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Keywords:

  • Co-oxidant;
  • Double bond cleavage;
  • Methyl oleate;
  • Molecular oxygen;
  • Oleic acid;
  • Osmium catalyst

Abstract

Different reaction pathways are discussed for the Os-catalyzed oxidation of methyl oleate and oleic acid using O2/aldehyde as oxidation system. Monomethyl azelate and pelargonic acid were the main products obtained in yields of approximately 50–70% starting from methyl oleate. Besides, varying amounts of methyl 9,10-epoxystearate and methyl 9,10-dihydroxystearate were found as by-products. Azelaic acid and pelargonic acid were obtained exclusively from oleic acid used as reactant. Some mechanistic considerations led to the conclusion that the observed products are formed in parallel reaction paths. The effective oxidant for the scission of the C=C double bond seems to be very likely an in situ formed peracid generated by Os-catalysis from O2/aldehyde. Additional investigations concerning the cleavage of oleic acid and methyl oleate with in situ formed performic acid from H2O2/formic acid corroborate this assumption.