Catalytic isomerization-hydroformylation of olefins by rhodium salicylaldimine pre-catalysts

Pamela N. Sekoto, Tseliso M. Magengenene, Leah C. Matsinha, Richard Tia, James Darkwa, Banothile C.E. Makhubela

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

A series of new Schiff-base rhodium(i) water-soluble complexes (C1-C3), were prepared and characterized. These complexes served as catalyst precursors for the hydroformylation of 1-octene and resulted in excellent substrate conversions (>98%) with 100% chemoselectivities to aldehydes, under mild conditions. Notably, good regioselectivities towards branched aldehydes were observed clearly demonstrating the catalysts’ ability in thermodynamically favoured isomerization followed by hydroformylation (n/iso ratio ranging between 0.7-1.2). Interestingly, catalystC1uniquely promoted contra-thermodynamic isomerization of 2-octene to 1-octene with up to 50% conversion. The efficacy of catalystC1was further evaluated in the hydroformylation of longer chain olefins (C10-C12), methyl acrylate, ethyl acrylate and styrene. The catalyst displayed conversions >99% with the long chain substrates and much lower conversions with the acrylates. These water-soluble (pre)catalysts were recycled up to three times with no significant loss in catalytic activity and selectivity. Mercury poisoning tests were conducted and the experiments revealed that the conversion of the substrates into aldehydes was due to molecular active catalysts and not as a result of colloidal particles that could have formedin situthrough the decomposition of the catalyst precursor. Finally, the molecular catalyst responsible for activity was established using preliminary computational calculations.

Original languageEnglish
Pages (from-to)8751-8762
Number of pages12
JournalNew Journal of Chemistry
Volume44
Issue number21
DOIs
Publication statusPublished - 7 Jun 2020

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Materials Chemistry

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