CATALYTIC DIMERIZATION OF PROPENE BY NICKEL-PHOSPHINE COMPLEXES IN 1-BUTYL-3-METHYLIMIDAZOLIUM CHLORIDE ALETXCL3-X (X=0,1) IONIC LIQUIDS/

The dimerization of propene was catalyzed by cationic nickel complexes in a two-phase solvent system using organochloroaluminate ionic liqui ds as the solvent for the catalyst. In ionic liquids containing an exc ess of strongly coordinating chloride ions, i.e., basic, no activity w as observed. In contrast, melts containing an excess of alkylchloroalu minum species, i.e., acidic, stabilized the active cationic nickel spe cies. The reaction products separate as an organic layer. Molecular or ganochloroaluminum species were extracted, and the composition of the salt was strongly modified. This was circumvented using a salt which c ontains an excess of aluminum chloride. The propene dimers obtained by this way can be transformed either into ethers or into alkanes to pro duce high octane number additives for gasoline. The effects of phosphi ne ligands coordinated on nickel and operating variables were investig ated in order to maximize the octane number of the corresponding alkan es and ethers.