Codimerization of Styrene with Ethylene or Propylene by Three-component Catalysts Consisting of Palladium Salt, Lewis Acid, and Tertiary Phosphine

Abstract

The codimerization of styrene with ethylene or propylene using, palladium-containing catalysts was studied. It was found that three-component catalysts consisting of palladium salt, Lewis acid, and tertiary phosphine were effective for the codimerization and that the products of the codimerization using the three-component catalysts were different from those of the cq, dimerization using one-component catalysts such as PdCI2, (PdC12. PhCH=CH2)2, and PdC12. (PhCN)2. The codimerization of styrene and ethylene with the three-component catalysts such as (rr C3H5PdC1) BF3, Ph3P, (PdC12, PhCH=CH2) BF3, Ph3P, and(π -C3H5PdC1)2-AIC13-Bu8P gives 3phenyl-1-butene and 2-phenyl-2-butene as codimers, though it has been known that the codimerization with the one-component catalysts gives 1-phenylbutenes. The difference between the catalytic behaviors of the former and latter catalysts was investigated in detail. As a reaction mechanism for the codimerization by the three-component catalysts, a mechanism involving the formation of a palladium hydride as a catalytic active species is proposed.