Investigation of the individual stages of 2-alkylbutadiene polymerization with bis-(π-crotylnickel iodide)—I

Druz, N.N.; Zak, Alla; Lobach, M. I.; Vasiliev, V. A.; Kormer, V. A.

doi:10.1016/0014-3057(77)90059-3

Cited by 19 publications

(5 citation statements)

References 13 publications

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“…Thus, our results agree with the general finding that homopolymerization of isoprene by transition metal catalysts is, in similar conditions, slower than that of butadiene. That is indeed the behavior observed in the presence of other catalytic systems, such as TiI 4 Al(alkyl) 3 , VCl 3 −Al(alkyl) 3 , ((C 4 H 7 )NiI) 2 , and Co(acac) 2 −Al(alkyl) 3 . To our knowledge, there is only one catalyst, (CoI−Al 2 OC 2 H 5 ), in the presence of which isoprene homopolymerization is faster than that for butadiene.…”

Section: Discussionsupporting

confidence: 74%

“…A general open question concerns the chemical and physical factors that determine the observed chemo- and stereoselectivity of the propagation reaction, but there are also many other puzzling results whose explanation could be of interest, because they could provide guidelines for a deeper understanding of the polymerization mechanism. To cite just a few, there is the case of the highly selective polymerization of pentadiene with CpTiCl 3 activated by MAO, which gives the cis 1,4 polymer at room temperature, with a relatively low rate, and the 1,2 syndiotactic polymer with higher rate at −20 °C, and the case of the very different homopolymerization rates of butadiene and isoprene, a peculiarity of many homogeneous organometallic catalysts, − particularly of CpTiCl 3 −MAO, in the presence of which the homopolymerization rates differ by 2−3 orders of magnitude, despite the fact that in copolymerizations the two monomers exhibit almost the same reactivity …”

Section: Introductionmentioning

confidence: 99%

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Polymerization Mechanism of Conjugated Dienes in the Presence of Ziegler−Natta Type Catalysts: Theoretical Study of Butadiene and Isoprene Polymerization with CpTiCl₃−MAO Initiator

2000

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The mechanism of butadiene and isoprene polymerization in the presence of CpTiCl 3 -MAO has been investigated by means of ab initio computations. According to experimental evidence, the catalytically active species are assumed to be [CpTi-P] + organotitanium cations (P ) growing polymer chain). The results show that (i) in the active species, P is coordinated to Ti both with the π allyl group of its ending unit and with the π bond of the penultimate unit; (ii) the cis η 4 coordination of an incoming monomer to the active species requires the breakage of the latter interaction and the change of the allyl coordination mode from η 3 to η 1 . That significant rearrangement of P is predicted to be the rate-determining step of the whole propagation reaction and is predicted to be much easier when the ending unit of P is butenyl rather than 2-methylbutenyl. That finding accounts both for the large difference observed in the homopolymerization rates of butadiene and isoprene and for the fact that in copolymerizations the two monomers exhibit almost the same reactivity.

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Section: Discussionsupporting

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Polymerization Mechanism of Conjugated Dienes in the Presence of Ziegler−Natta Type Catalysts: Theoretical Study of Butadiene and Isoprene Polymerization with CpTiCl₃−MAO Initiator

2000

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“…Determined by quantitative 13 C NMR analysis, the polyisoprene with cis ‐1,4 enchainment of 94.7 % is achievable (entry 6). Because as the polymer volume decreases the anti‐syn isomerization is blocked and cis ‐1,4‐contents are increased [30,31] . The cis ‐1,4 content increased with increasing M n of the resulting polymers, as shown in Table 1.…”

Section: Resultsmentioning

confidence: 89%

Synthesis of α,ω‐End Functionalized Polydienes: Allylic‐Bearing Heteroleptic Aluminums for Selective Alkylation and Transalkylation in Coordinative Chain Transfer Polymerization

Liu,

Yang,

et al. 2023

Angewandte Chemie

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There are still challenges in the preparation of difunctional stereoregular polydienes, especially for the construction of initiating chain‐end functionalization. Coordinative chain transfer polymerization (CCTP) provides a way to achieve the goal but usually requires sophisticated functionalized catalysts as well as expensive chain transfer agents (CTAs). In this work, heteroleptic aluminum with oligo(dienyl) substituents (oligo‐Al agents) were readily prepared by living anionic polymerization (LAP) technique. The oligo‐Al agents used in Nd‐mediated CCTPs of dienes exhibit highly selective alkylation and transalkylation features. Kinetics and transfer efficiency studies using 1H NMR, 13C NMR, 1H‐13C HSQC, and Dosy NMR analyses revealed that the resulting polydienes possess substituents at the initiating chain‐end that have transferred from the oligo‐Al agents. The functionalization efficiency of the initiating chain‐end is up to 99 %, and the molar mass regulation efficiency of heteroleptic aluminum is higher than that of the traditional CTA AliBu2H (0.608 vs. 0.410). Based on the experimental results and density functional theory (DFT) calculations, we propose a mechanism in which allylic‐Al acts as an efficient alkylating moiety in catalyst preformation and also as an effective transfer agent in polymerization. Taking advantage of these features, di‐functionalized polyisoprene, polybutadiene, and poly(isoprene‐co‐butadiene) can be facilely synthesized.

