Unraveling the o-methoxy effect in the CO/ethene copolymerization reaction by diphosphanepalladium(II) catalysis

Claudio Bianchini, Andrea Meli, Werner Oberhauser, Carmen Claver, Eduardo J. Garcia-Suarez

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Relevant steps in the CO/ethene copolymerization reaction, namely the migratory insertion of [Pd(Me)(CO)(P-P)[BAr'(4) and the carbonylation of the beta-keto chelates [Pd(CH2CH2C(0)Me)(P-P)]BAr'4 have been studied by in situ high-pressure NMR spectroscopy in CH2Cl2; P-P = 1,2-bis [bis (2-methoxyphenyl)phosphanyl] ethane or 1,3-bis[bis(2methoxyphenyl)phosphanyl]propane. This study, backed by batch catalytic reactions in the same solvent, has contributed to rationalizing the higher catalytic activity of Pd-II catalysts modified with o-methoxy-substituted diphosphane ligands as compared to analogous Pd-II catalysts with 1,2-bis(diphenyl-phosphanyl) ethane (dppe) and 1,3-bis(diphenylphosphanyl)propane (dppp) ligands. It was found that o-MeO substituents on the phosphorus aryl rings ease the opening of the beta-chelate ring by CO and affect the kinetics of the overall CO/ ethene copolymerization. Indeed, unlike the catalysts with the dppe and dppp ligands, the rate of carbortylation of the o-MeO-modified beta-keto chelates is limited by the Pd(alkyl)(CO) migratory insertion, which makes the overall copolymerization process independent of the CO pressure. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Original languageEnglish
JournalEuropean Journal of Organic Chemistry
Volume2007
Issue number18
Pages (from-to)2702-2710
Number of pages9
ISSN1434-193X
DOIs
Publication statusPublished - 2007
Externally publishedYes

Keywords

  • Catalysis
  • Copolymerization
  • Diphosphane ligands
  • Kinetics
  • Palladium
  • Polyketones
  • CHEMISTRY,
  • PALLADIUM-DIPHOSPHINE CATALYSIS
  • CARBON-MONOXIDE
  • ALTERNATING COPOLYMERIZATION
  • HYDROGENATION CATALYSTS
  • POLYKETONE CATALYST
  • MECHANISTIC ASPECTS
  • ETHENE
  • COMPLEXES
  • LIGANDS
  • NICKEL(II)
  • polyketones
  • palladium
  • diphosphane ligands
  • catalysis
  • copolymerization
  • kinetics

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