Pd-catalyzed copolymerization of methyl acrylate with carbon monoxide: Structures, properties and mechanistic aspects toward ligand design

Akifumi Nakamura, Kagehiro Munakata, Shingo Ito, Takuya Kochi, Lung Wa Chung, Keiji Morokuma, Kyoko Nozaki

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Full details are provided for the alternating copolymerization of acrylic esters with carbon monoxide (CO) catalyzed by palladium species bearing a phosphine-sulfonate bidentate ligand. The copolymer of methyl acrylate (MA) and CO had complete regioregularity with stereocenters that slowly epimerize in the presence of methanol. In the presence of ethylene, terpolymers of MA/ethylene/CO were also prepared. The glass transition temperatures of the co- and terpolymers were higher than that of the ethylene/CO copolymer. Both experimental and theoretical investigations were performed to clarify the superior nature of the palladium phosphine-sulfonate system compared to an unsuccessful conventional palladium diphosphine system: (i) The reversible insertion of CO was directly observed with the isolated alkylpalladium complexes, [{o-((o-MeOC6H4)2P)C 6H4SO3}PdCH(CO2Me)CH 2COMe], whereas it was not observed with the corresponding complex bearing 1,2-bis(diphenylphosphino)ethane (DPPE). (ii) The transition state of the subsequent MA insertion, the rate-determining step of the catalytic cycle, was lower in energy in the phosphine-sulfonate system than in the DPPE system. This stabilization could be attributed to the less hindered sulfonate moiety as well as the stronger back-donation from palladium to the electron-deficient olefin, which is located trans to the sulfonate.

Original languageEnglish
Pages (from-to)6761-6779
Number of pages19
JournalJournal of the American Chemical Society
Volume133
Issue number17
DOIs
Publication statusPublished - 2011 May 4

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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