title: Selector screening for enantioseparation of DL-α-methyl phenylglycine amide by liquid-liquid extraction.
abstract: Enantioseparation through liquid extraction technology is an emerging field, e.g., enantioseparations of amino acids (and derivatives thereof), amino alcohols, amines, and carboxylic acids have been reported. Often, when a new selector is developed, the versatility of substrate scope is investigated. From an industrial point of view, the problem is typically approached the other way around, and for a target racemate, a selector needs to be found in order to accomplish the desired enantioseparation. This study presents such a screening approach for the separation of the enantiomers of DL-α-methyl phenylglycine amide (DL-α-MPGA), a model amide racemate with high industrial relevance. Chiral selectors that were reported for other classes of racemates were investigated, i.e., several macrocyclic selectors and Pd-BINAP complexes. It appeared very challenging to obtain both high extraction yields and good enantioselectivity for most selectors, but Pd-BINAP-based selectors performed well, with enantioselectivities up to 7.4 with an extraction yield of the desired enantiomer of 95.8%. These high enantioselectivities were obtained using dichloromethane as solvent. Using less volatile chlorobenzene or 1-chloropentane, reasonable selectivities of up to 1.7 were measured, making these the best alternative solvents for dichloromethane.
authors.affiliation: University of Twente, Faculty of Science and Technology, Sustainable Process Technology Group, Enschede, The Netherlands.
authors.forename: Boelo
authors.initials: B
authors.lastname: Schuur
authors.forename: Marek
authors.initials: M
authors.lastname: Blahušiak
authors.forename: Caecilia R
authors.initials: CR
authors.lastname: Vitasari
authors.forename: Michal
authors.initials: M
authors.lastname: Gramblička
authors.forename: André B
authors.initials: AB
authors.lastname: De Haan
authors.forename: Ton J
authors.initials: TJ
authors.lastname: Visser
mesh_terms: D000577:Amides / Q000737:chemistry*; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification; D059625:Liquid-Liquid Extraction / Q000379:methods*; D015394:Molecular Structure; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000577:Amides; D012997:Solvents; C000602170:methyl phenylglycine amide; C033393:methyl phenylglycine; D005998:Glycine
keywords: Pd-BINAP; amides; calixarenes; crown ethers; enantioselective liquid-liquid extraction; heterocycles