Polyhedral Oligomeric-Silsesquioxane Modification of Metathesis Catalysts: Improved Recycling and Lifetime in Membrane Separation

摘要

We herein report the synthesis, application and recycling of stable, polyhedral oligomeric silsesquioxane (POSS)-modified ruthenium complexes. The efficiency of all catalysts was evaluated in the ring closing metathesis of a test system relative to the commercially available Grubbs-Hoveyda second generation catalyst. Recycling experiments were carried out with a ceramic membrane in a cat-in-a-cup setup, where the necessity of two POSS units, one on the N-heterocyclic carbene, as well as one on the benzylidene moiety, was shown. ICP analyses were carried out to prove the low levels of ruthenium contamination in the product solutions and thus the high retention of catalyst by the membrane.