From sunflower oil toward 1,19-diester: Mechanistic elucidation

During the last decade, an increased attention could be observed being paid on the use of renewables resources in the polymer and fine chemistry. Sunflower oil has been shown to be catalytically transformed into dimethyl 1,19-nonadecanedioate, using Pd/o-C6H4(CH2PtBu2)2 as catalyst. This article presents a complete elucidation of the reaction mechanism and provides a detailed understanding of what makes this catalyst so active and selective for the combined transesterification/isomerization/methoxycarbonylation. Besides kinetic and density functional theory (DFT) treatment to provide evidence for the elementary steps of this reaction, we corroborate our findings by microkinetic modeling. Here, the Cdouble bond; length as m-dashC double bond was found to be isomerized kinetically favored toward the terminal position, before a CO molecule may be inserted. The insertion of a methoxy group (rate-determining step) was found to proceed via intermolecular attack of MeOH to the catalyst.