• Journal of the Korean Chemical Society
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• v.26 no.3
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• pp.188-193
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• 1982

Four new thermotropic copolyesters were prepared and their liquid crystal properties were investigated by differential scanning calorimetry and on a hot-stage of a polarizing microscope. Three copolyesters had same mesogenic unit, triad aromatic ester structure, interconnected through a random combination of either odd-even, or odd-odd, or even-even number of methylene groups in the polymethylene flexible spacers. Another random copolyester consisted of mesogenic units of 1 : 1 mixture of central methyl-and bromohydroquinone moieties with two flanking p-oxybenzoate units connected by decamethylene spacer. All of the polyesters formed nematic liquid crystal phase upon melting. The transitions for melting and nematic ${\to}$ isotropic transformations could be reversibly observed by DSC as well as by microscopic study. The thermodynamic properties for their liquid crystal ${\to}$ isotropic phase transitions were discussed in relation to their chemical structures.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.3
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• pp.308-313
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• 1992

Volatile aromatic compounds collected from raw and roasted mugwort (Artemisia asictica nakai) leaves by the Tenax trap and some major volatile compounds were separated and identified by GC-MS. The identified compounds were tested for the antimutagenic and mutagenic activities against aflatoxin B$_1$(AFB$_1$) using their authentic compounds. Six compounds (myrcene, cineole, camphor, caryophyllen, coumarin, and farnesol) showed antimutagenic activities, but 2-pyrrolidine and thujone showed mutagenic activities. 1-Acetylpiperidine formed during roasting mugwort leaves exhibited mutagenic activities. When the mutagens and antimutagens were mixed, the mixture reduced the mutagenicity of AFB$_1$. These results suggested that the extract of mugwort leaves is not mutagenic and so the mugwort leaves might be used as a food and as medicinal sources without mutagenicity.

• Bulletin of the Korean Chemical Society
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• v.32 no.7
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• pp.2260-2266
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• 2011

4-Chlorotetrazolo[1,5-a]quinoxaline (III) was synthesized by azide (2+3) cycloaddition of 2,3-dichloroquinoxaline (II). Compound (III) on further refluxing with hydrazine hydrate furnished 4-hydrazinotetrazolo[1,5-a]quinoxaline (IV). Further refluxing of (IV) with different aromatic aldehydes in methanol yielded corresponding Schiff's bases V(a-j). Various 4-aminotetrazolo[1,5-a]quinoxaline based azetidinones VII(a-j) were synthesized by stirring the compounds V(a-j), at low temperature, with equimolar mixture of chloroacetylchloride & triethylamine in dry benzene, while 4-aminotetrazolo[1,5-a]quinoxaline based thiazolidinones VIII(a-j) were synthesized by refluxing Schiff's bases V(a-j) with thioglycolic acid in oil-bath. The structures of all the compounds were confirmed on the basis of $^1H$-NMR & FT-IR spectral data. All the newly synthesized compounds were screened for in-vitro antimicrobial activity against E. coli, S. aureus, K. pneumoniae & P. aeruginosa & antifungal activity against C. albicans. Few of them have exhibited the promising activity.

• Journal of Environmental Health Sciences
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• v.20 no.1
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• pp.39-53
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• 1994

This study aims to investigate organic compounds and its toxicity by Ames test and chromosomal aberration in the water of the Nak Dong River. Six sampling sites such as Goryung, Hagueun, Maelie, Duksan, Haedong and Myungiang were selected for these pur15oses. 200 l water samples were absorbed on XAD-2 resin columns (2.5X30cm), eluted with organic solvents mixture of acetone: cyclohexane and then dried under vacuum condition. The extracts from the XAD-2 resin was injected into GC/MS and 184 organic compounds were identified such as aldehydes, aromatic compounds, ketones, phenols, hydrocarbons, alcohols, carboxylic acids, alkanes and some unknowns. The US EPA priority pollutants such as naphthlene, bis(2-ethylhexyl)phthalate and other pollutants, 1,2-diethyl benzene, 1,2,3,4-tetrahydronaphthalene and cyclohexanol were detected in these samples. The concentration of chemical pollutants such as 1,2-diethyl benzene, nephthalene, 1,2,3,4-tetrahydronaphthalene, bis(2-ethylhexyl)phthalate and cyclohexanol were ranged into 1.228 $\mu$g/l, 298 $\mu$g/l, 30.191 $\mu$g/l, 1.147 $\mu$g/l and 2.839 $\mu$g/l, respectively. The mutagenic activity of XAD-2 extracts were tested on Salmonella typhimurium TA 98, TA 100, TA 1535 and TA 1537 and then exhibited strong mutagenic activity against S. typhimurium TA 98 and TA 100 in the presence of S$_9$. Amon them, bis(2-ethylhexyl)phtalate and 1,2-diethyl benzene showed the most strongest mutagenic activity against S. typhimurium TA 98 and TA 100 in the presence of S$_9$. On the other hands, chromosomal aberration of XAD-2 extracts in the human blood cells were not occurred by the sampling water at Goryung, Hagueun, Maelie and Duksan, Chromosomal aberration were also not occurred by the each concentration of 0.05, 0.1 amd 0.3 mg/l of each 1,2-diethyl benzol, bis(2-ethylhexyl)phthalate, naphthalene, phenol, cyclohexanol and benzothiazol test solution.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.6
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• pp.801-805
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• 2003

