Vinylferrocene homopolymerization

The organometallic acrylates and methacrylates containing the ferrocene nucleus undergo ready radical-initiated homo- and copolymerization. Unlike the unusual kinetic behavior of vinylferrocene, the homopolymerization of ferrocenylethyl acrylate 13 (Scheme 10-4) and ferrocenylethyl methacrylate 14 (Scheme 10-4) was found to be first-order in monomer and half-order in initiator, similar to that of their organic analogs. In these monomers, the vinyl groups are removed from the influence of the ferrocene nucleus. Monomers developed using this concept will also be discussed later. 

Since the Arimoto/Haven report of vinylferrocene polymerization was not detailed, this monomer was made and both its homopolymerization and its copolymerization were studied with a variety of organic comonomers such as styrene, methylacrylate, maleic anhydride, acrylonitrile, methyl methacrylate, N-vinylpyrolidone, vinyl acetate, and so on.31-38 The polymers were as well characterized as possible, and copolymer compositions were obtained versus feed mole ratios. 

The homopolymers of 10 were branched and exhibited broad GPC molecular weight distributions. Studies of the homopolymers molecular weights from polymerization at different monomer concentrations while (1) holding the [10]/[I] ratio constant, and (2) employing different [10]/[I] ratios confirmed that major differences existed in homopolymerizations of 10 versus vinylferrocene.56 In ethylacetate the rate law was r = k [M]1 [I]0 5. Polymerizations in benzene exhibited low initiator efficiencies. The rate was three halves order in the concentration of 10, similar to that found for 8.53 Polymers incorporating 10 were able to catalyze the selective 1,4-hydrogenation of methyl sorbate, but not terminal or internal olefins.56 This resembled the catalytic behavior of styrene/r 6-(styrene)tricarbonylchromium copolymers in hydrogenation.75... 

Shortly after the first synthesis of ferrocene by Kealy and Pauson, Arimoto and Haven reported the homopolymerization and copolymerization of vinylferrocene. 

Vinylferrocene is one of the few transition-metal-containing monomers that will both homopolymerize and copolymerize with other vinyl monomers in the presence of free-radical initiators. 

The excitement of metal-containing polymers appeared to languish until the landmark report of the preparation of ferrocene by Kealy and Pauson in 1951 and the elucidation of its structure and reactivity by Wilkinson and others in 1952. These discoveries set the stage for the birth of organo-transition-metal polymer chemistry. Thus, in 1955, Arimoto and Haven at die Dupont Co. reported the radical-initiated homopolymerization of vinylferrocene (Scheme 1). These reports did not appear to attract much attention until the work of Hayes and George and Pittman and coworkers. By the late 1960s and early 1970s Pittman, Carraher, Sheats, and others entered the arena. 

Since metals exhibit different oxidation states, the polymerization behavior of vinylferrocene (14) was in question. Hayes and George foimd that the rate law for the radical-initiated homopolymerization of vinylferrocene was r = A [M] [ ] instead of the classic one-half order in initiator concentration exhibited in most... 

Ritter H, Mondrzik BE, Rehahn M, Gallei M (2010) Free radical homopolymerization of a vinylferrocene/cyclodextrin complex in water. Beilstein J Org Chem 6 60... 

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