An Overview of the 13:8 Mean Motion Resonance between Venus and Earth

It is known since the seminal study of Laskar (1989) that the inner planetary system is chaotic with respect to its orbits and even escapes are not impossible, although in time scales of billions of years. The aim of this investigation is to locate the orbits of Venus and Earth in phase space, respectively to see how close their orbits are to chaotic motion which would lead to unstable orbits for the inner planets on much shorter time scales. Therefore we did numerical experiments in different dynamical models with different initial conditions -- on one hand the couple Venus-Earth was set close to different mean motion resonances (MMR), and on the other hand Venus' orbital eccentricity (or inclination) was set to values as large as e = 0.36 (i = 40deg). The couple Venus-Earth is almost exactly in the 13:8 mean motion resonance. The stronger acting 8:5 MMR inside, and the 5:3 MMR outside the 13:8 resonance are within a small shift in the Earth's semimajor axis (only 1.5 percent). Especially Mercury is strongly affected by relatively small changes in eccentricity and/or inclination of Venus in these resonances. Even escapes for the innermost planet are possible which may happen quite rapidly.Comment: 14 pages, 11 figures, submitted to CMD

Tethered ansa-bridged titanium complexes immobilized on 3-mercaptopropyl-functionalized silica gel and their application for the hydrosilylation of imines

Four tethered titanocene complexes were covalently immobilized onto 3-mercaptopropyl-functionalized silica gel. We have investigated the influence of the length of the tether and of the ansa-bridge on the activity in the heterogeneous hydrosilylation of the cyclic imine 2-phenylpyrroline, taken as an illustrative example. Possible metal leaching during the reaction was investigated using ICP/OES, recycling studies and the three-phase test. The novel immobilized catalysts exhibit an activity similar to their homogeneous analogues in the tested hydrosilylation reactions with a TOF of [similar]20 h−1. Furthermore, our results indicate that metal leaching is negligible under the applied reaction conditions

"Catalyst Recycling in Continuous Flow Reactors" in "Catalyst Immobilization. Methods and Applications"

This review summarizes the use of flow reactors, for the purpose of continuous catalyst separation and recycling in liquid‐phase fine chemistry organic transformations. An overview of the main separation strategies is provided, with a focus on cases where extended recycling of metal or metal‐free catalytic systems was demonstrated. Examples ranging from cross‐coupling and metathesis reactions to enantioselective transformations are discussed, trying to highlight the key factors towards the attainment of high total turnover number (TTON) and time on stream (TOS)