Polymer Activated Catalysts

摘要

Three different ways in which functionalized polymers can active hydrogenation catalysts will be discussed. In the first example, a sulfonated divinylbenzene-crosslinked polystyrene is converted to a silver(I) salt. This silver(I) containing polymer selectively absorbs triphenylphosphine from solution in the presence of transition metal complexes. As a result of this removal of nonvolatile phosphine ligand, the activity of conventional homogeneous hydrogenation catalysts such as ((C6H5)3P)3RhC1 or ((C6H5)3Rh(CO)H can be increased in cases where excess free ligand is known to lower catalytic activity. In a second example of polymer activation of hydrogenation catalysts we have shown that the hydrogenation activity of polystyrene supported bis(cyclopentadienyl)titanium dichloride is significantly altered when organomagnesium reagents instead of organolithium reagents are used to prepare an active catalyst. Rates of olefin isomerization of terminal alkenes to trans-2-alkenes and hydrogenation of terminal alkenes both are must faster with the organomagnesium reduced catalysts. Finally, transition metal complexes can be directly deposited on organometallic polymers to yield polymer supported heterogeneous catalysts whose activity in hydrogenation of terminal alkenes is comparable to that of catalysts supported on inorganic materials. (Author)