Kinetik der „polymerisation”︁ von isopren und styrol mit n‐butyllithium als katalysator. VII

Sinn, Von Hansjörg; Lundborg, Claes; Onsager, Olav T.

doi:10.1002/macp.1964.020700116

Cited by 68 publications

(10 citation statements)

References 24 publications

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“…The reaction of lithiumbutyl with isoprene in diethylether produces lithiumnonenyls, which yield after decomposition with water 36 yo 2-methyloctene-(l) and the cis-transisomers of 3-methyloctene- (2) in the ratio 63 : 1.…”

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confidence: 99%

Umlagerungen bei der durch Lithiumbutyl initiierten Polyreaktion der Diene Isopren und Butadien

1971

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ZUSAMMENFASSUNG:Bei der Reaktion von Lithiurnbutyl mit Isopren in Diathylather entstehen Lithiumnonenyle, die bei der Zersetzung mit Wasser 36% 2-Methylocten-(1) und die cis-trans-Isomeren des 3-Methyl-octens-(2) irn Verhaltnis 63 : 1 ergeben. Nach Entfernung des Diathylathers vom Lithiumnonenyl durch Abkondensation nach wiederholterZugabevon n-Heptanwerden dieKohlenwasserstoffe imverhaltnis 26 : 74 gefunden, wghrend nach erneuter Zugabe von Diathylather wieder das Verhaltnis 36 : 64 auftritt. Das Verhaltnis der verschiedenen isomeren Lithiumnonenyle ist vom Losungsmittel abhlngig. Die Isomeren lagern sich reversibel um; auch in Diathylather findet in erheblichem Umfange 1.4-Addition von Isopren an Lithiumbutyl statt. Wahrend bei -1OOC fur die Polyreaktion des Isoprens mit Lithiumbutyl als Initiator die Geschwindigkeitskonstanten ks = 1,6.10-4I/Mol.sec und k, = 1,5.10-2l/Mol.sec gefunden werden, betragen die entsprechenden Werte fur die Polyreaktion des Butadiens k, = 4,5.10-5l/Mol.sec und k , = 2,4.10-3 I/Mol.sec. Das kinetisch erfanbare Assoziationsverhalten von Lithiumpolyisoprenyl wird durch KI = 1,86.10-9 MoP/P und Kg = 2,80.10-21 Mo15/15 beschrieben, wahrend Lithiumpolybutadienyl durch Ks = 2,98.10-9 Mo12/12 und KO = 2,76.:0-20 Mo15/15 beschrieben wird. Die Vermutung, daB primar immer 1.4-Verknupfung erfolgt, deren Produkt dann unter der Wirkung des Initiators isomerisiert, wird gestutzt durch die Zunahme der 1.4-13s-Struktur mit fallender Initiatorkonzentration : 1.4-cis-Struktur Isopren I Butadien 80 % 35 ?' o 95 yo 70% -98 %

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confidence: 99%

Umlagerungen bei der durch Lithiumbutyl initiierten Polyreaktion der Diene Isopren und Butadien

1971

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“…74 The higher the concentration (.1 mmol) of alkyl Li, the greater the increase in the number of associated alkyl Li centers that directly influence the catalytic activity toward polymerization. 75 In this way, O'driscoll and Yonezawa reported sevenfold enhancement (7% to 47%) in the 1,2-polymerization product of 1,3-BD by increased concentration of t-butyl Li. 54 Tapia et al developed high trans-1,4-polybutadiene through anionic polymerization using an initiator system including alkyl aluminum, n-butyl Li, and barium alkoxide.…”

