Application of a homogeneous dodecakis(NCN-PdII) catalyst in a nanofiltration membrane reactor under continuous reaction conditions

A shape-persistent nanosize dodecakis(NCN-Pd-II-aqua) complex (4b) was applied as a homogeneous catalyst in the double Michael reaction between methyl vinyl ketone and ethyl cc-cyanoacetate under continuous reaction conditions in a nanofiltration membrane reactor. Due to its macromolecular dimensions, the catalyst is retained in the reactor (R = 99.5% determined by ICP-AAS) during catalysis. In addition, the catalyst was found to be stable under the continuous reaction conditions as a constant activity was obtained at prolonged reaction times (26 h, 65 exchanged reactor volumes). The turnover number of the catalyst was thus increased by a factor greater than 40 from 80 (batch) up to > 3000 mol/mol Pd. Further development of this technology will allow an increase of the number of (industrial) catalytic processes in which homogeneous catalysts are applied.