Dehydrogenation Of Polyethylene Catalyzed by Dihydrido Iridium PCP Pincer Complexes

Abstract

The dehydrogenation of polyethylene catalyzed by the pincer-ligated PCP iridium complexes, IrH2{C6H3-2,6-(CH2PBut2)2} (1) and IrH2{p-OMe-C6H2-2,6-(CH2PBut2)2} (2) have been investigated. The enormous problem of polyethylene is of increasing concern due to its negative environmental impact. This concern stems from the standpoint of environmental protection and conservation of energy. The degradation of polyethylene has been explored as a potential first step in a novel approach to its degradation and eventual recycling of the monomer products as chemical feedstocks. It has been discovered that the complexes 1 and 2 exhibit remarkably high activity for the transfer dehydrogenation of polyethylene in the presence of the hydrogen acceptor, tert-butylethylene, (ButHC=CH2, tbe) at temperatures of 150ºC. Conversions as high as 56% were achieved in perfluorodecalin. The dehydrogenation has been characterized by C CPMAS NMR spectroscopy and quantified by gas chromatography.