Experimental and Theoretical Study of Zirconocene-Catalyzed Oligomerization of 1-Octene

Nifant’ev, Ilya E.; Vinogradov, Alexander A.; Karchevsky, Stanislav G.; Ivchenko, Pavel V.

doi:10.3390/polym12071590

Cited by 14 publications

(15 citation statements)

References 87 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the way of synthesizing polyolefin with unique characterizations with narrow molar mass distributions and branching degree, academic and industrial researchers have devoted their consideration in polymer science and organometallic chemistry [ 1 , 2 , 3 , 4 ]. To design new polymerization technologies based on transition metal compound, homogeneous metallocene single-site catalyst precursors and main-group organometallic alkylaluminum cocatalysts can be considered valuable strategies to achieve this goal [ 5 , 6 , 7 , 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

Kinetic and Thermal Study of Ethylene and Propylene Homo Polymerization Catalyzed by ansa-Zirconocene Activated with Alkylaluminum/Borate: Effects of Alkylaluminum on Polymerization Kinetics and Polymer Structure

et al. 2021

View full text Add to dashboard Cite

The kinetics of ethylene and propylene polymerization catalyzed by homogeneous metallocene were investigated using 2-thiophenecarbonyl chloride followed by quenched-flow methods. The studied metallocene catalysts are: rac-Me2Si(2-Me-4-Ph-Ind)2ZrCl2 (Mt-I), rac-Et(Ind)2ZrCl2 (Mt-II) activated with ([Me2NPh][B(C6F5)4] (Borate-I), [Ph3C][B(C6F5)4] (Borate-II), and were co-catalyzed with different molar ratios of alkylaluminum such as triethylaluminium (TEA) and triisobutylaluminium (TIBA). The change in molecular weight, molecular weight distribution, microstructure and thermal properties of the synthesized polymer are discussed in detail. Interestingly, both Mt-I and Mt-II showed high activity in polyethylene with productivities between 3.17 × 106 g/molMt·h to 5.06 × 106 g/molMt·h, activities were very close to each other with 100% TIBA, but Mt-II/borate-II became more active when TEA was more than 50% in cocatalyst. Similarly, Polypropylene showed the highest activity of 11.07 106 g /molMt·h with Mt-I/Borate-I/TIBA. The effects of alkylaluminum on PE molecular weight were much more complicated; MWD curve changed from mono-modal in Mt-I/borate-I/TIBA to bimodal type when TIBA was replaced by different amounts of TEA. In PE, the active center fractions [C*]/[Zr] of Mt-I/borate were higher than that of Mt-II/borate and average chain propagation rate constant (kp) value slightly decreased with the increase of TEA/TIBA ratio, but the Mt-II/borate systems showed higher kp 1007 kp (L/mol·s). In PP, the Mt-I/borate presented much higher [C*]/[Zr] and kp value than the Mt-II. This work also extend to investigate the mechanistic features of zirconocenes catalyzed olefin polymerizations that addressed the largely unknown issues in zirconocenes in the distribution of the catalyst, between species involved in polymer chain growth and dormant state. In both metallocene systems, chain transfer with alkylaluminum is the dominant way of chain termination. To understand the mechanism of cocatalyst effects on PE Mw and (MWD), the unsaturated chain ends formed via β-H transfer have been investigated by 1H NMR analysis.

show abstract

Section: Introductionmentioning

confidence: 99%

Kinetic and Thermal Study of Ethylene and Propylene Homo Polymerization Catalyzed by ansa-Zirconocene Activated with Alkylaluminum/Borate: Effects of Alkylaluminum on Polymerization Kinetics and Polymer Structure

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Among the catalysts, Ti group metallocene complexes showed high efficiency in alkene di-, oligo-, and polymerization [ 9 , 10 , 11 , 12 ]. In this way, the process of zirconocene-catalyzed dimerization of terminal alkenes to give products with a vinylidene moiety >C=CH 2 is well-known ( Scheme 1 ) [ 5 , 6 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ].…”

