Selective propylene dimerization to 2,3-dimethylbutenes by homogeneous catalysts prepared by oxidative addition of alpha-nitroketones to nickel(0) complexes in the presence of phosphine ligands and organoaluminium co-catalysts
C. Carlini et al., Selective propylene dimerization to 2,3-dimethylbutenes by homogeneous catalysts prepared by oxidative addition of alpha-nitroketones to nickel(0) complexes in the presence of phosphine ligands and organoaluminium co-catalysts, APP CATAL A, 210(1-2), 2001, pp. 173-180
Novel nickel catalysts, prepared in situ by oxidative: addition of alpha -n
itroketones to nickel(O) complexes, in the presence of a phophine ancillary
ligand and activated by organoaluminium co-catalysts were investigated in
propylene oligomerization with the aim to selectively obtain 2,3-dimethylbu
tenes (DMB). In particular, the effect of the nature of the alpha -nitroket
onate ligand as well as of the basicity and bulkiness of the phosphine on c
atalyst performances were studied. Finally, the influence of the type of or
ganoaluminium co-catalyst and reaction temperature were examined.
In particular, when the Ni(cod)(2)/tricyclohexylphosphine (PCy3)/alpha -nit
roacetophenone (naph)/methylalumoxane (MAO) catalytic system was employed,
the highest up to now reported regioselectivity within C-6 cut (>90%) was a
chieved. Moreover, the use of balanced mixtures of MAO and Et2AlCl allowed
to optimize the catalyst performances up to an overall yield to DMB of almo
st 70%, a significant productivity being also achieved (TOF = 4500 h(-1)).
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