Hideto Tojima

Studies on nickel-containing Ziegler-type catalysts: V. Dimerization of propylene to 2,3-dimethylbutenes. Part III. 1,1,1,3,3,3-Hexafluoro-2-propanol as a new efficient activator

Abstract 1,1,1,3,3,3-Hexafluoro-2-propanol (HFIP) worked as an efficient activator for the catalyst system comprising nickel-naphthenate (Ni(II)naph.), triethylaluminum, tricyclohexylphosphine, and isoprene in place of the known activator, 2,4,6-trichlorophenol (TCP) and water, which we reported in the preceding papers [H. Sato, T. Noguti, S. Yasui, Bull. Chem. Soc. Jpn. 66 (1993) 3069; H. Sato, T. Noguti, H. Tojima, Bull. Chem. Soc. Jpn. 66 (1993) 3079] for regioselective dimerization of propylene to 2,3-dimethylbutenes. The new HFIP-containing catalyst has a high selectivity of 2,3-dimethylbutenes in contrast to a low selectivity of propylene dimers. These properties come from the Lewis acidity of ethylaluminum-1,1,1,3,3,3-hexafluoro-2-propoxide 5 formed in situ between triethylaluminum and HFIP. Introduction of an Al–Cl bond to 5 takes a balance of the selectivities between 2,3-dimethylbutenes and propylene dimers.