• Title/Summary/Keyword: enantioselectivity

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Optimization of the Optical Resolution of Racemic $\alpha$-Methylbenzylamine Catalyzed by Enzymatic Reaction in Organic Media (유기용매에서 효소반응을 통한 라세믹 $\alpha$-Methylbenzylamine 광학적 분할의 최적화)

  • 강병영;김병기
    • KSBB Journal
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    • v.9 no.3
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    • pp.306-311
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    • 1994

  • Optical resolution of racemic ${\alpha}$-methylbenzylamine was carried out by using Bacillus licheniformis protease in organic media. Enantioselective amidation of racemic amino with an ester as an acyl donor was successfully employed to resolve the racemate. To enhance reaction rate and enantioselectivity, pH-adjustment by lyophilization of enzyme dissolved in buffer, colyophilization with salts or lyoprotectants, selection of solvents and molecular design of esters were investigated. The optimization of the resolution reaction achieved about 30-fold increase in initial reaction rate and about 12-fold increase in enantioselectivity, respectively.

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Enantiomeric Separation of Amino Acids Using N-alkyl-L-proline Coated Stationary Phase

  • Lee Sun Haing;Oh Tae Sub;Lee Hae Woon
    • Bulletin of the Korean Chemical Society
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    • v.13 no.3
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    • pp.285-289
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    • 1992

  • Enantiomeric separation of underivatized amino acids using N-alkyl-L-proline (octyl, dodecyl or hexadecyl) coated HPLC has been accomplished. The anchoring N-alkyl groups of L-proline provides a permanent adsorption of there solving chiral agent on the hydrophobic interface layer of a reversed phase. The factors controlling retention and enantioselectivity such as the Cu(II) concentration, pH of the eluent, the type and concentration of organic modifier in the hydroorganic eluent, and extent of coating were examined. The elution orders between D- and L-amino acids were consistent, L-forms eluting first, except histidine and asparagine. The extremely high enantioselectivity $(\alpha$ upto 13 for proline) is observed. The retention mechanism for the chiral separation can be illustrated by a complexation and hydrophobic interaction.

  • https://doi.org/10.5012/bkcs.1992.13.3.285 인용 PDF

Chiral Recognition Models of Enantiomeric Separation on Cyclodextrin Chiral Staionary Phases

  • 이선행;김병학;이영철
    • Bulletin of the Korean Chemical Society
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    • v.16 no.4
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    • pp.305-309
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    • 1995

  • The enantiomeric separation of several amino acid derivatives by reversed-phase liquid chromatography using two (R)-and (S)-naphthylethylcarbamate-β-cyclodextrin(NEC-β-CD) bonded stationary phases was studied to illustrate the chiral recognition model of the enantiomeric separation. The retention and enantioselectivity of the chiral separations with (R)-and (S)-NEC-β-CD bonded phases were compared with similar separations with the native β-CD stationary phases. Especially, the enantioselectivity and elution orders between the derivatized amino acid enantiomers are carefully examined. These results can be illustrated by the chiral recognition models involving inclusion complexation, π-π interaction, and/or hydrophobic interaction. Inclusion complexation and hydrophobic interaction of the naphthyl group of the NEC moiety seem to be major chiral recognition components in the enantiomeric separation of 2,4-dinitrophenyl amino acids and dabsyl amino acids on (R)-and (S)-NEC-β-CD columns. For dansyl amino acids, only the inclusion complexation is the dominant factor. Three different chiral recognition models containing π-π interaction, inclusion complexation and hydrogen bonding were proposed for the separation of the 3,5-dinitrobenzoyl amino acid enantiomers, depending on the size and shape of amino acids.

  • https://doi.org/10.5012/bkcs.1995.16.4.305 인용 PDF