Volatile flavor components in chestnut (Castanea crenate Sieb. et Zucc.) flower were collected by SDE method using the mixture of n-pentane and diethylether as an extract solvent and were identified by GC-FID and GC/MS. A total of 122 components including 35 alcohols,5 hydrocarbons,20 terpene and derivatives,7 ketones, 24 aldehydes, 12 esters, 4 acids, 3 furans, and 2 miscellaneous were identified from total volatile extract of chestnut. Alcohols were comprise 36.58% of volatile extract and dominant constituents and the main components of flower volatiles were 1-phenylethanol (18.6%), (E)-geraniol, tricosane, heneicosane, benzyl alcohol, acetophenone and 2-phenylethanol as aromatic alcohols and odd carbon hydrocarbons. Especially 1-phenylethanol and acetophenone would be applicable to the markers to ascertain floral origin of chestnut honey. The powerful animal and floral notes of chestnut flower were characterized by compounds including nonanal.

• Analytical Science and Technology
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• v.15 no.5
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• pp.393-398
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• 2002

A method to determine simultaneously fluorene and anthracene in aqueous solution by synchronous fluorescence spectrometry has been studied. The emission characteristics and optimum wavelength interval (${\Delta}{\lambda}$) for synchronous spectra of fluorene and anthracene in aqueous solution were investigated. The optimum wavelength interval (${\Delta}{\lambda}$) was found to be 50 nm. The calibration curve for fluorene and anthracene in the synthetic mixture solution of both compounds was linear over the range from $5.0{\times}10^{-8}M$ to $1.0{\times}10^{-3}M$ and from $5.0{\times}10^{-8}M$ to $1.0{\times}10^{-3}M$ for fluorene and anthracene, respectively. The detection limit was $3.0{\times}10^{-9}M$ and $7.0{\times}10^{-9}M$, for fluorene and anthracene, respectively under the optimal wavelength interval.

• Applied Chemistry for Engineering
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• v.1 no.1
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• pp.73-82
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• 1990

Rosin-maleic anhydride adduct (RMA) was synthesized from rosin and maleic anhydride. The polyamideimides were obtained by reacting the adduct with two aromatic diisocyanates using sodium methoxide as catalyst. The yield and the inherent viscosity of polymers obtained by the reaction in NMP solvent were low because of the possible reaction of NMP solvent with diisocyanate monomer. The polymers were synthesized in solvent mixture of NMP and cosolvents such as xylene, acetophenone, benzonitrile, and nitrobenzene in order to minimize the side reaction of NMP with diisocyanates. The yield of polymer obtained by the reaction in NMP-nonpolar cosolvent mixtures was about 70% and that obtained by the reaction in NMP-polar cosolvent mixtures was over 90%, respectively. The polymers were either amorphous or poorly cystalline, and soluble only in highly polar solvents. The inherent viscosity of polymers ranges from 0.12-0.26dl/g. The results of thermal analysis showed that the polymer had good thermal stability with initial decomposition temperature over $330^{\circ}C$.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.530-535
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• 1996

Nitrochlorobenezenes are used as intermediates for dyes, pharmaceuticals and perfumes. By far the most common industrial nitration process employs a mixture of nitric acid and sulfuric acid. Due to water formed in the reaction, the mixed acid nitration requires subsequent separation of spent acid, mainly dilute sulfuric acid. In the stream of ozone, nitrogen dioxide can be used as a nitrating agent for the nitration of chlorobenzene. With 6eq of $NO_2$ and 1.0eq/hr of ozone flow, the mononitration of chlorobenzene ended within 3hr at $0^{\circ}C$ while the dinitration of chlorobenzene did in 12hr. This method can be employed for the nitration of some aromatic compounds to reduce pollutants from the present mixed-acid process.

