• Bulletin of the Korean Chemical Society
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• 제25권4호
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• pp.553-556
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• 2004

In this study we have performed ab initio computer simulations to investigate the conformational characteristics of the tetraethyl (1) and triethyl ester (2) of p-tert-butylcalix[4]arene. The structures of different conformational isomers for each compound have been optimized using ab initio RHF/6-31G methods. After optimization, B3LYP/6-31+G(d,p) single point calculations of the final structures are done to include the effect of electron correlation and the basis set with diffuse function and polarization function. Relative stability of tetraethyl ester (1) of p-tert-butylcalix[4]arene is in following order: cone (most stable) > partial cone > 1,3- alternate > 1,2-alternate isomer. Relative stability of triethyl ester (2) of p-tert-butylcalix[4]arene is in following order: cone (most stable) > 2-partial cone > 1-partial cone > 3-partial cone ~ 1,3-alternate ~ 1,2- alternate isomer.

• 분석과학
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• 제16권4호
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• pp.333-338
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• 2003

Inclusion selectivity of a three-dimensional piperazine-ligated cyanocadmate host complex, $[Cd_x(CN)_{2x}\{HN(CH_2CH_2)_2NH\}_y]{\cdot}zG$, has been investigated for benzene (B), toluene (T), ethylbenzene (E), o- (O), m- (M), and p-xylene (P) isomers as the aromatic guest molecules. From the binary, ternary and quarternary guest mixtures of E and xylene isomer (X), the order of inclusion selectivity in the host complex is O>E>P>M. From the binary to quinary BTX mixtures, the order of preference in the complex is seen to be B>T>O${\gg}$P>M.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.386-389
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• 2003

Pseudomonas savastanoi BCNU 106은 o-xylene 뿐만 아니라 m-, p-xylene을 분해할 수 있는 능력을 나타내었고, 비교적 높은 농도인 10 mM toluene, 2 mM o-xylene, 10 mM m-xylene, 10 mM p-xylene에서 높은 분해율을 보여주었다. Pseudomonas savastanoi BCNU 106의 resting cell을 이용하여 o-xylene의 중간대사산물을 GC-MS를 통하여 조사하였다. 주로 2-methylbenzyl alcohol, 2-methylbenzoic acid 등이 발견되었다.

• 한국응용과학기술학회지
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• 제3권2호
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• pp.23-28
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• 1986

The sulfuric acid sulfonation mixtures of 2-aminonaphthalene, contained 2-aminonaphthalene, Dahl's acid, Broenner's acid, amino-F-acid and Baden acid, can be determined quantitatively by multicomponent spectrophotometric analysis. The analysis was performed in diluted sodium hydroxide aqueous solution and based on the ultraviolet absorption of the sodium salts of each isomers. The determination of quantity of each isomers was performed by subjection the absorbances of the unknown mixture and of its constituents, gathered at a large number of wavelengths, to a least square treatment by an electronic personer computer. This method provided a rapid analysis of such complex mixture, and the standard deviation was ${\pm}1.65$ mole %.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.251.3-252
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• 2002

The present study was performed to compare the cardiovascular adverse effects of verapamil. KR30031 and their each optical isomers, and also to measure their ability to overcome multidrug resistance (MDR). R-isomer of KR30031 (R-KR30031) was equipotent with S-isomer of KR30031 (S-KR30031) and 25 fold less potent than R-isomer of verapamil (R-verapamil) in relaxing the aorta isolated from rat (EC50: 11.8, 10.2 and 0.46 ${\mu}$M, respectively). (omitted)

• Archives of Pharmacal Research
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• 제24권5호
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• pp.402-406
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• 2001

Gas chromatographic method was investigated for the chiral separation of several $\beta$-blockeros(atenolol, betaxolol, bisoprolol, metoprolol and pindolol) using (-)-$\alpa$-methoxy-$\alpa$-(trifluoromethyl)phenylacetyl chloride as a chiral derivatizing agent for amino group. Prior to N-acylation, hydroxyl group was converted into O-silyl ethers by react with N-methyl-H-(taimethylsilyl)trifluoroacetamide. The reaction was selective and rapid and the diasteromeric derivatives were well separated by capillary gas chromatography. (R)-isomers were eluted faster than (S)-isomers when (-)-$\alpa$-methoxy-$\alpa$-(trifluoromethyl)phenylacetyl chloride was used as the chiral derivatizing agent. But in the opposite sequence when (+)-$\alpa$-methoxy-$\alpa$-(trifluoromethyl)phenylacetyl chloride was used. No racemization was found during the reaction.

• 한국대기환경학회지
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• 제22권6호
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• pp.842-850
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• 2006

The role of chlorination reactions in the formation of polychlorinated dibenzofurans (PCDFs) in a municipal waste incinerator was assessed using a chlorination model for predicting PCDF isomer distributions. Complete distributions of PCDF congeners were obtained from a stoker-type municipal waste incinerator operated under 13 test conditions. Samples were collected from the flue gas prior to the gas cleaning system. While total PCDF yields varied by a factor of five to six, the distributions of congeners were similar. A chlorination model, dependent only on the observed distribution of monochlorinated isomers, was developed to predict the distributions of poly-chlorinated isomers formed by chlorination of dibenzofuran (DF). Agreement between predicted and measured PCDF isomer distributions was high for all homologues, supporting the hypothesis that DF chlorination can play an important role in the formation of PCDF byproducts.

• Archives of Pharmacal Research
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• 제23권2호
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• pp.104-111
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• 2000

Stereochemical isomers with hydroxy groups were synthesized by reacting 2-(dimethoxy-methyl)cyclohexanone with propargylmagnesium bromide. The stereo chemical structures were identified by NMR spectral interpretation and the geometry optimization. To assist the NMR interpretation, geometry optimization based on semi-empirical AM1 and PM3 methods was applied. Throughout this study, the structures of the two isomers were all determined and $^{1}H$ and $^{13}C$ NMR spectra were fully assigned. It was proven that the less polar isomer is an axial alcohol and the more polar one is an equatorial alcohol.

• 약학회지
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• 제37권2호
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• pp.113-118
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• 1993

3-Phenyl-5, 6, 7, 8-tetrahydrothiazolo[3, 2-$\alpha$][1, 3]diazepine, which has pharmaceutical activities, was reacted with phenyl isothiocyanate to give 3-phenyl-9-phenyl(thiocarbamoyl)-5, 6, 7, 8-tetrahydrothiazolo[3, 2-$\alpha$][1, 3]diazepi nium-betaine. New biheterocyclic compounds were prepared by the ring transformation reaction of the above reactive betaine with $\alpha$-haloesters and $\alpha$-haloketones such as ethyl bromoacetate, methyl bromoacetate, chloroacetone, and 4'-methoxyphenacyl bromide, respectively. In each ring transformation reaction, two major products supposed to be geometrical isomers were obtained.

• Bulletin of the Korean Chemical Society
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• 제30권5호
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• pp.1127-1130
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• 2009

The effects of different dihydroxybenzoic acid (DHB) isomers, when used as matrix materials in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), were investigated in analyses of polyethylene glycol (PEG) polymers. PEG polymers ranging from 400 to 8,000 Da were prepared in different DHB isomer matrices using solvent-based and solvent-free methods. PEG samples were detected only in matrices of 2,3-DHB, 2,5-DHB, and 2,6-DHB while the most intense peaks were observed using 2,6-DHB in both solvent-free and solvent-based preparations.