Vitamin B12 Derivative Enables Cobalt-Catalyzed Atom Transfer Radical Polymerization

Advances in controlled radical polymerizations by cobalt complexes have primarily taken advantage of the reactivity of cobalt as a persistent radical to reversibly deactivate propagating chains by forming a carbon–cobalt bond. However, cobalt-mediated radical polymerizations require stoichiometric r...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2023-09, Vol.145 (35), p.19387-19395
Main Authors: Dadashi-Silab, Sajjad, Preston-Herrera, Cristina, Stache, Erin E.
Format: Article
Language:English
Online Access:Get full text
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Summary:Advances in controlled radical polymerizations by cobalt complexes have primarily taken advantage of the reactivity of cobalt as a persistent radical to reversibly deactivate propagating chains by forming a carbon–cobalt bond. However, cobalt-mediated radical polymerizations require stoichiometric ratios of a cobalt complex, deterring its utility in synthesizing well-defined polymers. Here, we developed a strategy to use cobalt as a catalyst to control radical polymerizations via halogen atom transfer with alkyl halide initiators. Using a modified, hydrophobic analogue of vitamin B12 (heptamethyl ester cobyrinate) as a cobalt precatalyst, we controlled the polymerization of acrylate monomers. The polymerization efficiency of the cobalt catalyst was significantly improved by additional bromide anions, which enhanced the deactivation of propagating radicals yielding polymers with dispersity values
ISSN:0002-7863
1520-5126
DOI:10.1021/jacs.3c06783