Trapping the Short-Chain Odd Carbon Number Olefins Using Nickel(II)-catalyzed Tandem Ethylene Oligomerization and Friedel-Crafts Alkylation of Toluene

Nickel(II) complexes with pyrazole-based ligands are widely employed in catalysis of ethylene oligomerization and subsequent Friedel-Crafts alkylation of toluene. We have prepared ten new nickel(II) dibromide complexes with various substituted bis(azolyl)methanes. They have been characterized using 1 H NMR, IR, MALDI-TOF and elemental analysis. The structures of three complexes have been unambiguously established using X-ray diffraction. It was found that these complexes in the presence of Et 2 AlCl or Et 3 Al 2 Cl 3 are active both in ethylene oligomerization and Friedel-Crafts alkylation processes (activity up to 3720 kgoligomer·mol[Ni] −1 ·h −1 ). The use of Et 3 Al 2 Cl 3 results in the higher share of alkylated products (up to 60%). Moreover, catalytic systems activated with Et 3 Al 2 Cl 3 produced small amounts of odd carbon number olefins (up to 0.8%). The Friedel-Crafts alkylation was used as a trap for previously undetected short-chain odd carbon number olefins (C 3 and C 5 ).