Cis-1,4-Polymerization of Isoprene by 1,3-Bis(oxazolinymethylidene)isoindoline-Ligated Rare-Earth Metal Dialkyl Complexes

Yu, Chao; Zhou, Dahai; Yan, Xiangqian; Gao, Fei; Zhang, Li; Zhang, Shaowen; Li, Xiaofang

doi:10.3390/polym9100531

Cited by 15 publications

(8 citation statements)

References 47 publications

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“…With borate activator B(C 6 F 5 ) 3 , highly active (up to 4700 kg mol −1 h −1 ) and selective catalysts are obtained with both neodymium and yttrium metals, leading up to 96% cis-1,4-polyisoprene. A series of novel chiral non-metallocene pincer-type rareearth metal dialkyl complexes bearing the chiral monoanionic tridentate C2-symmetric 1,3-bis(oxazolinymethylidene)isoindoline (BOXMI-H) ligand, (BOXMI)Ln(CH 2 SiMe 3 ) 2 (Ln = Sc, Lu, Y), in the presence of a cocatalyst such as borate and AlR 3 , exhibited high activities [up to 6.8 × 10 4 g of polymer)/(mol Ln h)] and high cis-1,4 selectivities (up to 97%) in the polymerization of isoprene, yielding cis-1,4polyisoprenes with heavy molecular weights (M n of up to 710.000 g/mol) and bimodal molecular weight distributions (M w /M n = 2.0−4.5) 222 (Figure 57).…”

Section: Catalysts Based On Transition Metal and Lanthanide Complexes...mentioning

confidence: 99%

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Dienes Polymerization: Where We Are and What Lies Ahead

Ricci¹,

Pampaloni

Sommazzi

et al. 2021

Macromolecules

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Recently, the research activity in the field of the stereospecific polymerization of conjugated dienes has focused on the use of catalysts based on organometallic complexes having a well-defined structure and containing ligands of various types (e.g., phosphines, bis-imines, and pyridylimines), since it has been observed that the nature of the ligand, as expected on the basis of the diene polymerization mechanism proposed several years ago by Porri, is able to exert a strong influence on the polymerization regioand stereoselectivity, on the polymer molecular weights and their distribution, and in some cases to impart a living feature to the catalysts themselves. In this Perspective we highlight the most recent results obtained in this field and discuss possible future developments in this area.

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Section: Catalysts Based On Transition Metal and Lanthanide Complexes...mentioning

confidence: 99%

“…Figure 57. BOXMI-H-ligated rare-earth metal dialkyl complexes (BOXMI-H = 1,3-bis(oxazolinymethylidene)isoindoline) 222. …”

mentioning

confidence: 99%

Dienes Polymerization: Where We Are and What Lies Ahead

Ricci¹,

Pampaloni

Sommazzi

et al. 2021

Macromolecules

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“…40 On the other hand, the 1,3bis(oxazolinymethylidene) isoindoline-ligated rare-earth metal complexes could initiate isoprene polymerization with cis-1,4selectivity (Figure 1e). 41 Unsymmetrical diarylamido-oxazoline-based rare-earth alkyl complexes were developed for isoprene polymerization, and the type of central metal was found to play a decisive role in the stereoregularity of the polyisoprene (Figure 1f). 42 We have also been interested in the synthesis of new rare-earth metal complexes containing oxazoline-based ligands and the exploration of their reactivity and catalytic performance in polymerization.…”

Section: ■ Introductionmentioning

confidence: 99%

“… For example, bis(oxazolinato) Y and La complexes could initiate the ROP of rac -LA and rac -β-butyrolactone ( rac -BBL) with good activity and catalyze the intramolecular hydroamination of aminoalkenes with good stereoselectivity (Figure a,b). , The tris(oxazolinyl)ethane-ligated Sc and Tm alkyl complexes could catalyze 1-hexene polymerization with high activity and isotacticity upon activation with 2 equiv of borate (Figure c). − Cationic Sc and Lu alkyl species bearing a chiral ( S , S )-bis(oxazolinylphenyl)amido ligand exhibited high activities and trans -1,4-selectivity in quasi-living polymerization of isoprene (Figure d) . On the other hand, the 1,3-bis(oxazolinymethylidene) isoindoline-ligated rare-earth metal complexes could initiate isoprene polymerization with cis -1,4-selectivity (Figure e) . Unsymmetrical diarylamido-oxazoline-based rare-earth alkyl complexes were developed for isoprene polymerization, and the type of central metal was found to play a decisive role in the stereoregularity of the polyisoprene (Figure f) .…”

