Alternating copolymerization of ethylene

Palladium(II) complexes possessing bidentate ligands are known to efficiently catalyze the copolymerization of olefins with carbon monoxide to form polyketones.594-596 Sulfur dioxide is an attractive monomer for catalytic copolymerizations with olefins since S02, like CO, is known to undergo facile insertion reactions into a variety of transition metal-alkyl bonds. Indeed, Drent has patented alternating copolymerization of ethylene with S02 using various palladium(II) complexes.597 In 1998, Sen and coworkers also reported that [(dppp)PdMe(NCMe)]BF4 was an effective catalyst for the copolymerization of S02 with ethylene, propylene, and cyclopentene.598 There is a report of the insertion reactions of S02 into PdII-methyl bonds and the attempted spectroscopic detection of the copolymerization of ethylene and S02.599... 

When a sulfonated diphosphine is used as the ligand, the complex formed with palladium(0) catalyzes the alternating copolymerization of ethylene and... 

The first palladium complex-catalyzed alternating copolymerization of ethylene and carbon monoxide was disclosed by Gough at ICI [8] in 1967. The polymer was produced at relatively low rates in severe reaction conditions (250 °C, 200 MPa). 

Rhodium carbonyls have also been reported as catalysts for the alternating copolymerization of ethylene and carbon monoxide [11], but activities and yields as well as molecular weights were again very low. 

Waymouth has recently reported the alternated copolymerization of ethylene and propylene using 39. Preliminary analysis of the polymers using C NMR spectroscopy revealed that the alternated polymers are isotactic. ... 

Copolymers of ethylene and propylene show, in some cases, elastic properties (324,325). Further incorporation of dienes, such as ethylidenenorbomene or 1,4-hexadiene, produces ethylene-propylene-diene monomer (EPDM) elastomers. Kaminsky (326) and Waymouth (327) have reported the predominantly alternating copolymerization of ethylene and propylene, using Ci and Cg symmetric (cyclopentadienyD(fluorenyl) aasa-zirconocene-based catalysts (eq. 3), demonstrating yet another example of preparation of new materials through rational exploitation of SSC systems. 

Choo, T. N. Waymouth, R. M. Cyclocopolymerization a mechanistic probe for dual-site alternating copolymerization of ethylene and a-olefins. J. Am. Chem. Soc. 2002,124, 4188-4189. 

Metal catalyzed polymerizations are chain reactions necessitating a constant valence of the metal. In contrast to that metal catalyzed polycondensations are step growth reactions involving a change of the valence of the metal. Tuning of the reaction by structural variations of the metal catalyst are demonstrated with the Pd-catalyzed vinyl polymerization of norbomene, the alternating copolymerization of ethylene with carbon monoxide and the Heck reaction as examples. One and two electron processes can be involved in metal catalyzed polycondensations. The Heck reactions, the Ni-catalyzed synthesis of polyphenylenes, and Ru-catalyzed ArH-insertion reactions are discuss. ... 

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