• Journal of the Korean Applied Science and Technology
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• v.3 no.2
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• pp.41-47
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• 1986

The transesterification reaction between diethanolamine and methyl-methacrylate was kinetically investigated in the presence of various metal acetate catalysts at $120^{\circ}C$. The quantity of methylmethacrylate reacted in the reaction flask was measured by gas chromatography and liquid chromatography, and the reaction rate was investigated by measuring of the quantity of products and reactnts under various catalysts. The transesterification reaction was carried out in the first order reaction kinetics with respect to the concentration of diethanolamine and methylmethacrylate, respectively. The apparent rate constant was found to obey first-order kinetics with respect to the concentration of catalyst. The linear relationship was shown between apparent rate constant and reciprocal absolute temperature, and by the Arrhenius plot, the activation energy has been calculated as 11.08 Kcal with zinc acetate catalyst, 17.99 Kcal without catalyst. The maximum reaction rate was appeared at the range of 1.4 to 1.6 of electronegativity of metal ions and instability constant of metal acetates.

• Journal of Aquaculture
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• v.12 no.1
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• pp.63-69
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• 1999

A series of experiments were conducted to examine on what stimulus giant danio (Danio malabaricus) were mainly responsible for detecting alarm substance. When 0.15 ml alarm substance (10 ppm) was introduced into the tank, fish showed no notable change in swimming pattern. However, the introduction of 1.5 ml alarm substance (100 ppm) could induce fright reaction about in 6 minutes. Further, when 15 ml alarm substance (1,000 ppm) was introduced into the tank, fish showed the following fright reaction in a few seconds; suppressing to feed diet, no swimming, strong chasing, and visual alertness. In detecting alarm substance, fish were mainly depending on the chemical stimulus (nares) rather than the vision stimulus (eyes) because fish detected alarm substance by the chemical cue showed the significantly stronger fright reaction than by the visual cue. The time for fish to show the initial fright reaction after detecting alarm substance by the chemical cue was shorter than by the visual cue. Also after alarm substance was introduced into the tank, olfaction-deprived fish showed significantly weaker fright reaction and less frequency of chasing than the normal fish which detected alarm substance by both olfaction and gustation stimulus. These results indicated that chemical stimulus, especially olfaction might be the primary sensory modality used in the detection of the alarm substance for giant danio.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1934-1938
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• 2012

The reaction mechanism between cyclopropenylidene and formaldehyde has been systematically investigated employing the MP2/6-311+$G^*$ level of theory to better understand the cyclopropenylidene reactivity with carbonyl compound. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. Energies of all the species are further corrected by the CCSD(T)/6-311+$G^*$ single-point calculations. It was found that one important reaction intermediate (INTa) has been located firstly $via$ a transition state (TSa). After that, the common intermediate (INTb) for the two pathways (1) and (2) has been formed $via$ TSb. At last, two different products possessing three- and four-membered ring characters have been obtained through two possible reaction pathways. In the reaction pathway (1), a three-membered ring alkyne compound has been obtained. As for the reaction pathway (2), it is the formation of the four-membered ring conjugated diene compound. The energy barrier of the ratedetermining step of pathway (1) is lower than that of the pathway (2), and the ultima product of pathway (2) is more stable than that of the pathway (1).

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.744-748
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• 2010

2,3,4,5-Tetrafluorobenzoic acid, an important intermediates of fluoroquinolone antibiotics, was synthesized from tetrachloride phthalic anhydride through imidation, fluorination, hydrolysis and decarboxylation. The effects of phase transfer catalyst on imidation and fluorination reaction and the effects of surfactants on the hydrolysis reaction were studied, respectively. Experimental results showed that the imidation reaction time was greatly reduced in the presence of a phase transfer catalyst, hexadecyltrimethyl, resulting in imidation yield as high as 98.2%. The fluorination yield reached 81.3% when tetrabutylammonium bromide was chosen as a phase transfer catalyst. The hydrolysis reaction time was also decreased by adding hexadecyltrimethyl while increasing the yield to 88.6%. In the post-processing, the sublimation method was used to purify the product, and ideal effect was obtained. In the decarboxylation reaction, tetrafluoride phthalic acid was obtained by decarboxylation in the solvent of tri-n-butyl amine and decarboxylation yield reached 81.6%. Compared with the literature method, the overall reaction time of the improved method decreased from 53 h to 20.5 h and the total yield increased from 47.3% to 57.4%.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.875-879
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• 2008

