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218. Ring size enlargement in an ortho‐cycloalkyl‐substituted bis(imino)pyridine‐cobalt ethylene polymerization catalyst and its impact on performance and polymer properties.

Author

Han, Mingyang, Oleynik, Ivan I., Liu, Ming, Ma, Yanping, Oleynik, Irina V., Solan, Gregory A., Liang, Tongling, and Sun, Wen‐Hua

Subjects
POLYMERIZATION, CATALYSTS, POLYMERS, ETHYLENE, ALKENES, MOLECULAR weights, POLYETHYLENE
Abstract

Four unsymmetrical examples of bis(arylimino)pyridines that each possess an ortho‐cycloalkyl substituent of unique ring size, 2‐{CMeN(2,4,6‐Me3C6H2)}‐6‐{CMeN(2,4‐(CHPh2)2‐6‐RC6H2)}C5H3N (R = cyclopentyl L1, cyclohexyl L2, cyclooctyl L3, cyclododecyl L4), have been prepared and employed as reactants in the formation of the corresponding cobaltous chloride complexes, (N,N,N′)CoCl2 (Co1–Co4). Structural characterization of Co2 and Co3 spotlights the five‐coordinate geometry and the steric disparity imposed on the metal center by the inequivalent N‐mesityl and N‐2,4‐dibenzyhydryl‐6‐cycloalkylphenyl groups. Co1–Co4 all proved productive precatalysts for ethylene polymerization achieving optimal performance at a temperature of 60°C on activation with either MAO or MMAO. Cyclopentyl‐containing Co1 displayed the highest level (up to 10.3 × 106 g PE per mol [Co] per h), whereas its cyclododecyl counterpart Co4 the lowest (down to 0.14 × 106 g PE per mol [Co] per h). Strictly linear polyethylenes were produced with molecular weights spanning the range 22.0–36.0 kg per mol for Co1–Co4/MAO and 22.6–33.6 kg per mol for Co1–Co4/MMAO, with cyclohexyl Co2 producing the highest values with either activator. With the exception of the polymer produced using Co4, all catalysts afforded narrow unimodal distributions (Mw/Mn range: 1.7–2.2) for the polyethylenes in line with single site active species. By contrast, Co4 bearing the largest and conformationally flexible cycloalkyl group formed polyethylenes that were distinctly bimodal, which would imply the presence of two active species. End‐group analysis of lower molecular weight polymer samples identified vinyl groups congruent with a termination step involving β‐H elimination. [ABSTRACT FROM AUTHOR]

Published
2022
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219. Fluorinated bis(arylimino)‐6,7‐dihydro‐5H‐quinoline‐cobalt polymerization catalysts: Electronic versus steric modulation in the formation of vinyl‐terminated linear PE waxes.

Author

Zuo, Zheng, Han, Mingyang, Ma, Yanping, Solan, Gregory A., Hu, Xinquan, Liang, Tongling, and Sun, Wen‐Hua

Subjects
POLYMERIZATION, WAXES, MOLECULAR weights, CATALYSTS, COBALT chloride, POLYMERS, COBALT catalysts, VINYL polymers
Abstract

Condensation of 2‐benzoyl‐6,7‐dihydro‐5H‐quinolin‐8‐one with an excess of the respective fluorinated aniline in the presence of cobalt (II) chloride has provided an effective one‐flask synthesis of the 2‐(phenyl(arylimino)methyl)‐8‐arylimino‐6,7‐dihydro‐5H‐quinoline‐cobalt (II) chloride complexes, [2‐(ArN=CPh)‐8‐(NAr)‐C9H9N]CoCl2 (Ar = 2‐Me‐4,6‐(CH(p‐FC6H4)2)2C6H2Co1, 2,6‐Me2‐4‐(CH(p‐FC6H4)2)C6H2Co2, 2,4‐Me2‐6‐(CH(p‐FC6H4)2)C6H2Co3, 2‐Et‐4,6‐(CH(p‐FC6H4)2)2C6H2Co4, 2‐i‐Pr‐4,6‐(CH(p‐FC6H4)2)2C6H2Co5, 2‐F‐4,6‐(CH(p‐FC6H4)2)2C6H2Co6). Structural characterization of Co2 and Co4 revealed the unsymmetrical nature of the N,N,N‐chelating ligands and the five‐coordinate geometries around the metal ions. Complexes Co1–Co6 all exhibited high activities as precatalysts for ethylene polymerization when treated with either MAO or MMAO producing highly linear (Tm′s > 118°C) low molecular weight polyethylene (Mw range: 0.69–31.51 kg mol−1) with a variety of dispersities (Mw/Mn range: 2.2–17.5). 2,6‐Dimethyl‐containing Co2 was the most productive precatalyst of the series reaching an exceptionally high activity of 27.06 × 106 g (PE) mol−1 (Co) h−1 at a temperature of 50°C. Additionally, ortho‐fluoride Co6 maintained an impressive level of activity at an operating temperature of 70°C and was able to maintain a long catalytic lifetime. Furthermore, the presence of vinyl end groups (–CH=CH2) in the 1H/13C NMR and IR spectra of their polymers supports the key role played by β‐H elimination in chain transfer. [ABSTRACT FROM AUTHOR]

Published
2022
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227. 6-Arylimino-2-(2-(1-phenylethyl)naphthalen-1-yl)-iminopyridylmetal (Fe and Co) Complexes as Highly Active Precatalysts for Ethylene Polymerization: Influence of Metal and/or Substituents on the Active, Thermostable Performance of Their Complexes and Resultant Polyethylenes

Author

Lin, Wenhua, primary, Zhang, Liping, additional, Gao, Jiahao, additional, Zhang, Qiuyue, additional, Ma, Yanping, additional, Liu, Hua, additional, and Sun, Wen-Hua, additional

Published
2020
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235. Alkyl substituents triggered an unexpected formation of mono‐and dinuclear zirconium hydrazonate complexes: synthesis, characterization and their catalytic behavior toward ethylene polymerization

Author

Duan, Xin‐E, primary, Yuan, Bo, additional, Li, Rui, additional, Vignesh, Arumugam, additional, Bariashir, Chantsalnyam, additional, Li, Zilong, additional, Bai, Sheng‐Di, additional, Ma, Yanping, additional, Chao, Jian‐Bin, additional, Tong, Hong‐Bo, additional, and Sun, Wen‐Hua, additional

Published
2020
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