Separation of binaphthol enantiomers through achiral chromatography

Baciocchi, Renato; Zenoni, Gianmarco; Mazzotti, Marco; Morbidelli, Massimo

doi:10.1016/s0021-9673(01)01366-8

Cited by 43 publications

(26 citation statements)

References 14 publications

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“…The same happened with their corresponding deuterated compounds (381.1-157.0; 4.02 and 4.64 min, respectively). This could explain the ability of the UHPLC-QqQ-MS/MS technique to separate epimers under nonchiral conditions, as described previously in several cases for isomers separation by nonchiral columns [26,27]. Another transition (381.0-337.1) was selected for the identification of two compounds (17-epi-17-F 2t -Dihomo-IsoP and 17-F 2t -Dihomo-IsoP), as happened with the MRM transition 381.1-362.2, that was used for ent-7(RS)-7-F 2t -Dihomo-IsoP and ent-7-epi-7-F 2t -Dihomo-IsoP.…”

Section: Discussionsupporting

confidence: 55%

Dihomo-isoprostanes—nonenzymatic metabolites of AdA—are higher in epileptic patients compared to healthy individuals by a new ultrahigh pressure liquid chromatography–triple quadrupole–tandem mass spectrometry method

Medina

Miguel-Elízaga

Oger

et al. 2015

Free Radical Biology and Medicine

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Section: Discussionsupporting

confidence: 55%

Dihomo-isoprostanes—nonenzymatic metabolites of AdA—are higher in epileptic patients compared to healthy individuals by a new ultrahigh pressure liquid chromatography–triple quadrupole–tandem mass spectrometry method

Medina

Miguel-Elízaga

Oger

et al. 2015

Free Radical Biology and Medicine

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“…This is highly probable, particularly in view of the results given in paper, [9] although an ultimate confirmation could only by provided by the in situ polarimetric measurements. Thus, the upper spot in Figures 5, 6b, and 7b can probably be attributed to the optically active S ... S naproxen dimer and the lower spot can be attributed to the optically inactive S ... R dimer.…”

Section: Use Of Video and Scanning Densitometry 2381mentioning

confidence: 83%

Use of Video Densitometry and Scanning Densitometry to Study an Impact of Silica Gel and L‐Arginine on the Retention of Ibuprofen and Naproxen in TLC Systems

Sajewicz

Gontarska

Dąbrowa

et al. 2007

Journal of Liquid Chromatography & Related Technologies

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In our earlier articles, we demonstrated the phenomenon of the two-dimensional enantioseparation of the selected 2-arylpropionic acids (2-APAs) in the onedimensional thin-layer chromatographic mode, yet our measuring results originated from the classical scanning densitometry only. A basic precondition of the discussed phenomenon is the omnipresence of the two-dimensional effective diffusion in planar chromatography. However, one should anticipate an action of the two different-and apparently chiral -elements, one responsible for the vertical enantioseparation (in the direction of the mobile phase migration) and another one responsible for the horizontal enantioseparation (inducing deviation of the chiral analytes' migration tracks from the vertical). In the investigated chromatographic systems two chiral elements are in fact present. One chiral element is the microcrystalline silica gel layer and the other one is L-arginine as the impregnating chiral selector. Upon our earlier results originating from the scanning densitometry, it could be deduced that the crystalline chirality of silica gel is responsible for the horizontal enantioseparation, and the molecular chirality of L-arginine is responsible for the vertical separation. In this study, we confirm our earlier findings in a more immediate way, using the flatbed video densitometry to record the pictures of the whole chromatograms and also those of the individual chromatographic spots of ibuprofen and naproxen. We combine these results with the data obtained from the classical scanning densitometry to monitor the discussed enantioseparations by means of the concentration profiles of the respective antimers. Combination of the results originating from the video and the scanning densitometry allows a deep enough insight in the chromatographic behavior

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“…In the case of the enantiomers of binaphthol in CHCl 3 , we have recently been able, using an achiral chromatography column, to collect two fractions constituted of the pure enantiomer present in excess (reaching 100% e.e.) and of the racemic mixture, respectively [20]. In the case of Pirkle×s alcohol, the enantiomer enrichment of a nonracemic solution in hexane/CH 2 Cl 2 was also achieved through achiral chromatography on a silica stationary phase [12].…”

mentioning

confidence: 99%

Determination of the Dimerization Equilibrium Constants of Omeprazole and Pirkle's Alcohol through Optical‐Rotation Measurements

Baciocchi

Juza²,

Classen³

et al. 2004

Helvetica Chimica Acta

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A new procedure to measure the equilibrium constants for the dimerization (homochiral and heterochiral) reactions of enantiomers in solution was applied to two different compounds, namely omeprazole and Pirkle×s alcohol, both in CHCl 3 . This procedure is based on the measurement of the optical rotation of the solution as a function of its composition, which exhibits a nonlinear dependence on the enantiomer enrichment. Such nonlinearity depends on the extent of dimerization, and it is a strong effect in the case of omeprazole, whose equilibrium constants are 14.0 AE 3.5 l/mol and 25.2 AE 4.0 l/mol for the formation of homochiral and of heterochiral dimers, respectively. Pirkle×s alcohol exhibits a weaker effect that allows only to estimate the order of magnitude of these constants, i.e., ca. 0.10 and 0.34 l/mol, respectively. Although, in solution, enantiomers and racemates of chiral compounds usually exhibit identical NMR spectra, small differences in the chemical shifts are sometimes observed (see [18] for an overview, as well as the ref. cit. therein). It is also known that nonracemic mixtures of enantiomers of compounds that strongly self-associate, e.g., amino alcohols, amides, and carboxylic acids, can exhibit anisochrony, thus reflecting the enantiomer composition even in the absence of shift reagents [19]. Association is often limited to the formation of dimers that may take place through the formation of H-bonds between enantiomers. This is the case for the enantiomers of the chiral [1,1'-binaphthalene]-2,2'-diol ( binaphthol) and 1-(anthracen-9-yl)-2,2,2-trifluoroethanol ( Pirkle×s alcohol). In the case of the enantiomers of binaphthol in CHCl 3 , we have recently been able, using an achiral chromatography column, to collect two fractions constituted of the pure enantiomer present in excess (reaching 100% e.e.) and of the racemic mixture, respectively [20]. In the case of Pirkle×s alcohol, the enantiomer enrichment of a nonracemic solution in hexane/CH 2 Cl 2 was also achieved through achiral chromatography on a silica stationary phase [12].

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Separation of binaphthol enantiomers through achiral chromatography

Cited by 43 publications

References 14 publications

Dihomo-isoprostanes—nonenzymatic metabolites of AdA—are higher in epileptic patients compared to healthy individuals by a new ultrahigh pressure liquid chromatography–triple quadrupole–tandem mass spectrometry method

Dihomo-isoprostanes—nonenzymatic metabolites of AdA—are higher in epileptic patients compared to healthy individuals by a new ultrahigh pressure liquid chromatography–triple quadrupole–tandem mass spectrometry method

Use of Video Densitometry and Scanning Densitometry to Study an Impact of Silica Gel and L‐Arginine on the Retention of Ibuprofen and Naproxen in TLC Systems

Determination of the Dimerization Equilibrium Constants of Omeprazole and Pirkle's Alcohol through Optical‐Rotation Measurements

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