• Korean Journal of Environmental Agriculture
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• v.11 no.1
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• pp.59-66
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• 1992

An enzyme immunoassay(EIA) was developed for the analysis of insecticide endosulfan and its degradation products. The sensitivity and specificity of the antibody produced were examined. Optimal conditions in the ELISA system for residue analysis were also discussed. A mixed suspension of endosulfan-hemocyanin conjugate(ES-KLH) 1.1 mg/ml and Freund's adjuvant was injected subcutaneously to white rabbits and then collected antisera were tested for titers by indirect ELISA(1/24,000). Because of difficulties in the synthesis of endosulfan peroxidase conjugate, amine derivative of endosulfan-diol was synthesized and it showed 40% of conjugate yields(2mg/ml of conjugate). the highest sensitivity obtained enzyme-conjugate was a concentration of 200ng/ml. The detection limit of endosulfan in ELISA system was 5 ppb on the standard curve. In application of ELISA for residue analysis, the recoveries were really 100% both in the spiked soil and apple sample regardless of endosulfan concentration treated. On the other hand, chlorinated hydrocarbons of similar structure with endosulfan showed low cross-reactivity$(2.2%{\sim}29.2%).$

• Polymer(Korea)
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• v.38 no.4
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• pp.441-448
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• 2014

Polyurethane/melamine phosphate composite foam (MP-PUF) was prepared from poly(adipate)diol/melamine phosphate composite (f=2), polyether-polyol (f=4.6), and PMDI (f=2.5). The thermal properties of MP-PUF such as morphology, closed-cell content, thermal conductivity, and thermal stabilities were characterized. Water was used as a blowing agent, and the composition of melamine phosphate (MP) was maintained at $1.43{\pm}0.3wt%$ of MP-PUF. As the content of water increased, the thermal conductivity of pure polyurethane foam (PUF) decreased, whereas the thermal conductivity of MP-PUF increased. The thermal stabilities of the PUF and the MP-PUF were maximized at 5 php $H_2O$, and then decreased at the higher $H_2O$ contents. The thermal stabilities of MP-PUF were greatly enhanced due to the synergetic effect of MP and urea, which was generated during the blowing process. The temperature of 50% residual mass of MP-PUF increased to $370{\sim}450^{\circ}C$ and the temperature of 30% residual mass exceeded over $700^{\circ}C$. Compared to the PUF, the temperature of 50% residual mass and 30% residual mass were higher than 25 and $70^{\circ}C$, respectively.

• Applied Biological Chemistry
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• v.19 no.1
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• pp.1-23
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• 1976

The female moths of Lepidoptera comprising over 1,000,000 described species possess long-chain unsaturated alcohols or esters as the typical structure of potential sex attractants. In this experiment, various stereoisomers of $C_{16}-unsaturated$ acetates were synthesized for potential sex attractants; e.g., $CH_3(CH_2)_mCH=CH(CH_2)_nOR$ (m=0-12, n=1-13, R=H and $-COCH_3$). Seventeen acetates were spectrometrically examined so that the data would provide a ready catalog of gas chromatography and mass spectrometric data for comparison with natural insect sex attractants. Exclusively cis and trans isomers were obtained by the catalytic and chemical reduction methods, respectively. Commercially available $CH_3(CH_2)_mBr,\;CH_3(CH_2)_mC{\equiv}CH,\;HC{\equiv}C(CH_2)_nOH\;and\;HO(CH_2)_n\;OH$ were used for the synthetic starting material. 1-Alkynes, $CH_3(CH_2)_m\;C{\equiv}CH$ exceeding nine methylene groups did not condense with alkyl dihalides. The yield of coupling products was gradually decreased with increasing the molecular weight of diols. In the coupling reaction of $BrCH_2CH_2$ OTHP with acetylene gas, the tetrahydropyranyl ether of bromohydrin produced undesirable elimination product. In this experiment, it seems that p-toluenesulfonic acid is greatly favoured hydrolyzing agent over dilute sulfuric acid in the hydrolysis of the tetrahydropyranyl ether of long-chain alkynols.

• Journal of the Korean Chemical Society
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• v.54 no.3
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• pp.261-268
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• 2010

In this account, three synthetic methodologies that serve as the basis for new strategies for the preparation of selected natural products are briefly introduced. One process, involving ruthenium carbene catalyzed ring rearrangement metathesis developed by Grubbs and his coworkers, transforms alkene-tethered cycloalkenes to thermodynamically more favored alkene-tethered cycloalkenes. Another ruthenium carbene promoted reaction, referred to as dienyne metathesis, was uncovered in early studies by Grubbs and his collaborators. This process converts dienynes to fused bicyclic conjugated dienes. Finally, a novel photo-electrocyclization reaction of pyridinium salts, which leads to the formation of 4-aminocyclopenten-3,5-diol derivatives, is discussed. Examples are provided to show the utility of these methodologies in natural product synthesis. Emphasis is given to studies in which pyridinium salt photochemistry is coupled with ring rearrangement and dienyne metathesis in routes for the synthesis of polyhydroxyalted indolizidine alkaloids and the construction of the tricyclic core of the lepadiformine and cylindricine alkaloids.