Section: A Lithium Catalystsmentioning

confidence: 96%

Butadiene Rubber: Synthesis, Microstructure, and Role of Catalysts

Kumar

Mohanty

Gupta

2021

Rubber Chemistry and Technology

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Butadiene rubber (BR) is one of the most useful and second most produced rubber worldwide. Polymerization of 1,3-butadiene (BD) is a highly stereospecific reaction that offers a wide variety of BR with different microstructures and influences the fundamental properties of the rubber. Since the first successful polymerization of conjugated diene using the Ziegler–Natta–based catalyst (TiCl4 or TiCl3 with aluminum alkyls) in 1954, the research on producing synthetic rubber with an appropriate catalyst system has been accelerated. Subsequently, various research groups are actively engaged in designing active catalyst systems based on a suitable combination of transition metal complexes with alkyl-aluminum and successfully using them in BD polymerization. Although various scientific inventions have proven their significance for the production of high-quality BR, with the rising demands in improving the quality of the product, research on developing new catalyst systems with enhanced catalytic activity and high stereoselectivity is still in progress. The present review focuses on the synthesis of BR using various transition metal catalysts and discusses their microstructures. The catalysts based on new-generation metal complexes with phosphorus, nitrogen, and oxygen donor ligands (e.g., phosphines, imines, 1,10-phenanthroline, and imino-pyridines) have been introduced. The role that catalysts play in the production of BR with different microstructures (i.e., high-cis, high-trans or low-cis, low-trans polybutadiene) has also been described. The combination of catalyst (transition metal complex) and suitable co-catalyst (alkyl-aluminum) is the major factor influencing the reaction and microstructure of the resulting polymer. This report focuses on the effect of transition metal catalysts (i.e., lithium [Li], titanium [Ti], zirconium [Zr], iron [Fe], cobalt [Co], nickel [Ni], and neodymium [Nd]) on the activity and stereoselectivity of polymers such as 1,4-cis-, 1,4-trans-, and 1,2-vinyl-polybutadiene.

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“…O'Driscoll [ 2 ] reported that only the unassociated alkyl lithium initiator had catalytic activity in non-polar solvent, which might cause the efficiency problem of initiator. Sinn et al [ 3 ] suggested that there was no unassociated alkyl lithium when the concentration of alkyl lithium was more than 10 −3 mol l −1 , which indicated that the associated alkyl lithium was the main active centre under this circumstance. Natta [ 4 ] indicated that 1,2 structure of butadiene polymerized by tert -butyl lithium increased from 7% to 47% when the concentration of tert -butyl lithium concentration increased from 0.005 mol l −1 to 0.5 mol l −1 .…”

Section: Introductionmentioning

confidence: 99%

Utilization of steric hindrance of alkyl lithium-based initiator to synthesize high 1,4 unit-containing hydroxyl- terminated polybutadiene

Min¹,

Fan²,

Liu³

2018

R. Soc. open sci.

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A novel alkyl lithium-based initiator with relatively large steric hindrance, tert-butyldimethylsiloxydimethylpropyl lithium (TBDMSODPrLi), was designed and synthesized. By using TBDMSODPrLi, hydroxyl-terminated polybutadiene (HTPB) was prepared via anionic polymerization. The macromolecular structure of HTPB was characterized and verified by FTIR and 1H-NMR. It was found that 1,4 unit content in HTPB initiated by TBDMSODPrLi was significantly higher (over 90%) compared to a HTPB (1,4 unit content of 70%) initiated with another initiator possessing smaller steric hindrance. The possible mechanism, which was based on initiator steric hindrance affecting monomer chain addition behaviour, was deduced. It was that the initiator's larger steric hindrance blocked lithium's intermolecular association during anionic polymerization; as a result, it could effectively increase the 1,4 unit content in HTPB. To further study how to obtain higher and stable 1,4 unit content, the optimal anionic polymerization technique for HTPB was explored including polymerization temperature, time and the amount of initiator used. The study concluded that utilization of an initiator with larger steric hindrance and reducing the polymerization temperature were two important factors to raise the 1,4 unit content in HTPB.

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Kinetik der „polymerisation”︁ von isopren und styrol mit n‐butyllithium als katalysator. VII

Cited by 68 publications

References 24 publications

Umlagerungen bei der durch Lithiumbutyl initiierten Polyreaktion der Diene Isopren und Butadien

Umlagerungen bei der durch Lithiumbutyl initiierten Polyreaktion der Diene Isopren und Butadien

Butadiene Rubber: Synthesis, Microstructure, and Role of Catalysts

Utilization of steric hindrance of alkyl lithium-based initiator to synthesize high 1,4 unit-containing hydroxyl- terminated polybutadiene

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