Advances in selective ethylene trimerisation – a critical overview

Selective Ethylene Oligomerization with Chromium Complexes Bearing Pyridine–Phosphine Ligands: Influence of Ligand Structure on Catalytic Behavior

“…By evaporation of the solvent in vacuo, the product was collected as a red oil (3.0 g, 9 mmol, 90%). 1 (6). Ligand 6 was synthesized similarly to ligand 1, using methyl(2-pyridyl)methylamine (1.25 mL, 10 mmol) and chlorodiisopropylphosphine (1.6 mL,10 mmol).…”

“…By evaporation of the solvent in vacuo, the product was collected as a brown oil (2.1 g, 8.8 mmol, 88%). 1 3 (0.375 g, 1 mmol) in CH 2 Cl 2 (15 mL) was treated with ligand 1 (0.292 g, 1 mmol). The suspension was stirred overnight at room temperature.…”

Distinguishing Chain Growth Mechanisms in Metal-catalyzed Olefin Oligomerization and Polymerization Systems: C2H4/C2D4 Co-oligomerization/Polymerization Experiments Using Chromium, Iron, and Cobalt Catalysts

“…We were interested to establish whether or not this method can be extended to polymerization systems, utilizing 13 C NMR spectroscopy as a method for analysis of the polymer. The iron polymerization catalyst 5 was employed, because this catalyst is closely related to the oligomerization catalyst 4 and therefore can be reasonably anticipated to operate via a Cossee-type chain growth mechanism, resulting in extensive H/D scrambling.…”

“…In order to determine the limits of this technique for distinguishing between different chain growth mechanisms, an iron-based polymerization catalyst 5 where k p >> k t has also been investigated. The lower molecular weight oligomeric products have been analyzed by GC and GC/MS, whereas the higher molecular weight fractions have been analyzed by 13 C NMR spectroscopy. Statistical analyses of the isotopologue distributions and mathematical models for the calculation of the theoretical mass spectra have been included in the Supporting Information.…”

Insights in the mechanism of selective olefin oligomerisation catalysis using stopped-flow freeze-quench techniques: A Mo K-edge QEXAFS study

“…1,2 However, the selective trimerisation and tetramerisation of ethene to produce the linear alpha-olefins (LAOs) 1-hexene and 1-octene respectively are of major significance due to the importance of these co-monomers in the production of linear low-density polyethylene (LLDPE). 2,3,4 LLDPE accounts for around 50% of the LAO co-monomers produced industrially. A variety of transition metal catalysts facilitate the selective trimerisation of ethene, most of which are based on early transition metals such as titanium, tantalum or, most importantly, chromium.…”