Selektive katalytische Metathese und Hydrierung von Monoterpenen

The aim of this thesis was to study metathesis and hydrogenation reactions of the monoterpenes Limonene, beta-Myrcene and Terpinolene catalysed by transition metal nanoparticles. When using known homogeneous and heterogeneous catalysts, no selective metathesis of monocyclic and acyclic monoterpenes can be achieved. Merely the ring-closing metathesis of beta-Myrcene can be achieved with the Grubbs-II- and the Hoveyda-Grubbs-II-catalysts, respectively. The hydrogenation of monoterpenes is very efficient and gives access to both branched aliphats and interesting olefins. The reaction pathways are determined by the activity, selectivity and stability of the catalyst systems. In this study, it was found that complete hydrogenation of limonene over heterogeneous catalysts can be achieved within a few hours. Different transition metal nanoparticles were prepared and stabilized successfully by using different stabilizers. Stable Ru-nanoparticles could be obtained with polyethylene glycol (Ru@PEG-NP) as well as with a variety of imidazolium-based Ionic Liquids (Ru@IL-NP). For the first time these catalysts were tested in the selective hydrogenation of terpenes. It was found that Ru-nanoparticles, stabilized by ionic liquids, are suitable for the hydrogenation of terpenes. Both the fully hydrogenated products and the partially hydrogenated intermediates could be obtained. In addition to the Ru-nanoparticles, Pd- and Pt-nanoparticles were synthesized and were found to be active in the hydrogenation of monoterpenes as well. Both, the cyclic and the acyclic monoterpenes could be hydrogenated. In the case of beta-myrcene, even a chemoselective hydrogenation could be observed. However, since they are more sensitive to high temperatures and hydrogen pressures than Ru-nanoparticles, the Pd- and Pt-nanoparticles agglomerated under the reaction conditions, thereby impeding recycling.