Copolymerization of Ethylene with Acrylate Monomers by Amide-Functionalized α-Diimine Pd Catalysts

Abstract

We report the ethylene homopolymerization and ethylene/methyl-acrylate (MA) and ethylene/acrylic-acid (AA) copolymerization behavior of a series of (N,N′-diaryl-α-diimine)Pd catalysts that contain secondary amide (−CONHMe) or tertiary amide (−CONMe2) substituents on the N-aryl rings, including the “first-generation” catalysts {(2,6-iPr2-Ph)N═CMeCMe═N(2-CONHMe-6-iPr-Ph)}PdMeCl (1a,a′) and {(2,6-iPr2-Ph)N═CMeCMe═N(2-CONMe2-6-iPr-Ph)}PdMeCl (1b,b′) and the “second-generation” catalysts [{2,6-(CHPh2)2-4-Me-Ph}N═CMeCMe═N(2-CONHMe-6-iPr-Ph)]PdMeCl (1d,d′) and [{2,6-(CHPh2)2-4-Me-Ph}N═CMeCMe═N(2-CONMe2-6-iPr-Ph)]PdMeCl (1e,e′). Activation of 1d,d′ and 1e,e′ by NaB{3,5-(CF3)2C6H3}4 generates active ethylene polymerization catalysts that produce highly branched (77–81 br/1000 C) polyethylenes with number-average molecular weights (Mns) in the range 26–60 kDa. The replacement of two isopropyl units in 1a,a′ and 1b,b′ with benzhydryl groups in 1d,d′ and 1e,e′ leads to a significant improvement in ethylene homopolyme...