• Journal of the Korean Chemical Society
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• v.37 no.11
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• pp.967-973
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• 1993

${\alpha},{\omega}$-Diols such as 1,6-hexanediol and 1,7-heptanediol react with secondary amines in the presence of catalytic amount of ruthenium complex at 180$^{\circ}$C for 24 hrs to give the corresponding diamino compounds in good yields. The yield of diamino compound was affected by the molar ratio of ${\alpha},{\omega}$-diol to secondary amine. The reaction was also affected by the nature of the phosphorus ligands employed. On the other hand, aromatic primary amines react with 1,2,6-hexanetriol in the presence of RuCl_3{\cdot}H_2O-3PPh_3$ at 180$^{\circ}$C for 3 hours under argon atmosphere to give selectively 1-substituted aryl-3-hydroxyperhydroazepines in good yields. Selective synthesis of these products show that two primary hydroxy groups (1,6-positions) oxidize predominantly than secondary hydroxy group (2-position) by ruthenium-phosphorus complex. The yields were decreased according to the order of para-, meta- and ortho-substituent.

• Journal of the Korean Society of Clothing and Textiles
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• v.10 no.3
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• pp.71-81
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• 1986

In order to control the formaldehyde release from D.P. finished fabric, cotton fabric was padded in DMDHEU resin bath containing either $Zn(NO_3)_2$ or $MgCl_2$ catalyst and a form-aldehyde scavenger like Glycerol, Sorbitol, Formamide, Polyvinyl alcohol (PVA, n= 2000) or diols, then dried and cured. The results are as follows : 1. When Lewis acid catalyst like $Zn(NO_3)_2$ or $MgCl_2$ was added in pad bath, the fabric finished with $Zn(NO_3)_2$ catalyst released the lower formaldehyde than with $MgCl_2$. 2. When the effect of pad bath pH was examined with varying the kinds of catalyst and the scavenger, it was found that the pad bath pH influenced on the amount of formaldehyde release and the optimum pad bath pH is at 4.3. Especially, in case of finishing at pad bath pH 4.3 with adding Formamide, the amount of formaldehyde release was decreased by about $45\~$35\%$ with $Zn(NO_3)_2$, while by about $20\~$45\%$ with $MgCl_2$ catalyst. In case of varying the concentration of a scavenger (Formamide), $1\%$ concentration of a scavenger was found to be the optimum level ana the higher the curing temperature up to $180^{\circ}C$, the lesser the amount of formaldehyde release were observed. 3. When the diol was used as scavenger, the amount of formaldehyde release was decreased by about $40\~$50\%$, but the longer the intramolecular length between OH groups, the lessor the amount of decrease of formaldehyde release were observed. 4. When the mixture of scavengers (Formamide and Glycerol) was added in the pad bath, .synergistic effect on formaldehyde release between the two scavengers wasn't observed. 5. The tensile strength of the resin finished fabric was reduced with increasing the pad lath pH and was influenced by the kind of scavengers, and the tensile strength was severely reduced when scavengers, especially Formamide, was added. The wrinkle recovery property is generally improved by resin finish on cotton fabric. When Formamide was added, the wrinkle recovery property is slightly decreased compared with that of the fabrics resin finished without a scavenger, and when polyol was added, the wrinkle recovery property showed almost no change.

• Korean Journal of Food Science and Technology
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• v.13 no.1
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• pp.57-66
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• 1981

An effective method for isolation of the major components of ginseng saponin such as $ginsenoside-Rb_{1},\;-Rb_2,$ -Rc, -Rd, -Re and $-Rg_1$, and the minor components such as ginsenoside-Rf, $-Rg_2,\;and-Rh_1$, was developed and reported in previous papers (J. Korean Agr. Chem. Soc., 23(4), 199 and 206(1980) The conditions and procedures used for isolation and identification for ginsenosides described in the previous papers were not sufficient enough for clean separation of minor components, $ginsenoside-Rh_1,\;and-Rh_2$. In this work, modifications in extraction method and in mobile phase for HPLC were attempted. It was found that application of ethyl acetate extraction at $60^{\circ}C$ for 3 hr on crude saponin resulted in a removal of diol group saponin from crude saponin which made it possible for using higher portion of acetonitrile in mobile phase. The mixed solvents of acetonitrile : water (92 : 8 and 94 : 6) gave excellent resolution of $ginsenoside-Rh_1\;and\;-Rh_2$.

