An aspect of selecting resolving agents: The role of differences in molecule length in diastereomeric salt resolutions

Szeleczky, Zsolt; Semsey, Sándor; Bagi, Péter; Fődi, Balázs; Faigl, Ferenc; Pálovics, Emese; Fogassy, Elemér

doi:10.1080/01496395.2015.1117105

Cited by 2 publications

(3 citation statements)

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“…In the context of an optical resolution through diastereomeric salt formation, a basic compound and an acidic compound can form various kinds of crystals depending on their molecular structures and functional groups, respectively. In the process of crystallization, it is well-recognized that these molecules arrange as compactly as possible through interactions like hydrogen bonding, CH/π, and van der Waals force to realize the minimization of energy [9,10,11,12,13,14,15,16,17,18]. The hydrogen bond was conventionally considered to be the most important factor in accounting for chiral discrimination because it is stronger than other interactions in determining the crystal structure.…”

Section: Resultsmentioning

confidence: 99%

“…Most research efforts have focused on experimentally obtaining crystal structures of diastereomeric salts, followed by qualitative analysis of the difference in molecule packing and intermolecular interactions in the crystal lattices. A number of characteristic features were of great interest, including the structural similarity [9], relative molecular length [10,11,12], hydrogen bonding network [13,14], the CH/π interaction and packing mode of aromatic groups [15,16], and the role of incorporated solvent molecules in diastereomeric salts [17,18]. Recently, two case studies reported the role of halogen bonding interactions in diastereomeric resolution [19,20].…”

Section: Introductionmentioning

confidence: 99%

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Improved Resolution of 4-Chloromandelic Acid and the Effect of Chlorine Interactions Using (R)-(+)-Benzyl-1-Phenylethylamine as a Resolving Agent

et al. 2018

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In order to avoid the disadvantage of commonly used resolving agent 1-phenylethylamine (hereafter: PEA), which is soluble in water, (R)-(+)-benzyl-1-phenylethylamine ((R)-(+)-BPA) was used to resolve 4-chloromandelic acid (4-ClMA) in this study. The optimal resolution conditions were determined: absolute ethanol as a solvent, the molar ratio of 4-ClMA to (R)-(+)-BPA as 1:1, the filtration temperature as 15 °C, and the amount of solvent as 1.6 mL/1 mmol 4-ClMA. Thermophysical properties, such as melting point, heat of fusion, and solubility, exhibited significant differences between the less and more soluble salts. The single crystals for the pair of diastereomeric salts were cultivated and their crystal structures were examined thoroughly. In addition to commonly observed interactions like hydrogen bonding and CH/π interactions. The chlorine…chlorine interaction was observed in the less soluble salt presenting as Cl…Cl between adjacent hydrogen network columns, while the Cl/π interaction was observed in the more soluble salt. It was found that halogen interactions played an important role in chiral recognition of 4-ClMA by (R)-(+)-BPA.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improved Resolution of 4-Chloromandelic Acid and the Effect of Chlorine Interactions Using (R)-(+)-Benzyl-1-Phenylethylamine as a Resolving Agent

et al. 2018

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“…Based on the results of 49 resolutions, by plotting the average enantiomeric excess and efficiency of resolution values in function of the difference of molecular length, respectively, the following diagrams are received (Schemes 17 and 18). Accordingly, higher enantiomeric excess can be reached in case of higher difference of molecular length of the racemic compound and the resolving agent [75]. For the resolution of racemic acids basic amino acids were also applied, for example (S)-lysine (Lys) (Scheme 20) [77,78].…”

Section: Ratio Of the Molecules Composing The Diastereomermentioning

confidence: 99%

Separation of Chiral Compounds: Enantiomeric and Diastereomeric Mixtures

Pálovics¹,

Szeleczky²,

Szolnoki³

et al. 2018

Laboratory Unit Operations and Experimental Methods in Chemical Engineering

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Despite the dramatic development of enantioselective synthesis and chromatographic separation methods, optical resolution still remains the cheapest and operationally simplest method for producing pure enantiomers on a larger scale. No extreme conditions or expensive reagents are required, and the eventually expensive resolving agents can be recovered. This chapter is based mainly on the authors' long experience in the resolution of industrially important molecules, and it presents new observations and establishments as well. Several methods for separation of chiral mixtures, enantiomeric and diastereomeric mixtures, are shown, and possibilities for predicting the efficiency of resolution based on the analysis of physico-chemical properties of the reactants are also described.

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An aspect of selecting resolving agents: The role of differences in molecule length in diastereomeric salt resolutions

Cited by 2 publications

References 24 publications

Improved Resolution of 4-Chloromandelic Acid and the Effect of Chlorine Interactions Using (R)-(+)-Benzyl-1-Phenylethylamine as a Resolving Agent

Improved Resolution of 4-Chloromandelic Acid and the Effect of Chlorine Interactions Using (R)-(+)-Benzyl-1-Phenylethylamine as a Resolving Agent

Separation of Chiral Compounds: Enantiomeric and Diastereomeric Mixtures

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