• Journal of Environmental Health Sciences
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• v.26 no.2
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• pp.97-107
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• 2000

PCBs [Polychlorinated biphenyls] are halogenated aromatic compounds with the empirical formula C12H10-nCln(n=1~10), and are a mixture of possible 209 different chlorinated congeners. PCBs were widely used as dielectric fluids for capacitors, transformers, plasticizers, lubricant inks, and paint additives. once released into the environment, PCBs persist for years because they are so resistant to degradation. In addition to their high degree of lipophilicity. In 1970s, the worldwide production of PCBs seem to be still in use. The environmental load of PCBs was prohibited since 1983 in Korea. In spite of these actions, many PCBs seem to be still in use. The environmental load of PCBs will continue to be recycled through air, land, water, and the biosphere for decades to come. This study was conducted to measure the concentrations of PCBs I the serum samples of 112 women by GC/MSD(Hewlett Packard 5897 Gas Chromatography-Mass Chromatography Detector) and CG/ECD(Hewlett Packard 5890 series-II gas chromatography-Electron capture detector, U.S.A). The main results of this study were as follows; The mean and standard deviation of serum PCBs were 3.613, 0.759 ppb, respectively and median of it was 3.828 ppb. The correlation coefficients of the concentrations of 13 PCB congeners ranged from 0.7913 to 0..9985 and were significantly correlated between each items(p=0.0001). The PCB concentrations were positively associated with age(simple linear regression; R2=0.86, =0.08023, p<0.001) and with total lipids in serums(simple linear regression; R=0.7058, =0.00486, p<0.001). The age adjusted model (Y=$\beta$0+$\beta$1age+$\beta$2X) was applied for possible predictors of PCBs levels in serum. For BMI(Body Mass Index), major residential area, and fish, meat, and dairy consumption, there was no association with PCBs levels, Also there was negative association for the number of pregnancy and lactation period with PCBs levels.

• Bulletin of the Korean Chemical Society
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• v.13 no.5
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• pp.531-537
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• 1992

The approximate rates and stoichiometry of the reaction of excess potassium 2-thexyl-1,3,2-dioxaborinane hydride(KTDBNH) with 55 selected compounds containing representative functional groups under standardized conditions (tetrahydrofuran, TEX>$0^{\circ}C$, reagent : compound=4 : 1) was examined in order to define the characteristics of the reagent for selective reductions. Benzyl alcohol and phenol evolve hydrogen immediately. However, primary, secondary and tertiary alcohols evolve hydrogen slowly, and the rate of hydrogen evolution is in order of $1^{\circ}$> $2^{\circ}$> $3^{\circ}$. n-Hexylamine is inert toward the reagent, whereas the thiols examined evolve hydrogen rapidly. Aldehydes and ketones are reduced rapidly and quantitatively to give the corresponding alcohols. Cinnamaldehyde is rapidly reduced to cinnamyl alcohol, and further reduction is slow under these conditions. The reaction with p-benzoquinone dose not show a clean reduction, but anthraquinone is cleanly reduced to 9,10-dihydro-9,10-anthracenediol. Carboxylic acids liberate hydrogen immediately, further reduction is very slow. Cyclic anhydrides slowly consume 2 equiv of hydride, corresponding to reduction to the caboxylic acid and alcohol stages. Acid chlorides, esters, and lactones are rapidly and quantitatively reduced to the corresponding carbinols. Epoxides consume 1 equiv hydride slowly. Primary amides evolve 1 equiv of hydrogen readily, but further reduction is slow. Tertiary amides are also reduced slowly. Both aliphatic and aromatic nitriles consume 1 equiv of hydride rapidly, but further hydride uptake is slow. Analysis of the reaction mixture with 2,4-dinitrophenylhydrazine yields 64% of caproaldehyde and 87% of benzaldehyde, respectively. 1-Nitropropane utilizes 2 equiv of hydride, one for hydrogen evolution and the other for reduction. Other nitrogen compounds examined are also reduced slowly. Cyclohexanone oxime undergoes slow reduction to N-cyclohexylhydroxyamine. Pyridine ring is slowly attacked. Disulfides examined are reduced readily to the correponding thiols with rapid evolution of 1 equiv hydrogen. Dimethyl sulfoxide is reduced slowly to dimethyl sulfide, whereas the reduction of diphenyl sulfone is very slow. Sulfonic acids only liberate hydrogen quantitatively without any reduction. Finally, cyclohexyl tosylate is inert to this reagent. Consequently, potassium 2-thexyl-1,3,2-dioxaborinane hydride, a monoalkyldialkoxyborohydride, shows a unique reducing characteristics. The reducing power of this reagent exists somewhere between trialkylborohydrides and trialkoxyborohydride. Therefore, the reagent should find a useful application in organic synthesis, especially in the field of selective reduction.