Methylalumoxane – History, Production, Properties, and Applications

Zijlstra, Harmen S.; Harder, Sjoerd

doi:10.1002/ejic.201402978

Cited by 131 publications

(118 citation statements)

References 211 publications

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“…In our catalytic system, MAO is most expensive and takes the majority of the cost, which is another major restriction for its commercialization . Thus, the yield of α‐olefins relative to unit mass of MAO is of great significance.…”

Section: Resultsmentioning

confidence: 99%

Tuning Bis(imino)pyridyl Iron‐Catalyzed Ethylene Oligomerization by Modification of MAO with p‐BrPhOH

Zhang

Jiang

et al. 2018

Macro Reaction Engineering

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To reduce the simultaneous production of insoluble polymers during the bis(imino)pyridyl iron‐catalyzed ethylene oligomerization, in this study, p‐BrPhOH (4‐bromophenol) has been chosen as the most optimal modifier for the production of linear α‐olefins. It is found that the polymer share in the total products is largely reduced with the use of p‐BrPhOH as the modifier. The catalytic system also possesses a high activity with the liquid production maintained high level of linearity. Moreover, the introduction of p‐BrPhOH promoted the high‐temperature stability of the catalytic system, leading to the enhanced oligomerization activity as the catalytic system can catalyze ethylene oligomerization at higher temperatures. A characterization of the catalytic system with electron paramagnetic resonance shows that introduction of p‐BrPhOH significantly inhibits the formation of ferric ions, which can be the main active centers responsible for generating undesired insoluble polymers, thus this can largely retard the production of insoluble polymers during ethylene oligomerization.

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Section: Resultsmentioning

confidence: 99%

Tuning Bis(imino)pyridyl Iron‐Catalyzed Ethylene Oligomerization by Modification of MAO with p‐BrPhOH

Zhang

Jiang

et al. 2018

Macro Reaction Engineering

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“…Technologically, aluminium oxides and the related alumoxanes (e.g. methylalumoxane, MAO, [MeAlO] n ), have attracted significant interest due to their ability to act as catalysts and/or co‐catalysts in a range of reactions, including the polymerisation of aldehydes, epoxides and alkenes . Binary aluminium oxides are also active catalysts in a number of industrial transformations, including the Claus process, which converts H 2 S into elemental sulphur, while alumina is widely exploited as a heterogeneous catalyst support.…”

Section: Figurementioning

confidence: 99%

Trapping and Reactivity of a Molecular Aluminium Oxide Ion

et al. 2019

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Aluminium oxides constitute an important class of inorganic compound that are widely exploited in the chemical industry as catalysts and catalyst supports. Due to the tendency for such systems to aggregate via Al‐O‐Al bridges, the synthesis of well‐defined, soluble, molecular models for these materials is challenging. Here we show that reactions of the potassium aluminyl complex K2[(NON)Al]2 (NON=4,5‐bis(2,6‐diiso‐propylanilido)‐2,7‐di‐tert‐butyl‐9,9‐dimethylxanthene) with CO2, PhNCO and N2O all proceed via a common aluminium oxide intermediate. This highly reactive species can be trapped by coordination of a THF molecule as the anionic oxide complex [(NON)AlO(THF)]−, which features discrete Al−O bonds and dimerizes in the solid state via weak O⋅⋅⋅K interactions. This species reacts with a range of small molecules including N2O (to give a hyponitrite ([N2O2]2−) complex) and H2, the latter offering an unequivocal example of heterolytic E−H bond cleavage across a main group M−O bond.

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“…[10][11][12] Owing to its capability to fulfil multiple functions, methylalumoxane (MAO) is the most widely used cocatalyst (Scheme 1). [13][14][15][16][17] It functions as a methylating agent, a methyl group abstractor, a stabilizer for the cation, and it also scavenges impurities that are fatal for catalytic activity (e.g. water).…”

Section: Introductionmentioning

confidence: 99%

Oxide‐Bridged Heterobimetallic Aluminum/Zirconium Catalysts for Ethylene Polymerization

2015

Self Cite

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Protein‐based pharmaceuticals typically display high selectivity and low toxicity, but are also characterized by low oral availability, mainly because of enzymatic degradation in the gastrointestinal tract and poor permeability across the intestinal wall. One way to increase the proteolytic stability of peptides and proteins is by intramolecular crosslinking, such as the introduction of disulfide bridges. However, disulfide bridges are at risk of thiol‐disulfide exchange or reduction during production, purification, and/or therapeutic use, whereas thioether bridges are expected to be stable under the same conditions. In this study, thioether crosslinking was investigated for a 46 aa albumin‐binding domain (ABD) derived from streptococcal protein G. ABD binds with high affinity to human serum albumin (HSA) and has been proposed as a fusion partner to increase the in vivo half‐lives of therapeutic proteins. In the study, five ABD variants with single or double intramolecular thioether bridges were designed and synthesized. The binding affinity, secondary structure, and thermal stability of each protein was investigated by SPR‐based biosensor analysis and CD spectroscopy. The proteolytic stability in the presence of the major intestinal proteases pepsin (found in the stomach) and trypsin in combination with chymotrypsin (found in pancreatin secreted to the duodenum by the pancreas) was also investigated. The most promising crosslinked variant, ABD_CL1, showed high thermal stability, retained high affinity in binding to HSA, and showed dramatically increased stability in the presence of pepsin and trypsin/chymotrypsin, compared to the ABD reference protein. This suggests that the intramolecular thioether crosslinking strategy can be used to increase the stability towards gastrointestinal enzymes.

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Methylalumoxane – History, Production, Properties, and Applications

Cited by 131 publications

References 211 publications

Tuning Bis(imino)pyridyl Iron‐Catalyzed Ethylene Oligomerization by Modification of MAO with p‐BrPhOH

Tuning Bis(imino)pyridyl Iron‐Catalyzed Ethylene Oligomerization by Modification of MAO with p‐BrPhOH

Trapping and Reactivity of a Molecular Aluminium Oxide Ion

Oxide‐Bridged Heterobimetallic Aluminum/Zirconium Catalysts for Ethylene Polymerization

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