The influence of end-capping on the enantioselectivity of a chiral phase

Pirkle, William H.; Readnour, Robin S.

doi:10.1007/bf02274559

Cited by 51 publications

(30 citation statements)

References 12 publications

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“…This CBP degradation is easily confirmed by the saturation different phases by gaseous ammonia [60]. In conclusion, trimethylchlorosilane in the presence of an activator is recommended for end-capping, if that is necessary [60,61].…”

Section: Secondary Silanization (End-capping)mentioning

confidence: 81%

Survey and Trends in the Preparation of Chemically Bonded Silica Phases for Liquid Chromatographic Analysis

Buszewski¹,

Jezierska

Wełniak

et al. 1998

J. High Resol. Chromatogr.

145

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Section: Secondary Silanization (End-capping)mentioning

confidence: 81%

Survey and Trends in the Preparation of Chemically Bonded Silica Phases for Liquid Chromatographic Analysis

Buszewski¹,

Jezierska

Wełniak

et al. 1998

J. High Resol. Chromatogr.

145

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“…Several authors reported on the negative role played by residual unreacted polar groups on the silica surface in the chiral recognition process. [30][31][32][33] When residual aminopropyl groups have been suggested to be beneficial for enantioselectivity, no mechanism has been proposed. 34 It is interesting to note that in a recent report Balsells and Walsh 35 demonstrated that achiral ligands can promote chiral catalysis by organometallic complexes.…”

Section: Resultsmentioning

confidence: 98%

Mechanism of chiral recognition in the enantioseparation of 2‐aryloxypropionic acids on new brush‐type chiral stationary phases

et al. 2001

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New brush-type chiral stationary phases (CSP I-IV) comprising N-3,5,6-trichloro-2,4-dicyanophenyl-L-alpha-amino acids (1-4) were prepared by binding of chiral selectors 1-4 to gamma-aminopropyl silica gel. To check the role of excess free aminopropyl groups, CSP V was prepared by binding N-3,5,6-trichloro-2,4-dicyanophenyl-L-alanyl-(3-triethoxysilyl)propylamide to unmodified silica gel. The best separation of racemic 2-aryloxypropionic acids (TR-1-13) was obtained with CSP I; the -(-)-S enantiomer were regularly eluted first, as determined by a CD detector. The mechanism of chiral recognition implies a synergistic interaction of carboxylic acid analyte with the chiral selector and achiral free gamma-aminopropyl units on silica. In fact, CSP V, which is lacking an achiral aminopropyl spacer, shows a lower separation ability for 2-aryloxypropionic acids, but a similar enantioselective discrimination of esters TR-19-20, in comparison with CSP I. CSP I-IV retain unaltered separation ability after a few months of continuous work using a large number of various mobile phases.

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“…11,12 A 4.6 × 250 mm column was packed by conventional means (methanol slurry) and endcapped with hexamethyldisilazane. 13 The column containing CSP 2 was evaluated initially using 5% ethanol in dichloromethane (v/v) containing 0.5 g/L of ammonium acetate as the mobile phase. Data relevant to the separation of the enantiomers of a variety of β-blockers is given in Tables 1 and 2, several temperatures being used.…”

Section: Resultsmentioning

confidence: 99%

Separation of the Enantiomers of β-Blockers Using Brush Type Chiral Stationary Phase Derived from Conformationally Rigid α-Amino β-Lactam

Pirkle¹,

Lee

2010

Bulletin of the Korean Chemical Society

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A brush type chiral stationary phase (CSP 2) derived from α-amino β-lactam was prepared for the separation of the enantiomers of β-blockers. Compared to the CSP derived from α-amino phosphonate (CSP 1), in general, the conformationally rigid CSP 2 showed greater scope and much enhanced enantioselectivity for the resolution of β-blockers. The effect of various salt additives on enantioseparation of β-blockers in the mobile phase was investigated. The unusual effect of temperature on the chromatographic behaviors was observed on CSP 2. It also afforded appreciable increases in enantioselectivity without significantly affecting resolution, as the column temperature was reduced.

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The influence of end-capping on the enantioselectivity of a chiral phase

Cited by 51 publications

References 12 publications

Survey and Trends in the Preparation of Chemically Bonded Silica Phases for Liquid Chromatographic Analysis

Survey and Trends in the Preparation of Chemically Bonded Silica Phases for Liquid Chromatographic Analysis

Mechanism of chiral recognition in the enantioseparation of 2‐aryloxypropionic acids on new brush‐type chiral stationary phases

Separation of the Enantiomers of β-Blockers Using Brush Type Chiral Stationary Phase Derived from Conformationally Rigid α-Amino β-Lactam

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