Electrospun Cellulosic Membranes toward Efficient Chiral Resolutions via Enantioselective Permeation

Cellulose tris­(3,5-dimethylphenylcarbamate) (CDMPC), known as one of the most versatile chiral selectors packed in columns for chiral chromatography, is electrospun for the first time. The electrospun nanofibers with a mean diameter of 329 nm form a self-standing nonwoven textile with a specific surface area of 5.6 m²/g. The textile is sandwiched between commercially available polytetrafluoroethylene membrane filters as a support material to fabricate a CDMPC membrane system for the chiral resolution of a racemic mixture, (R,S)-1-(1-naphthyl)­ethanol. A vacuum filtration of the racemic mixture through the membrane system using a mixed solvent of n-hexane/2-propanol = 9/1 (v/v) enriches the S-enantiomer in the filtrate due to an enantioselective sorption of the R-enantiomer. The sorption capacity can be regenerated repeatedly via extractions of the adsorbed enantiomers from the membrane system after the filtrations. By repeating the vacuum filtration–extraction process for 15 cycles, the enantiomeric excess (e.e.) of the S-isomer in the filtrate increases up to 32.9%.