Section: Introductionmentioning

confidence: 99%

Ti Group Metallocene-Catalyzed Synthesis of 1-Hexene Dimers and Tetramers

et al. 2021

View full text Add to dashboard Cite

1-Hexene transformations in the catalytic systems L2MCl2–XAlBui2 (L = Cp, M = Ti, Zr, Hf; L = Ind, rac-H4C2[THInd]2, M = Zr; X = H, Bu i) and [Cp2ZrH2]2-ClAlR2 activated by MMAO-12, B(C6F5)3, or (Ph3C)[B(C6F5)4] in chlorinated solvents (CH2Cl2, CHCl3, o-Cl2C6H4, ClCH2CH2Cl) were studied. The systems [Cp2ZrH2]2-MMAO-12, [Cp2ZrH2]2-ClAlBui2-MMAO-12, or Cp2ZrCl2-HAlBui2-MMAO-12 (B(C6F5)3) in CH2Cl2 showed the highest activity and selectivity towards the formation of vinylidene head-to-tail alkene dimers. The use of chloroform as a solvent provides further in situ dimer dimerization to give a tetramer yield of up to 89%. A study of the reaction of [Cp2ZrH2]2 or Cp2ZrCl2 with organoaluminum compounds and MMAO-12 by NMR spectroscopy confirmed the formation of Zr,Zr-hydride clusters as key intermediates of the alkene dimerization. The probable structure of the Zr,Zr-hydride clusters and ways of their generation in the catalytic systems were analyzed using a quantum chemical approach (DFT).

show abstract

“…It was identified that at the trimer level, orbital energies well correlated with experimental results 16 . An extensive theoretical analysis of the free‐radical copolymerization of maleic anhydride with α‐olefins was performed by DFT 17 . The copolymerization reaction mechanism between cyclic ketene acetals and traditional vinyl monomers was studied with DFT 18 .…”

Section: Introductionmentioning

confidence: 74%

Computational mechanistic studies on persulfate assisted p‐phenylenediamine polymerization

2022

View full text Add to dashboard Cite

p‐Phenylenediamine (p‐PDA) is a monomer of many important polymers such as kevlar, twaron, poly‐p‐PDA. Most of the noticed polymers formation is initiated by a free‐radical, but their polymerization mechanism is not elucidated computationally. The proposed study helps to fully understand the frequently utilized initiator/oxidant, potassium persulfate (K2S2O8) role in the aromatic diamines polymerization, which support experimental protocols, and a polymer scope. The formation of the poly‐p‐PDA is studied with the density functional theory (DFT) B3LYP‐D3 functional using experimental polymerization parameters (0°C and aqueous media). K2S2O8 initiated free‐radical polymerization of p‐PDA is studied in detail, taking into account sulfate free‐radical (SO4−)·, SFR, persulfate anion (S2O8)2−, PA and K2S2O8 cluster, PP. The reaction mechanism is calculated as the conversion of p‐PDA to free‐radical, the p‐PDA free‐radical attack to the next p‐PDA (dimerization), ammonia extrusion from the dimer adduct, the dimer adduct conversion to the free‐radical (completion of p‐PDA polymerization cycle) for the polymer chain elongation. Calculations show that the dimerization step is the rate‐limiting step with a 29.2 kcal/mol energy barrier when SFR initiates polymerization. In contrast, the PA‐assisted dimerization energy barrier is only 12.7 kcal/mol. PP supported polymerization is calculated to have very shallow energy barriers completing the polymerization cycle, i.e., dimerization (TS2K, ∆G‡ = 11.6 kcal/mol) and ammonia extrusion (TS3K, ∆G‡ = 6.7 kcal/mol).

show abstract

Experimental and Theoretical Study of Zirconocene-Catalyzed Oligomerization of 1-Octene

Cited by 14 publications

References 87 publications

Kinetic and Thermal Study of Ethylene and Propylene Homo Polymerization Catalyzed by ansa-Zirconocene Activated with Alkylaluminum/Borate: Effects of Alkylaluminum on Polymerization Kinetics and Polymer Structure

Kinetic and Thermal Study of Ethylene and Propylene Homo Polymerization Catalyzed by ansa-Zirconocene Activated with Alkylaluminum/Borate: Effects of Alkylaluminum on Polymerization Kinetics and Polymer Structure

Ti Group Metallocene-Catalyzed Synthesis of 1-Hexene Dimers and Tetramers

Computational mechanistic studies on persulfate assisted p‐phenylenediamine polymerization

Contact Info

Product

Resources

About