• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.637-641
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• 2006

Although chiral separation has been one of the main topics of chromatographic practice for over twenty-five years, it still presents many difficulties. In this work, the ultrasonic dependence of chiral resolution was investigated at various temperatures to improve resolution and reduce analysis time. The chiral resolution was performed on recently commercialized two HPLC chiral stationary phases (CSP 1 and CSP 2) with the analogues of racemic N-acylnaphthylethylamines (1a-d) and racemic amino acid derivatives (2a-c, 3a-c) as analytes. The CSP 1 was prepared from a (R)-N-(3,5-dinitrobenzoyl)phenylglycinol and the CSP 2 was prepared from a (S)-N-3,5-(dinitrobenzoyl) leucine. From the comparison of the chromatographic results under sonic condition with those under non-sonic condition, we found that the ultrasound decreased the elution time in chiral chromatography at all temperatures and improved the enantioselectivity at high temperature (45, 50, 60 ${^{\circ}C}$).

• Analytical Science and Technology
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• v.24 no.5
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• pp.360-367
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• 2011

Optical purities of 10 commercialized naproxens prepared from eight Korean drug companies were examined by an optimized chiral HPLC condition. The Chiralcel OD-H column and ChiralHyun-LE(S)-1 column were used as chiral stationary phases and the mixed eluent of hexane/isopropanol/acetic acid as 100:2.85:0.1 was used as a mobile phase for effective enantioseparation. Optical purity values of most samples were higher than 97 percents, only one of them was about 95 percents. The average relative standard deviation of them appeared very small (0.034%).

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1291-1294
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• 2002

Various racemic N-protected ${\alpha}-amino$ acids such as N-t-BOC-(tert-butoxycarbonyl), N-CBZ-(benzyloxycarbonyl) and N-FMOC-(9-fluorenylmethyloxycarbonyl) ${\alpha}-amino$ acids were resolved as their anilide and 3,5-dimethylanilde derivatives on an HPLC chira l stationary phase (CSP) developed by modifying a commercial (S)-leucine CSP. The chromatographic resolution results were compared to those on the commercial (S)-leucine CSP. The resolutions were greater on the modified CSP than those on the commercial CSP with only one exception, the resolution of N-t-BOC-phenylglycine anilide. In addition, the chromatographic resolution behaviors were quite consistent except for the resolution of N-protected phenylglycine derivatives, the (S)-enantiomers being retained longer. Based on the chromatographic resolution behaviors and with the aid of CPK molecular model studies, we proposed a chiral recognition mechanism for the resolution of N-protected ${\alpha}-amino$ acid derivatives. However, for the resolution of N-protected phenylglycine derivatives, a second chiral recognition mechanism, which competes in the opposite sense with the first chiral recognition mechanism, was proposed. The two competing chiral recognition mechanisms were successfully used in the rationalization of the chromatographic behaviors for the resolution of N-protected phenylglycine derivatives.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.396.3-397
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• 2002

Because of the differences in biological and pharmacological properties between enantiomers of chiral acidic non-steroidal antiinflammatory drugs (NSAIDs) in human body. accurate determinations of their optical purities have been in great need. Racemic ibuprofen. tiaprofen. suprofen. flubiprofen and napoxen were reacted with (1R. 28. 5R)-(－)-menthol to convert them to corresponding diastereomeric (1R. 2S. 5R)-(－ )-menthyl esters. (omitted)

• Bulletin of the Korean Chemical Society
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• v.27 no.4
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• pp.589-592
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• 2006

• Bulletin of the Korean Chemical Society
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• v.29 no.9
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• pp.1850-1852
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• 2008

• Bulletin of the Korean Chemical Society
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• v.25 no.11
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• pp.1699-1702
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• 2004

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.215.1-215.1
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• 2003

A various ${\alpha}$-arylmethylpropionic acids(profen) have been widely used as non-steroidal anti-inflammatory drugs for the relief of acute and chronic rheumatoid arthritis and osteoarthritis, as well as for other connective tissue disorders and pains. Example is fenoprofen, ibuprofen, ketoprofen, and naproxen. All are chiral and, except for naproxen and ibuprofen, are marketed in racemic form. Enantioseparations of profens have been of considerable interest becaus their anti-inflammatory and analgesic effects have been attirbuted almost exclusively to their (S)-enantiomer. (omitted)

• YAKHAK HOEJI
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• v.32 no.2
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• pp.112-116
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• 1988

The resolution of N-trifluoroacetyl (N-TFA) ter-isopropylesters of Ala, Ile, Leu, Val and Phe by gas chromatography on the (S)-5-isobutyl-$N^3$-phenyl-2-thiohydantoin as stationary phase was investigated. The phase was employed at several column temperatures $(140^{\circ}C{\sim}200^{\circ}C)$ and the separation factors were $1.18{\sim}1.45$ range for five amino acid enantiomers. The possible mechanism of chiral recognition was investigated by NMR technique and the association constant$(K_c)$ was calculated as 201.3(r=0.98) for alanyl derivative.

• Bulletin of the Korean Chemical Society
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• v.13 no.3
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• pp.280-285
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• 1992

Enantiomeric separation of free amino acids has been achieved by a reversed phase liquid chromatography with addition of a Cu(Ⅱ) complex of N-alkyl-L-proline (alkyl: propyl, pentyl or octyl) to the mobile phase. The amino acids eluted were detected by a postcolumn OPA system. N-alkyl-L-proline was prepared and used as a chiral ligand of Cu(Ⅱ) chelate for the enantiomeric separation. The concentration of the Cu(Ⅱ) chelate, the organic modifier and pH affect the enantiomeric separation of free amino acids. The retention behaviour, varied with change in pH and the concentration of the Cu(Ⅱ) chelate, was different compared with those of the derivatized amino acids. The elution orders between D- and L-forms were consistent except histidine showing that L-forms elute earlier than D-forms. The retention mechanism for the enantiomeric separation can be illustrated by the stereospecificity of the ligand exchange reaction and the hydrophobic interaction between the substituent of amino acids and reversed phase, $C_18$.