Section: Introductionmentioning

confidence: 99%

Flexible Coordination of the Bis(amino-oxazoline) Ligand in Rare-Earth Metal Complexes: Synthesis, Structure, and Their Reactivity and Polymerization Performance

et al. 2022

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Mononuclear rare-earth metal alkyl complexes supported by tetradentate dianionic bis(amino-oxazoline) ligands have been synthesized, and their reactivity toward small molecules and catalytic performance on ring-opening polymerization have been studied. Treatment of Ln(CH2SiMe3)3(THF)2 (Ln = Sc, Y; THF = tetrahydrofuran) with the bis(amino-oxazoline) proligand H2L afforded the corresponding rare-earth metal monoalkyl complexes L-Ln(CH2SiMe3)(THF) x (Ln = Sc, x = 0 (1); Ln = Y, x = 1 (2)). The isopropyl-substituted Sc alkyl complex L′-Sc(CH2SiMe3) (3) and the analogue Y silylamide complex L-Y[N(SiHMe2)2] (4) have been prepared by a similar method. Complexes 1 and 2 were stable in solution at room temperature but transformed gradually at elevated temperature to give a nucleophilic addition product for Sc (5) and an oxazoline ring-opened dimeric complex for Y (6). Reactions of 1 with elemental sulfur and selenium each led to insertion of one chalcogen into the Sc-C bond, and the corresponding six-coordinate mononuclear chalcogenolate complexes L-Sc(ECH2SiMe3)(THF) (E = S (7), Se (8)) were isolated. Treatment of 1 with an equimolar amount of aniline yielded the Sc anilide complex L-Sc(NHC6H5) (9), whereas the reaction of 1 with [NHEt3][BPh4] afforded the Sc ion-pair [L-Sc][BPh4] (10), which upon recrystallization led to formation of a THF-solvated product [L-Sc(THF)][BPh4] (11). Single-crystal X-ray diffraction analyses of complexes 1–3, 7–9, and 11 revealed the flexible coordination capability of the tetradentate bis(amino-oxazoline) ligand of upholding a mononuclear metal center via a torsion of the diaminobiphenyl axis. Complexes 1–4 were active catalysts for initiating the ring-opening polymerization of rac-lactide with good activity (TOF up to 3204 h–1) and heteroselectivity (P r = 0.65–0.71). This study highlights the applicability of the well-defined tetradentate bis(amino-oxazoline) ligands for mononuclear rare-earth metal complexation and shed light on the new potential of rare-earth metal catalysts bearing this type of easily derivatizable polydentate ligand.

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“…The method for increasing the surface activity of polyisoprene has been confirmed by covalently grafting the ammonium group, for example, from the amine precursor to each oligomer. 6 Yu et al 7 have developed an extremely efficient polymerization reaction of isoprene to the cis-1,4 form through the formation of non-metallocene dialkyl complexes of rare earth metals. Modification of isoprene units was carried out in a butyl copolymer of isobutylene and IRs, nitrilesyntactically functional by grafting with maleic anhydride or styrene 8 The resulting copolymer served as a compatibilizer and modifier of polyamide synthetic materials, which in turn showed, for example, a significant increase in impact resistance.…”

Section: Introductionmentioning

confidence: 99%

Effect of modified keratin from renewable sources on composites properties of synthetic isoprene rubber

Prochoń

2019

Journal of Elastomers & Plastics

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The present conducted research focused on elastomeric materials containing reinforcing modified keratin fibers in their composition. The applied keratin was modified by solvolysis reaction to obtain the product in the form of a hydrolysate. Then, the hydrolysate was modified by the addition reaction of keratin adduct with a plasticizer—technical stearin is commonly used in processing elastomers. The keratin hydrolysate adducts were used in a different weight proportion in the composites in which the carrier was isoprene rubber (IR; Cariflex 305). The obtained composites (rubber Cariflex composites (RC)) were subjected to a series of tests aimed at understanding the structure and interactions between biopolymers and other components of elastomeric mixtures. Mechanical properties, including hardness, the cross-linking density, and thermo-oxidative aging were investigated. Microbiological tests were carried out, which in turn allowed to determine the effect of introduced keratin in a modified hybrid form, to the elastomeric matrix. The test results indicate a significant improvement of some properties, especially when using 10 parts by weight of keratin adducts introduced into 100 parts by weight of IR rubber.

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Cis-1,4-Polymerization of Isoprene by 1,3-Bis(oxazolinymethylidene)isoindoline-Ligated Rare-Earth Metal Dialkyl Complexes

Cited by 15 publications

References 47 publications

Dienes Polymerization: Where We Are and What Lies Ahead

Dienes Polymerization: Where We Are and What Lies Ahead

Flexible Coordination of the Bis(amino-oxazoline) Ligand in Rare-Earth Metal Complexes: Synthesis, Structure, and Their Reactivity and Polymerization Performance

Effect of modified keratin from renewable sources on composites properties of synthetic isoprene rubber

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