• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.87-94
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• 1992

The elution behavior of polystyrenes(PS), polymethylmethacrylates (PMMA), polybutadienes(PB), PS-PMMA(SM) block copolymers and PS-PB star shaped copolymers on the cross-linked polystyrene gels was studied. An interpretation was proposed for the plots of log hydrodynamic volume versus retention volume of solutes in the mobile phases such as tetrahydrofuran, toluene, chloroform, methylene chloride and tetrahydrofuran-cyclohexane mixture. In order to predict the retention of solutes from their physical properties, multiple stepwise regression analysis was applied to obtain the correlation. The distribution coefficients($K_p$) of solute-gel interactions in GPC for homopolymers and PS copolymers were also obtained in terms of network-limited separation mechanism. In the cases of PS and PB, $K_p$ values approach unity, while $K_p$ values for PMMA decrease as MW increase in the good solvent, but in poor solvent, $K_p$ values increase as MW increase. $K_p$ values of PS copolymers are dependent on their MW and composition, therefore, morohology of SM block copolymer is predicted to be random phase. A single universal plot of log[η]M vs. $(V_r-V_o)/K_p$

• Journal of Food Hygiene and Safety
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• v.36 no.1
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• pp.1-8
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• 2021

The inverted Y-shaped strip detection method based on acetylcholinesterase (AChE) was developed for the rapid detection of organophosphorus and carbamate pesticides. The inactivation of AChE by organophosphorus and carbamate pesticides has been well known. The AChE catalyzes acetylthiocholine into thiocholine having (-) and (+) charges, and the (+) charge results in aggregation of gold nanoparticle (GNP). Malaoxon and carbofuran were used as standard organophosphorus and carbamate for the development of the inverted Y-shaped strip, respectively. In order to optimize the method, various angles of the Y-shaped strip, different types of nitrocellulose membrane, and concentration of AChE were tested as key parameters. The detection limit of the method was 10 ng/mL for both malaoxon and carbofuran pesticides. No cross-reaction was observed to other pesticides such as atrazine, cyanazine, simazine, bifenthrin, boscalid, metalaxyl, and chlorobenzilate. Recoveries from lettuce spiked when known concentrations of malaoxon and carbofuran were found ranging from 96.4 to 100.7% and 81 to 112.7%, respectively. This study suggests that the inverted Y-shaped strip method based on AChE may be a useful tool for the sensitive, specific, rapid detection of organophosphorus and carbamate pesticides in agricultural products.

• Journal of Food Hygiene and Safety
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• v.36 no.3
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• pp.213-219
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• 2021

Hazardous substances are formed during food manufacturing, processing, or cooking, and may pose a threat to food safety. Here, we present a dietary exposure assessment of Korean consumer's intake of hazardous materials through a Total Diet Study (TDS) which was conducted by the Ministry of Food and Drug Safety (MFDS). The levels of exposure to materials such as acrylamide, furan, biogenic amines, etc., were estimated and risk assessments were then performed. Acrylamide and furan were selected as hazards with high priority of reduction control due to their having a margin of exposure (MOE) lower than 10,000. Risk assessment of exposure to ethyl carbamate, benzene and 3-MCPD showed MOEs higher than 100,000, indicating "safe". Dietary exposure to polycyclic aromatic hydrocarbons and benzopyrene was also found to be safe MOE levels >10,000. In addition, the results indicated safe MOEs (>1,000,000) for heterocyclic amines, nitrosamines, and biogenic amines. Most of the potential food contaminants were being kept at safe levels, however, it is necessary to continue to monitor and control exposure levels in accordance with the 'as low as reasonably achievable' (ALARA) principle.

• Journal of the Korean Chemical Society
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• v.47 no.4
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• pp.354-362
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• 2003

A strategy for synthesis of the furan-fused tetracyclic system of xestoquinone was explored through a model study. Using 3-butyn-1-ol as a starting material, 5-iodo-1-methoxymethoxy pentyne (5) was prepared in 5 steps. Reaction of ethyl 2-phenylpropanoate with 5 gave ethyl 7-methoxymethoxy-2-methyl-2-phenyl-5-heptynoate (6) in 88% yield, and then methyl 9-oxo-4-methyl-4-phenyl-2,7-nonadiynoate (13), the key intermediate, was synthesized in 6 steps from the ester 6. Intramolecular cycloaddition reaction of 13 afforded isobenzofuran 14 in 5% yield, which was converted to the tetracyclic structure 15 in the presence of Lewis acid.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.10-15
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• 2016

In this new energy economy era, the importance of renewable energy resource needs to be highly addressed, as the demand of energy dramatically increases and fossil fuel is being exhausted. Lignocellulosic biomass is considered as the sustainable and renewable feedstock to produce biochemicals and biofuels that are the alternative for petroleum derived products. Furfural is a natural precursor for the range of furan based chemicals and solvents such as methylfuran, tetrahydrofuran, methyltetrahydrofuran, ethyltetrahydrofuryl ether, ethyl levulinate, levulinic acid, and alkanes. Thus, furfural should be a renewable platform chemical for biochemicals and renewable biofuels. In this paper, the concept of biorefinery, furfural production and its applications are briefly reviewed.