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“…pointed out that the monomer was predominantly inserted by the cis structure with a low steric hindrance to form a syn‐η 3 ‐allyl configuration, which could isomerized to a trans structure with a high thermodynamically stability to form an anti‐η 3 ‐allyl configuration. The active center of syn‐η 3 ‐π‐allyl was quickly formed due to the dynamic control, whereas the anti‐η 3 ‐π‐allyl was more stable due to the thermodynamic control . Moreover, these researchers also showed that syn‐η 3 ‐allyl isomerized to anti‐η 3 ‐allyl more easily when the steric hindrance of active center was higher.…”

Section: Resultsmentioning

confidence: 97%

Effect of electronegativity and steric hindrance of the cocatalyst on the activity and selectivity of butadiene polymerization catalyzed by molybdenum

Liu

Geng

et al. 2018

J of Applied Polymer Sci

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Molybdenum‐based random 1,2‐polybutadiene (1,2‐PB) rubber, with its excellent wet skid resistance, low rolling resistance, and low heat buildup, can be used for green tread rubber, and it has significant benefits for the enhancement of the mechanical strength of 1,2‐PB. In this study, we investigated in detail the effects of the electronegativity and steric hindrance of the cocatalyst on the stereoselectivity of the resulting polymers. In the case of cocatalysts with moderate electronegativities, the active centers were more stable; this resulted in a larger molecular weight and a higher conversion, whereas a cocatalyst with excessive electronegativity tended to initiate cationic polymerization. The high sterically hindered substituent restricted the coordination configuration of the monomer; this ultimately resulted in the increase in the 1,2 structure to 90%. Fourier transform infrared analysis showed that the content of trans‐1,4 structure increased from 7 to 66%, and its crystallinity reached 59.2%, as calculated with differential scanning calorimetry when triethyl aluminum was used as the cocatalyst. Consequently, trans‐1,4‐polybutadiene crystals were introduced into the 1,2‐PB elastomer in one step; this could be a promising facile route for strengthening 1,2‐PB. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46906.

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Investigation of the individual stages of 2-alkylbutadiene polymerization with bis-(π-crotylnickel iodide)—I

Cited by 19 publications

References 13 publications

Polymerization Mechanism of Conjugated Dienes in the Presence of Ziegler−Natta Type Catalysts: Theoretical Study of Butadiene and Isoprene Polymerization with CpTiCl₃−MAO Initiator

Polymerization Mechanism of Conjugated Dienes in the Presence of Ziegler−Natta Type Catalysts: Theoretical Study of Butadiene and Isoprene Polymerization with CpTiCl₃−MAO Initiator

Synthesis of α,ω‐End Functionalized Polydienes: Allylic‐Bearing Heteroleptic Aluminums for Selective Alkylation and Transalkylation in Coordinative Chain Transfer Polymerization

Effect of electronegativity and steric hindrance of the cocatalyst on the activity and selectivity of butadiene polymerization catalyzed by molybdenum

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Investigation of the individual stages of 2-alkylbutadiene polymerization with bis-(π-crotylnickel iodide)—I

Cited by 19 publications

References 13 publications

Polymerization Mechanism of Conjugated Dienes in the Presence of Ziegler−Natta Type Catalysts: Theoretical Study of Butadiene and Isoprene Polymerization with CpTiCl3−MAO Initiator

Polymerization Mechanism of Conjugated Dienes in the Presence of Ziegler−Natta Type Catalysts: Theoretical Study of Butadiene and Isoprene Polymerization with CpTiCl3−MAO Initiator

Synthesis of α,ω‐End Functionalized Polydienes: Allylic‐Bearing Heteroleptic Aluminums for Selective Alkylation and Transalkylation in Coordinative Chain Transfer Polymerization

Effect of electronegativity and steric hindrance of the cocatalyst on the activity and selectivity of butadiene polymerization catalyzed by molybdenum

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Polymerization Mechanism of Conjugated Dienes in the Presence of Ziegler−Natta Type Catalysts: Theoretical Study of Butadiene and Isoprene Polymerization with CpTiCl₃−MAO Initiator

Polymerization Mechanism of Conjugated Dienes in the Presence of Ziegler−Natta Type Catalysts: Theoretical Study of Butadiene and Isoprene Polymerization with CpTiCl₃−MAO Initiator