Methods for separation of organic and pharmaceutical compounds by different polymer materials

Abstract

The discrimination of enantiomers is a challenging task in separation technology, and using a membrane is most promising for separating enantiomers from racemic mixture. The optical resolution of chiral compounds is of interest to researchers working in a variety of fields from analytical, organic and medicinal chemistry, to pharmaceutics and materials, to process engineering for fabricating pharmaceuticals, agrochemicals, fragrances and foods, and so on. There is considerable demand for separation techniques appropriate for the large-scale resolution of chiral molecules. The separation of chiral compounds using chiral or achiral/non-chiral polymeric membranes with or without chiral selector represents a promising system for future commercial applications. This review focuses on an active field of chiral separation, membrane-based enantioseparation technique, which has potential for large-scale production of singleenantiomers. Enantiomeric separation by membrane processes has been studied using various configurations of liquid and solid polymer membranes. Selectivity and permeability of liquid-membranes is reasonably good because the rate of diffusion of solute molecules is high in liquids but has inferior durability and stability. Solid polymer membranes have inferior permeability because diffusion of solute through solids is slow but quite stable and durable; however, commercial application of membrane technology for optical resolution is yet to be realized. Several chiral separation membranes were prepared from chiral polymers where enantioselectivity was generated from chiral carbons in the main chain. However, it is rather tricky to generate excellent chiral separation membranes from chiral polymers alone, because racemic penetrants mainly encounter the flexible side chains of the membrane polymers.

Chiral Recognition for Chromatography and Membrane-Based Separations: Recent Developments and Future Prospects

“…Membrane-mediated chiral separation is a new technology with broad application prospects, and it has received more and more attention in recent years. Membrane-based chiral separation methods have unique advantages compared to traditional chiral chromatographic separation methods, such as low cost and energy consumption, simple equipment, sustainable operation, high environmental protection, and easy realization of large-scale industrial production and many more [ 134 , 135 , 136 , 137 ]. The common preparation method of chiral separation membrane is base membrane modification and modification method, that is, by coating, dipping, grafting, etc., the material with chiral recognition function is loaded on the support layer based on polysulfone, polyamide, cellulose, and other materials.…”

Microreaction and membrane technologies for continuous single-enantiomer production: A review

“…Based on their properties, these membranes are expected to simultaneously have relatively high flux and enantioselectivity. For these reasons, they have a higher potential for industrial-scale productions of optically pure compounds than diffusion-enantioselective membranes [138] and are, therefore, more commercially valuable.…”

Chiral Separation in Preparative Scale: A Brief Overview of Membranes as Tools for Enantiomeric Separation

“…The liquid membrane phase should not be miscible in either the two aqueous phases, and to allow the dissolution of the chiral selector. A complex is formed between the chiral selector and one enantiomer at the interface of donating and organic solutions, which is then transported through the liquid membrane to another aqueous solution (receiving phase), frequently in the presence of a pH or concentration gradients [26,51]. Several liquid membranes containing different types of chiral selectors, including biomacromolecules such as human serum albumin [61,62] or enzymes [63], chiral crown ethers [64,65], cyclodextrins [66][67][68], chiral small molecules [69][70][71], and calixarenes [72,73], have been reported.…”