Recyclable homogeneous catalyst for the hydroesterification of methyl oleate in thermomorphic solvent systems

• A very stable catalyst for the hydroesterification of oleic acid methyl ester was found.
• The linearity of the product spectrum can be influenced by choosing the catalyst system and reaction conditions.
• The palladium catalyst can be recycled via thermomorphic solvent system
• The leaching of the palladium catalyst and ligand in the product phase is very low (3 ppm).

In the development of commodity markets alternatives to fossil resources are of high interest. One alternative is the usage of oleo compounds. In this paper an atom economic hydroesterification of methyl oleate to linear and branched diesters is described. The selectivity to linear or branched products can be influenced by reaction parameters. These diesters can be used in polymers, plasticizers, lubricants or to adjust crystallinity in these materials. To the best of our knowledge we provide the first efficient catalyst recycling in the hydroesterification of fatty compounds. The catalyst system of palladium and XANTphos proved to be very stable. Products with the tough palladium XANTphos catalyst are mostly branched, while the selectivity to linear products can be influenced by temperature, carbon monoxide pressure and choice of solvent up to 64%. A high selectivity of 94% towards branched products was obtained if no solvent was used. Separation of products and catalyst was realised using thermomorphic solvent systems (TMS). The catalyst was recycled in a methanol/decane system with low leaching values. A recycling of the catalyst phase was conducted three times with no significant activity loss.

Easy assesible renewable Diesters: Hydroesterification of the renewable methyl olate leads to branched and linear diesters. A catalyst system from XANTphos and palladium governs the selectivity for the products by simple variation of reaction parameters. Thermomorphic solvent system technique is used for a catalyst separation. The catalyst can be recovered and reused for a number of cycles with negligible loss in activity.Figure optionsDownload high-quality image (124 K)Download as PowerPoint slide