Oligomerisation of Ethylene by Bis(imino)pyridyliron and -cobalt Complexes
摘要:
A series of bis(imino)pyridyliron and -cobalt complexes [[2,6-(CR=NAr)2C5H3N]MX2] (R=H, Me; M=Fe, Co; X=Cl, Br) 8-16 containing imino-aryl rings (Ar) with at least one small ortho substituent, as well as Ar=biphenyl and Ar=naphthyl, has been synthesised. Crystallographic analyses of complexes 9 (Ar = 2,3-dimethylphenyl), 13 and 14 (Ar= biphenyl; X= Cl or Br, respectively) reveal a distorted trigonal-bipyramidal geometry in the solid state. These complexes, in combination with methyl aluminoxane (MAO), are active catalysts for the oligomerisation of ethylene, yielding >99% linear alpha-olefin mixtures that follow a Schulz-Flory distribution. Iron ketimine (R = Me) precatalysts give the highest activities and a greater alpha-value than their aldimine (R = H) analogues. Cobalt precatalysts follow a similar trend, though their activities are almost two orders of magnitude lower than those of the corresponding iron catalysts. Ethylene pressure studies on cobalt precatalyst 15 reveal a first-order dependence on ethylene for both the rate of propagation and the rate of chain transfer, and a pressure independence of the alpha value.
Processes for oligomerizing olefins utilizing a catalyst system including a) a transition metal complex that is transition metal compound complexed to a pyridine bisimine ligand and b) a metal alkyl and controlling the olefin oligomer product distribution K value by adjusting i) a transition metal of the transition metal complex concentration in the reactor, ii) a metal of the metal alkyl concentration in the reactor, iii) a metal of the metal alkyl to transition metal of the transition metal complex molar ratio in the reactor, and iv) any combination thereof.
Processes for oligomerizing olefins utilizing a catalyst system including a) a transition metal complex that is transition metal compound complexed to a pyridine bisimine ligand and b) a metal alkyl and controlling the olefin oligomer product distribution K value by adjusting i) a transition metal of the transition metal complex concentration in the reactor, ii) a metal of the metal alkyl concentration in the reactor, iii) a metal of the metal alkyl to transition metal of the transition metal complex molar ratio in the reactor, and iv) any combination thereof.