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

Abstract

Given the importance of chirality in the biological response, regulators, industries and researchers require chiral compounds in their enantiomeric pure form. Therefore, the approach to separate enantiomers in preparative scale needs to be fast, easy to operate, low cost and allow obtaining the enantiomers at high level of optical purity. A variety of methodologies to separate enantiomers in preparative scale is described, but most of them are expensive or with restricted applicability. However, the use of membranes have been pointed out as a promising methodology for scale-up enantiomeric separation due to the low energy consumption, continuous operability, variety of materials and supports, simplicity, eco-friendly and the possibility to be integrated into other separation processes. Different types of membranes (solid and liquid) have been developed and may provide applicability in multi-milligram and industrial scales. In this brief overview, the different types and chemical nature of membranes are described, showing their advantages and drawbacks. Recent applications of enantiomeric separations of pharmaceuticals, amines and amino acids were reported.

Enantiomeric Recognition and Separation by Chiral Nanoparticles

“…Further, in preparative scale separations the cost of production may significantly vary depending on the type of CSP/CAMP used and the technique in which the separation process is conducted. Thus the primary challenge is to find an optimum (cost effective and most productive) separation process, especially by using all possible combinations of more efficient CSPs/CAMPs [213,215]. In this regard, the use of nanoparticles and nanocomposites in separation processes has the potential to circumvent such challenges.…”

Chiral Separations in Preparative Scale: A Medicinal Chemistry Point of View

“…Membranes technologies are widely used in various separation processes due to their low cost, reliability, variety of materials, low energy consumption, eco-friendly and scalability compared with conventional separation processes. Based on their nature, the membranes can be classified into solid and liquid membranes [104]. Solid membranes are used extensively in different industries in processes like reverse osmosis, microfiltration and ultrafiltration.…”

“…The three basic types of liquid membranes are bulk liquid membrane (BLM), emulsion liquid membrane (ELM) and the supported liquid membrane (SLM) [105]. Many different types of chiral membranes and a variety of materials are described; however, their applications are still restricted to enantioseparation at a small scale, mainly, of pharmaceuticals and amino acids as exploratory projects [104][105][106][107]. Nevertheless, tremendous efforts have been made to develop chiral efficient membranes to achieve enantiomers with high enantiomeric purity [104,106].…”

Supramolecular Chiral 2D Materials and Emerging Functions

“…Considering the advantages of membrane tech nology such as easy to scaleup and save energy, the membrane structures can be continuously operated with high efficiency, which fulfil the need for commercialscale preparation of enantiomerically pure substances. [66][67][68] 2D Porous sheets with homochiral pores as a promising chiral membrane may pave the way to realize continuous separation of enantiomers in a racemic solution.…”

“…When a series of guests with different molecular sizes were investigated, only the guest molecules with compatible size can be encapsulated, indicative of remarkable size selectivity. Considering the advantages of membrane technology such as easy to scale‐up and save energy, the membrane structures can be continuously operated with high efficiency, which fulfil the need for commercial‐scale preparation of enantiomerically pure substances . 2D Porous sheets with homochiral pores as a promising chiral membrane may pave the way to realize continuous separation of enantiomers in a racemic solution.…”