1350754-46-9Relevant academic research and scientific papers
Oligomerization of ethylene using tridentate nickel catalysts bearing ether-pyrazol ligands with pendant O- and S-donor groups
Ulbrich, Ana H.D.P.S.,Bergamo, Ad?o L.,Casagrande Jr., Osvaldo De L.
, p. 245 - 249 (2011)
A series of tridentate pyrazol ligands with pendant O- and S-donor groups (L1-L5) and their corresponding nickel(II) chloride complexes (1-5) were synthesized and fully characterized. All nickel precatalysts, activated with methylaluminoxane (MAO), exhibited high activities for ethylene oligomerization [TOF = 17.1-75.8 × 103 mol(ethylene)(mol(Ni))- 1 h- 1)] with good selectivities for 1-butene produced (62.9 - 81.3%). The catalytic performance was substantially affected by the ligand environment regarding the pendant oxygen- and sulfur-donor groups, and the substituents on the phenol group. Activation of nickel precatalyst 1 with ethylaluminum sesquichloride (Et3Al2Cl3, EASC) instead of MAO produced a significantly better catalyst system than 1/MAO (TOF = 227,000 vs. 30,900 (mol C2H4)·(mol Ni- 1 h - 1); however, the 1-butene selectivity was drastically reduced, attaining only 28% with a concomitant production of larger amounts of internal butenes (51.4%) and hexenes (28.2%). Under optimized conditions ([Ni] = 10μmol, 30°C, oligomerization time = 20 min, 40 bar ethylene, [Al]/[Ni] = 250), precatalyst 1 led to TOF = 75,800 (mol C2H4) ·(mol Ni- 1 h- 1) and 76.1% selectivity for 1-butene.