• Korean Journal of Food Science and Technology
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• v.21 no.4
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• pp.480-485
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• 1989

Changes of color intensity and components during browning reaction of water extracts from white tail ginseng were investigated. Temperature dependence was described by the Arrhenius relationship with an activation energy of 16kcal/mole. Temperature sensitivities$(Q_{10}\;value)$ for water extracts of ginseng was 1.90 between $70^{\circ}C\;and\;80^{\circ}C$, 1.57 between $80^{\circ}C\;and\;90^{\circ}C$ and 1.46 between $90^{\circ}C\;and\;100^{\circ}C$. pH value of the solution treated at $90^{\circ}C\;and\;100^{\circ}C$ slightly increased with an increase in reaction time. Among ginseng saponins ginsenoside-Re was most unstable against heat-treatment, white diol group saponins were more stable against heat-treatment. Hydrogen donating activity (reducing activity for ${\alpha},\;{\alpha}'-diphenyl-{\beta}-picrylhydrazyl$) and 3,5-dinitrosalicylic acid(DNS) positive substances of browning reaction products increased in proportion to the length of browning reaction time and temperature, whereas folin positive substances decreased by heat-denaturation of ginseng protein at initial reaction time and then increased thereafter.

• Korean Journal of Food Science and Technology
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• v.39 no.6
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• pp.593-599
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• 2007

In this study, we examined the volatile flavor components in the mashes of takju prepared using different yeasts such as Saccharomyces coreanus, S. ellipsoideus, S. carlsbergensis, S. cerevisiae (Baker's yeast), and S, rouxii by GC and GC-MS. Fourteen alcohols, 13 esters, 5 acids, 3 aldehydes, 7 amines, and 2 other compounds were identified in the mash after 6 days of fermentation. On day 6, the takju fermented by S. coreanus had the greatest variety of volatile flavor components. Fifteen flavor components, including ethanol, isobutyl alcohol, isoamyl alcohol, methyl pentanol, 1,3-butanediol, 3-methylthio-1-propanol, benzeneethanol, ethyl lactate, acetic acid, acetaldehyde, and 1,3-cyclohexane diamine, were typically detected in all the treatments. The relative peak areas of the volatile components were as follows: alcohols (96.758-99.387%), esters (0.081-0.968%), acids (0.040-0.640%), aldehydes (0.266-0.959%), and amines (0.011-0.047%). In particular, 1-propanol, isobutyl alcohol, 3-methyl-1-butanol, 2,3-butanediol, trimethyl benzylalcohol, heptene-2,4-diol, ethyl lactate, diethyl succinate, ethyl nonanoate, methyl hexadecanoate, linoleic acid, hexadecanoic acid, and acetaldehyde were hish in the takju made by S. coreanus. Also, ethyl stearate was high in the takju made by S. carlsbergensis, and hexanoic acid was high in the takju made by S. cerevisiae. Finally, methyl pentanol, 1,3-butanediol, 3-methylthio-1-propanol, benzene ethanol, ethyl octadecanoate, acetic acid, pentanal, and 1,3-cyclohexane diamine were high in the takju made by S. rouxii.

• Applied Chemistry for Engineering
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• v.9 no.4
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• pp.491-496
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• 1998

The composition of isocyanates and polyols influence prepolymeric properties of adhesive and calking sealant based on polyurethanes (PU). One component moisture curing prepolymers, which reacted with surface humidity of substrate, were synthesized in several kinds of composition. Reactivity, structural change and properties of the prepolymers were studied as a preliminary step to manufacture PU based adhesive and sealant. To study the effects of mole ratio ([NCO]/[OH]), we used toluene diisocyanate (TDI), 4, 4'-diphenylmethane diisocyanate (MDI), and ether-polyols such as PTMG and PPG which have good resistance to hydrolysis and excellent low-temperature properties. The each prepolymers could be prepared in different molecular weight without any significant structural change. The mole ratio 1.78 of [NCO] to [OH] showed the fastest reactivity. It was confirmed that effect of polyols was larger than that of isocyanates on the prepolymer in reactivity. Several kinds of compounds were manufactured with each prepolymer, and tensile and properties were tested. And the optimum quantity of curing accelerator for the PU was 0.05~0.1%. In the tensile test, TDI based PU was superior to MDI based PU, and also PTMG based PU was superior PPG based PU.