Multi-stage crystallization for resolution of enantiomeric mixtures in a solid solution forming system

Balawejder, Maciej; Galan, Kamila; Elsner, M. P.; Seidel‐Morgenstern, A.; Pia̧tkowski, Wojciech; Antos, Dorota

doi:10.1016/j.ces.2011.07.051

Cited by 18 publications

(26 citation statements)

References 16 publications

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“…The rest of the solvents were removed using a vacuum drier for 1 h at 80°C. The white crystalline base of citalopram was obtained . Then crude products were subjected to further purification by recrystallization .…”

Section: Methodsmentioning

confidence: 99%

Enantiomeric separation of citalopram base by supercritical fluid chromatography

Bao

et al. 2013

J. Sep. Science

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The chiral separation of citalopram base by supercritical fluid chromatography on a semipreparative Chiralpak AD column was studied with the use of three alcohol-type modifiers (methanol, ethanol, and 2-propanol) with different volume percentages (5, 10, and 15%). The best separation was achieved when 10% 2-propanol was used in the presence of 0.1% diethylamine as additive. Under these conditions, the resolution reached 2.15 and the selectivity was 1.388. In addition, other parameters that affected the retention and separation properties, i.e. temperature, pressure, and density, were studied in detail. At the same pressure, a decrease in the temperature improved the enantioselectivity as the experimental temperature range was below the isoelution temperature. However, the temperature dependence of the retention factor was complicated. As a rule, the retention factor decreased when the temperature increased at the same density. A satisfactory regression of the logarithm of the retention factor versus density and temperature was obtained using a simplified lattice-fluid model. Surprisingly, the relationship between the Henry constant and density can be accurately correlated by using the same quadratic equation.

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Section: Methodsmentioning

confidence: 99%

Enantiomeric separation of citalopram base by supercritical fluid chromatography

Bao

et al. 2013

J. Sep. Science

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“…The 2D analogue of a solubility phase diagram provides a clear overview of the results of the concentration dependence of the surface coverage. Figure c shows the concentration conditions of ( R , R )‐ and ( S , S )‐ 1 at which the ordering of 1 was observed or not by STM.…”

Section: Figurementioning

confidence: 99%

Discrimination between Conglomerates and Pseudoracemates Using Surface Coverage Plots in 2D Self‐Assemblies at the Liquid–Graphite Interface

2017

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The two‐dimensional (2D) molecular ordering of two photochromic diarylethenes was investigated using scanning tunneling microscopy at the liquid–graphite interface. The racemic mixture of the closed‐ring isomer of one of the diarylethenes showed spontaneous separation of its enantiomers upon 2D crystallization, whereas that of the other diarylethene formed a pseudoracemic crystal in which two enantiomers coexist in a 2D ordering domain. The mixing of enantiomers in 2D assemblies can be analyzed by the dependence of the surface coverage on the concentration of enantiomers at different enantiomeric ratios.

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“…Ref. is an exception to this statement where such tradeoffs were evaluated; albeit in the context of an atypical case (solid‐solution). This lack of analysis of the tradeoffs between yield and purity has been true for equilibrated batch crystallization processes …”

Section: Introductionmentioning

confidence: 99%

Chiral control of enantiomers through crystallization: Moving from ternary phase diagrams to design spaces

Lovette

2018

AIChE Journal

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Although chiral purity is a critical quality attribute for many synthetic drugs, current industrial strategies for establishing chiral purity control are underdeveloped. Such strategies have relied on the construction of ternary phase diagrams, system classification, and case-specific operating policies. These policies have been developed to provide enantiopure solids, regardless of product specification or target. In this article, new operating policies are developed for obtaining solids that meet, but do not exceed, chiral purity specifications for arbitrary systems. These policies can provide significant yield improvements over the current practice. Additionally, this work provides an approach for the creation of design spaces based on the collection of limited, small scale data. This approach has been extended to sequential re-crystallizations and can be used to determine "global" optimal policies within a synthetic route.

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Multi-stage crystallization for resolution of enantiomeric mixtures in a solid solution forming system

Cited by 18 publications

References 16 publications

Enantiomeric separation of citalopram base by supercritical fluid chromatography

Enantiomeric separation of citalopram base by supercritical fluid chromatography

Discrimination between Conglomerates and Pseudoracemates Using Surface Coverage Plots in 2D Self‐Assemblies at the Liquid–Graphite Interface

Chiral control of enantiomers through crystallization: Moving from ternary phase diagrams to design spaces

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