Methyl 9(10)‐formylstearate by selective hydroformylation of oleic oils

TLDR: In this paper, a highly selective catalyst system was proposed for the hydroformylation of methyl oleate into methyl 9(10)-formylstearate in high yields.

Abstract: A highly selective catalyst system has been discovered for the hydroformylation of methyl oleate into methyl 9(10)-formylstearate in high yields. A rhodium catalyst in the presence of triphenylphosphine is used with oleic esters, acids or triglycerides. Hydroformylation proceeds smoothly at 95-110C with a 1:1 mixture of H2 and CO at 500 to 2000 psi with or without a solvent, such as toluene. The formylstearate obtained in 90% to 99% conversion from oleate can be either hydrogenated (Raney Ni) or reduced (NaBH4) to hydroxymethylstearate or oxidized (KMnO4) to carboxystearate. According to TLC and mass spectrometry, the methylated carboxystearate consists of about equal proportions of the 9 and 10 isomers. Addition of triphenylphosphine inhibits isomerization of the double bond and leads to the formation of a rhodium carbonyl triphenylphosphine complex, which is apparently the active catalyst. Other known methods for hydroformylation (cobalt carbonyl) and carboxylation (Koch’s method) of oleate give a wide distribution of isomers.