Enantioseparation with liquid membranes

Abstract

Chiral resolution of racemic products is a challenging and important task in the pharmaceutical, agrochemical, flavor, polymer and fragrances industries. One of the options for these challenging separations is to use liquid membranes. Although liquid membranes have been known for almost four decades and have been used for optical resolutions, no comprehensive review has been published about the use of this technology for enantioseparations. In this review, the various liquid membrane‐related technologies are described and compared, including bulk liquid membranes, emulsion liquid membranes, micelle‐extraction and micellar enhanced ultrafiltration, as well as supported liquid membranes. Next to technological advances, an overview of recent developments in chiral recognition chemistry in liquid–liquid equilibria is presented. The following extractant classes have recently been reported in conjunction with chiral separation: cyclodextrines, BINOL's, calixarenes, crown ethers, BINAP's, tartaric acids and ionic liquids. The use of two supported (non‐liquid) membranes with an inner loop of extract phase appears to be the most stable liquid membrane configuration, allowing for a large degree of freedom in operational conditions such as solvent to feed ratio. The library of solvents still needs broadening to make the technology more versatile and based on the variety of successes with catalytically active organometallic complexes, development of new chiral selector systems based on asymmetric catalysis literature is suggested for future selector screening studies. © 2017 Society of Chemical Industry

Enantioseparation of flurbiprofen enantiomers using chiral ionic liquids by liquid‐liquid extraction

“…[12][13][14] Nevertheless, the resolution of the racemate is relatively simple and it is possible to obtain two enantiomers simultaneously, which need to be considered. 15,16 Most of the resolution methods, such as crystallization, [17][18][19] kinetic resolution method, [20][21][22] chromatographic resolution method, 23 membrane separation method, 24 etc., are difficult to achieve industrialization due to low capacity and narrow application range. Chromatography and electrochemical methods are mainly used for the analysis of enantiomers, currently.…”

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

“…Liquid membranes consist of a liquid phase that acts as a membrane between two fluid phases (aqueous solutions or gas mixtures). 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].…”

“…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].…”

Membrangestützte Flüssig/Flüssig‐Extraktion – Wo stehen wir heute?

“…B. chemische Beständigkeit, keine herauslösbaren Inhaltsstoffe, gute Reinigbarkeit etc. ), liegen die Vorteile der membrangestützten Flüssig/Flüssig‐Extraktion klar auf der Hand und sind folgerichtig dort schon in einem fortgeschrittenen Entwicklungsstadium . Mehrstufige Prozesse sind ebenfalls möglich und wurden auch bereits beschrieben .…”

“…Für [13][14][15][16][17][18][19][20]. Mehrstufige Prozesse sind ebenfalls möglich und wurden auch bereits beschrieben [21].…”