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Abstract:
The resolution of chiral compounds has been of enormous interest to pharmaceutical, agricultural and food industries. The need for efficient techniques for the production of enantiomerically pure compounds is increasing due to the recent high demand for single enantiomers [1]. Resolution of racemates can be realized by using various methods such as kinetic resolution (chemical catalysis and biocatalysis), diastereomeric salts formation, (preparative) chromatography, preferential crystallization, and enantioselective membranes (molecularly imprinted polymeric membranes). In this work, a new approach for chiral separation based on enantioselective crystallization using chiral solvents will be presented. In principle, it is expected that a chiral solvent can create some selective interactions which will enable differentiation between the two single enantiomers. This differentiation can be used for the resolution of racemates. The chiral solvents are classified into two main groups that are a) classical chiral solvents and b) non-classical chiral solvent (ionic liquids and liquid crystals). In literature a few work do exist in the field of classical chiral solvents [2], but none for using chiral ionic liquids for enantioselective crystallization. However, recently Reichert and co-workers reviewed the general possibilities and the potential of ionic liquids as solvents in crystallization processes [3].
The work to be presented is concerned with studying the potential of both classical chiral solvents and chiral ionic liquids in enantioselective crystallization on the example of two selected pharmaceutical model systems. The effect of the used chiral solvent on thermodynamics and crystallization kinetics will be shown. The results obtained for each of the systems will be discussed and comparatively evaluated.
