Applications for racemic versions of chiral stationary phases

Pirkle, William H.; Däppen, Richard; Reno, D. S.

doi:10.1016/s0021-9673(01)92619-6

Cited by 27 publications

(5 citation statements)

References 4 publications

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“…Investigation of more than a dozen additional achiral stationary phases, including several prepared in-house, did not reveal any columns with suitable resolving power to be generally useful in this approach. As Pirkle has pointed out, racemic versions of chiral stationary phases are often well suited for the separation of mixtures of diastereomers, positional isomers, or other closely related compounds, 15 and we did note that racemic CSPs performed best for our diastereomer separation experiments. Nevertheless, the relatively few columns of this type that are available commercially ultimately led us toward the configuration depicted in Figure 3c.…”

Section: Resultssupporting

confidence: 49%

Solving multicomponent chiral separation challenges using a new SFC tandem column screening tool

et al. 2006

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A tool for improved tandem column chiral supercritical fluid chromatography (SFC) method development screening was prepared by modification of a commercial analytical SFC instrument with two different software-controllable, six position high-pressure column selection valves, each controlling a bank of five different columns and a pass through line. The resulting instrument, which has the ability to screen 10 different individual columns and 25 different tandem column arrangements, is a useful tool for facilitating the screening of tandem column SFC arrangements for separation of complex mixtures of stereoisomers or other multicomponent mixtures. Strategies for optimal use of the instrument are discussed, and several examples of the use of the instrument in developing tandem SFC methods for resolution of multicomponent mixtures are presented.

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Section: Resultssupporting

confidence: 49%

Solving multicomponent chiral separation challenges using a new SFC tandem column screening tool

et al. 2006

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“…[1][2][3] In principle, this could be extended from monomeric to dimeric-type chiral selector molecule units to be immobilized onto the support surface, as shown in Figure 1a. [1][2][3] In principle, this could be extended from monomeric to dimeric-type chiral selector molecule units to be immobilized onto the support surface, as shown in Figure 1a.…”

mentioning

confidence: 99%

“…[4][5][6][7][8][9][10][11][12][13][14][15][16][17] Recently, we investigated the effects on overall enantioselectivity by linking together two QN or QD carbamate subunits to form socalled "dimeric" selectors with two SO subunits. [1][2][3]18 Taking this into consideration, we synthesized three C 9dimeric QN-and QD-derived SOs inserting an ethylene spacer between the two carbamate functions (for structures, see Fig. Therefore, these interactions led to a significant decrease in the overall chiral recognition abilities when compared with the corresponding monomers, which varied slightly as a function of the carbamate spacer between the QN-QN or QD-QD unit which was introduced.…”

mentioning

confidence: 99%

“…The concept of chiral and corresponding racemic stationary phases to be used for enantioseparation in liquid chromatography has been discussed. [1][2][3] In principle, this could be extended from monomeric to dimeric-type chiral selector molecule units to be immobilized onto the support surface, as shown in Figure 1a. If all the selectors and chiral stationary phases (CSPs) defined behave fully enantiomerically to each other, one should observe reversal of the elution order while the loss of enantioselectivity should be the case for the so-called racemic stationary phases.…”

mentioning

confidence: 99%

“…4 The presence of both QN-and QD-derived SOs in a 1:1 ratio, leading to a "pseudoracemic" stationary phase, should suppress stereoselectivity, due to their opposite recognition abilities, as has been reported for other racemic mixtures of enantiomers. [1][2][3]18 Taking this into consideration, we synthesized three C 9dimeric QN-and QD-derived SOs inserting an ethylene spacer between the two carbamate functions (for structures, see Fig. 2): one SO consisted of two QN subunits (QN-QN, 1), another of two QD subunits (QD-QD, 2), and a third simultaneously bearing both cinchona scaffolds (QN-QD, 3).…”

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confidence: 99%

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Evaluation of the contribution to enantioselectivity of quinine and quinidine scaffolds in chemically and physically mixed chiral selectors

et al. 2001

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Three "dimeric" C(9)-carbamates of quinine (QN) and quinidine (QD), that is, QN-QN, QD-QD, and QN-QD (chemically prepared mixture of the two cinchona-derived subunits), separated by an ethylene spacer were synthesized and used as chiral selectors for HPLC and capillary electrophoresis (CE) for the resolution of chiral acids. The chiral recognition abilities of these dimers and of several physically prepared mixtures thereof were compared in order to estimate the contribution of every cinchona scaffold to the overall enantioselectivity. The diverse phenomena observed in nonaqueous capillary electrophoresis (NACE), either using the selector added to the background electrolyte (BGE) in the total filling or partial filling mode, led us to rationalize, taking into account the relative mobilities of the chiral selectors in the capillary. The chromatographic and electrophoretic properties were compared with those of the corresponding "monomeric" QN and QD carbamates.

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Gas and Liquid Chromatography, Column Selection for, in Drug Analysis

Duff

2000

Encyclopedia of Analytical Chemistry

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Within the realm of pharmaceutical drug analyses, two techniques currently dominate the field. High‐performance liquid chromatography (HPLC) is at the forefront, followed somewhat distantly by gas chromatography (GC). HPLC is more prevalent than GC owing mainly to the heat‐labile nature of the majority of drug substances. Still GC continues to play a very active role. In comparison to HPLC and GC, combined, the frequency of use of other techniques is quite small. Perhaps the major reason for this is that chromatography not only involves qualitative and quantitative detection of targeted species, but also provides a medium for isolating these analytes from potential interfering impurities prior to measurement. The proficiency of this combination is unparalleled by any other blending of means to clean up a sample and detect the target compound. These more prominent techniques are often complementary, although each has its own strengths and limitations. General guidelines are given to assist the chromatographer to elect HPLC and/or GC for a particular separation. Considerations for choosing hardware type and sizes, solid support and bonded phase are presented. Particular emphasis is placed on the latest, which is of primary importance for obtaining rugged methods. The reader is directed towards optimum phase selection based on the compound of interest's functional group type, or by its drug activity classification (e.g. barbiturate, cardiovascular, etc.). Assistance in developing new methods frequently arises when starting with an existing published method for a compound with similar structure. This article provides 514 references for more in‐depth separation information. In addition, background knowledge on bonded‐phase chemistry, chromatographic modes of separation, approaches to chromatographic chiral drug discrimination and processes for developing rugged methods is contributed.

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Applications for racemic versions of chiral stationary phases

Cited by 27 publications

References 4 publications

Solving multicomponent chiral separation challenges using a new SFC tandem column screening tool

Solving multicomponent chiral separation challenges using a new SFC tandem column screening tool

Evaluation of the contribution to enantioselectivity of quinine and quinidine scaffolds in chemically and physically mixed chiral selectors

Gas and Liquid Chromatography, Column Selection for, in Drug Analysis

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