The role of aluminum species in biphasic butene dimerization catalyzed by nickel complexes

The effect of the composition of the 1-butyl-3-methyl-imidazolium organochloroaluminate ionic liquid on the activity and distribution of the products of 1-butene dimerization catalyzed by a nickel complex under biphasic conditions is described. Three classes of ionic liquids have been employed, the first one with an aluminum (AlCl3) molar fraction of 0.50, the second one with an aluminum molar fraction of 0.55 and the third one with an aluminum molar fraction of 0.65. These ionic liquids were modified with different amounts of AlEtCl2 co-catalyst. An increase in the amount of co-catalyst added to the ionic liquid increases the global activity of the system, except for an AlCl3 molar fraction of 0.50. Changing the cation from 1-butyl-3-methylimidazolium to 1-butyl-2,3-dimethylimidazolium gives rise to no modification in selectivity towards dimer products.

Graphical abstractA systematic approach on the effects of the addition of different amounts of co-catalyst on organoaluminate ionic liquids bulk composition taking into account the interaction between the original anions and the added co-catalyst and, particularly, the effects on catalytic performance of cationic nickel complexes is evaluated. Figure optionsDownload full-size imageDownload as PowerPoint slide