Palladium/Ruthenium catalyzed isomerizing metathesis of fatty acids

A new palladium / ruthenium catalyzed method facilitates the synthesis of industrially useful multi-component blends, consisting of functionalized olefins with tunable chain length distributions.[1] The use of such mixtures as monomers can be advantageous, but they are hitherto exclusively accessed from petrochemical resources.[2,3] Our process facilitates the efficient conversion of uniform bio-based starting materials, i.e. readily available fatty acids, into the desired mixtures of olefins, unsaturated mono- and dicarboxylates, surpassing the literature by far.[4] In the presence of a bimetallic system consisting of a palladium dimer and a common metathesis catalyst, a technical quality fatty acid can be employed in an isomerizing self-metathesis, ethenolysis, or cross-metathesis with another functionalized olefin. The chain length distribution can be influenced by the catalyst ratio and the reactants’ stoichiometry, leading to product blends of different compositions with quantitative conversions. This way, olefin blends of tailored medium chain lengths become available from renewable resources rather than from crude oil, yielding valuable mono- and dicarboxylates as side products. The new methods disclosed above extend the chemist’s toolbox for the utilization of oleochemicals by making use of bimetallic catalysis, contributing to the necessary change from uncatalyzed to greener catalytic processes.

References:
[1] a) D. M. Ohlmann, L. J. Gooßen, M. Dierker, patent application, 2011. b) D. M. Ohlmann, L. J. Gooßen, M. Dierker, publication in preparation, 2012.
[2] a) K. Schmitt, F. Gude, Patent US 3723350, 1973. b) E. J. Vandenberg, Patent US 3058963, 1962. c) H. P. Rath, H. Mach, M. Röper, J. Stephan, J. Karl, R. Blackborow, Patent WO 016290A2, 2002.
[3] K. Maenz, D. Stadermann, Angew. Makromol. Chem. 1996, 242, 183–197.
[4] M. B. France, J. Feldman, R. H. Grubbs, J. Chem. Soc., Chem. Commun. 1994, 1307–1308.