1‐Decene oligomerization by new complexes bearing diamine‐diphenolates ligands: Effect of ligand structure
Ahad Hanifpour, Naeimeh Bahri‐Laleh, Mehdi Nekoomanesh, Albert Poater
Abstract
A series of new titanium (IV) complexes bearing tetradentate diamine‐diphenolates, homologous to [ONNO] salan type ligands: [Ti{2,2′‐(OC 6 H 2 –4,6‐ t Bu 2 ) 2 NHC 3 H 6 NH}(Cl) 2 ] ( Cat1 ), [Ti{2,2′‐(OC 6 H 2 –4,6‐ t Bu 2 ) 2 NHC 4 H 8 NH}(Cl) 2 ] ( Cat2 ), and [Ti{2,2′‐(OC 6 H 2 –4,6‐ t Bu 2 ) 2 NHC 6 H 4 NH}(Cl) 2 ] ( Cat3 ) were synthesized and fully characterized by elemental analysis and NMR spectroscopy. All three synthesized catalysts, after activation with ([Ph 3 C][B(C 6 F 5 ) 4 ]) as a cocatalyst, exhibited high activities in 1‐decene oligomerization experiments. Gel permeation chromatography (GPC) analysis showed that molecular weight of the obtained oligomers had a close relationship with employed ligand structures, so that by increasing length of the aliphatic linkage between nitrogen donor atoms, PDI ( M w / M n ) shifted to the higher values. 1‐decene oligomers obtained by the Cat3 exhibited highest isotactic value (92% tacticity). Kinetic calculations allowed us to formulate the elementary reaction steps in oligomerization process of the 1‐decene. At the viscosity characterization, KV 100 amounts of 2.9, 3.9, and 4.1 cSt were determined for synthesized oligomers with Cat1 , Cat2 , and Cat3 , respectively. High catalyst activity, capability of producing PAOs with KV 100 < 6, less toxicity and corrosiveness of the catalytic system (compared to commercialized process based on the hazardous BF 3 catalyst), and simplicity of the preparation procedure are the merits of the new reported catalysts.