• Analytical Science and Technology
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• v.5 no.1
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• pp.33-39
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• 1992

THF-based crown-4 of 16-membered rings having tetrahydrofuran unit was synthesized by an acid-catalyzed condensation of furan and acetone followed by hydrogenation in an effort to obtain highly elective ionophores for lithium ions. The new ionophore was compared with previously reported ionophores under similar measurement conditions with the same plasticizer, tris(2-ethylhexyl) phosphate in poly(vinyl chloride)(PVC) membrane electrodes. Separate solution method was used to determine relative selectivity coefficients for the electrode. The selectivity coefficients($K_{LiM}^{POT}$) of lithium over ammonium, alkali and alkaline earth metal ions go from about $2.4{\times}10^{-1}$ to $2.3{\times}10^{-4}$ to working range and pH dependence have also been studied.

• Journal of Environmental Science International
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• v.13 no.4
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• pp.435-440
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• 2004

The thiophene or furan-containing hexadentate ligands 1, 12-bis (2-theophene )-2,5,8,ll-tetraazadodecane(Thiotrien ㆍ 4HCl) and 1,12-bis (2-furan)-2,5,8,11-tetraazadodecane(Furatrienㆍ4HC1) were synthesized as their tetrahydrochloride salt and characterized by EA, IR, NMR, and Mass spectrum. Their protonation constants (logK$_{nH}$) and stability constants (logK$^{M}_{L}$ for Cd$^{2+}$, Pb$^{2+}$, $Zn^{2+}$ and Cu$^{2+}$ ions were determined in aqueous solution by potentiometry and compared with 1, 12-bis(2-pyridyl)-2,5,8, 11-tetra-azadodecane(Pytrien) of pyridyl-containing ligand. The effect stability constants of ligands and metal ion for removal of heavy metals in aqueous solution were described.

• Journal of the Korean Chemical Society
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• v.9 no.2
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• pp.88-95
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• 1965

The exo adduct between furfuryl derivatives (furan, furfuryl acetate and furfuryl alcohol) and maleic anhydride were prepared in the presence of ethyl ether. The bromination of the exo adduct of each derivatives gave a monobromolactone and dibromoacid when the reaction was done in the presence of water. The formation of the bromolactone was proved to be dependent to the carboxylic participation to the incipient rearranged carbonium ion of a classical type, and the participation was sterically hindered by the steric structure of the substituents. The bromination of the furan-maleic anhydride adduct in the presence of organic solvent $(CCl_4,\;CH_2Cl_2)$ gave the dibromide, whereas the photochlorination of the same adduct in the presence of carbon tetrachloride gave the tetrachloride. The procedure of the preparation and the reaction path of the halogenation were described.

• Journal of the Korean Chemical Society
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• v.23 no.6
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• pp.339-348
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• 1979

The kinetics of the solvolysis of 2-furoyl chloride and 2-thenoyl chloride in $MeOH-H_2O,\;EtOH-H_2O,\;(Me)_2CO-H_2O,\;MeCN-H_2O$ and MeCN-MeOH has been investigated. The rates were faster in protic solvents than in aprotic solvents. This was caused by the bond breaking of leaving group through hydrogen-bonding solvation of protic solvents. In MeCN-M$\'{e}$OH the rate in MeOH rich solvents was faster than in MeCN rich solvents by the specific solvation of alcoholic hydrogen and there was a maximum rate of reaction at MeOH mole fraction of 0.8. The reaction rates of solvolysis were considerably slower than those of benzoyl chloride owing to the electron withdrawing effect of thienyl and furyl groups. It was concluded that solvolytic reaction proceeds via a dissociative $S_N2$ mechanism in which bond-breaking precedes bond-formation at the transition state.

• Journal of the Korean Chemical Society
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• v.24 no.5
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• pp.371-379
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• 1980

The spectral properties of the solvated electrons in tetrahydrofuran(THF)-water binary system have been investigated. In this study, the solvated electrons have been produced by applying nsec Q-switch Nd(YAG) laser photolysis technique. The experimental method photolysis were schematically described. The solvent and the temperature effects on the absorption spectrum of solvated electrons have also been studied. The observation of the spectrum with increasing THF content and temperatue showed a trend that the former shifted to longer wavelength and the other showed broadening effect. The half-life of solvated electrons were also increased with THF content. The absorption maxima of the mixtures were always observed in the middle of that of pure water and THF. The correlation between the volume and the absorption energy of solvated electrons were discussed from the results.