Use of ionic liquids in recycle of palladium catalysts for synthesis of polyketone

Abstract

Room temperature ionic liquids as solvents for palladium-catalyzed copolymerization of carbon monoxide and styrene were prepared by reaction of aqueous lead tetrafluoroborate with correspond-ing chloride or bromide salts. The recyclability of palladium composite catalyst in various ionic liquids was investigated. [Pd(bipy)₂][BF₄]₂ showed a lower catalytic activity than [Pd(bipy)₂][PF₆]₂ in similar conditions, although the catalytic activity of each composite catalyst in ionic liquids still existed after 4 successive recycles. It was shown the catalytic activity of palladium composite catalyst was higher than that of the catalyst formed in situ from palladium acetate, 2,2′-bipyridyl, and HA (A=PF₆ ⁻, BF₄ ⁻) in ionic liquids. The effects of volume of ionic liquids, reaction time, and the dosage of benzoquinone on the copolymerizati on were also studied.

Keywords

ionic liquids / catalytic activity / palladium composite catalyst / polyketone

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