• YAKHAK HOEJI
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• v.33 no.2
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• pp.129-139
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• 1989

New diamide chiral stationary phases of four systematically substituted optically active N-(N-benzoyl-L-amino acid)-anilide synthesized from L-valine, L-leucine, L-isoleucine, and L-phenylalanine were described. The behaviors of these diamides as optically active stationary phases for the separation of N-trifluoroacetyl-D,L-amino acids were examined with respect to separation factors(${\alpha}$) and thermodynamic properties of interaction. The separation of twelve N-trifluoroacetyl-D,L-amino acid isopropyl esters were improved by the order of N-(N-benzoyl-L-leucyl)-anilide>N-(N-benzoyl-L-isoleucyl)-anilide>N-(N-benzoyl-L-valyl)-anilide>N-(N-benzoyl-L-phenylalanyl)-anilide. Eight amino acid derivatives with non-polar R-group and threonine, serine, aspartic acid, and glutamic acid enantiomers were separated on N-(N-benzoyl-L-leucyl)-anilide as chiral stationary phase with good separation factor between 1.07-1.25. The separation factors decreased with respect to increasing column temperature. Possible working temperature of diamide phase was between $130-190^{\circ}C$ for N-(N-benzoyl-L-phenylalanyl)-anilide and $130-180^{\circ}C$ for other three diamide phases. The differential Gibb's free energy (${\Delta}{\Delta}G$) of enantiomers was in the range of -100--180 cal/mol for ten amino acids and -40--60 cal/mol for alanine and aspartic acid.

• Korean Journal of Materials Research
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• v.3 no.1
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• pp.72-83
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• 1993

Abstract A new and versatile method for the preparation of biphenyl thioester series was studied in ferroelectric liquid crystal. Many of the resulting liquid crystal showed a ferroelectric chiral smectic C phase in addition to the chiral nematic and smectic A phase. We obtained a large spontaneous polarization exceeding $10^{-8}$C/c$m^2$ in new biphenyl thioester series. It was found that the size and polarity of the substituent in chiral carbon influenced the magnitude of spontaneous polarization. The series allow us to determine the influence of substituent size in the chiral carbon the existence and the stability of the Sc* phase.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.804-807
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• 1999

New copper complexes with a ligand, L(L=N,N'-cyclohexane bis(ferrocenylmethylene)amine) which was obtained from ferrocene carboxaldehyde and 1,2-diaminocyclohexane with a mole ratio of 2:1, were prepared and characterized. Those were adapted to asymmetric catalysis. The copper(II) complexes do not work in cyclopropanation of styrene and ethyl diazoacetate but copper(I) complex catalyzes. The Cu(I)LOTf (OTf=trifluorometanesulfonate) shows a good regioselectivity giving high trans to cis ratio of up to 80:20.

• Journal of the Korean Chemical Society
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• v.49 no.3
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• pp.283-287
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• 2005

• YAKHAK HOEJI
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• v.32 no.3
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• pp.170-176
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• 1988

The resolution of five amino acids derivatives by gas chromatography on phenylthiohydantoin derivatives as chiral stastionary phase was investigated. (S)-5-isopropyl, isobutyl, (sec)-butyl and benzoyl derivatives of $N^3-phenyl-2-thiohydantoin$ were synthesized from L-valine, L-leucine, L-isoleucine and L-phenylalanine, respectively. The phases were employed at several column temperatures ($140^{\circ}C{\sim}210^{\circ}C$). The separation factors were compared with each stationary phase with varying R groups. The possible mechanism of chiral recognition was investigated by NMR technique.

• Applied Biological Chemistry
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• v.37 no.1
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• pp.25-29
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• 1994

2-methyl-5(S)-hexanolide(1); the major component of pheromonal blend of the male carpenter bee was synthesized via Homer-Emmons reaction from Ethyl(S)-3-hydroxybutyrate(2a) which had been obtained by Baker's Yeast reduction in overall yield 39%.

• Journal of the Korean Society of Industry Convergence
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• v.12 no.3
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• pp.143-147
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• 2009

The enantioselective reduction of representative prochiral alkyl-aryl ketones with a new chiral alkoxy-amine-aluminum derivatives from aluminum hydride and ${\alpha},{\alpha}$-diphenyl-${\beta}$-amino alcohols, such as (S)-(-)-2-amino-3-methyl-1,1-diphenylbutan-1-ol(AMDPB) and (S)-(-)-2-(diphenylhydroxy-methyl)pyrrolidine(DPHMP), in THF at $0^{\circ}C$ was studied. In the reduction of alkoxy-amine-aluminum derivatives, acetophenone, propiophenone, isopropiophenone, and butyrophenone are reduced to corresponding aromatic secoundary alcohols with 34~60 % enantiomeric excess of (S)-isomers. For such ketones, the optical induction was enhanced by increasing a size of alkyl groups.

• KSBB Journal
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• v.20 no.3
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• pp.177-182
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• 2005

Simulated moving bed (SMB) chromatography was used in the petrochemical industry in the 1960s and its use has been widened to separate chiral compounds in the 1990s. Chiral stationary phase (CSP) is the key component in SMB for the separation of the chiral compounds. CSP has been developed for the analytical use in HPLC, however, its development successfully adapted for the preparative use in SMB chromatography. This review covers the present state-art technology of CSP for SMB chromatography in terms of selectivity, stability, and capacity.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.2
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• pp.113-124
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• 2000

It is well known that the characteristics of liquid crystal polymer composite(LCPC) films are possessed of large-area and flexible display, polarizer free, high contrast, wide angle of visual filed and high responsiveness. In this study, we have investigated to the best optimal mixing rates chiral nematic liquid crystals and UV-curable resins having different properties acrylate moleculars. The purpose of this study has been the development of new functional application with liquid crystal polymer composite films. For example the films were applied a new thermal sensor. In results, best phase separation behaviors turned out liquid crystal/monomer/oilgomer mixture system.

• Analytical Science and Technology
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• v.9 no.1
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• pp.52-61
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• 1996

Detectable levels of several free D-amino acids were found in some food. This was accomplished by using a column switching method. The determination of total amount of D- and L-amino acids was based on an achiral separation with a $C_{18}$ column. The level of D-amino acids to L-amino acids was determined by the column switching system including the postcolumn reaction detection of the amino acids derivatized with O-phthalaldehyde. The chiral separation of the postcolumn detection system was carried out with chiral crown ether column. This system was applied for the micro-determination of D-amino acids in food such as soy sauce, fermented soy bean and beans. It turned out that the sampling process is critical for the trace analysis of D-amino acids under this achiral / chiral coupled-column system. It was found that commercial soy sauce contained 42ppm, conventional soy sauce 102ppm, fermented soy bean 8.34mg per 1g and bean 2.87mg per 1g sample for phenylalanine. D-phenylalanine was found 0.67% in commercial soy sauce, 0.34% in conventional soy sauce, less than 1.81% in fermented soy bean, and Jess than 2.82% in bean.