Catalyst Encapsulation and Substrate Solubilization in Polymer‐Surfactant Complexes and Their Use in a Membrane Reactor

A chiral non‐racemic Rh complex was entrapped in a number of charged polymer‐surfactant complexes (PSCs) and used as micellar‐enlarged catalyst for the enantioselective hydrogenation of an α‐amino acid precursor in a membrane reactor. The retention behavior of different ultrafiltration membranes in dependence on the chemical nature and the molar mass of the PSCs as well as the loading behavior of the system were investigated. The chiral hydrogenation product was obtained with good enantioselectivity and space‐time yield. A lowering of the activity of the multiply used catalyst was caused mainly by a blockage of the PSC and not by the decomposition and leaching of the encapsulated catalyst. TEM images before and after the solubilization of the catalytic system support the view that a PSC with a loose, gel‐like structure and incorporated micelles yields the best results in the repetitive batch process.