Coupling Chromatography and Crystallization for Efficient Separations of Isomers
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Coupling Chromatography and Crystallization for Efficient Separations of Isomers KNUT GEDICKE∗ Otto-von-Guericke-University, IVT, Universit¨atsplatz 2, 39106 Magdeburg, Germany [email protected]
WOLFGANG BECKMANN AND ANDREAS BRANDT Schering Aktiengesellschaft, Verfahrenstechnik, M¨ullerstr. 178, 13342 Berlin, Germany DRAGOMIR SAPOUNDJIEV AND HEIKE LORENZ Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106 Magdeburg, Germany UWE BUDDE Schering Aktiengesellschaft, Verfahrenstechnik, M¨ullerstr. 178, 13342 Berlin, Germany ANDREAS SEIDEL-MORGENSTERN Otto-von-Guericke-University, IVT, Universit¨atsplatz 2, 39106 Magdeburg, Germany; Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106 Magdeburg, Germany
Abstract. Within the pharmaceutical industry and in biotechnology there is an increasing need for selective and efficient separation technologies to isolate and purify value-added products. A hybrid process approach combining chromatography and fractional crystallization is studied below. The work presented is concerned with the application and evaluation of this concept in order to isolate a certain pharmaceutical intermediate from a binary mixture. A comparison with performing the same separation exclusively in a single chromatographic process is given also. Keywords: chromatography, simulated moving bed process, crystallization, hybrid processes 1.
Introduction
The preparation of pure isomers is an important issue for the pharmaceutical industry (Crosby, 1997). Time to market is typically the critical parameter and affects the selection of the technology used to produce the required products. Besides asymmetric synthesis an assortment of separation methods is used. In the last years chromatographic methods based on the simulated moving bed technology (SMB) have been increasingly proposed to perform these separations, especially for ∗ To
whom correspondence should be addressed.
chiral systems. Schulte and Strube (2001) gave a review regarding preparative enantioseparations by means of SMB technology. Alternatively, direct crystallization such as fractional crystallization of partially resolved mixtures or preferential crystallization is widely used to obtain isomers as discussed in detail by Jacques et al. (1981). It is well known that the productivity of chromatographic methods decreases with increasing purity demands (Kaspereit et al., 2002). Thus, process combinations appear to be attractive. One possibility to perform such separations is the coupling of a chromatographic enrichment step with subsequent crystallization, as discussed for enantioseparations in
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Lim et al. (1995) and Lorenz et al. (2001). There is still a need of analyzing more examples in order to evaluate the potential of this concept.
2.
Principle of the Hybrid Process
The system under consideration is a mixture of 2 diastereomers and an additional impurity. The structure of the molecules (pharmaceutical intermediates) is of no relevance to t
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