Das Mülheimer Normaldruck‐Polyäthylen‐Verfahren

Ziegler, E.; Holzkamp, Erhard; Breil, H.; Martin, H.

doi:10.1002/ange.19550671902

Cited by 797 publications

(347 citation statements)

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“…Instead, the formation of 1-butene due to chain cleavage after one olefin insertion was detected. 238 A systematic search for the reasons of the unexpected but highly useful reactivity revealed that traces of nickel were responsible and the term "nickel effect" was coined. This observation led to the foundations of Ziegler catalysts 239 and set the basis for a revolution in different areas of chemistry and, in particular, in organonickel chemistry.…”

Section: Tm-ch3 As Intermediates In Catalysismentioning

confidence: 99%

Methyl Complexes of the Transition Metals

Campos

López‐Serrano

Peloso

et al. 2016

Chemistry A European J

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Organometallic chemistry can be considered as a wide area of knowledge that combines concepts of classic organic chemistry, i.e. based essentially on carbon, with molecular inorganic chemistry, especially with coordination compounds. Transition metal methyl complexes probably represent the simplest and most fundamental way to view how these two major areas of chemistry combine and merge into novel species with intriguing features in terms of reactivity, structure, and bonding. Citing more than 500 bibliographic references, this review aims to offer a concise view of recent advances in the field of transition metal complexes containing M-CH3 fragments. Taking into account the impressive amount of data that are continuously provided by organometallic chemists in this area, this review is mainly focused on results of the last 5 years. After a panoramic overview on M-CH3 compounds of groups 3 to 11 which includes the most recent landmark findings in this area, two further sections are dedicated to methyl-bridged complexes and reactivity.

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Section: Tm-ch3 As Intermediates In Catalysismentioning

confidence: 99%

Methyl Complexes of the Transition Metals

Campos

López‐Serrano

Peloso

et al. 2016

Chemistry A European J

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“…The active catalytic centre originated by both precursors is assumed to be the same (figure 1d) because the polyethylene obtained in the two cases is the same. By analogy with the Cossee-Arlman mechanism (Arlman & Cossee 1964;Cossee 1964), proposed for classical Ziegler-Natta catalysts (Ziegler et al 1955;Natta 1956;Busico et al 1999), as well as for metallocene catalysts (Resconi et al 2000;Kaminsky & Laban 2001), it is arbitrarily assumed that the catalytic centre contains a coordination vacancy (coloured shadow in figure 1d), where the olefin molecule can insert, and a growing hydrocarbon chain. However, the initiation steps leading to the formation of the active centres constituted a matter of debate for many years, and were the subject of many investigations, also by means of surface science methods (Groppo et al 2005b).…”

Section: (B) Mechanism Of Initiation Of Ethylene Polymerizationmentioning

confidence: 99%

Surface chromium single sites: open problems and recent advances

Zecchina

Groppo

2012

Proc. R. Soc. A.

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The results of decades of studies on the Phillips chromium (Cr)/silica polymerization catalyst are briefly summarized. The application of several characterization methods has allowed a detailed knowledge of the structure and reactivity of Cr centres to be obtained. In particular, many aspects of this apparently simple single-site catalyst, including the heterogeneity, the modification of the ligand sphere upon interaction with many molecules and the initiation mechanism of the ethylene polymerization reaction, have been clarified. It is shown that based on the acquired knowledge, it is now possible to proceed further towards the intelligent modification of the ligand sphere with the scope to increase the reaction rate and selectivity. It is also illustrated that, besides polymerization/oligomerization reactions, it is possible to extend the study of Cr II reactivity towards new reactions.

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“…The polyolefin industries began in the 1950s because of discoveries of TiCl 3 catalysts by Ziegler and Natta. [1][2][3][4] However, the catalyst activities and stereospecificities were so low that enormous effort was invested to increase them. In 1968, our discovery of an MgCl 2 -supported TiCl 4 catalyst 5 brought about a breakthrough and led to innovative improvement of the properties of the polyolefins and a drastic cut of the production costs of them.…”

Section: Introductionmentioning

confidence: 99%

The discovery and progress of MgCl₂‐supported TiCl₄ catalysts

Kashiwa

2003

J. Polym. Sci. A Polym. Chem.

166

109

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Polyolefins represented by polyethylene (PE) and polypropylene (PP) are indispensable materials in our daily lives. TiCl 3 catalysts, established by Ziegler and Natta in the 1950s, led to the births of the polyolefin industries. However, the activities and stereospecificities of the TiCl 3 catalysts were so low that steps for removing catalyst residues and low stereoregular PP were needed in the production of PE and PP. Our discovery of MgCl 2 -supported TiCl 4 catalysts led to more than 100 times higher activities and extremely high stereospecificities, which enabled us to dispense with the steps for the removals, meaning the process innovation. Furthermore, they narrowed the molecular weight and composition distributions of PE and PP, enabling us to control the polymer structures precisely and create such new products as very low density PE or heat-sealable film at low temperature. The typical example of the product innovations by the combination of the high stereospecificity and the narrowed composition distribution is highperformance impact copolymer used for an automobile bumper that used to be made of metal. These process and product innovations established these polyolefin industries. The latest MgCl 2 -supported TiCl 4 catalyst is very close to perfect control of isotactic PP structure and is expected to bring about further innovations. Keywords: MgCl 2 -supported TiCl 4 catalysts; polyolefins; stereospecific polymers; copolymerization; polyethylene (PE); poly(propylene) (PP) Dr. Norio Kashiwa is a senior research fellow of Mitsui Chemicals, Inc., who is offering that position only to him. He graduated from Osaka University (Japan) in 1964 and received his masters degree in engineering from the same university in 1966. Then, he joined Mitsui Petrochemical Industries in the same year. He discovered MgCl 2 -supported TiCl 4 catalysts in 1968. It brought about process and product innovations in polyolefin industries, and now those catalysts constitute the majority of global polyolefin production. Since then, he has been in the front line of olefin polymerization catalyst research including not only MgCl 2 -sup-

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Das Mülheimer Normaldruck‐Polyäthylen‐Verfahren

Cited by 797 publications

References 0 publications

Methyl Complexes of the Transition Metals

Methyl Complexes of the Transition Metals

Surface chromium single sites: open problems and recent advances

The discovery and progress of MgCl₂‐supported TiCl₄ catalysts

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Das Mülheimer Normaldruck‐Polyäthylen‐Verfahren

Cited by 797 publications

References 0 publications

Methyl Complexes of the Transition Metals

Methyl Complexes of the Transition Metals

Surface chromium single sites: open problems and recent advances

The discovery and progress of MgCl2‐supported TiCl4 catalysts

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Product

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The discovery and progress of MgCl₂‐supported TiCl₄ catalysts