An Efficient Titanium Amidinate Catalyzed Version of Ziegler's “Aufbaureaktion”

Obenauf, Johannes; Kretschmer, Winfried P.; Bauer, Tobias; Kempe, Rhett

doi:10.1002/ejic.201201194

Cited by 18 publications

(9 citation statements)

References 59 publications

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“…The linear α olefins or 1-alkene precursors of PAOs are most often derived from ethylene via processes like the Aufbau or SHOP processes. , The source of ethylene is determined by economics. Currently ethylene is derived from nonrenewable resources in the U.S.…”

Section: Resultsmentioning

confidence: 99%

Alternatives for Conventional Alkane Solvents

et al. 2016

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The studies described in this paper show that hydrocarbon oligomers are alternatives for low molecular weight alkane solvents. These oligomeric solvents are nontoxic, nonvolatile, and recyclable alternatives to heptane in thermomorphic solvent mixtures that use a polar solvent such as methanol, aqueous ethanol, or DMF or in biphasic mixtures that use acetonitrile. Regardless of which polar solvent is used, hydrocarbon oligomers like poly(α-olefin)s (PAOs) exhibit very low leaching into the polar phase. UV-visible spectroscopy studies show that these solvents have the solubility properties of heptane. For example, PAOs dissolve heptane soluble dyes and quantitatively separate them from polar phases in thermomorphic solvent mixtures. PAOs either as pure solvents or as additives in heptane act as antileaching agents, decreasing the already low leaching of such dyes into a polar phase in heptane/polar solvent mixtures. These oligomeric hydrocarbon solvents were also compared to heptane in studies of azo dye isomerization. The results show that thermal isomerization of an azo dye occurs at the same rate in heptane and a PAO. Further studies of carboxylic acid promoted dye isomerization in heptane and a PAO show that low molecular weight and oligomeric carboxylic acids are kinetically equivalent at accelerating this isomerization. The results suggest that these and other hydrocarbon oligomers behave as solvents like their low molecular weight nonpolar hydrocarbon solvents and that they can be substituted successfully for conventional solvents like heptane.

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Section: Resultsmentioning

confidence: 99%

Alternatives for Conventional Alkane Solvents

et al. 2016

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“…Gibson and co-workers attribute the exceptional performance of this Fe/Zn dual-site catalyst to the relatively weak Zn–C bonds matching the Fe–C bond strength and the presence of monomeric ZnEt 2 . Unlike Ziegler’s ethylene oligomerization on AlR 3 , known as the “Aufbaureaktion” and which is restricted to ethylene feedstock, catalytic chain-transfer polymerization enables the facile production of a large variety of low and high molecular-weight tailored hydrocarbon materials with precisely controlled molecular architectures by exploiting a large variety of 1-olefin feedstocks. ,,− …”

Section: Homogeneous Multisite Polyolefin Catalysismentioning

confidence: 99%

From Multisite Polymerization Catalysis to Sustainable Materials and All-Polyolefin Composites

Mihan²,

2015

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“…The reduction of the steric bulk of the guanidinato ligand from 2,6‐diisopropylphenyl to 2,6‐dimethylphenyl substituents led to a significant decrease in the activity, especially when high amounts of triethylaluminium were used (Table 3, entries 5–8). A lower steric protection of the guanidinato ligand allows an easier transfer of the ligand towards aluminium 36. It becomes especially relevant at high Al concentrations.…”

Section: Resultsmentioning

confidence: 99%

Efficient Synthesis of Aluminium‐Terminated Polyethylene by Means of Irreversible Coordinative Chain‐Transfer Polymerisation Using a Guanidinatotitanium Catalyst

2014

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A series of guanidinato‐ligand‐stabilised titanium complexes has been synthesised and characterised. These compounds can be prepared by carbodiimide insertion into titanium–amide bonds. Reaction of carbodiimides N,N′‐bis(2,6‐diisopropylphenyl)carbodiimide, N,N′‐bis(2,6‐dimethylphenyl)carbodiimide and N‐tert‐butyl‐N′‐(2,6‐diisopropylphenyl)carbodiimide (2a–2c, respectively) with [(Et2N)TiCl3] led to mono(guanidinato)trichloridotitanium(IV) complexes (3a–3c). Subsequent conversion with methylmagnesium chloride gave the corresponding trimethyl complexes (4a and 4b). Single‐crystal X‐ray diffraction analyses were carried out for all complexes. Compound 4a showed very high activities in the polymerisation of ethylene in the presence of very high amounts of triethylaluminium and undergoes polymeryl chain transfer to aluminium. Irreversible coordinative chain‐transfer polymerisation and a unique combination of catalyst economy and high activity were observed. In the presence of 1000 equivalents of aluminium, a chain elongation of 83.3 % could be achieved with an activity of 9900 kgPE molcat–1 h–1 bar–1. The influence of the steric demand of the ligand on the polymerisation capability is significant and was investigated too.

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An Efficient Titanium Amidinate Catalyzed Version of Ziegler's “Aufbaureaktion”

Cited by 18 publications

References 59 publications

Alternatives for Conventional Alkane Solvents

Alternatives for Conventional Alkane Solvents

From Multisite Polymerization Catalysis to Sustainable Materials and All-Polyolefin Composites

Efficient Synthesis of Aluminium‐Terminated Polyethylene by Means of Irreversible Coordinative Chain‐Transfer Polymerisation Using a Guanidinatotitanium Catalyst

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