene with CO2

Carboxylation of toluene with CO₂ for the production of p‐toluic acid was shown to be promoted by the addition of Me₂PhSiCl, Ph₂SiCl₂, Ph₃SiH, or Ph₃SiCl into the AlCl₃ activated system, and the reaction activity was in the increasing order of Ph₂SiCl₂ < Me₂PhSiCl < Ph₃SiH < Ph₃SiCl. The spectrum of IR indicated that CO₂ could be effectively activated by AlCl₃ or Ph₃SiCl independently. DFT calculation was carried out to estimate the electrophilic potentials of the chlorine bridged AlCl₃···chlorosilane complex in the form of the APT atomic charges of Si and Al. The much higher activity of Ph₃Si‐Cl···AlCl₃ over AlCl₃‐AlCl₃ was considered due to its higher valences of Si and Al which are +2.107 and +1.833 compared with the +1.814 of Al in the latter. The mechanism of CO₂ activation under the action of double Lewis acid sites of Si and Al and the subsequent carboxylation of toluene was consequently proposed. © 2016 American Institute of Chemical Engineers AIChE J, 63: 185–191, 2017     

Polymerization of Methyl Methacrylate with Nickel(II) and Palladium(II) Iminopyridyl Mononuclear Bimetallic Complexes

Methyl methacrylate polymerizations with a series of Pd(II) or Ni(II) bimetallic catalysts having general formula [(2-C₅H₄N)–C=N–(Z)–N=C–(2-C₅H₄N)] [MX₂]₂ {Z = (2,6-C₆H₂R₂)₂CH(4-C₆H₅); R = Me, iPr, MX₂ = PdCl₂, NiBr₂} in combination with methylaluminoxane showed that bimetallic Pd(II) catalysts are much more active than their bimetallic Ni(II) nickel and monometallic analogs to give syndiorich poly(methyl methacrylate) with moderate molecular weight.