New chiral catalytic membranes created by coupling UV-photografting with covalent immobilization of Calen-Co(III) for hydrolytic kinetic resolution of racemic epichlorohydrin

New chiral catalytic functional membranes (HFM-salens) were obtained successfully by covalent immobilizing aminated mono-CH ₂Cl-salen- Co(III) catalysts onto polyethylene (PE) hollow fiber membranes (HFMs) that had been, in advance, modified by UV-induced graft polymerization of acrylic acid. The catalytic properties of HFM-salens were investigated by carrying out hydrolytic kinetic resolution experiments of racemic epichlorohydrin. For homogeneous mono-CH ₂Cl-salen-Co(III) catalyst, the enantioselectivity (ee) and yield (Y) of S-epichlorohydrin were 86.67% and 57.26%, respectively. For the HFM-salens in type of segments, on which only about 2% of mono-CH ₂Cl-salen-Co(III) used in homogeneous catalysis was immobilized, an ee of 5.45% and a Y of 8.23% were achieved. Moreover, the ee and Y values reached 44.78% and 47.01%, respectively, using only eight HFM-salens packed in a catalytic membrane reactor (CMR), and the ee and Y values can be further improved by increasing packing density of fibers in the CMR. As an environment-friendly technology, immobilization of catalysts on membranes makes it easy to reuse the catalysts and reduce the amount of catalysts significantly. The results offer great potential for these modified membranes in the CMR for further research.