Selective catalytic hydrogenations in a microfluidics-based high throughput flow reactor on ion-exchange supported transition metal complexes: A modular approach to the heterogenization of soluble complex catalysts

Water-soluble ruthenium(II) and rhodium(I) complexes containing monosulfonated triphenylphosphine (mtppms) ligands were immobilized on commercially available anion-exchangers. The resulting solid catalysts were suitable for use in a microfluidics-based flow reactor (H-Cube™) of high throughput capability. With the heterogenized [{RuCl2(mtppms)2}2] disubstituted alkynes were hydrogenated to cis-alkenes with up to 85% selectivity, while the use of the immobilized [RhCl(mtppms)3] yielded 1,2-diphenylethane as the major product. The ruthenium catalyst also reduced trans-cinnamaldehyde to 3-phenylpropanal selectively and catalyzed the isomerization of 1-octen-3-ol to octan-3-one. This simple and versatile method of the immobilization of water-soluble complexes yields active and durable molecularly dispersed yet solid catalysts.