A method for the depolymerization of polycarbonate waste by glycolysis using ethylene glycol without catalyst was explored in order to get the monomer bisphenol A (BPA). The effect of operation variables such as reaction time, reaction temperature, EG/PC weight ratio and the kinetic of glycolysis were studied. It was found that the polymerization reaction has two different activation energies depending on the reaction temperature. A drop in activation energy with temperature indicates that the reaction mechanism has shifted from one of a succession of elementary steps to another in the series. The maximum yield of BPA of 95.6% was achieved at reaction temperature $220^{\circ}C$ for 85min with EG/PC weight ratio 4.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.204-208
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• 2012

A novel chemiluminescence (CL) flow injection method for the determination of balofloxacin is described. The method is based on the weak CL signal arising from the reaction of $KBrO_3$ with $Na_2S_2O_4$ in acidic medium being significantly enhanced by balofloxacin in the presence of europium (III) ion and sodium dodecyl benzene sulfonate (SDBS). The experimental conditions that affected CL intensity were carefully optimized and the CL reaction mechanism was briefly discussed. Under the optimum conditions, the relative CL intensity was proportional to the concentration of balofloxacin in the range of $7.0{\times}10^{-11}$ to $3.0{\times}10^{-7}g\;mL^{-1}$. The detection limit was $2.7{\times}10^{-11}g\;mL^{-1}$ and the relative standard deviation was 2.1% for $7.0{\times}10^{-10}g\;mL^{-1}$ balofloxacin (n = 13). The proposed method was successfully applied to the determination of balofloxacin in pharmaceutical formulations and biological fluids.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1898-1904
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• 2008

Study of computational model of the concerted Diels-Alder reaction between 9,10-dimethyl anthracene (as donor) and tetracyanoethylene (as acceptor) in absence and in presence of aromatic solvents (benzene, mesitylene and hexamethylbenzene, as donors) using an AM1 semi-empirical method. AM1 method used to study the neutral charge transfer complex models that could be expected between donor and acceptor during the course of the concerted Diels-Alder reaction. Calculated enthalpies of reaction of the charge transfer complexes models showed physical and chemical meaning for explain the effect of aromatic solvents on the kinetic process of concerted Diels-Alder reaction that contains tetracyanoethylene.

• Journal of the Korean institute of surface engineering
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• v.38 no.3
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• pp.112-117
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• 2005

In this paper, CdS thin films, which were widely used as a window layer of the CdS/CdTe and the $CdS/CuInSe_2$heterojunction solar cell, were grown by chemical bath deposition, and the structural, optical and electrical properties of the films on reaction temperatures were investigated. Cadmium acetate and thiourea were used as cadmium and sulfur source, respectively. And Ammonium acetate was used as the buffer solution. As the reaction temperatures were increased, the deposition rate of CdS fllms prepared by CBD was increased and the grain size was large due to increasing reaction rate in solution, also optical transmittance of the films in visible lights was increased on rising reaction temperatures.

• Journal of the Korean Applied Science and Technology
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• v.4 no.1
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• pp.67-71
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• 1987

The transesterification reaction between diethanolamine and methyl methacrylate was kinetically investigated in the presence of various metal acetate catalysts at $120^{\circ}C$. The amount of reacted methyl methacrylate was measured by gas chromatography and liquid chromatography, and the reaction rate also measured from the amount of reaction products and reactants under each catalyst. The transesterification reaction was carried out in the first order with respect to the concentration of diethanolamine and methyl methacrylate, respectively. The over-all order is 2nd. The apparent rate constant was found to obey first-order kinetics with respect to the concentration of catalyst. The maximum reaction rate was appeared at the range of 1.4 to 1.6 of electronegativity of metal ions and instability constant of metal acetates.

• Bulletin of the Korean Chemical Society
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• v.23 no.9
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• pp.1272-1287
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• 2002

Sonochemical Reformatsky reaction of aldehydes or ketones with ethyl bromoacetate in the presence of indium afforded $\beta-hydroxyesters$ in good to excellent yields under mild conditions. 2- or 3-Hydroxybenzaldehyde that contains an acidic hydrogen r eacted with ethyl bromoacetate to provide the desired compounds with the same efficiency. In the case of ethyl 2-bromopropanoate and ethyl 2-bromo-2-methylpropanoate, the desired products were obtained in good yields. Reaction of aldehyde with indium reagent in the presence of ketone group proceeded chemoselectively.